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Onishi, Natsuko. "Apparent Diffusion Coefficient as a Potential Surrogate Marker for Ki-67 Index in Mucinous Breast Carcinoma". 京都大学 (Kyoto University), 2017. http://hdl.handle.net/2433/225449.
Pełny tekst źródłaKuwahara, Ryo. "A Predictor of Tumor Recurrence in Patients With Endometrial Carcinoma After Complete Resection of the Tumor: The Role of Pretreatment Apparent Diffusion Coefficient". Kyoto University, 2020. http://hdl.handle.net/2433/253483.
Pełny tekst źródłaFlötotto, Felix [Verfasser], i Christian [Akademischer Betreuer] Habermann. "Bestimmung des Einflusses von Alter und des Zigarettenkonsums auf die erhobenen ADC-Werte (apparent-diffusion-coefficient) der Glandula submandibularis / Felix Flötotto. Betreuer: Christian Habermann". Hamburg : Staats- und Universitätsbibliothek Hamburg, 2013. http://d-nb.info/1045024112/34.
Pełny tekst źródłaRabaszowski, Svenja [Verfasser], Gerald [Gutachter] Antoch i Hans-Jürgen [Gutachter] Laws. "Diffusionswichtung und der Apparent Diffusion Coefficient (ADC) zur Diagnostik und Differenzierung von Bauchtumoren bei pädiatrischen Patienten / Svenja Rabaszowski ; Gutachter: Gerald Antoch, Hans-Jürgen Laws". Düsseldorf : Universitäts- und Landesbibliothek der Heinrich-Heine-Universität Düsseldorf, 2021. http://d-nb.info/1239893736/34.
Pełny tekst źródłaJaouen, Tristan. "Caractérisation du cancer de la prostate de haut grade à l’IRM multiparamétrique à l’aide d’un système de diagnostic assisté par ordinateur basé sur la radiomique et utilisé comme lecteur autonome ou comme second lecteur". Electronic Thesis or Diss., Lyon, 2022. http://www.theses.fr/2022LYSE1140.
Pełny tekst źródłaWe developed a region of interest-based (ROIs) computer-aided diagnosis system (CAD) to characterize International Society of Urological Pathology grade (ISUP) ≥2 prostate cancers at multiparametric MRI (mp-MRI). Image parameters from two multi-vendor datasets of 265 pre-prostatectomy and 112 pre-biopsy MRIs were combined using logistic regression. The best models used the ADC 2nd percentile (ADC2) and normalized wash-in rate (WI) in the peripheral zone (PZ) and the ADC 25th percentile (ADC25) in the transition zone (TZ). They were combined in the CAD system. The CAD was retrospectively assessed on two multi-vendor datasets containing respectively 158 and 105 pre-biopsy MRIs from our institution (internal test dataset) and another institution (external test dataset). Two radiologists independently outlined lesions targeted at biopsy. The Prostate Imaging-Reporting and Data System version 2 (PI-RADSv2) score prospectively assigned at biopsy and the CAD score were compared to biopsy findings. At patient level, the areas under the Receiver Operating Characteristic curve (AUC) of the PI-RADSv2 score were 82% (95% CI: 74-87) and 85% (95% CI: 79-91) in the internal and external test datasets respectively. For both radiologists, the CAD score had similar AUC results in the internal (82%, 95% CI: 76-89, p=1; 84%, 95% CI: 78-91, p=1) and external (82%, 95% CI: 76-89, p=0.82; 86%, 95% CI: 79-93, p=1) test datasets. Combining PI-RADSv2 and CAD findings could have avoided 41-52% of biopsies while missing 6-10% of ISUP≥2 cancers. The CAD system confirmed its robustness showing good discrimination of ISUP ≥2 cancers in a multicentric study involving 22 different scanners with highly heterogeneous image protocols. In per patient analysis, the CAD and the PI-RADSv2 had similar AUC values (76%, 95% CI: 70-82 vs 79%, 95% CI: 73-86; p=0.34) and sensitivities (86%, 95% CI: 76-96 vs 89%, 95% CI: 79-98 for PI-RADSv2 ≥4). The specificity of the CAD (62%, 95% CI: 53-70 vs 49%, 95% CI: 39-59 for PI-RADSv2 ≥4) could be used to complement the PI-RADSv2 score and potentially avoid 50% of biopsies, while missing 13% of ISUP ≥2 cancers. These findings were very similar to those reported in the single center test cohorts. Given its robustness, the CAD could then be exploited in more specific applications. The CAD first provided good discrimination of ISUP ≥2 cancers in patients under Active Surveillance. Its AUC (80%, 95% CI: 74-86) was similar to that of the PI-RADS score prospectively assigned by specialized uro-radiologists at the time of biopsy (81%, 95% CI: 74-87; p=0.96). After dichotomization, the CAD was more specific than the PI-RADS ≥3 (p<0.001) and the PI-RADS ≥4 scores (p<0.001). It could offer a solution to select patients who could safely avoid confirmatory or follow-up biopsy during Active Surveillance (25%), while missing 5% of ISUP≥2 cancers. Finally, the CAD was tested with the pre-prostatectomy mp-MRIs of 56 Japanese patients, from a population which is geographically distant from its training population and which is of interest because of its low prostate cancer incidence and mortality. The CAD obtained an AUC similar to the PI-RADSv2 score assigned by an experience radiologist in the PZ (80%, 95% CI: 71-90 vs 80%, 95% CI: 71-89; p=0.886) and in the TZ (79%, 95% CI: 66-90 vs 93%, 95%CI: 82-96; p=0.051). These promising and robust results across heterogeneous datasets suggest that the CAD could be used in clinical routine as a second opinion reader to help select the patients who could safely avoid biopsy. This CAD may assist less experience readers in the characterization of prostate lesions
Moraes, M?rcia Cristina Gon?alves de Oliveira. "O estudo da acur?cia da resson?ncia magn?tica multiparam?trica no diagn?stico do c?ncer de pr?stata". Pontif?cia Universidade Cat?lica do Rio Grande do Sul, 2017. http://tede2.pucrs.br/tede2/handle/tede/8227.
