Статті в журналах: "Phantom arteries"

1

Roldan, Maria, and Panicos A. Kyriacou. "Head Phantom for the Acquisition of Pulsatile Optical Signals for Traumatic Brain Injury Monitoring." Photonics 10, no. 5 (April 26, 2023): 504. http://dx.doi.org/10.3390/photonics10050504.

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(1) Background: Tissue phantoms can provide a rigorous, reproducible and convenient approach to evaluating an optical sensor’s performance. The development, characterisation and evaluation of a vascular head/brain phantom is described in this study. (2) Methods: The methodology includes the development of mould-cast and 3D-printed anatomical models of the brain and the skull and a custom-made in vitro blood circulatory system used to emulate haemodynamic changes in the brain. The optical properties of the developed phantom were compared to literature values. Artificial cerebrospinal fluid was also incorporated to induce changes in intracranial pressure. (3) Results: A novel head model was successfully developed to mimic the brain and skull anatomies and their optical properties within the near-infrared range (660–900 nm). The circulatory system developed mimicked normal arterial blood pressure values, with a mean systole of 118 ± 8.5 mmHg and diastole of 70 ± 8.5 mmHg. Similarly, the cerebrospinal fluid circulation allowed controlled intracranial pressure changes from 5 to 30 mmHg. Multiwavelength pulsatile optical signals (photoplethysmograms (PPGs)) from the phantom’s cerebral arteries were successfully acquired. Conclusions: This unique head phantom technology forms the basis of a novel research tool for investigating the relationship between cerebral pulsatile optical signals and changes in intracranial pressure and brain haemodynamics.

2

Yang, Ke, Peter R. Hoskins, George A. Corner, Chunming Xia, and Zhihong Huang. "Wall Shear Stress Measurement in Carotid Artery Phantoms with Variation in Degree of Stenosis Using Plane Wave Vector Doppler." Applied Sciences 13, no. 1 (January 2, 2023): 617. http://dx.doi.org/10.3390/app13010617.

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Wall shear stress (WSS) plays an important role in the formation, growth, and rupture of atherosclerotic plaques in arteries. This study measured WSS in diseased carotid artery phantoms with degrees of stenosis varying from 0 to 60% with both steady and pulsatile flow. Experiments were performed using in silico and real flow phantoms. Blood velocities were estimated using plane wave (PW) vector Doppler. Wall shear stress was then estimated from the velocity gradient near the wall multiplied by the viscosity of a blood-mimicking fluid. The estimated WSS using the in silico phantom agreed within 10% of the ground-truth values (root-mean-square error). The phantom experiment showed that the mean WSS and maximum WSS increased with the increasing degree of stenosis. The simulation and experiment results provide the necessary validation data to give confidence in WSS measurements in patients using the PW vector Doppler technique.

3

Chamaani, Somayyeh, Jürgen Sachs, Alexandra Prokhorova, Carsten Smeenk, Tim Erich Wegner, and Marko Helbig. "Microwave Angiography by Ultra-Wideband Sounding: A Preliminary Investigation." Diagnostics 13, no. 18 (September 14, 2023): 2950. http://dx.doi.org/10.3390/diagnostics13182950.

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Angiography is a very informative method for physicians such as cardiologists, neurologists and neuroscientists. The current modalities experience some shortages, e.g., ultrasound is very operator dependent. The computerized tomography (CT) and magnetic resonance (MR) angiography are very expensive and near infrared spectroscopy cannot capture the deep arteries. Microwave technology has the potential to address some of these issues while compromising between operator dependency, cost, speed, penetration depth and resolution. This paper studies the feasibility of microwave signals for monitoring of arteries. To this aim, a homogenous phantom mimicking body tissue is built. Four elastic tubes simulate arteries and a mechanical system creates pulsations in these arteries. A multiple input multiple output (MIMO) array of ultra-wideband (UWB) transmitters and receivers illuminates the phantom and captures the reflected signals over the desired observation time period. Since we are only interested in the imaging of dynamic parts, i.e., arteries, the static clutters can be suppressed easily by background subtraction method. To obtain a fast image of arteries, which are pulsating with the heartbeat rate, we calculate the Fourier transform of each channel of the MIMO system over the observation time and apply delay and sum (DAS) beamforming method on the heartbeat rate aligned spectral component. The results show that the lateral and longitudinal images and motion mode (M-mode) time series of different points of phantom have the potential to be used for diagnosis.

4

Ngaile, Justin E., Peter K. Msaki, Evarist M. Kahuluda, Furaha M. Chuma, Jerome M. Mwimanzi, and Ahmed M. Jusabani. "Effect of Lowering Tube Potential and Increase Iodine Concentration of Contrast Medium on Radiation Dose and Image Quality in Computed Tomography Pulmonary Angiography Procedure: A Phantom Study." Tanzania Journal of Science 47, no. 3 (August 15, 2021): 1211–24. http://dx.doi.org/10.4314/tjs.v47i3.29.

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The aim of the study was to examine the effect of lowering tube potential and increase iodine concentration on image quality and radiation dose in computed tomography pulmonary angiography procedure. The pulmonary arteries were simulated by three syringes. The syringes were filled with 1:10 diluted solutions of 300 mg, 350 mg and 370 mg of iodine per millilitre concentration in three water-filled phantoms simulating thin, intermediate and thick patients. The phantoms were scanned at 80 kVp, 110 kVp and 130 kVp and 0.6 second rotation time using a 16 slice computed tomography (CT) scanner. The tube current was either fixed at 80, 100, 200, 250 and 300 mA or automatically adjusted with quality reference tube current-time product (mAsQR). In comparison with 130 kVp, images acquired at 80 kVp and 110 kVp, respectively, showed 76.2% to 99% and 19% to 26% enhancement in CT attenuation of iodinated contrast material. A volume CT dose index (CTDIvol) reduction by 35.3% was attained in small phantom with the use of 80 kVp, while in the medium phantom, a CTDIvol reduction by 29.9% was attained with the use of 110 kVp instead of 130 kVp. In light of the above, lowering tube potential and increase iodinated CM could substantially reduce the dose to small-sized adults and children. Keywords: Angiography; Computed tomography; Low tube potential; Iodinated contrast medium; Radiation dose

5

Cooper, Benjamin Z., Jon D. Kirwin, Thomas F. Panetta, F. Michele Weinreb, Jose A. Ramirez, John G. Najjar, Seth B. Blattman, William Rodino, and Mark Song. "Accuracy of Intravascular Ultrasound for Diameter Measurement of Phantom Arteries." Journal of Surgical Research 100, no. 1 (September 2001): 99–105. http://dx.doi.org/10.1006/jsre.2001.6214.

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6

Johnson, Jami L., Kasper van Wijk, and Michelle Sabick. "Characterizing Phantom Arteries with Multi-channel Laser Ultrasonics and Photo-acoustics." Ultrasound in Medicine & Biology 40, no. 3 (March 2014): 513–20. http://dx.doi.org/10.1016/j.ultrasmedbio.2013.10.011.

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7

Mai, Jerome J., Fermin A. Lupotti, and Michael F. Insana. "Vascular Elasticity from Regional Displacement Estimates." Ultrasonic Imaging 25, no. 3 (July 2003): 171–92. http://dx.doi.org/10.1177/016173460302500305.

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A recently-developed ultrasonic technique for measuring elastic properties of vascular tissue is evaluated using computer simulations, phantom and in vivo human measurements. A time sequence of displacement images is measured over the cardiac cycle to describe the spatial and temporal patterns of deformation surrounding arteries. This information is combined with a mathematical model to estimate an elastic modulus. Computer simulations of ultrasonic echo data from deformed tissues are analyzed to define a signal processing approach. Measurements in flow phantoms, with and without vessel-simulating channel walls, provide an assessment of the accuracy and precision of this technique for vascular elasticity measurements. Finally, preliminary results for the stiffness index (β) in a study group of healthy human volunteers are compared with previously reported data. We find that careful measurement technique is required to control measurement variability.

8

Udekwe, Charles Nnamdi, and Akinlolu Adeniran Ponnle. "Application of Cardinal Points Symmetry Landmarks Distribution Model to B-Mode Ultrasound Images of Transverse Cross-section of Thin-walled Phantom Carotid Arteries." European Journal of Engineering Research and Science 4, no. 12 (December 19, 2019): 96–101. http://dx.doi.org/10.24018/ejers.2019.4.12.1656.

