Littérature scientifique sur le sujet « TA : thermal ablation »

AbstractColorectal cancer (CRC) is responsible for approximately 10% of cancer-related deaths in the Western world. Liver metastases are frequently seen at the time of diagnosis and throughout the course of the disease. Surgical resection is often considered as it provides long-term survival; however, few patients are candidates for resection. Percutaneous ablative therapies are also used in the management of this patient population. Different thermal ablation (TA) technologies are available including radiofrequency ablation, microwave ablation (MWA), laser, and cryoablation. There is growing evidence about the role of interventional oncology and image-guided percutaneous ablation in the management of metastatic colorectal liver disease. This article aims to outline the technical considerations, outcomes, and rational of TA in the management of patients with CRC liver metastases, focusing on the emerging role of MWA.

Thyroid nodules are a common, benign condition with a higher prevalence in women, individuals with iodine deficiency, and radiation exposure. Treatment options for benign thyroid nodules include pharmaceutical therapy, thyroidectomy, and thermal ablation (TA). TA, including laser ablation (LA), radiofrequency ablation (RFA), and microwave ablation (MWA), is a procedure that uses heat to cause tissue necrosis. It is commonly used for large, firm, benign, non-functioning thyroid nodules that cause severe symptoms or pain when surgery is not recommended or desired. When thyroid nodules do not respond to TA, they undergo surgery to resolve the symptoms and clarify the diagnosis. This study aims to analyze the histological alterations found in surgically excised TA-treated thyroid nodules and to evaluate the morphological criteria of differential diagnosis between benign and malignant nodules, establishing whether the alterations observed on the histological sample are a consequence of TA or indicative of neoplastic disease. For this purpose, the adoption of ancillary methods, such as immunohistochemistry, is fundamental to distinguish the artifacts induced by TA from the typical morphological characteristics of malignant neoplasms.

Microwave-induced thermoacoustic (TA) signals are of emerging interest for monitoring microwave ablation (MWA) in real-time. TA signals can be generated using an interstitial ablation antenna with a pulsed microwave energy source. When a microsecond microwave pulse is absorbed by tissue, the tissue undergoes a small-scale temperature rise, inducing a thermoelastic expansion that leads to acoustic generation. TA signal characteristics are linked to the dielectric, thermal, and acoustic properties of the local ablation environment. These relevant properties evolve significantly during the ablation process. We conducted a simulation-based study to examine the evolution of microwave-induced TA signal characteristics generated during pulsed microwave ablation. We experimentally validated our multi-physics simulation model for a spatially uniform temperature profile. Then, using the validated simulation model, we investigated TA signals generated in tissue exhibiting spatially nonuniform temperature profiles that arise during MWA. We find that TA signal characteristics are highly influenced by the local environment temperature within the region of initial TA generation and, thus, contain rich information to be exploited for real-time ablation monitoring.

Thermal ablation (TA) procedures are effective treatments for several kinds of cancers. In the recent years, several medical imaging advancements have improved the use of image-guided TA. Imaging technique plays a pivotal role in improving the ablation success, maximizing pre-procedure planning efficacy, intraprocedural targeting, post-procedure monitoring and assessing the achieved result. Fusion imaging (FI) techniques allow for information integration of different imaging modalities, improving all the ablation procedure steps. FI concedes exploitation of all imaging modalities’ strengths concurrently, eliminating or minimizing every single modality’s weaknesses. Our work aims to give an overview of FI, explain and analyze FI technical aspects and its clinical applications in ablation therapy and interventional oncology.

Background: Identify risk factors for local recurrence (LR) after radiofrequency (RFA) and microwave (MWA) thermoablations (TA) of colorectal cancer liver metastases (CCLM). Methods: Uni- (Pearson’s Chi2 test, Fisher’s exact test, Wilcoxon test) and multivariate analyses (LASSO logistic regressions) of every patient treated with MWA or RFA (percutaneously and surgically) from January 2015 to April 2021 in Centre Georges François Leclerc in Dijon, France. Results: Fifty-four patients were treated with TA for 177 CCLM (159 surgically, 18 percutaneously). LR rate was 17.5% of treated lesions. Univariate analyses by lesion showed factors associated with LR: sizes of the lesion (OR = 1.14), size of nearby vessel (OR = 1.27), treatment of a previous TA site LR (OR = 5.03), and non-ovoid TA site shape (OR = 4.25). Multivariate analyses showed that the size of the nearby vessel (OR = 1.17) and the lesion (OR = 1.09) remained significant risk factors of LR. Conclusions: The size of lesions to treat and vessel proximity are LR risk factors that need to be considered when making the decision of thermoablative treatments. TA of an LR on a previous TA site should be reserved to specific situations, as there is an important risk of another LR. An additional TA procedure can be discussed when TA site shape is non-ovoid on control imaging, given the risk of LR.