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Abstract: Today, the incidence of prostate cancer is considered high, however, unlike other malignant tumours, there is an expressive number of cases in which prostate cancer does not progress to clinical disease. The management of patients with prostate cancer should be individually fitted due to the broad behaviour spectrum of this cancer, ranging from low grade tumours with low aggressive biological characteristics to high grade tumours with metastatic capacity. The possibility of predicting the future behavior of the disease allows the selection of the most appropriate conduct for each case. Studies have shown that mpMRI (multiparametric Magnetic Resonance Imaging) has a high negative predictive value for clinically significant prostate cancer, indicating that its application as a screening method and as assessment method of disease progression is promising. To standardize the protocols and reports of prostate mpMRI, the PI-RADS v2 (Prostate Imaging Reporting and Data System version 2) was launched in 2015. Multiparametric Magnetic Resonance Imaging standardized by PI-RADSv2 has been taking a prominent place in the management of prostate cancer, but the specificity and positive predictive value still need to be improved. Purpose: To assess whether the ADC (Apparent diffusion coefficient) value and tumour ADC ratio associated with PI-RADS v2 may increase accuracy in predicting clinically significant prostate cancer. Materials and methods: 91 individuals with suspected prostate cancer were retrospectively studied through mpMRI imaging standardized by PI-RADS v2, obtaining the ADC value from the tumour and the contralateral tissue. The findings were correlated to anatomopathological study (biopsy, prostatectomy or transurethral resection). Results: Accuracy, sensitivity, specificity, positive predictive value and negative predictive value for the consensus between the two reviewers using PI-RADS v2, category 3 associated with categories 4 and 5 for the detection of clinically significant cancer were 70.3%, 97.4%, 50.9%, 58.7% and 96.4% (p <0.001), respectively. The association of the ADC value (<0.795x10-3) to categories 3, 4 and 5 of the PI-RADSv2, in turn, demonstrated accuracy, specificity and positive predictive value of 78.9%, 84.9% and 76.5%; and the association with the tumour ADC ratio (<0.62) presented 77.5%, 86.5% and 77.4% of accuracy, specificity and positive predictive value, respectively. Conclusion: The association of the ADC value and the tumour ADC ratio to the PI-RADS v2 in mpMRI increases the accuracy, specificity and positive predictive value in the detection of aggressive prostate cancer, and may help in the screening of individuals who would undergo invasive procedures and radical therapy, or conservative management, as active surveillance or watchful waiting.
Introdu??o: ? considerada alta a incid?ncia de c?ncer de pr?stata na atualidade, contudo, diferentemente de outras neoplasias, existe um n?mero expressivo de casos em que o c?ncer de pr?stata n?o evolui para a doen?a cl?nica. Por este motivo, o manejo dos pacientes com neoplasia prost?tica deve ser moldado individualmente face ao amplo espectro que varia desde tumores de baixo grau, com caracter?sticas biol?gicas de baixa agressividade, a tumores de alto grau, com capacidade metast?tica. A possibilidade de prever o comportamento futuro da doen?a permite a sele??o da conduta mais adequada para cada caso. Estudos vem comprovando que a Resson?ncia Magn?tica multiparam?trica (RMmp) apresenta um alto valor preditivo negativo para o c?ncer de pr?stata com signific?ncia cl?nica, indicando que sua aplica??o como m?todo de triagem e na avalia??o da progress?o da doen?a ? promissora. Para padronizar os protocolos e os relat?rios da RMmp da pr?stata foi lan?ado em 2015 o PI-RADS v2 (?Prostate Imaging Reporting and Data System? vers?o 2). A RMmp padronizada pelo PI-RADS v2 vem assumindo um lugar de destaque no manejo do c?ncer de pr?stata, contudo, ainda s?o considerados baixos a Especificidade e o Valor Preditivo Positivo. Objetivos: Avaliar se o valor de ADC (?Apparent diffusion coefficient? = Coeficiente de Difus?o Aparente) e a raz?o tumoral do ADC associados ao PI-RADS v2 podem aumentar a acur?cia da RMmp na predi??o do c?ncer de pr?stata com signific?ncia clinica. Materiais e m?todos: Foram estudados retrospectivamente 91 indiv?duos com suspeita de c?ncer de pr?stata, submetidos a RMmp padronizada pelo PI-RADS v2, obtendo-se o ADC quantitativo da les?o e do tecido contralateral. Os achados foram correlacionados ao estudo anatomopatol?gico (bi?psia, prostatectomia ou ressec??o transuretral). Resultados: A acur?cia, sensibilidade, especificidade, valor preditivo positivo e valor preditivo negativo para o consenso entre os dois avaliadores utilizando a RMmp padronizada pelo PI-RADS v2, com a categoria 3 associada as categorias 4 e 5 para a detec??o do c?ncer com signific?ncia cl?nica foram 70,3%; 97,4%; 50,9%; 58,7% e 96,4% (p<0,001), respectivamente. A associa??o do valor do ADC (<0,795x10-3) ?s categorias 3, 4 e 5 do PI-RADS v2, por sua vez, demonstrou acur?cia, especificidade e valor preditivo positivo de 78,9%; 84,9% e 76,5%; e a associa??o com a raz?o tumoral do ADC (< 0,62), apresentou 77,5%; 86,5% e 77,4% de acur?cia, especificidade e valor preditivo positivo, respectivamente. Conclus?o: A associa??o do valor do ADC e da raz?o tumoral do ADC ao PI-RADS v2 na RMmp aumenta a acur?cia, especificidade e valor preditivo positivo na detec??o do c?ncer agressivo da pr?stata, podendo auxiliar na triagem dos indiv?duos e na decis?o entre a conduta agressiva, com procedimentos invasivos e terapia radical, ou a conduta conservadora, com vigil?ncia ativa ou observa??o.
Demir, Ayhan. "Apport de l'imagerie de diffusion avec calcul du coefficient apparent de diffusion et du tenseur de diffusion dans la myélopathie cervicarthrosique". Bordeaux 2, 2000. http://www.theses.fr/2000BOR23058.
Pełny tekst źródłaSilva, Matthew S. "NMR characterization of changes in the apparent diffusion coefficient of water following transient cerebral ischemia". Link to electronic thesis, 2002. http://www.wpi.edu/Pubs/ETD/Available/etd-0327102-221251.
Pełny tekst źródłaIima, Mami. "Apparent Diffusion Coefficient as an MR Imaging Biomarker of Low-Risk Ductal Carcinoma in Situ: A Pilot Study". Kyoto University, 2014. http://hdl.handle.net/2433/188640.
Pełny tekst źródłaGauthier, Yvan. "Measurement of the apparent diffusion coefficient of water in white matter using magnetic resonance imaging, a phantom study". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0016/MQ48500.pdf.
Pełny tekst źródłaUmemura, Atsushi. "Diagnostic Accuracy of Apparent Diffusion Coefficient and 123I-Metaiodobenzylguanidine for Differentiation of Multiple System Atrophy and Parkinson's Disease". Kyoto University, 2015. http://hdl.handle.net/2433/200316.
Pełny tekst źródłaPathak, Ryan. "Investigating methods to improve sensitivity of the Apparent Diffusion Coefficient, a potential imaging biomarker of treatment response, for patients with colorectal liver metastasis". Thesis, University of Manchester, 2018. https://www.research.manchester.ac.uk/portal/en/theses/investigating-methods-to-improve-sensitivity-of-the-apparent-diffusion-coefficient-a-potential-imaging-biomarker-of-treatment-response-for-patients-with-colorectal-liver-metastasis(cf5b0308-7959-40ea-832e-862b7b816e26).html.
Pełny tekst źródłaMosavi, Firas. "Whole-Body MRI including Diffusion-Weighted Imaging in Oncology". Doctoral thesis, Uppsala universitet, Enheten för radiologi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-209777.
Pełny tekst źródłaRosso, Charlotte. "Prédiction de la récupération après un accident ischémique carotidien grâce à la séquence de diffusion : de la pénombre ischémique aux échelles cliniques". Paris 6, 2009. http://www.theses.fr/2009PA066299.
Pełny tekst źródłaHimoto, Yuki. "Pretreatment Mean Apparent Diffusion Coefficient Is Significantly Correlated With Event-Free Survival in Patients With International Federation of Gynecology and Obstetrics Stage Ib to IIIb Cervical Cancer". Kyoto University, 2016. http://hdl.handle.net/2433/215383.