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We had earlier developed a technique based on cardinal point symmetry landmark distribution model (CPS-LDM) to completely characterize the Region of Interest (ROI) of the geometric shape of thick-walled simulated B-mode ultrasound images of carotid artery imaged in the transverse plane. In this paper, this developed technique was applied to completely characterize the region of interest of the geometric shape of B-mode ultrasound images of thin-walled phantom carotid artery imaged in the transverse plane. The developed model employs a combination of fixed landmarks (FLs) and movable landmarks (MLs) to obtain the total landmarks (TLs) that can sufficiently segment the shape of the ROI of the carotid artery. For the phantom carotid arteries, three FLs are fixed on each of the four ROIs determined by the cardinal points North (N), South (S), East (E) and West (W) drawn on the ROIs of the phantom carotid artery. The MLs are determined by the inter-cardinal directions such as North-East (NE), North-West (NW) and so on. The obtained CPS-LDM equation developed allows graphical visualization the optimum number of points that can sufficiently segment the ROIs. ImageJ2 software was used to generate the Cartesian coordinates for each landmark which were then used to generate the Shape Space Pattern (SSP) of the phantom carotid artery ready for further statistical analysis. The results showed that the CPS-LD model is generic and adaptable to a variety of transverse cross-sectional B-mode ultrasound images of thin-walled phantom carotid artery

9

Udekwe, Charles Nnamdi, and Akinlolu Adeniran Ponnle. "Application of Cardinal Points Symmetry Landmarks Distribution Model to B-Mode Ultrasound Images of Transverse Cross-section of Thin-walled Phantom Carotid Arteries." European Journal of Engineering and Technology Research 4, no. 12 (December 19, 2019): 96–101. http://dx.doi.org/10.24018/ejeng.2019.4.12.1656.

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We had earlier developed a technique based on cardinal point symmetry landmark distribution model (CPS-LDM) to completely characterize the Region of Interest (ROI) of the geometric shape of thick-walled simulated B-mode ultrasound images of carotid artery imaged in the transverse plane. In this paper, this developed technique was applied to completely characterize the region of interest of the geometric shape of B-mode ultrasound images of thin-walled phantom carotid artery imaged in the transverse plane. The developed model employs a combination of fixed landmarks (FLs) and movable landmarks (MLs) to obtain the total landmarks (TLs) that can sufficiently segment the shape of the ROI of the carotid artery. For the phantom carotid arteries, three FLs are fixed on each of the four ROIs determined by the cardinal points North (N), South (S), East (E) and West (W) drawn on the ROIs of the phantom carotid artery. The MLs are determined by the inter-cardinal directions such as North-East (NE), North-West (NW) and so on. The obtained CPS-LDM equation developed allows graphical visualization the optimum number of points that can sufficiently segment the ROIs. ImageJ2 software was used to generate the Cartesian coordinates for each landmark which were then used to generate the Shape Space Pattern (SSP) of the phantom carotid artery ready for further statistical analysis. The results showed that the CPS-LD model is generic and adaptable to a variety of transverse cross-sectional B-mode ultrasound images of thin-walled phantom carotid artery

10

Cha, Hyo-Jeong, Byung-Ju Yi, and Jong Yun Won. "An assembly-type master–slave catheter and guidewire driving system for vascular intervention." Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine 231, no. 1 (December 22, 2016): 69–79. http://dx.doi.org/10.1177/0954411916679328.

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Current vascular intervention inevitably exposes a large amount of X-ray to both an operator and a patient during the procedure. The purpose of this study is to propose a new catheter driving system which assists the operator in aspects of less X-ray exposure and convenient user interface. For this, an assembly-type 4-degree-of-freedom master–slave system was designed and tested to verify the efficiency. First, current vascular intervention procedures are analyzed to develop a new robotic procedure that enables us to use conventional vascular intervention devices such as catheter and guidewire which are commercially available in the market. Some parts of the slave robot which contact the devices were designed to be easily assembled and dissembled from the main body of the slave robot for sterilization. A master robot is compactly designed to conduct insertion and rotational motion and is able to switch from the guidewire driving mode to the catheter driving mode or vice versa. A phantom resembling the human arteries was developed, and the master–slave robotic system is tested using the phantom. The contact force of the guidewire tip according to the shape of the arteries is measured and reflected to the user through the master robot during the phantom experiment. This system can drastically reduce radiation exposure by replacing human effort by a robotic system for high radiation exposure procedures. Also, benefits of the proposed robot system are low cost by employing currently available devices and easy human interface.

11

Song, Ilseob, Jongmin Yoon, Jinbum Kang, Min Kim, Won Seuk Jang, Na-Young Shin, and Yangmo Yoo. "Design and Implementation of a New Wireless Carotid Neckband Doppler System with Wearable Ultrasound Sensors: Preliminary Results." Applied Sciences 9, no. 11 (May 29, 2019): 2202. http://dx.doi.org/10.3390/app9112202.

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Noninvasive monitoring of blood flow in the carotid artery is important for evaluating not only cerebrovascular but also cardiovascular diseases. In this paper, a wireless neckband ultrasound Doppler system, in which two 2.5-MHz ultrasonic sensors are utilized for acquiring Doppler signals from both carotid arteries, is presented for continuously evaluating blood flow dynamics. In the developed wireless neckband Doppler system, the acquired Doppler signals are quantized by 14-bit analog-to-digital-converters running at 40 MHz, and pre-processing operations (i.e., demodulation and clutter filtering) are performed in an embedded field programmable gate array chip. Then, these data are transferred to an external smartphone (i.e., Galaxy S7, Samsung Electronics Co., Suwon, Korea) via Bluetooth 2.0. Post-processing (i.e., Fourier transform and image processing) is performed using an embedded application processor in the smartphone. The developed carotid neckband Doppler system was evaluated with phantom and in vivo studies. In a phantom study, the neckband Doppler system showed comparable results with a commercial ultrasound machine in terms of peak systolic velocity and resistive index, i.e., 131.49 ± 3.97 and 0.75 ± 0.02 vs. 131.89 ± 2.06 and 0.74 ± 0.02, respectively. In addition, in the in vivo study, the neckband Doppler system successfully demonstrated its capability to continuously evaluate hemodynamics in both common carotid arteries. These results indicate that the developed wireless neckband Doppler system can be used for continuous monitoring of blood flow dynamics in the common carotid arteries in point-of-care settings.

12

Shigematsu, Yoshinori, Yukunori Korogi, Toshinori Hirai, Tomoko Okuda, Takeshi Sugahara, Luxia Liang, and Mutsumasa Takahashi. "3D TOF turbo MR angiography for intracranial arteries: Phantom and clinical studies." Journal of Magnetic Resonance Imaging 10, no. 6 (December 1999): 939–44. http://dx.doi.org/10.1002/(sici)1522-2586(199912)10:6<939::aid-jmri5>3.0.co;2-k.

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13

Zhou, Yufeng, and Wei Chun Daniel Lim. "Influence of High-Intensity Focused Ultrasound (HIFU) Ablation on Arteries: Ex Vivo Studies." Micromachines 12, no. 5 (April 25, 2021): 485. http://dx.doi.org/10.3390/mi12050485.

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High-intensity focused ultrasound (HIFU) has been used to ablate solid tumors and cancers. Because of the hypervascular structure of the tumor and circulating blood inside it, the interaction between the HIFU burst and vessel is a critical issue in the clinical environment. Influences on lesion production and the potential of vessel rupture were investigated in this study for the efficiency and safety of clinical ablation. An extracted porcine artery was embedded in a transparent polyacrylamide gel phantom, with bovine serum albumin (BSA) as an indicator of the thermal lesion, and degassed water was driven through the artery sample. The HIFU focus was aligned to the anterior wall, middle of the artery, and posterior wall. After HIFU ablation, the produced lesion was photographically recorded, and then its size was quantified and compared with that in the gel phantom without artery. In addition, the bubble dynamics (i.e., generation, expansion, motion, and shrinkage of bubbles and their interaction with the artery) were captured using high-speed imaging. It was found that the presence of the artery resulted in a decrease in lesion size in both the axial and lateral directions. The characteristics of the lesion are dependent on the focus alignment. Acoustic and hydrodynamic cavitation play important roles in lesion production and interaction with the artery. Both thermal and mechanical effects were found on the surface of the artery wall after HIFU ablation. However, no vessel rupture was found in this ex vivo study.

14

GEOGHEGAN, PATRICK H., MARK C. JERMY, and DAVID S. NOBES. "A PIV COMPARISON OF THE FLOW FIELD AND WALL SHEAR STRESS IN RIGID AND COMPLIANT MODELS OF HEALTHY CAROTID ARTERIES." Journal of Mechanics in Medicine and Biology 17, no. 03 (July 21, 2016): 1750041. http://dx.doi.org/10.1142/s0219519417500415.

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Certain systems relevant to circulatory disease have walls which are neither rigid nor static, for example, the coronary arteries, the carotid artery and the heart chambers. In vitro modeling allows the fluid mechanics of the circulatory system to be studied without the ethical and safety issues associated with animal and human experiments. Computational methods in which the equations are coupled governing the flow and the elastic walls are maturing. Currently there is a lack of experimental data in compliant arterial systems to validate the numerical predictions. Previous experimental work has commonly used rigid wall boundaries, ignoring the effect of wall compliance. Particle Image Velocimetry is used to provide a direct comparison of both the flow field and wall shear stress (WSS) observed in experimental phantoms of rigid and compliant geometries representing an idealized common carotid artery. The input flow waveform and the mechanical response of the phantom are physiologically realistic. The results show that compliance affects the velocity profile within the artery. A rigid boundary causes severe overestimation of the peak WSS with a maximum relative difference of 61% occurring; showing compliance protects the artery from exposure to high magnitude WSS. This is important when trying to understand the development of diseases like atherosclerosis. The maximum, minimum and time averaged WSS in the rigid geometry was 2.3, 0.51 and 1.03[Formula: see text]Pa and in the compliant geometry 1.4, 0.58 and 0.84[Formula: see text]Pa, respectively.

15

Shapo, B. M., J. R. Crowe, R. Erkamp, S. Y. Emelianov, M. J. Eberle, and M. O'Donnell. "Strain Imaging of Coronary Arteries with Intraluminal Ultrasound: Experiments on an Inhomogeneous Phantom." Ultrasonic Imaging 18, no. 3 (July 1996): 173–91. http://dx.doi.org/10.1177/016173469601800302.

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16

Shapo, B. "Strain Imaging of Coronary Arteries with Intraluminal Ultrasound: Experiments on an Inhomogeneous Phantom." Ultrasonic Imaging 18, no. 3 (July 1996): 173–91. http://dx.doi.org/10.1006/uimg.1996.0010.

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17

Shih, Cho-Chiang, Pei-Yu Chen, Teng Ma, Qifa Zhou, K. Kirk Shung, and Chih-Chung Huang. "Development of an intravascular ultrasound elastography based on a dual-element transducer." Royal Society Open Science 5, no. 4 (April 2018): 180138. http://dx.doi.org/10.1098/rsos.180138.

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The ability to measure the elastic properties of plaques and vessels would be useful in clinical diagnoses, particularly for detecting a vulnerable plaque. This study demonstrates the feasibility of the combination of intravascular ultrasound (IVUS) and acoustic radiation force elasticity imaging for detecting the distribution of stiffness within atherosclerotic arteries ex vivo . A dual-frequency IVUS transducer with two elements was used to induce the propagation of the shear wave (by the 8.5 MHz pushing element) which could be simultaneously monitored by the 31 MHz imaging element. The wave-amplitude image and the wave-velocity image were reconstructed by measuring the peak displacement and wave velocity of shear wave propagation, respectively. System performance was verified using gelatin phantoms. The phantom results demonstrate that the stiffness differences of shear modulus of 1.6 kPa can be distinguished through the wave-amplitude and wave-velocity images. The stiffness distributions of the atherosclerotic aorta from a rabbit were obtained, for which the values of peak displacement and the shear wave velocity were 3.7 ± 1.2 µm and 0.38 ± 0.19 m s −1 for the lipid-rich plaques, and 1.0 ± 0.2 µm and 3.45 ± 0.45 m s −1 for the arterial walls, respectively. These results indicate that IVUS elasticity imaging can be used to distinguish the elastic properties of plaques and vessels.

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Meinders, Jan M., Lilian Kornet, Peter J. Brands, and Arnold P. G. Hoeks. "Assessment of Local Pulse Wave Velocity in Arteries Using 2D Distension Waveforms." Ultrasonic Imaging 23, no. 4 (October 2001): 199–215. http://dx.doi.org/10.1177/016173460102300401.

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The reciprocal of the arterial pulse wave velocity contains crucial information about the mechanical characteristics of the arterial wall but is difficult to assess noninvasively in vivo. In this paper, a new method to assess local pulse wave velocity (PWV) is presented. To this end, multiple adjacent distension waveforms are determined simultaneously along a short arterial segment, using a single 2D-vessel wall tracking system with a high frame rate (651 Hz). Each B-mode image consists of 16 echo lines spanning a total width of 15.86 mm. Dedicated software has been developed to extract the end-diastolic diameter from the B-mode image and the distension waveforms from the underlying radiofrequency (rf) information for each echo-line. The PWV is obtained by determining the ratio of the temporal and spatial gradient of adjacent distension velocity waveforms. The proposed method is verified in a phantom and in the common carotid artery (CCA) of humans. Phantom experiments show a high concordance between the PWV obtained from 2D distension velocity waveforms (4.21 ± 0.02 m/s) and the PWV determined using two pressure catheters (4.26 ± 0.02 m/s). Assuming linear spatial gradients, the PWV can also be obtained in vivo for CCA and averages to 5.5 ± 1.5 m/s (intersubject variation, n = 23), which compares well to values found in literature. Furthermore, intrasubject PWV compares well with those calculated using the Bramwell-Hill equation. It can be concluded that the PWV can be obtained from the spatial and temporal gradient if the spatial gradient is linear over the observed length of the artery, i.e. the artery should be homogenous in diameter and distension and the influence of reflections must be small.

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Bos, Denise, Britta König, Sebastian Blex, Sebastian Zensen, Marcel Opitz, Sandra Maier, Michael Forsting, et al. "EXPERIMENTAL EXAMINATION OF RADIATION DOSES OF DUAL- AND SINGLE-ENERGY COMPUTED TOMOGRAPHY IN CHEST AND UPPER ABDOMEN IN A PHANTOM STUDY." Radiation Protection Dosimetry 193, no. 3-4 (March 2021): 237–46. http://dx.doi.org/10.1093/rpd/ncab052.

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Abstract The aim of this phantom study is to examine radiation doses of dual- and single-energy computed tomography (DECT and SECT) in the chest and upper abdomen for three different multi-slice CT scanners. A total of 34 CT protocols were examined with the phantom N1 LUNGMAN. Four different CT examination types of different anatomic regions were performed both in single- and dual-energy technique: chest, aorta, pulmonary arteries for suspected pulmonary embolism and liver. Radiation doses were examined for the CT dose index CTDIvol and dose-length product (DLP). Radiation doses of DECT were significantly higher than doses for SECT. In terms of CTDIvol, radiation doses were 1.1–3.2 times higher, and in terms of DLP, these were 1.1–3.8 times higher for DECT compared with SECT. The third-generation dual-source CT applied the lowest dose in 7 of 15 different examination types of different anatomic regions.

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Hamamoto, Kohei, Emiko Chiba, Katsuhiko Matsuura, Tomohisa Okochi, Keisuke Tanno, and Osamu Tanaka. "Ultra-short echo time magnetic resonance imaging for detection of pulmonary arteriovenous malformation recanalization after coil embolization: a case report and a phantom study." Acta Radiologica Open 6, no. 9 (August 2017): 205846011773210. http://dx.doi.org/10.1177/2058460117732101.

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A pulmonary arteriovenous malformation (PAVM) is a direct connection between the pulmonary arteries and veins for which metallic coil transcatheter embolization is the standard of care. Detecting recanalization after PAVM treatment is crucial, but direct visualization with computed tomography or magnetic resonance imaging (MRI) is generally difficult. Here, we report a case of a recanalized PAVM that was directly detected with ultra-short echo time MRI. The detection of these signals in the coils was confirmed in a phantom study.

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Choi, Kyu Sung, Whal Lee, Joon Hyung Jung, and Eun-Ah Park. "Reproducibility of calcium scoring of the coronary arteries: comparison between different vendors and iterative reconstructions." Acta Radiologica Open 9, no. 4 (April 2020): 205846012092214. http://dx.doi.org/10.1177/2058460120922147.