Pełny tekst źródłaKyoto University (京都大学)
0048
新制・課程博士
博士(医学)
甲第19557号
医博第4064号
新制||医||1013(附属図書館)
32593
京都大学大学院医学研究科医学専攻
(主査)教授 武藤 学, 教授 平岡 眞寛, 教授 古川 壽亮
学位規則第4条第1項該当
Hevia, Montiel Nidiyare. "Analyse de l'imagerie par résonance magnétique du coefficient apparent de diffusion pour l'évaluation en phase aiguë du potentiel de croissance des infarctus cérébraux". Paris 11, 2006. http://www.theses.fr/2006PA112112.
Pełny tekst źródłaWe introduce a new approach to the prediction of the final infarct growth in human acute ischemic stroke based on image analysis of the Apparent Diffusion Coefficient (ADC) MR maps acquired in the acute stage. The ADC maps are likely to reveal brain regions belonging to the ischemic penumbra, that is, areas that will certainly may be affected by the infarction in the following next few hours. In a context where “time is brain”, and contrarily to the much explored – though still-debated – perfusion-diffusion mismatch approach, the ADC MR sequences are fast to acquire and do not necessitate injection of a contrast agent. Image analysis consists of the segmentation of the ischemic penumbra using a fast 3D region-growing infarct approach. Retrospective evaluation on 77 patients has shown that our methodlology is superior to the alternative techniques with much less practical constraints to the clinical environment
Nguyen, Huyen Thanh. "Dynamic Contrast-Enhanced MRI and Diffusion-Weighted MRI for the Diagnosis of Bladder Cancer". The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1365176629.
Pełny tekst źródłaJelescu, Ileana O. "Magnetic resonance microscopy of Aplysia neurons : studying neurotransmitter-modulated transport and response to stress". Phd thesis, Université Paris Sud - Paris XI, 2013. http://tel.archives-ouvertes.fr/tel-00979419.
Pełny tekst źródłaValfouskaya-Fonade, Alena. "Modélisation numérique de la diffusion en milieux poreux : applications à la résonance magnétique nucléaire". Paris 6, 2005. http://www.theses.fr/2005PA066363.
Pełny tekst źródłaAtstupėnaitė, Vaida. "Magnetinio rezonanso tomografijos reikšmė vertinant gimdos kaklelio vėžio išplitimą ir chemospindulinio gydymo efektyvumą". Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2011. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2011~D_20110922_122611-36279.
Pełny tekst źródłaMagnetic resonance imaging (MRI) is the optimal method for evaluation of spread of cervical cancer. Only a few diffusion–weighted (DW) MRI studies in the field of cervical cancer have been accomplished around the world. Most of them included a small number of subjects. This is the first clinical study in Lithuania that assesses the cervical cancer by DW–MRI and it has the scientific value in optimizing the use of MRI potential in the evaluation of the diagnostics and treatment efficiency of the mentioned illness. The aim – to identify the significance of conventional and DW–MRI in the assessment of the outspread of cervical cancer and of the efficiency of chemoradiation therapy. The objectives: 1. To assess the interrelationship of prognostic factors of cervical cancer detected by conventional MRI with clinical and histological findings. 2. To calculate the diagnostic value parameters of conventional MRI for the malignant cervical tumor and for the residual tumor tissue after chemoradiation therapy. 3. To compare the mean value of apparent diffusion coefficient (ADC) in a healthy, cancer affected cervix and the cervix after chemoradiation therapy. To identify the value range of ADC typical for cervical cancer. To evaluate the correlation of ADC with the various clinical and histological findings. 4. To calculate the diagnostic value parameters of conventional and DW–MRI combination for the malignant cervical tumor and for the residual tumor tissue after chemoradiation therapy... [to full text]
Najac, Chloé. "Spectroscopie RMN du 1H pondérée en diffusion, du 13C et du 17O : développements méthodologiques pour l’étude de la structure et de la fonction cellulaire in vivo". Thesis, Paris 11, 2014. http://www.theses.fr/2014PA112242/document.
Pełny tekst źródłaMagnetic Resonance Spectroscopy is a unique tool that allows acquiring brain biochemical profiles and quantifying many cellular parameters in vivo. During this thesis, three different techniques have been developed: (i) 1H diffusion-weighted, (ii) carbone-13 (13C) and (iii) oxygen-17 (17O) NMR spectroscopy to study brain structure and function in vivo. Brain metabolites are cell-specific endogeneous tracers of the intracellular space whose translational diffusion depends on many cellular properties (e.g.: cytosol vicosity and intracellular restriction). Studying the variation of the diffusion coefficient (ADC) as a function of diffusion time (td) allows untangling and quantifying those parameters. In particular, measuring metabolites ADC at long diffusion times gives information about the metabolites compartmentation in cells. In a first study, we measured neuronal and astrocytic metabolites ADC over a large time window (from ~80 ms to ~1 s) in a large voxel in the macaque brain. No dependence of all metabolites ADC on td was observed suggesting that metabolites primarily diffuse in neuronal (dendrites and axons) and astrocytic processes and are not confined inside the cell body and organelles (nucleus, mitochondria). The large size of the voxel, due to low detection sensitivity, did not allow us to study metabolites compartmentation in pure white (WM) and grey matters (GM). Therefore, we performed a new study in the human brain. Results showed that in both WM and GM metabolites diffuse in fiber-like cell structure. Finally, using an even larger time window (up to 2 s) in the macaque brain and analytical models mimicking the cell structure, we estimated the length of neuronal (~110 μm) and astrocytic (~70 μm) processes. ATP (adenosine triphosphate), the main source of energy in the organism, is produced thanks to glucose oxidation inside the mitochondria. 13C NMR spectroscopy is a well-known technique to study brain energy metabolism and can be used to estimate the rate of glucose degradation within the Krebs cycle (VTCA). However, many limitations, concerning data modeling when performing indirect detection or power deposition due to heteronuclear decoupling during direct detection, were encountered on our MRI scanner. Therefore, 17O NMR spectroscopy was developed to quantify the rate of oxygen consumption during oxidative phosphorylation (CMRO2). Methodological and technological developments were necessary and are still ongoing to validate this technique, which has never been used with macaque
BRESCHI, GIAN LUCA. "STUDIO ANATOMICO E FUNZIONALE DELLA REGIONE DI PENOMBRA IN UN MODELLO DI ISCHEMIA IN VITRO". Doctoral thesis, Università degli Studi di Milano, 2013. http://hdl.handle.net/2434/215236.
Pełny tekst źródłaKebe, Mouhamadou. "Incidence de traitements thermiques sur le parenchyme de Pomme (Malus Domestica) et diffusion des composés phénoliques". Thesis, Avignon, 2014. http://www.theses.fr/2014AVIG0253/document.
Pełny tekst źródłaApple (Malus domestica Borkh. ) fruit widespread in temperate countries, is much consumed.It represents an important source of phenolic compounds. This study was interestedin polyphenol content of apple tissue parenchyma. The problem concerns effects of texturedegradation on the diffusion of polyphenols molecules. The originality of the approach isbased on the combination of texture, osmotic pressure and polyphenol leaching. Physicaland biochemical methods were used to measure changes at macroscopic scale and chemicalchanges occurring in the parenchymateous tissue . The study of mass transfer highlightedvarious factors that may affect apparent coefficient diffusion. The result showed that thedisintegration of texture , thickness, apple variety and osmotic pressure of leaching mediacan influence mass transfer yield. The study of the Cell walls components showed changesthat occur during leaching process. Light microscopic analysis revealed changes at cellularscale, procyanidins the major polyphenols, leaching phenomena and also interactionswith cell walls matrix
Dieckmeyer, Michael [Verfasser], Thomas [Akademischer Betreuer] Baum, Dimitrios C. [Gutachter] Karampinos, Jan S. [Gutachter] Kirschke i Thomas [Gutachter] Baum. "Quantitative Magnetic Resonance Imaging and Spectroscopy of Vertebral Bone Marrow: Addressing Confounding Effects in the Measurement of Fat Fraction and Apparent Diffusion Coefficient / Michael Dieckmeyer ; Gutachter: Dimitrios C. Karampinos, Jan S. Kirschke, Thomas Baum ; Betreuer: Thomas Baum". München : Universitätsbibliothek der TU München, 2019. http://d-nb.info/1201086248/34.
Pełny tekst źródłaDubois, Justin. "Caractérisation et optimisation d'un réacteur pour l'ingénierie tissulaire 3D". Mémoire, Université de Sherbrooke, 2011. http://savoirs.usherbrooke.ca/handle/11143/1641.
Pełny tekst źródłaOliveira, Tatiane Mendes Gonçalves de. "Associação entre os valores do coeficiente de difusão aparente nas imagens de ressonância magnética ponderadas em difusão e marcadores prognósticos e de células tronco tumorais no câncer de mama em pacientes que realizaram quimioterapia neoadjuvante". Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/17/17145/tde-28072016-092219/.
Pełny tekst źródłaThe diffusion-weighted magnetic resonance imaging (DWMRI) is a functional technique able to reflect structural and cellular changes in the tumors. In the breast cancer, the diffusion-weighted images and its numeric value known as the apparent diffusion coefficient (ADC) has been applied to evaluate pathologic response in patients treated with neoadjuvant chemotherapy (NC). The difference in the clinical results after breast cancer treatment, including different rates of responses to the NC has been associated to the heterogeneity of the disease. The presence of the breast cancer stem cells (BCSC) is an accepted hypothesis to explain the different biologic breast cancers behaviors. The aim of this study was to correlate the ADC value of invasive breast cancer with the presence of cancer stem cells markers and the major prognostic factors in patients treated with neoadjuvant chemotherapy. Prospectively, the MRI pre-treatment of twenty-seven consecutive patients with invasive breast cancer posteriorly treated with NC followed by surgery were evaluated. The ADC values mean, 10th percentile, 25th percentile, 50th percentile were obtained from two measurements, one of them with a unique ROI and the other with multiple ROIs encompassing the entire lesion. The ADC values were correlated to: presence of BCSCs (cell surface markers CD44+/CD24-, ABCG2 and ALDH1) identified by flow cytometric analysis, tumor grade, breast cancer staging, lymph nodal involvement, expression of estrogen receptors (ER), expression of progesterone receptors (PR) and expression of HER2. The assay mammospheres (Mammocult ®) were analyzed in 18 samples. Additionally, the ADC values were correlated to the pathologic complete response after QN treatment. There were no correlations between ADC values and breast cancer stem cells markers or mammospheres formation efficiency. For all parameters calculated, the ADC values (x10- 3 mm 2 /s) were lower in: breast cancer stage III and IV than stage II (0,90±0,16; 1,02±0,18), tumors with lymph node metastasis than without lymph node metastasis (0,89±0,16; 1,01±0,17), ER expression than ER negative (0,90±0,16; 1,00±0,18), PR expression than PR 10 negative (0,91±0,16; 0,98±0,18) and HER2 expression than HER2 negative (0,92±0,17; 0,97±0,18). The ADC values were significantly higher in grade-1 tumors (difference 0,18; CI: 0,03-0,33) compared to grade-2 tumors (p=0,02). The tumors values of ADC pretreatment were not correlated to the pathologic complete response after NC. The ADC values in pre-treatment invasive breast cancers are not a predictor of BCSC presence, mammospheres formation efficiency or pathologic complete response to QN. However it is correlated to the tumor grade, breast cancer staging, lymph nodal involvement, expression of ER, PR and HER2 and may represent a promising marker of tumor aggressiveness
Wu, Evan. "Integrated Study of Rare Earth Drawdown by Electrolysis for Molten Salt Recycle". The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1503267714820028.
Pełny tekst źródłaTeixeira, Sara Reis. "Contribuição dos métodos de imagem no estudo das glândulas suprarrenais em pacientes com hiperplasia congênita de suprarrenal, com ênfase nas técnicas quantitativas por ressonância magnética". Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/17/17138/tde-21102014-224356/.
Pełny tekst źródłaCongenital adrenal hyperplasia (CAH) is an autossomic recessive disorder caused by impaired steroidogenesis. A morphological hallmark in CAH is enlarged adrenal glands. Imaging studies have addressed mainly morphological aspects and dimensions of the adrenal glands, which correlate to the patients hormonal statuses. However, no imaging technique was used to evaluate changes in the adrenal glands at a cellular level in these patients. Diffusion-weighted magnetic resonance imaging (DWI) is a magnetic resonance imaging (MRI) technique with the ability to provide quantitative information about intracellular and extracellular space, given by the apparent diffusion coefficient (ADC) values. The role of ADC in evaluation of adrenal lesions has already been studied. However, ADC of the normal adrenals has not yet been described. The main purposes of this study were: to investigate the role of imaging in CAH, to validate the method of calculating ADC values of the normal adrenal glands and to assess hormonal status in patients with CAH and its correlation to quantitative MRI. This is an article-based thesis divided in three articles. The first article, The role of imaging in congenital adrenal hyperplasia, is a systematic review of imaging in congenital adrenal hyperplasia, with emphasis on genitography, ultrasonography, computed tomography and MRI. The article Apparent diffusion coefficient (ADC) of the normal adrenal glands: premilinary results aimed to validate the method of measuring ADC of the adrenal glands. The study of quantitative parameters (ADC, volume and linear measurements) of the adrenals evaluated by MRI that correlate with hormonal status in patients with CAH is described in the third article, Quantitative magnetic resonance imaging in evaluation of the adrenal glands in children and young adults with congenital adrenal hyperplasia due to 21-hydroxylase deficiency. Measuring ADC of the normal adrenal glands is feasible and reproducible. In healthy subjects, ADC values were significantly lower after adrenarche. However, neither a difference between ADC values of controls and patients, nor correlations with patients hormonal statuses were found. Volume and linear measurements of the adrenal glands were the best parameter to differentiate patients from controls. Moreover, a positive correlation was found between short-term hormonal control status and adrenal size. Adrenal size assessed by MRI might be a useful tool in the follow-up of patients with CAH. Although adrenal cell structure modifications in patients with CAH have been described, they were not detectable by DWI.