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Background The coronary artery calcium scoring (CCS) has been widely used for cardiac risk stratification for asymptomatic patients. Purpose To assess the reproducibility of CCS performed on four different computed tomography (CT) scanners, and compare the variability between two reconstruction algorithms, filtered back projection (FBP), and iterative reconstruction (IR). Material and Methods A CCS phantom was made from agar and contained 23 pieces of chicken bones. The phantom was repeatedly scanned using four different CT scanners: Toshiba; GE; Philips; and Siemens. Images were reconstructed using FBP and IR. Agatston and volume scores of total bone fragments were calculated and the overall differences between the instruments were evaluated using the Friedman test. Comparison of the Agatston and volume scores between the two reconstruction algorithms, for each instrument, was evaluated using the Wilcoxon signed rank test. Results The difference in the Agatston scores was significantly different between the four machines ( P = 0.001). The Toshiba scanner yielded the highest score followed by Philips, GE, and Siemens scanners. There was no difference in the CCS evaluated using the two reconstruction algorithms, except in case of the Siemens scanner ( P = 0.032). Conclusion CCS performed on different scanners varied significantly. In the Toshiba, Philips, and GE scanners, there was no significant difference in the CCS determined using either an IR or the FBP algorithm. In the Siemens scanner, applying the IR algorithm resulted in a slightly different scores, which might not be clinically significant.

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Guberina, N., U. Dietrich, M. Forsting, and A. Ringelstein. "Comparison of eye-lens doses imparted during interventional and non-interventional neuroimaging techniques for assessment of intracranial aneurysms." Journal of NeuroInterventional Surgery 10, no. 2 (February 27, 2017): 168–70. http://dx.doi.org/10.1136/neurintsurg-2016-012970.

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BackgroundA neurointerventional examination of intracranial aneurysms often involves the eye lens in the primary beam of radiation.ObjectiveTo assess and compare eye-lens doses imparted during interventional and non-interventional imaging techniques for the examination of intracranial aneurysms.MethodsWe performed a phantom study on an anthropomorphic phantom (ATOM dosimetry phantom 702-D; CIRS, Norfolk, Virginia, USA) and assessed eye-lens doses with thermoluminescent dosimeters (TLDs) type 100 (LiF:Mg, Ti) during (1) interventional (depiction of all cerebral arteries with triple 3D-rotational angiography and twice 2-plane DSA anteroposterior and lateral projections) and (2) non-interventional (CT angiography (CTA)) diagnosis of intracranial aneurysms. Eye-lens doses were calculated following recommendations of the ICRP 103. Image quality was analysed in retrospective by two experienced radiologists on the basis of non-interventional and interventional pan-angiography examinations of patients with incidental aneurysms (n=50) on a five-point Likert scale.ResultsThe following eye-lens doses were assessed: (1) interventional setting (triple 3D-rotational angiography and twice 2-plane DSA anteroposterior and lateral projections) 12 mGy; (2) non-interventional setting (CTA) 4.1 mGy. Image quality for depiction of intracranial aneurysms (>3 mm) was evaluated as good by both readers for both imaging techniques.ConclusionsEye-lens doses are markedly higher during the interventional than during the non-interventional diagnosis of intracranial aneurysms. For the eye-lens dose, CTA offers considerable radiation dose savings in the diagnosis of intracranial aneurysms.

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Driscoll, Brandon, Tina Shek, Douglass Vines, Alex Sun, David Jaffray, and Ivan Yeung. "Phantom Validation of a Conservation of Activity-Based Partial Volume Correction Method for Arterial Input Function in Dynamic PET Imaging." Tomography 8, no. 2 (March 21, 2022): 842–57. http://dx.doi.org/10.3390/tomography8020069.

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Dynamic PET (dPET) imaging can be utilized to perform kinetic modelling of various physiologic processes, which are exploited by the constantly expanding range of targeted radiopharmaceuticals. To date, dPET remains primarily in the research realm due to a number of technical challenges, not least of which is addressing partial volume effects (PVE) in the input function. We propose a series of equations for the correction of PVE in the input function and present the results of a validation study, based on a purpose built phantom. 18F-dPET experiments were performed using the phantom on a set of flow tubes representing large arteries, such as the aorta (1” 2.54 cm ID), down to smaller vessels, such as the iliac arteries and veins (1/4” 0.635 cm ID). When applied to the dPET experimental images, the PVE correction equations were able to successfully correct the image-derived input functions by as much as 59 ± 35% in the presence of background, which resulted in image-derived area under the curve (AUC) values within 8 ± 9% of ground truth AUC. The peak heights were similarly well corrected to within 9 ± 10% of the scaled DCE-CT curves. The same equations were then successfully applied to correct patient input functions in the aorta and internal iliac artery/vein. These straightforward algorithms can be applied to dPET images from any PET-CT scanner to restore the input function back to a more clinically representative value, without the need for high-end Time of Flight systems or Point Spread Function correction algorithms.

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M. Noor, A. Fahmi Huwaidi, Nasrul Hadi Johari, Adi Azriff Basri, and Xiao Yun Xu. "Comparison of Velocity Profiles in Stented Carotid Artery Bifurcation Between Computational Fluid Dynamics and Particle Image Velocimetry Measurements." International Journal of Automotive and Mechanical Engineering 21, no. 2 (June 20, 2024): 11386–97. http://dx.doi.org/10.15282/ijame.21.2.2024.16.0879.

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Cardiovascular disease remains the leading cause of morbidity and mortality globally, necessitating extensive research into the hemodynamics of blood flow under pathological conditions, such as atherosclerosis in carotid arteries. In vitro studies, particularly Computational Fluid Dynamics (CFD), are crucial for advancing our understanding of arterial blood flow and predicting pathological states. However, the accuracy of CFD simulations relies heavily on their validation against empirical data, such as those obtained from Particle Image Velocimetry (PIV). This study focuses on the comparative analysis of CFD predictions and PIV measurements of blood velocity vectors in a stented carotid artery bifurcation model under steady flow conditions derived from patient-specific data. The methodology involves simulating blood flow within a CFD framework and conducting PIV experiments using a blood-mimicking fluid seeded with particles in a carotid artery bifurcation phantom. The results indicate a reasonable agreement between the axial velocity vector profiles obtained via PIV and those predicted by CFD, with CFD predicting 10% higher than that recorded by PIV, especially in terms of recirculation areas and velocity values, despite some discrepancies in the velocity contours distribution, highlighting potential differences in how each method captures flow separation or recirculation areas. Despite some discrepancies in velocity contour distribution, which highlight potential differences in capturing flow separation or recirculation areas, the findings confirm that CFD simulations can effectively replicate the hemodynamics observed in carotid arteries and potentially other arterial segments. This study emphasizes the importance of integrating CFD simulations with experimental PIV data to validate and refine our understanding of arterial flow dynamics, significantly contributing to cardiovascular research and the development of interventions for arterial diseases.

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Song, Hwa-Seob, Hyun-Soo Yoon, Seongpung Lee, Chang-Ki Hong, and Byung-Ju Yi. "Surgical Navigation System for Transsphenoidal Pituitary Surgery Applying U-Net-Based Automatic Segmentation and Bendable Devices." Applied Sciences 9, no. 24 (December 16, 2019): 5540. http://dx.doi.org/10.3390/app9245540.

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Conventional navigation systems used in transsphenoidal pituitary surgery have limitations that may lead to organ damage, including long image registration time, absence of alarms when approaching vital organs and lack of 3-D model information. To resolve the problems of conventional navigation systems, this study proposes a U-Net-based, automatic segmentation algorithm for optical nerves and internal carotid arteries, by training patient computed tomography angiography images. The authors have also developed a bendable endoscope and surgical tool to eliminate blind regions that occur when using straight, rigid, conventional endoscopes and surgical tools during transsphenoidal pituitary surgery. In this study, the effectiveness of a U-Net-based navigation system integrated with bendable surgical tools and a bendable endoscope has been demonstrated through phantom-based experiments. In order to measure the U-net performance, the Jaccard similarity, recall and precision were calculated. In addition, the fiducial and target registration errors of the navigation system and the accuracy of the alarm warning functions were measured in the phantom-based environment.

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Lauk-Dubitsky, S. E., T. A. Astrelina, A. A. Fedyunin, I. A. Burkov, E. M. Kildyushov, S. V. Lischuk, I. A. Novikov, et al. "COMPLEX APPROACH FOR PORTABLE CRYOPRESERVATION OF SEGMENTS OF BLOOD VESSELS WITH POLYDIMETHYLSILOXANE." Russian Journal of Transplantology and Artificial Organs 20, no. 1 (April 24, 2018): 86–95. http://dx.doi.org/10.15825/1995-1191-2018-1-86-95.