Yusuf, Kehinde Quasim. "An exploratory study of the potential of resurfacing articular cartilage with synthetic phospholipids". Thesis, Queensland University of Technology, 2013. https://eprints.qut.edu.au/63317/1/Kehinde_Yusuf_Thesis.pdf.
Pełny tekst źródłaIbarrola, Danielle. "Application des techniques d'imagerie par résonance magnétique nucléaire à l'étude préclinique de l'ischémie cérébrale focale : action d'un agent de contraste superparamagnétique et essai pharmacologique de l'effet d'un antagoniste du récepteur NMDA chez le rat in vivo". Université Joseph Fourier (Grenoble), 1997. http://www.theses.fr/1997GRE19003.
Pełny tekst źródłaBandola, Nicolas. "Diffusion in inhomogenous media". Master's thesis, 2009. http://hdl.handle.net/10155/78.
Pełny tekst źródłaUOIT
Goßrau, Peter [Verfasser]. "Wertigkeit des apparent diffusion coefficient (ADC) in der Funktionsdiagnostik der großen Speicheldrüsen und der Beurteilung pathologischer Veränderungen mittels Magnetresonanztomographie bei 1,5T und 3T / vorgelegt von Peter Goßrau". 2005. http://d-nb.info/976606933/34.
Pełny tekst źródłaΤσέκα, Σοφία. "Απεικόνιση σταθμισμένης διάχυσης στη [sic] τομογραφία πυρηνικού μαγνητικού συντονισμού του μαστού". Thesis, 2014. http://hdl.handle.net/10889/8003.
Pełny tekst źródłaΟ καρκίνος του μαστού είναι ένα σημαντικό παγκόσμιο πρόβλημα υγείας και η πιο διαδεδομένη μορφή καρκίνου στον γυναικείο πληθυσμό. Η ολοένα και πιο έγκαιρη διάγνωση του καρκίνου του μαστού έχει οδηγήσει σε σημαντική βελτίωση του ρυθμό θεραπείας της νόσου. Σημαντικές πρόοδοι στην τεχνολογία της απεικόνισης παρέχουν τη βελτιωμένη ανίχνευση και ευαισθησία του καρκίνου και οδηγούν σε όλο ένα και λιγότερες περιττές βιοψίες. Οι πιο συνηθισμένες μέθοδοι απεικόνισης, που χρησιμοποιούνται, περιλαμβάνουν την Μαστογραφία, την Υπερηχογραφία, την Μαγνητική Τομογραφία (MRI), την σπινθηρομαστογραφία, την Τομογραφία Εκπομπής Φωτονίων (SPECT) και την Τομογραφία Εκπομπής Ποζιτρονίων (PET). Η παρούσα μελέτη επικεντρώνεται στην τεχνολογία της Απεικόνισης Μαγνητικού Συντονισμού ειδικά σε μία πρόσφατη και ελπιδοφόρα τεχνική απεικόνισης του καρκίνου του μαστού, που ονομάζεται Απεικόνιση Σταθμισμένης Διάχυσης στη Τομογραφία Πυρηνικού Μαγνητικού Συντονισμού (Diffusion Weighted Imaging breast MRI (DWI)). Η DWI είναι μια MRI ακολουθία χωρίς χρήση σκιαγραφικής ουσίας, η οποία βασίζεται σε αλληλουχίες για διάφορες τιμές του παράγοντα διάχυσης b (η τιμή b προσδιορίζει την διαχυτότητα και καθορίζει την ένταση και τη διάρκεια των βαθμωτών πεδίων διάχυσης). Η DWI ποσοστικοποιεί την κινητικότητα των μορίων του νερού (Brownian κίνηση) in vivo (σε ιστούς) και παρέχει διαφορετικές και ενδεχομένως συμπληρωματικές πληροφορίες στην μαστογραφία μαγνητικής τομογραφίας με χρήση σκιαγραφικού (Dynamic Contrast-Enhanced Magnetic Resonance Imaging: DCE-MRI). Η DWI με βάση τις ιδιότητες διάχυσης των μορίων του νερού, αντανακλά την τυχαία κίνησής τους λόγω της θερμικής τους ενέργειας. Η διάχυση του νερού στον μαστό μπορεί να ποσοτικοποιηθεί με τη μέτρηση της μέσης διαχυτότητας, η οποία αναφέρεται ως Φαινόμενος Συντελεστής Διάχυσης (Apparent Diffusion Coefficient-ΑDC). Ο ADC υπολογίζεται ύστερα από μετρήσεις για δυο b τιμές, μια χαμηλή b1 και μια υψηλότερη b2 τιμή. Η DWI επιτρέπει την χαρτογράφηση της διάχυσης των μορίων του νερού μέσω του ADC χάρτη. Ο ADC χάρτης είναι μια παραμετρική εικόνα της οποίας η κλίμακα χρωμάτων ή κλίμακα των τόνων του γκρι, αντιπροσωπεύει τις ADC τιμές των voxels και συνήθως παράγεται από λογισμικό. Οι παραμετρικοί ADC χάρτες απεικόνισης DWI αναπαριστούν τη μικροδομή των ιστών για διάφορους συνδυασμούς τιμών της παραμέτρου b. Η DWI εκτός από 3D ανατομική πληροφορία, παρέχει μια μη επεμβατική διερεύνηση της αγγειοβρίθειας του ιστού, έναν νέο μηχανισμό αντίθεσης στην MRI, και χαρακτηρίζεται από υψηλή ευαισθησία στην ανίχνευση ενδεχόμενων αλλαγών στο τοπικό βιολογικό περιβάλλον, οι οποίες οφείλονται σε παθολογία. Ως εκ τούτου, εκτός από τον χαρακτηρισμό αλλοιώσεων βάση σκιαγραφικής ενίσχυσης (DCE - MRI), η ποσοτικοποίηση της κίνησης των μορίων του νερού στην DWI παρέχει επιπλέον στοιχεία για τον χαρακτηρισμό της αλλοίωσης, κάτι το οποίο μπορεί να αυξήσει περαιτέρω την ειδικότητα της MRI για την ταξινόμηση των αλλοιώσεων του μαστού. Το διαγνωστικό πρόβλημα το οποίο αντιμετώπισε/εστίασε η παρούσα διπλωματική εργασία, αφορά στο χαρακτηρισμό/διάγνωση χωροκατακτητικών αλλοιώσεων (mass-like) του μαστού στην Απεικονιση Μαγνητικου Συντονισμου Σταθμισμενης Διαχυσης (DWI) και την ποσοτικη αναλυση του Φαινομενου Συντελεστη Διαχυσης (ADC) για διαγνωση καρκινου του μαστου. Η ικανότητα διάχυσης των μορίων του νερού περιορίζεται σε περιβάλλον υψηλής κυτταροβρίθιας, ενδοκυττάριων και εξωκυττάριων οιδημάτων, υψηλού ιξώδους και ίνωσης, όπως συμβαίνει στους κακοήθεις όγκους, διότι οι παράγοντες αυτοί εμποδίζουν την κυκλοφορία των μορίων του νερού. Αποτέλεσμα αυτού είναι οι περισσότεροι καρκίνοι του μαστού να παρουσιάζουν χαμηλές ADC τιμές σε σύγκριση με τους καλοήθεις όγκους ή τον φυσιολογικό ιστό. Πολλές μελέτες έχουν δείξει τη χρησιμότητα των ADC τιμών στη διαφορική διάγνωση των αλλοιώσεων του μαστού. Εν τούτοις, το κλινικό αποτέλεσμα παραμένει περιορισμένο λόγω της σημαντικής επικάλυψης καλοήθων και κακοήθων αλλοιώσεων, γεγονός που αποτελεί πρόκληση για την εφαρμογή ενός χρήσιμου διαγνωστικού ορίου της μέσης ADC. Στη πλειοψηφία των μελετών, όπως και στη παρούσα μελέτη, τα βέλτιστα επίπεδα αποκοπής της ADC μεταξύ κακοήθων και καλοήθων αλλοιώσεων προσδιορίστηκαν με τη χρήση ROC ανάλυσης. Στις μέχρι τώρα μελέτες τα διαγνωστικά όρια της μέσης ADC κυμαίνονται από 0.90 έως 1.76 × 10-3 mm2 / s, με ευαισθησία και ειδικότητα να κυμαίνονται από 63% έως 100% και 46% έως 97%, αντίστοιχα. Γεγονός αποτελεί, επίσης, η διαφορετική μέθοδος υπολογισμού της ADC που ακολουθεί η κάθε μελέτη, με πιο συχνή μέθοδο, ο υπολογισμός της μέσης τιμής της ADC (μέση τιμή ± τυπική απόκλιση) σε μια περιοχή ενδιαφέροντος (ROI) μιας αλλοίωσης του μαστού. Σκοπός της παρούσας μεταπτυχιακής διπλωματικής εργασίας ήταν να διερευνηθεί η ικανότητα των χαρακτηριστικών ιστογράμματος του Φαινόμενου Συντελεστή Διάχυσης (Apparent Diffusion Coefficient-ADC) να διαφοροποιούν κακοήθεις από καλοήθεις αλλοιώσεις του μαστού στην Απεικόνιση Μαγνητικού Συντονισμού Σταθμισμένης Διάχυσης (Diffusion Weighted MRI-DWI). Για το σκοπό αυτό, δημιουργήθηκε ο ADC παραμετρικός χάρτης ο οποίος αποτέλεσε τη βάση για την εφαρμογή μεθόδου ανάλυσης υφής εικόνας, και τον υπολογισμό πέντε χαρακτηριστικών υφής πρώτης τάξης: την μέση τιμή, την τυπική απόκλιση, την κύρτωση, την λοξότητα και την εντροπία. Η προσέγγιση αυτή θεωρήθηκε ότι θα προσφέρει μια πιο ολοκληρωμένη αξιολόγηση της υφής του όγκου και της ετερογένειας. Η προσέγγιση εφαρμόσθηκε σε κλινικό δείγμα 92 ιστολογικά αποδεδειγμένων αλλοιώσεων του μαστού, οι οποίες προέρχονται από 69 γυναίκες οι οποίες είχαν νωρίτερα ανιχνευθεί μέσω μαστογραφίας ή/και υπερηχογραφίας ή από ψηλαφητά ευρήματα. Η ιστολογική εξέταση αποκάλυψε 53 κακοήθεις αλλοιώσεις που προέρχονταν από 45 γυναίκες και 39 καλοήθεις αλλοιώσεις από 26 γυναίκες. Όλες οι εξετάσεις μαγνητικής τομογραφίας του μαστού έγιναν με σύστημα MRI 3T και για b=0 και 900 s/mm2. Η διαγνωστική απόδοση/επίδοση των παραμέτρων αυτών συγκρίθηκε με την ανάλυση λειτουργικού χαρακτηριστικού δέκτη (ROC analysis). Τα αποτελέσματα υποδεικνύουν τον σημαντικό ρόλο της ανάλυσης ADC ιστογράμματος χρησιμοποιώντας τα 5 παραπάνω χαρακτηριστικά υφής για την ταυτοποίηση των αλλοιώσεων του μαστού. Οι μετρήσεις της μέσης τιμής, της λοξότητας και της εντροπία της ADC των καλοήθων και κακοήθων αλλοιώσεων του μαστού είχαν στατιστικώς σημαντική διαφορά. Ειδικότερα, η μέση ADC τιμή των καλοήθων όγκων [(1.470 ± 0.342) × 10-3 mm2/s] ήταν σημαντικά υψηλότερη από εκείνη των κακοήθων, [(0.965 ± 0.268) × 10-3 mm2/s, (ρ < 0.00001)]. Η λοξότητα της ADC των καλοήθων όγκων [-0.303 ± 0.584], διέφερε σημαντικά από εκείνη των κακοήθων, [0.210 ± 0.725. (ρ= 0.0008)]. Και η εντροπία της ADC των καλοήθων όγκων [4.794 ± 0.665], ήταν σημαντικά χαμηλότερη από εκείνη των κακοήθων, [5.569 ± 0.649, (ρ < 0.00001)]. Ωστόσο, η τυπική απόκλιση και η κύρτωση της ADC των καλοήθων και κακοήθων αλλοιώσεων του μαστού δεν είχαν στατιστικώς σημαντική διαφορά. Συγκεκριμένα, η τυπική απόκλιση της ADC των καλοήθων όγκων ήταν [(0.184 ± 0.999) × 10-3 mm2/s] ενώ των κακοήθων ήταν [(0.192 ± 0.151) × 10-3 mm2/s, (ρ = 0.6581)] και η κύρτωση της ADC των καλοήθων όγκων ήταν [3.003 ± 1.065] ενώ των κακοήθων ήταν [3.337 ± 1.334, (ρ = 0.0987)]. Η περιοχή κάτω από την ROC καμπύλη (AUC) για τη μέση ADC τιμή ήταν 0.862 ± 0.042 (95% διάστημα εμπιστοσύνης: 0.754, 0.925), για την λοξότητα της ADC ήταν 0.705 ± 0.054 (95% διάστημα εμπιστοσύνης: 0.589, 0.800) και για η εντροπία της ADC ήταν 0.800 ± 0.046 (95% διάστημα εμπιστοσύνης: 0.691, 0.874), και είχαν ως αποτέλεσμα μια καλή διαγνωστική απόδοση/ επίδοση της DWI για τις παραμέτρους αυτές. Από την άλλη πλευρά, η AUC με 0.527 ± 0.063 (95% διάστημα εμπιστοσύνης: 0.393, 0.640) και με 0.601 ± 0.061 (95% διάστημα εμπιστοσύνης: 0.470, 0.707) για την τυπική απόκλιση και την κύρτωση, αντίστοιχα, υποδηλώνει ένα βαθμό επικάλυψης στις ADC τιμές μεταξύ καλοήθων και κακοήθων όγκων. Τα βέλτιστα κατώφλια αποκοπής για διαφοροποίηση καλοήθων έναντι κακοήθων αλλοιώσεων καθορίστηκαν με τον εντοπισμό των σημείων όπου η ακρίβεια ήταν μέγιστη στις καμπύλες ROC. Από τη συγκεκριμένη μελέτη, προέκυψαν δύο τιμές κατωφλίου αποκοπής της μέσης ADC, με