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Aim.To develop a safe protocol for cryopreservation of segments of iliac arteries straight after their retrieval from post-mortem donor with the use of polydimethylsiloxane as a coolant and cryoprotectant.Materials and methods.Eleven segments of iliac arteries were retrieved from post-mortem donor and divided into four groups including control. Based on preliminary heat and cold transfer mathematical modeling and tests with tissueequivalent phantom arterial segments were placed on plastic mounts and cryopreserved by following protocol: groups 1 and 2 were immersed in polydimethylsiloxane and cooled rapidly at 180 °С/min to –75 °С. Group 3 segments were cryopreserved at 1,6 °С/min in PDMS – fi lled cryo-container placed in the freezer at –80 °С. All segments were defrosted by immersion in PDMS at +24 °С and then examined for morphology changes by histological methods and SEM. EDS analysis with the use of AzTech software also was performed for Si – content evaluation. Restricted biomechanical tests were conducted for group 2 segments.Results.There were no signifi cant morphological differences between segments of the control and cryopreserved groups except for the segment with slow cooling.Conclusion.Mobile cryopreservation may allow increasing the effi ciency of retrieval of a large number of donor tissues for possible later use in the processing of bioprostheses of blood vessels; or, after decellularization, as well as tissue-specifi c matrices for tissue-engineering blood vessels.

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Jeon, Sang-Hyun, Dong-Hee Ko, Pil Hyeon Jeon, Sung Min Ko, and D. D. "Diagnostic Value of Stent Images using Ultra-High Resolution Deep Learning Algorithms in Coronary CT Angiography." Korean Society of Computed Tomographic Technology 26, no. 1 (March 30, 2024): 25–36. http://dx.doi.org/10.31320/jksct.2024.26.1.25.

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Recently, with the advancement of artificial intelligence image reconstruction technology, we are attempting to evaluate the accuracy of coronary artery stent lumen by developing ultra-high-resolution deep learning image reconstruction technology based on the most accurate 0.25mm multi-detector available. This study was divided into patient studies and phantom studies. Images were reconstructed in the same patient using four different methods: filter correction reverse projection, repetitive reconstruction, deep learning reconstruction, and artificial intelligence ultra-high resolution reconstruction. To objectively evaluate image quality, four parameters, image noise, CT density, signal-to-noise ratio, and contrast-to-noise ratio, were analyzed for each dataset. The phantom study installed a latex Nelaton sterilized catheter to express the coronary artery in the dummy chest phantom. Subsequently, a coronary stent (2.5mm and 3.5mm in diameter) was inserted into each catheter. Images were obtained using various reconstruction techniques (FBP, IR, DLR, and UHR-DLR) for each CT manufacturer. Stent clarity was evaluated using edge rise distance (ERD) and edge rise slope (ERS). We showed that the average Signal-to-Noise Ratio (SNR) and Contrast-to-Noise Ratio (CNR) of coronary arteries reconstructed with Ultra-High Resolution Deep Learning Reconstruction (UHR-DLR) improved by 29.2% and 36.4% compared to those reconstructed with DLR, respectively. Image noise was reduced by about 21.4% in UHR-DLR. The ERS average value of the coronary stent phantom measured by the CT manufacturers was highest in the UHR-DLR of Aquilion ONE Prism (Canon), and the ERD value is statistically significant for each CT manufacturer. Compared to FBP, HIR, and DLR, UHR-DLR not only improved image clarity and reduced image noise and blooming artifacts but also clearly showed the stent support structure and stent lumen.

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Fraser, Katharine H., Christian Poelma, Bin Zhou, Eleni Bazigou, Meng-Xing Tang, and Peter D. Weinberg. "Ultrasound imaging velocimetry with interleaved images for improved pulsatile arterial flow measurements: a new correction method, experimental and in vivo validation." Journal of The Royal Society Interface 14, no. 127 (February 2017): 20160761. http://dx.doi.org/10.1098/rsif.2016.0761.

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Blood velocity measurements are important in physiological science and clinical diagnosis. Doppler ultrasound is the most commonly used method but can only measure one velocity component. Ultrasound imaging velocimetry (UIV) is a promising technique capable of measuring two velocity components; however, there is a limit on the maximum velocity that can be measured with conventional hardware which results from the way images are acquired by sweeping the ultrasound beam across the field of view. Interleaved UIV is an extension of UIV in which two image frames are acquired concurrently, allowing the effective interframe separation time to be reduced and therefore increasing the maximum velocity that can be measured. The sweeping of the ultrasound beam across the image results in a systematic error which must be corrected: in this work, we derived and implemented a new velocity correction method which accounts for acceleration of the scatterers. We then, for the first time, assessed the performance of interleaved UIV for measuring pulsatile arterial velocities by measuring flows in phantoms and in vivo and comparing the results with spectral Doppler ultrasound and transit-time flow probe data. The velocity and flow rate in the phantom agreed within 5–10% of peak velocity, and 2–9% of peak flow, respectively, and in vivo the velocity difference was 9% of peak velocity. The maximum velocity measured was 1.8 m s −1 , the highest velocity reported with UIV. This will allow flows in diseased arteries to be investigated and so has the potential to increase diagnostic accuracy and enable new vascular research.

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Hugenberg, Nicholas R., Tuhin Roy, Hadiya Harrigan, Margherita Capriotti, Hyoung-Ki Lee, Murthy Guddati, James F. Greenleaf, Matthew W. Urban, and Wilkins Aquino. "Toward improved accuracy in shear wave elastography of arteries through controlling the arterial response to ultrasound perturbation in-silico and in phantoms." Physics in Medicine & Biology 66, no. 23 (November 26, 2021): 235008. http://dx.doi.org/10.1088/1361-6560/ac38fe.

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Abstract Dispersion-based inversion has been proposed as a viable direction for materials characterization of arteries, allowing clinicians to better study cardiovascular conditions using shear wave elastography. However, these methods rely on a priori knowledge of the vibrational modes dominating the propagating waves induced by acoustic radiation force excitation: differences between anticipated and real modal content are known to yield errors in the inversion. We seek to improve the accuracy of this process by modeling the artery as a fluid-immersed cylindrical waveguide and building an analytical framework to prescribe radiation force excitations that will selectively excite certain waveguide modes using ultrasound acoustic radiation force. We show that all even-numbered waveguide modes can be eliminated from the arterial response to perturbation, and confirm the efficacy of this approach with in silico tests that show that odd modes are preferentially excited. Finally, by analyzing data from phantom tests, we find a set of ultrasound focal parameters that demonstrate the viability of inducing the desired odd-mode response in experiments.

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Zhang, Alex Ce, and Yu-Hwa Lo. "Non-Invasive Blood Flow Speed Measurement Using Optics." Sensors 22, no. 3 (January 25, 2022): 897. http://dx.doi.org/10.3390/s22030897.

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Non-invasive measurement of the arterial blood speed gives important health information such as cardio output and blood supplies to vital organs. The magnitude and change in arterial blood speed are key indicators of the health conditions and development and progression of diseases. We demonstrated a simple technique to directly measure the blood flow speed in main arteries based on the diffused light model. The concept is demonstrated with a phantom that uses intralipid hydrogel to model the biological tissue and an embedded glass tube with flowing human blood to model the blood vessel. The correlation function of the measured photocurrent was used to find the electrical field correlation function via the Siegert relation. We have shown that the characteristic decorrelation rate (i.e., the inverse of the decoherent time) is linearly proportional to the blood speed and independent of the tube diameter. This striking property can be explained by an approximate analytic solution for the diffused light equation in the regime where the convective flow is the dominating factor for decorrelation. As a result, we have demonstrated a non-invasive method of measuring arterial blood speed without any prior knowledge or assumption about the geometric or mechanic properties of the blood vessels.

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Johari, N. H., N. B. Wood, Z. Cheng, R. Torii, M. Oishi, M. Oshima, and X. Y. Xu. "Disturbed Flow in a Stenosed Carotid Artery Bifurcation: Comparison of RANS-Based Transitional Model and LES with Experimental Measurements." International Journal of Applied Mechanics 11, no. 04 (May 2019): 1950032. http://dx.doi.org/10.1142/s1758825119500327.

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Blood flow in the carotid arteries is usually laminar, but can undergo laminar-turbulent transition in the presence of a high-grade stenosis. In this study, pulsatile flow in a patient-based stenosed carotid artery bifurcation was examined using both large eddy simulation (LES) with dynamic Smagorinsky eddy viscosity model, and a Reynolds-averaged Navier-Stokes (RANS) method with a transitional version of the shear stress transport (SST-Tran) model. In addition, an experimental phantom was built for the same bifurcation geometry and velocity measurements were made using particle image velocimetry (PIV). Comparisons with PIV measurements of axial velocity profiles demonstrated that both SST-Tran and LES predicted the experimental results fairly well, with LES being slightly superior. Furthermore, LES predicted cycle-to-cycle variations in the region where transition to turbulence occurred, indicating the unsteady nature of turbulence transition. On the other hand, the SST-Tran model was able to capture important flow features observed in the PIV experiment, demonstrating its potential as a cost-effective alternative to LES for haemodynamic analyses of highly disturbed flow in diseased arteries.