την ίδια ακρίβεια 83.15%. Το πρώτο κατώφλι με τιμή 1.21 x 10-3 mm2/s χαρακτηρίζεται με ευαισθησία 86.27% και ειδικότητα 78.95%. Και το δεύτερο κατώφλι με τιμή 1.32 x 10-3 mm2/s χαρακτηρίζεται με ευαισθησία 92.16% και ειδικότητα 71.05%. Το κατώφλι για την λοξότητα της ADC ήταν στα -0.06 με ακρίβεια 68.54%, ευαισθησία 66.03% και ειδικότητα 66.67%. Τέλος, προέκυψαν δύο τιμές κατωφλίου αποκοπής της εντροπίας της ADC με την ίδια ακρίβεια ακρίβεια 76.40%. Το πρώτο κατώφλι με τιμή 5.17 χαρακτηρίζεται με ευαισθησία 75.47% και ειδικότητα 71.80%. Και το δεύτερο κατώφλι με τιμή 5.21 χαρακτηρίζεται με ευαισθησία 73.59% και ειδικότητα 74.36%. Συμπερασματικά, τα αποτελέσματα της παρούσας μελέτης δείχνουν τη συνεισφορά των μεθόδων ανάλυσης υφής εικόνας στη Απεικονιση Μαγνητικου Συντονισμου Σταθμισμενης Διαχυσης (DWI) του μαστού για την ποσοτικοποίηση της ετερογένειας του ιστού, παρέχοντας σημαντικές πληροφορίες για τη διάγνωση του καρκίνου του μαστού. Η ανάλυση ιστογράμματος των ADC τιμών στον καρκίνο του μαστού έχει τη δυνατότητα διαφοροποίησης καλοήθων και κακοήθων όγκων, παρέχοντας πληροφορίες για το σύνολο του όγκου. Η μέση τιμή, η λοξότητα και η εντροπία του ADC είναι πολύτιμες παράμετροι που συσχετίζονται με παθολογικό χαρακτηρισμό των όγκων του μαστού. Αυτές οι 3 ADC παράμετροι αύξησαν σημαντικά την ποσοτική διαγνωστική απόδοση της DWI του μαστού και πιθανότατα να είναι αποτελεσματικές παράμετροι όσον αφορά τη διάκριση μεταξύ καλοήθων και κακοήθων αλλοιώσεων του μαστού Μελλοντικές προσπάθειες πρόκειται να εστιάσουν στη διερεύνηση της συσχέτισης των εξαχθέντων χαρακτηριστικών υφής με ιστοπαθολογικούς δείκτες, με σκοπό την περαιτέρω επιβεβαίωση των προτεινόμενων προσεγγίσεων και ενδεχομένως την χρήση συγκεκριμένων χαρακτηριστικών υφής ως μη επεμβατικών προγνωστικών δεικτών καρκίνου του μαστού.
LEE, LI-YU, i 李莉淯. "Application of Apparent Diffusion Coefficient map and Magnetic Resonance Spectroscopy in glioma classification". Thesis, 2018. http://ndltd.ncl.edu.tw/handle/nbnmx5.
Pełny tekst źródła元培醫事科技大學
醫學影像暨放射技術系碩士班
106
Glioma is the most common malignant brain tumor. According to its degree of malignancy, the World Health Organization divided it into four levels, and there are differences in tumor invasion trends between different levels, suggesting different prognosis and treatment options. The histopathology of tumor standard examination generally gave sampling errors. Therefore, magnetic resonance imaging (MRI) has been widely used in brain tumor evaluation in recent years, providing non-invasive and high-resolution brain imaging, assisting clinical identification and classification, and as a therapeutic evaluation and long-term evaluation. The MRI images of patients with gliomas confirmed by pathological section were collected in this retrospective study of Taipei Veterans General Hospital since April 2010 for eight years. These images were obtained using the GE 1.5 T system. Patients were aged 30 to 64 years old and there are 70 cases in total. According to the tumor levels, the patient's apparent diffusion coefficient map (ADC map) and the pre-operative magnetic resonance spectrum (MRS) were combined with gender, age, height, weight, body mass index and body surface area for statistical analysis. Alpha reliability, one way-ANOVA, receiver operating characteristic curve (ROC) and Pearson’s correlation analysis on differential staging showed that the diagnostic benefit of MRS was better than ADC map, and the differential diagnoses were highly or moderately correlated with most of the MRS metabolites and ADC. An ADC map (p < 0.05) with 120% tumor area preoperatively selected was more appropriate determined by multivariate analysis. In addition, the ADC map has excellent tracking benefit in the paired sample t-test. By the way, the ADCs of preoperative/postoperative lesions (p ≦ 0.001, r = 0.23) and preoperative disease/health ratio to postoperative disease/health ratio (p ≦ 0.001, r = 0.45) showed low and medium correlation, respectively. Finally, the ROC test is used to calculate the thresholds and analyze the diagnostic efficacy. It is found that the MRS metabolites ratio are more suitable for disease diagnoses, while the MRS single metabolite concentrations are more suitable for identifying the tumor stage. Overall, MRS has better sensitivity, while ADC has better specificity. These two techniques complement with each other, which can effectively improve the diagnostic value and implement precise treatment goals.
Filipe, João Pedro dos Santos. "Diffusion-weighted imaging of the liver : value of apparent diffusion coefficient and influence of region of interest". Master's thesis, 2011. http://hdl.handle.net/10316/83809.
Pełny tekst źródłaPurpose: To measure apparent diffusion coefficient (ADC) values of liver parenchyma and focal hepatic lesions (FHL), investigate the utility of ADC for the differential diagnosis of hepatic findings, and determine the influence of region of interest (ROI) characteristics in the overall ADC measurements. Materials and Methods: Ninety-three patients (47 men, 46 women; mean age, 58 years) with at least one FHL ≥ 10 mm, or parenchyma abnormalities, were retrospectively evaluated. Reference standard for diagnosis was obtained from histopathologic data, consensus between imaging methods, follow-up imaging and patient clinical history. A total of 90 lesions were evaluated: 14 hepatocellular carcinomas (HCC), 18 metastases, 10 focal nodular hyperplasias (FNH), 4 adenomas, 30 hemangiomas and 14 cysts. Respiratory-Triggered (RT) DWI was performed using b-values of 50 and 700 s/mm2. ADC was measured in hepatic parenchyma by placing ROIs in four different segments, and in FHL by using three circular 1 cm2 ROIs and one ROI encompassing all lesion volume. Data was statistically compared in SPSS software using the Mann-Whitney and Friedman tests. Wilcoxon test was used to confirm ROI influence and receiver operating characteristic (ROC) curve was analyzed to evaluate the utility of ADC for diagnosis of malignancy. P<0.05 was significant. Results: Mean ADCs (×10−3mm2/s) were 1.45, 1.28 and 1.25 for normal, cirrhotic and steatotic liver parenchyma and 1.16, 1.18, 1.30, 1.64, 1.89 and 2.77 for metastases, HCCs, adenomas, FNHs, hemangiomas and cysts, respectively. Parenchyma ADCs in segment II were significantly higher than in any other region. ADCs of malignant lesions were significantly lower than those of benign lesions (p<0.001). Individually, ADCs of Cysts were significantly higher than all other lesions except hemangiomas. There was significant overlap between benign solid lesions and malignant lesions and between HCCs and cirrhotic parenchyma. The area under the curve for diagnosis of malignancy was 0.939, with sensitivity of 89.7% and specificity of 90.6%, using a cutoff ADC of 1.43×10−3 mm2/s. No significant difference was found between the different ROI sampling methods, but only homogeneous lesions were studied. Conclusion: We concluded that (a) quantitative measurements of ADC can be useful in differentiating normal from pathological liver parenchyma and in the characterization of focal hepatic lesions, (b) left hepatic lobe is more subject to cardiac motion artifacts, and (c) the size of ROI does not influence ADC measurements in homogeneous lesions
Objectivo: Medir o coeficiente de difusão aparente (ADC) do parênquima hepático e de lesões hepáticas focais (LHF), investigar a utilidade do ADC no diagnóstico diferencial de lesões hepáticas e determinar a influência das características da região de interesse (ROI) nos valores de coeficiente obtidos. Materiais e Métodos: Noventa e três doentes (47 homens, 46 mulheres; idade média, 58 anos) com pelo menos uma LHF maior ou igual que 10 mm, ou parênquima patológico, foram retrospectivamente avaliados. Confirmação diagnóstica foi obtida por histopatologia, concordância entre métodos de imagem, follow-up e historial do doente. No total, 90 lesões foram avaliadas: 14 carcinomas hepatocelulares (CHC), 18 metástases, 10 hiperplasias nodular focais (HNF), 4 adenomas, 30 hemangiomas e 14 quistos. Foi efectuado estudo ponderado em difusão com trigger respiratório (valores b de 50 e 700 s/mm2). Medições de ADC foram efectuadas no parênquima através de ROIs colocadas em quarto segmentos hepáticos e, nas LHF, através de três ROIs de 1 cm2 e uma ROI englobando toda a lesão. O tratamento estatístico foi efectuado, através do software SPSS, pelos testes Mann-Whitney e Friedman. O teste Wilcoxon foi utilizado para confirmar a influência do ROI e uma curva ROC foi analisada para avaliar o ADC como ferramenta diagnóstica de malignidade. P<0.05 foi considerado significativo. Resultados: ADCs médios (×10−3mm2/s) foram 1.45, 1.28 e 1.25 para parênquima normal, cirrótico e esteatótico, e 1.16, 1.18, 1.30, 1.64, 1.89 e 2.77 para metástases, CHCs, adenomas, HNFs, hemangiomas e quistos, respectivamente. ADCs medidos (×10−3mm2/s) no parênquima do segmento II foram significativamente mais altos do que em qualquer outro segmento. Lesões malignas apresentaram ADCs significativamente mais baixos que lesões benignas (p<0.001). Individualmente, os ADCs de quistos foram significativamente maiores do que os de outras lesões, exceptuando hemangiomas. Verificou-se uma sobreposição significativa entre lesões sólidas benignas e leso+es malignas, e entre CHCs e parênquima cirrótico. A área sobre a curva para diagnóstico de malignidade foi 0.939, com um ADC limiar de 1.43×10−3 mm2/s (sensibilidade de 89.7% e especificidade de 90.6%). Não foi encontrada diferença significativa entre as medições efectuadas com as ROIs de diferentes tamanhos. Conclusão: Concluímos que (a) medições quantitativas de ADC são úteis na distinção entre parênquima normal e patológico e na caracterização de LHF, (b) o lobo hepático esquerdo é mais susceptível a artefactos cardíacos, e (c) o tamanho da ROI não influencia o valor do ADC calculado.
Ferreira, Ana Sofia Rocha Ramos. "Diffusion-weighted magnetic resonance imaging role in the hepatocellular carcinoma diagnosis". Master's thesis, 2015. http://hdl.handle.net/10316/30544.
Pełny tekst źródłaPurpose: To assess the relevance of diffusion-weighted imaging (DWI) in the hepatocellular carcinoma (HCC) detection as a stand-alone procedure or in combination to conventional magnetic resonance imaging (MRI). Methods: Medical records from nineteen patients with pathological confirmation of HCC, who have been submitted to conventional MRI and DWI in a time frame 3 months prior and 3 months after diagnosis, were retrospectively reviewed. For each patient, apparent diffusion coefficient (ADC) values were measured in the HCC lesion, in the liver parenchyma and in the spleen. Tumor ADC and parenchyma ADC, obtained with and without normalization, were compared through paired-samples t-test. Tumor ADC was analyzed according to lobe, size category and acquisition system using the Mann-Whitney test. For sensitivity assessment of DWI and conventional MRI, individually and combined, a contingency table was made. Results: The calculated DWI sensitivity for HCC detection (47.4%) was lower than conventional MRI sensitivity (68.4%). The highest sensitivity was obtained with the combined reading of both techniques (78.9%). A statistically significant difference between tumor ADC and parenchymal ADC was found, both for normalized and non-normalized values, with lower values for the HCC lesions. Comparison of tumor ADC values according to lobe, size and acquisition system did not show a statistically significant difference. Conclusions: For HCC detection in the setting of liver cirrhosis the use of DWI increases tumor detection compared to conventional MR alone and its use is recommended. This result corroborates other literature reports regarding the added value of DWI in HCC diagnosis, irrespective of the magnetic field strength. Due to the small patient sample of the current series further investigation may be warranted.
Objectivo: Determinar a relevância da ressonância magnética ponderada em difusão (DWI) no diagnóstico do carcinoma hepatocelular (CHC) a título individual e enquanto complemento à ressonância magnética (RM) convencional. Métodos: Registos médicos de dezanove pacientes com confirmação anatomopatológica de CHC, que tinham sido submetidos a RM convencional e DWI na faixa temporal 3 meses antes e 3 meses depois do diagnóstico, foram revistos retrospectivamente. Para cada paciente foram medidos os valores do coeficiente de difusão aparente (ADC) na lesão tumoral, no parênquima hepático e no baço. O ADC do tumor e o ADC do parênquima, com e sem normalização, foram comparados através do t-teste para amostras emparelhadas e o ADC do tumor foi analisado de acordo com lobo, categoria dimensional e sistema de aquisição utilizando o teste de Mann-Whitney. Para determinação da sensibilidade da DWI e da RM convencional, individualmente e em conjunto, foi feita uma tabela de contingência. Resultados: A sensibilidade calculada da DWI (47.4%) foi inferior à da RM convencional (68.4%). Contudo, a sensibilidade calculada quando ambos os métodos foram combinados (78.9%) revelou-se superior. Foi encontrada uma diferença estatisticamente significativa entre o ADC do tumor e o ADC do parênquima hepático, tanto para os valores não normalizados como para os normalizados, com valores menores registados para as lesões tumorais. Após comparação dos ADC tumorais de acordo com lobo, categoria dimensional e sistema de aquisição, não foi encontrada uma diferença estatisticamente significativa. Conclusões: Os resultados do nosso estudo estão em concordância com a literatura mais recente que sustenta o valor adicional da DWI no diagnóstico do CHC. No entanto, as limitações que reconhecemos ao presente trabalho sugerem a necessidade de mais investigação nesta área.