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Jonas, Svensson. "Contrast-enhanced magnetic resonance angiography." Acta Radiologica 44, suppl_429 (July 2003): 1–30. http://dx.doi.org/10.1080/ard.44.s429.1.

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Svensson J. Contrast-Enhanced Magnetic Resonance Angiography. Development and optimization of techniques for paramagnetic and hyperpolarized contrast media. Stockholm 2001. ISBN 91-628-5322-8. Contrast-enhanced magnetic resonance angiography (CE-MRA) is a diagnostic method for imaging of vascular structures based on nuclear magnetic resonance. Vascular enhancement is achieved by injection of a contrast medium (CM). Studies were performed using two different types of CM: conventional paramagnetic CM, and a new type ofCMbased on hyperpolarized (HP) nuclei. The effects of varying CM concentration with time during image acquisition were studied by means of computer simulations using two different models. It was shown that a rapid concentration variation during encoding of the central parts of k-space could result in signal loss and severe image artifacts. The results were confirmed qualitatively with phantom experiments. A postprocessing method was developed to address problems with simultaneous enhancement of arteries and veins in CE-MRA of the lower extremities. The method was based on the difference in flow-induced phase in the two vessel types. Evaluation of the method was performed with flow phantom measurements and with CE-MRA in two volunteers using standard pulse sequences. The flow-induced phase in the vessels of interest was sufficient to distinguish arteries from veins in the superior-inferior direction. Using this method, the venous enhancement could be extinguished. The possibility of using HP nuclei as CM for CE-MRA was evaluated. Signal expressions for a flow of HP CMimaged with a gradient echo sequence were derived. These signal expressions were confirmed in phantom experiments using HP 129Xe dissolved in ethanol. Studies were also performed with a new CM based on HP 13C. The CM had very long relaxation times ( T1,in vivo/ T2,in vivo ≈ 38/1.3 s). The long relaxation times were utilized in imaging with a fully balanced steady-state free precession pulse sequence (trueFISP), where the optimal flip angle was found to be 180°. CE-MRA with the 13C-based CM in rats resulted in images with high vascular SNR (∼500). CE-MRA is a useful clinical tool for diagnosing vascular disease. With the development of new contrast media, based on hyperpolarized nuclei for example, there is a potential for further improvement in the signal levels that can be achieved, enabling a standard of imaging of vessels that is not possible today.

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Sorteberg, A., and D. Farhoudi. "The Influence of Aneurysm Configuration on Intra-Aneurysmal Pressure and Flow." Interventional Neuroradiology 12, no. 3 (September 2006): 203–14. http://dx.doi.org/10.1177/159101990601200302.

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Aneurysm rupture may occur in conjunction with swift pressure increases like heavy lifting. We therefore investigated the transmission of pressure waves as well as local flow rates in various types of experimental aneurysms and their parent arteries. 0.014-inch guidewires containing a combined pressure and thermistor sensor were inserted into both the dome and the parent artery of idealized silicone aneurysms mounted in a pulsatile flow phantom. Intravascular pressure and thermodilution responses to injections of room-temperatured normal saline at a rate of 5cc.s−1 over two seconds were recorded simultaneously at both sites. Flow was evaluated semiquantitatively applying the thermodilution principle. We found that the propagation of pressure was attenuated at the dome of the aneurysms compared to their respective parent arteries. This difference was more distinct in side-wall aneurysms than in bifurcational aneurysms. The attenuation of traveling pressure in the aneurysm was most effective at low systemic pressures. The intraaneurysmal flow rate was unique, always lower than in the respective parent arteries and highly dependent on the configuration of the aneurysm. We observed considerably higher flow rates in bifurcational aneurysms compared to side-wall aneurysms. Bifurcational aneurysms were hence characterized by a relatively high pressure transmission and high flow rates which may represent a stimulus for enlargement of untreated aneurysms and promote coil compaction in endovascularly treated lesions.

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Padasdao, Blayton, Zahra Khashei Varnamkhasti, and Bardia Konh. "3D Steerable Biopsy Needle with a Motorized Manipulation System and Ultrasound Tracking to Navigate inside Tissue." Journal of Medical Robotics Research 05, no. 03n04 (September 2020): 2150003. http://dx.doi.org/10.1142/s2424905x21500033.

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Needle insertion techniques have been used in several minimally invasive procedures for diagnostic and therapeutic purposes. For example, in tissue biopsy, a small sample of suspicious tissue is extracted using percutaneous needles for further analysis. A clinically significant biopsy sample is a definitive factor in cancer diagnosis; therefore, precise placement of the needle tip at target location is necessary. However, it is often challenging to guide and track the needle in a desired path to reach the target precisely, while avoiding sensitive organs or large arteries. Needle steering has been an active field of research in the past decade. Researchers have introduced passive and active needles to improve navigation and targeting inside the tissue. This work introduces a novel active steerable biopsy needle capable of bending inside the tissue in multiple directions. The needle is equipped with a biopsy mechanism to extract suspicious tissue. A motorized manipulation system is developed and programmed to pull the cable tendons and control the needle deflection inside tissue. To show the feasibility of the design concept, the active needle manipulation in air and in a tissue-mimicking phantom is evaluated. An average angular deflection of about 12.40∘ and 11.34∘ in three principal directions is realized in air and phantom tissue, respectively, which is expected to assist in breast cancer biopsy. A robot-assisted ultrasound tracking method is also proposed to track the active needle tip inside the phantom tissue in real time. It is shown that using this method, the needle tip can be tracked in real time with an average and maximum tracking error of [Formula: see text][Formula: see text]mm and [Formula: see text][Formula: see text]mm, respectively.

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Bellemann, M. E., H. Hauser, J. Doll, and G. Brix. "Recovery-Koeffizienten zur Quantifizierung der arteriellen Inputfunktion aus dynamischen PET-Messungen: experimentelle und theoretische Bestimmung." Nuklearmedizin 41, no. 04 (2002): 184–90. http://dx.doi.org/10.1055/s-0038-1623894.

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Summary Aim: For kinetic modelling of dynamic PET data, the arterial input function can be determined directly from the PET scans if a large artery is visualized on the images. It was the purpose of this study to experimentally and theoretically determine recovery coefficients for cylinders as a function of the diameter and level of background activity. Methods: The measurements were performed using a phantom with seven cylinder inserts (Ø = 5-46 mm). The cylinders were filled with an aqueous 68Ga solution while the main chamber was filled with a 18F solution in order to obtain a varying concentration ratio between the cylinders and the background due to the different isotope half lives. After iterative image reconstruction, the activity concentrations were measured in the center of the cylinders and the recovery coefficients were calculated as a function of the diameter and the background activity. Based on the imaging properties of the PET system, we also developed a model for the quantitative assessment of recovery coefficients. Results: The functional dependence of the measured recovery data from the cylinder diameter and the concentration ratio is well described by our model. For dynamic PET measurements, the recovery correction must take into account the decreasing concentration ratio between the blood vessel and the surrounding tissue. Under the realized measurement and data analysis conditions, a recovery correction is required for vessels with a diameter of up to 25 mm. Conclusions: Based on the experimentally verified model, the activity concentration in large arteries can be calculated from the measured activity concentration in the blood vessel and the background activity. The presented approach offers the possibility to determine the arterial input function for pharmacokinetic PET studies non-invasively from large arteries (especially the aorta).

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Stuban, Norbert, Masatsugu Niwayama, and Hunor Santha. "Phantom with Pulsatile Arteries to Investigate the Influence of Blood Vessel Depth on Pulse Oximeter Signal Strength." Sensors 12, no. 1 (January 16, 2012): 895–904. http://dx.doi.org/10.3390/s120100895.

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DeKornfeld, George M., Julia Boll, Kenneth R. Ziegler, Jonathan Ratcliff, Thomas C. Naslund, C. Louis Garrard, R. James Valentine, and John A. Curci. "Initial and intermediate-term treatment of the phantom thrombus (primary non-occlusive mural thrombus on normal arteries)." Vascular Medicine 23, no. 6 (August 19, 2018): 549–54. http://dx.doi.org/10.1177/1358863x18788952.

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Stepniak, Karolina, Ali Ursani, Narinder Paul, and Hani Naguib. "Novel 3D printing technology for CT phantom coronary arteries with high geometrical accuracy for biomedical imaging applications." Bioprinting 18 (June 2020): e00074. http://dx.doi.org/10.1016/j.bprint.2020.e00074.

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Björkdahl, Peter, and Ulf Nyman. "Using 100- instead of 120-kVp computed tomography to diagnose pulmonary embolism almost halves the radiation dose with preserved diagnostic quality." Acta Radiologica 51, no. 3 (April 2010): 260–70. http://dx.doi.org/10.3109/02841850903505222.

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Background: Concern has been raised regarding the mounting collective radiation doses from computed tomography (CT), increasing the risk of radiation-induced cancers in exposed populations. Purpose: To compare radiation dose and image quality in a chest phantom and in patients for the diagnosis of pulmonary embolism (PE) at 100 and 120 peak kilovoltage (kVp) using 16-multichannel detector computed tomography (MDCT). Material and Methods: A 20-ml syringe containing 12 mg I/ml was scanned in a chest phantom at 100/120 kVp and 25 milliampere seconds (mAs). Consecutive patients underwent 100 kVp ( n = 50) and 120 kVp ( n = 50) 16-MDCT using a “quality reference” effective mAs of 100, 300 mg I/kg, and a 12-s injection duration. Attenuation (CT number), image noise (1 standard deviation), and contrast-to-noise ratio (CNR; fresh clot = 70 HU) of the contrast medium syringe and pulmonary arteries were evaluated on 3-mm-thick slices. Subjective image quality was assessed. Computed tomography dose index (CTDIvol) and dose–length product (DLP) were presented by the CT software, and effective dose was estimated. Results: Mean values in the chest phantom and patients changed as follows when X-ray tube potential decreased from 120 to 100 kVp: attenuation +23% and +40%, noise +38% and +48%, CNR −6% and 0%, and CTDIvol −38% and −40%, respectively. Mean DLP and effective dose in the patients decreased by 42% and 45%, respectively. Subjective image quality was excellent or adequate in 49/48 patients at 100/120 kVp. No patient with a negative CT had any thromboembolism diagnosed during 3-month follow-up. Conclusion: By reducing X-ray tube potential from 120 to 100 kVp, while keeping all other scanning parameters unchanged, the radiation dose to the patient may be almost halved without deterioration of diagnostic quality, which may be of particular benefit in young individuals.

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Nayak H. S., Sathvik, Nitesh Kumar, S. M. A. Khader, and Raghuvir Pai. "Effect of dome size on flow dynamics in saccular aneurysms – A numerical study." Journal of Mechanical Engineering and Sciences 14, no. 3 (September 30, 2020): 7181–90. http://dx.doi.org/10.15282/jmes.14.3.2020.19.0564.

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Image-based Computational Fluid Dynamic (CFD) simulations of anatomical models of human arteries are gaining clinical relevance in present days. In this study, CFD is used to study flow behaviour and hemodynamic parameters in aneurysms, with a focus on the effect of geometric variations in the aneurysm models on the flow dynamics. A computational phantom was created using a 3D modelling software to mimic a spherical aneurysm. Hemodynamic parameters were obtained and compared with the available literature to validate. Further, flow dynamics is studied by varying the dome size of the aneurysm from 3.75 mm to 6.25 mm with an increment of 0.625 mm keeping the neck size constant. The aneurysm is assumed to be located at a bend in the arterial system. Computational analysis of the flow field is performed by using Navier – Stokes equation for laminar flow of incompressible, Newtonian fluid. Parameters such as velocity, pressure, wall shear stress (WSS), vortex structure are studied. It was observed that the location of the flow separation and WSS vary significantly with the geometry of the aneurysm. The reduction of WSS inside the aneurysm is higher at the larger dome sizes for constant neck size.

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Garin, Etienne, Yan Rolland, Laurence Lenoir, Marc Pracht, Habiba Mesbah, Philippe Porée, Sophie Laffont, Bruno Clement, Jean-Luc Raoul, and Eveline Boucher. "Utility of Quantitative 99mTc-MAA SPECT/CT for 90yttrium-Labelled Microsphere Treatment Planning: Calculating Vascularized Hepatic Volume and Dosimetric Approach." International Journal of Molecular Imaging 2011 (July 28, 2011): 1–8. http://dx.doi.org/10.1155/2011/398051.

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Objectives. The aim of this study was to assess the effectiveness of SPECT/CT for volume measurements and to report a case illustrating the major impact of SPECT/CT in calculating the vascularized liver volume and dosimetry prior to injecting radiolabelled yttrium-90 microspheres (Therasphere). Materials and Methods. This was a phantom study, involving volume measurements carried out by two operators using SPECT and SPECT/CT images. The percentage of error for each method was calculated, and interobserver reproducibility was evaluated. A treatment using Therasphere was planned in a patient with three hepatic arteries, and the quantitative analysis of SPECT/CT for this patient is provided. Results. SPECT/CT volume measurements proved to be accurate (mean error <6% for volumes ≥16 cm3) and reproductive (interobserver agreement = 0.9). In the case report, 99mTc-MAA SPECT/CT identified a large liver volume, not previously identified with angiography, which was shown to be vascularized after selective MAA injection into an arterial branch, resulting in a large modification in the activity of Therasphere used. Conclusions. MAA SPECT/CT is accurate for vascularized liver volume measurements, providing a valuable contribution to the therapeutic planning of patients with complex hepatic vascularization.

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Siepmann, Robert, Henning Nilius, Florian Mueller, Katrin Mueller, Claudio Luisi, Seyed Mohammadali Dadfar, Marcel Straub, Volkmar Schulz, and Sebastian Daniel Reinartz. "Image-derived mean velocity measurement for prediction of coronary flow reserve in a canonical stenosis phantom using magnetic particle imaging." PLOS ONE 16, no. 4 (April 22, 2021): e0249697. http://dx.doi.org/10.1371/journal.pone.0249697.

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Introduction Aim of this study is to evaluate whether magnetic particle imaging (MPI) is capable of measuring velocities occurring in the coronary arteries and to compute coronary flow reserve (CFR) in a canonical phantom as a preliminary study. Methods For basic velocity measurements, a circulation phantom was designed containing replaceable glass tubes with three varying inner diameters, matching coronary-vessel diameters. Standardised boluses of superparamagnetic-iron-oxide-nanoparticles were injected and visualised by MPI. Two image-based techniques were competitively applied to calibrate the respective glass tube and to compute the mean velocity: full-duration-at-half-maximum (FDHM) and tracer dilution (TD) method. For CFR-calculation, four necessary settings of the circulation model of a virtual vessel with an inner diameter of 4 mm were generated using differently sized glass tubes and a stenosis model. The respective velocities in stenotic glass tubes were computed without recalibration. Results On velocity level, comparison showed a good agreement (rFDHM = 0.869, rTD = 0.796) between techniques, preferably better for 4 mm and 6 mm inner diameter glass tubes. On CFR level MPI-derived CFR-prediction performed considerably inferior with a relative error of 20–44%. Conclusions MPI has the ability to reliably measure coronary blood velocities at rest as well as under hyperaemia and therefore may be suitable for CFR calculation. Calibration-associated accuracy of CFR-measurements has to be improved substantially in further studies.

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Hopper, Kenneth D., Diane C. Strollo, and David T. Mauger. "Comparison of Electron-Beam and Ungated Helical CT in Detecting Coronary Arterial Calcification by Using a Working Heart Phantom and Artificial Coronary Arteries." Radiology 222, no. 2 (February 2002): 474–82. http://dx.doi.org/10.1148/radiol.2222000551.

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Bazan, Ivonne, Carlos Negreira, Antonio Ramos, Javier Brum, and Alfredo Ramirez. "A New High-Resolution Spectral Approach to Noninvasively Evaluate Wall Deformations in Arteries." Computational and Mathematical Methods in Medicine 2014 (2014): 1–15. http://dx.doi.org/10.1155/2014/606202.

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By locally measuring changes on arterial wall thickness as a function of pressure, the related Young modulus can be evaluated. This physical magnitude has shown to be an important predictive factor for cardiovascular diseases. For evaluating those changes, imaging segmentation or time correlations of ultrasonic echoes, coming from wall interfaces, are usually employed. In this paper, an alternative low-cost technique is proposed to locally evaluate variations on arterial walls, which are dynamically measured with an improved high-resolution calculation of power spectral densities in echo-traces of the wall interfaces, by using a parametric autoregressive processing. Certain wall deformations are finely detected by evaluating the echoes overtones peaks with power spectral estimations that implement Burg and Yule Walker algorithms. Results of this spectral approach are compared with a classical cross-correlation operator, in a tube phantom and “in vitro” carotid tissue. A circulating loop, mimicking heart periods and blood pressure changes, is employed to dynamically inspect each sample with a broadband ultrasonic probe, acquiring multiple A-Scans which are windowed to isolate echo-traces packets coming from distinct walls. Then the new technique and cross-correlation operator are applied to evaluate changing parietal deformations from the detection of displacements registered on the wall faces under periodic regime.

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Lee, Ki Baek, Jae Jon Sheen, Jong-Tae Yoon, Mi Hyeon Kim, Jun Young Maeng, Sun Moon Hwang, Joon Ho Choi, and Deok Hee Lee. "Feasibility of a silicone vascular phantom replicating real arterial contrast filling dynamics on cerebral angiography: An in-vitro pilot study." PLOS ONE 18, no. 1 (January 17, 2023): e0280395. http://dx.doi.org/10.1371/journal.pone.0280395.

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Some cerebral arterial silicone phantoms have been used in preclinical evaluations. However, typical silicone-based phantoms are limited in their capacity to reproduce real contrast filling dynamics of the human cerebral artery. This study aimed to develop a cerebral arterial silicone phantom to analyze the feasibility of real contrast filling dynamics. The fluid circulation phantom system consisted of a cerebral arterial silicone phantom without or with additional devices, a pump, an injection system, a pressure-monitoring system, a constant-temperature bath, and a venous drainage container. Vascular resistance was reproduced with a plastic cistern only or a plastic cistern filled with a sponge pad. Three phantom groups were constructed as follows: a) the cerebral arterial silicone phantom used as the control group (type A), b) phantom with the incorporated plastic cistern (type B), and c) phantom with the incorporated plastic cistern filled with a sponge pad (type C). The contrast concentration–time curve patterns of the three groups obtained from digital subtraction angiography (DSA) were compared. Consequently, the DSA pattern of the type C phantom was the most similar to that obtained from the control group as the reference data, which showed the broadest full-width-at-half-maximum and the area under the curve values and the highest maximum contrast concentration. In conclusion, we could emulate the arterial contrast filling dynamics of clinical cerebral angiography by applying a small cistern filled with a sponge pad at the drainage side of the phantom.

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Groves, Leah, Natalie Li, Terry M. Peters, and Elvis C. S. Chen. "Towards a First-Person Perspective Mixed Reality Guidance System for Needle Interventions." Journal of Imaging 8, no. 1 (January 7, 2022): 7. http://dx.doi.org/10.3390/jimaging8010007.

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While ultrasound (US) guidance has been used during central venous catheterization to reduce complications, including the puncturing of arteries, the rate of such problems remains non-negligible. To further reduce complication rates, mixed-reality systems have been proposed as part of the user interface for such procedures. We demonstrate the use of a surgical navigation system that renders a calibrated US image, and the needle and its trajectory, in a common frame of reference. We compare the effectiveness of this system, whereby images are rendered on a planar monitor and within a head-mounted display (HMD), to the standard-of-care US-only approach, via a phantom-based user study that recruited 31 expert clinicians and 20 medical students. These users performed needle-insertions into a phantom under the three modes of visualization. The success rates were significantly improved under HMD-guidance as compared to US-guidance, for both expert clinicians (94% vs. 70%) and medical students (70% vs. 25%). Users more consistently positioned their needle closer to the center of the vessel’s lumen under HMD-guidance compared to US-guidance. The performance of the clinicians when interacting with this monitor system was comparable to using US-only guidance, with no significant difference being observed across any metrics. The results suggest that the use of an HMD to align the clinician’s visual and motor fields promotes successful needle guidance, highlighting the importance of continued HMD-guidance research.

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Abbas, Mohamed, Mohammed S. Alqahtani, Ali Murayah, Ali Algahtani, Amir Kessentini, Hassen Loukil, Muneer Parayangat, Thafasal Ijyas, and Abdul Wase Mohammed. "Novel Nanoelectromechanical System Pressure Biosensing Method for Early Detection of Cholesterol Accumulation in Blood Vessels." Science of Advanced Materials 13, no. 5 (May 1, 2021): 966–80. http://dx.doi.org/10.1166/sam.2021.3976.

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High cholesterol could be dangerous, along with the deposits of other substances, such as fat, on the walls of the arteries. These plaques can reduce blood flow through the arteries, which in turn can cause complications such as chest pain, blood clots, and heart attack. Hence, there is a need for an efficient way to measure the concentration of cholesterol in blood vessels with great accuracy to predict its risk on health. The present study aims to measure the concentration of cholesterol and track it accurately in the blood vessels using an ultrasound pressure sensor, which detects the concentration of cholesterol and produces a pressure field around its surface that is directly proportional to the concentration. This field can be tracked by ultrasound. In this study, the experiments conducted involved the insertion of aluminum nanoparticles, which represent a pressure sensor coated with a massless piezoelectric aluminum nitride nanoplate, into simulated blood vessels containing different concentrations that mimic human blood. The sensitivity of the blood vessels was monitored at different time periods. Moreover, an experimental setup was constructed to validate the possibility of using existing ultrasound medical imaging technologies in tracking the proposed nano biosensors. The setup involves prototyping a medical phantom with a specific acoustic characteristic for simulating human tissues. Various clinical scenarios have been imitated and the possibility of tracking these novel micro electromechanical pressure biosensors has been discussed.

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Yazdi, Sina G., Larissa Huetter, Paul D. Docherty, Petra N. Williamson, Don Clucas, Mark Jermy, and Patrick H. Geoghegan. "A Novel Fabrication Method for Compliant Silicone Phantoms of Arterial Geometry for Use in Particle Image Velocimetry of Haemodynamics." Applied Sciences 9, no. 18 (September 11, 2019): 3811. http://dx.doi.org/10.3390/app9183811.

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Cardiovascular diseases (CVDs) are one of the leading causes of death globally. In-vitro measurement of blood flow in compliant arterial phantoms can provide better insight into haemodynamic states and therapeutic procedures. However, current fabrication techniques are not capable of producing thin-walled compliant phantoms of complex shapes. This study presents a new approach for the fabrication of compliant phantoms suitable for optical measurement. Two 1.5× scaled models of the ascending aorta, including the brachiocephalic artery (BCA), were fabricated from silicone elastomer Sylgard-184. The initial phantom used the existing state of the art lost core manufacturing technique with simple end supports, an acrylonitrile butadiene styrene (ABS) additive manufactured male mould and Ebalta-milled female mould. The second phantom was produced with the same method but used more rigid end supports and ABS male and female moulds. The wall thickness consistency and quality of resulting stereoscopic particle image velocimetry (SPIV) were used to verify the fidelity of the phantom for optical measurement and investigation of physiological flow fields. However, the initial phantom had a rough surface that obscured SPIV analysis and had a variable wall thickness (range = 0.815 mm). The second phantom provided clear particle images and had a less variable wall thickness (range = 0.317 mm). The manufacturing method developed is suitable for fast and cost-effective fabrication of different compliant arterial phantom geometries.

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Pascart, Tristan, and Jean-François Budzik. "Does Monosodium Urate Crystal Vascular Deposition Exist? Review of the Evidence." Gout, Urate, and Crystal Deposition Disease 1, no. 3 (September 11, 2023): 208–16. http://dx.doi.org/10.3390/gucdd1030017.

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Cardiovascular disease in gout is a central issue, but the underlying mechanisms linking the two are unclear. The existence of monosodium (MSU) crystal deposition directly inflaming vessel walls has been recurrently suggested and challenged since the 1950s and is again a matter of active debate since recent studies using dual-energy computed tomography (DECT) suggested a higher prevalence of plaques considered to be containing MSU crystals in patients with gout. The objective of this review is to critically cover the evidence gathered on MSU crystal deposition in the cardiovascular system. In patients affected with gout, histological evidence of MSU crystals in arteries lacks a biochemical characterization supporting the observation in polarized light microscopy, while current knowledge on vascular lesions identified in DECT as containing MSU crystals suggests that they may be only artifacts, including in cadaveric and phantom studies. In individuals without gout, MSU crystal deposition in vessel walls have not been demonstrated, despite higher urate local plaque concentrations and increased xanthine oxidase activity. Gout is associated with increased arterial calcification and atherosclerosis, both being potential confounders of suspected MSU crystal deposition for the analysis of DECT scans and histopathology, respectively. In summary, the reality of the presence of MSU crystals in vascular plaques has not been demonstrated so far, and needs further investigation as it represents a potential outcome for cardiovascular complications of gout.

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Oie, Takahiro, and Shunsuke Sato. "Adaptive laplacian-gaussian filter method for edge detection and diameter estimation of coronary arteries on cineangiograms: Applications to phantom profiles." Systems and Computers in Japan 23, no. 12 (1992): 55–65. http://dx.doi.org/10.1002/scj.4690231205.

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