Background: Colorectal cancer (CRC) is the second most common cause of cancer-related deaths in the US. Thermal ablation (TA) can be a comparable alternative to partial hepatectomy for selected cases when eradication of all visible tumor with an ablative margin of greater than 5 mm is achieved. This systematic review and meta-analysis aimed to encapsulate the current clinical evidence concerning the optimal TA margin for local cure in patients with colorectal liver metastases (CLM). Methods: MEDLINE, EMBASE, and the CENTRAL databases were systematically searched from inception until 1 May 2023, in accordance with the PRISMA Guidelines. Measure of effect included the risk ratio (RR) with 95% confidence interval (CI) using the random-effects model. Results: Overall, 21 studies were included, comprising 2005 participants and 2873 ablated CLMs. TA with margins less than 5 mm were associated with a 3.6 times higher risk for LTP (n = 21 studies, RR: 3.60; 95% CI: 2.58–5.03; p-value < 0.001). When margins less than 5 mm were additionally confirmed by using 3D software, a 5.1 times higher risk for LTP (n = 4 studies, RR: 5.10; 95% CI: 1.45–17.90; p-value < 0.001) was recorded. Moreover, a thermal ablation margin of less than 10 mm but over 5 mm remained significantly associated with 3.64 times higher risk for LTP vs. minimal margin larger than 10 mm (n = 7 studies, RR: 3.64; 95% CI: 1.31–10.10; p-value < 0.001). Conclusions: This meta-analysis solidifies that a minimal ablation margin over 5 mm is the minimum critical endpoint required, whereas a minimal margin of at least 10 mm yields optimal local tumor control after TA of CLMs.

Surgery with either partial or radical nephrectomy remains the standard of care for localized primary renal cell carcinoma (RCC). However, most RCCs are detected in an older age group, and some may have multiple comorbidities that preclude surgery. Thermal ablation (TA) with radiofrequency ablation (RFA), cryoablation (CA), or microwave ablation (MWA) is considered an alternative to extirpative surgical procedures for select patients with small renal tumors. There is more than 90% post-ablation local control in carefully selected patients with reported complication rates of less than 10%. Most thermal ablation require only a single procedure. More recently, stereotactic ablative body radiotherapy (SABR) has emerged as an attractive noninvasive treatment modality for elderly patients with comorbidities and localized RCC. It has shown more than 90% local control rates for both small and relatively larger tumors (> 4 cm). Modest post-SABR renal function decline has been observed. Despite most patients presenting with mild or moderate chronic kidney disease there is less than a 5% chance of progression to end-stage renal disease. This article aims to summarize the key evidence and ablative treatment’s optimal patient selection, efficacy, and toxicity.

4602 Background: Thermal ablation (TA) is used as a local cure for selected colorectal liver metastases (CLM) with minimal risk. A critical limitation of TA has been early local tumor progression (LTP). The goal of this study is to establish the role of ablation zone (AZ) biopsy in predicting LTP. Methods: This institutional review board-approved prospective study included patients with CLM of 5cm or less in maximum diameter, with confined liver disease or stable, limited extrahepatic disease. Both radiofrequency(RF) and microwave(MW) ablation modalities were used. A biopsy of the center and margin of the AZ was performed immediately after ablation. The applicators were also examined for the presence of viable tumor cells. All samples containing morphologically identified tumor cells were further interrogated with immunohistochemistry to determine the proliferative and viability potential of the detected tumor cells. Ablation margin size was evaluated on the first CT scan performed 4–8 weeks after ablation and was confirmed by 3D assessment with Ablation Confirmation Software (Neuwave™). Variables were evaluated as predictors of time to LTP with the competing-risks model (uni- and multivariate analyses). Results: Between November 2009 and February 2019, 102 patients with 182 CLMs were enrolled. Mean tumor size was 2.0 cm (range, 0.6–4.8 cm). MW was used in 95/182 (52%) tumors and RF in 87/182 (48%). Median follow-up was 19 months. Technical effectiveness was evident in 178/182 (97%) ablated tumors on the first contrast material–enhanced CT at 4–8-weeks post-ablation. The cumulative incidence of LTP at 12 months was 19% (95% confidence interval [CI]: 14, 27). Samples from 64 (35%) of the 178 technically successful cases contained viable tumor. At univariate analysis, tumor size, minimal margin size, and biopsy results were significant in predicting LTP. In a multivariate model, margin size of less than 5 mm (P < .001; hazard ratio [HR], 4.3), and positive biopsy results (P = .02; HR, 1.8) remained significant. LTP within 12 months after TA was noted in 3% (95% CI: 1, 6) of tumor-negative biopsy CLMs with margins of at least 5 mm. Conclusions: Biopsy and pathologic examination of the AZ predicts LTP regardless of TA modality used. This can optimize ablation as a potential local cure for patients with limited CLM.

Purpose. Thermal ablations (TA) are gaining ground as alternative options to conventional therapies for symptomatic benign thyroid nodules. Little is known about the impact of nodule biology on the outcomes of TA. The aim of our study was to evaluate the baseline immunocytochemistry profile of thyroid nodules that were poorly responsive to TA in order to identify potential predictors of the treatment response. Methods. From a cohort of 406 patients with benign thyroid nodules treated with TA and followed for 5 years, we retrospectively selected two groups of patients: NONRESPONDERS (patients who did not respond to TA and were later surgically treated) and RESPONDERS (patients who responded to TA). The fine-needle aspiration cytology (FNAC) slides obtained before TA were stained for Galectin-3, HBME-1, CK-19, and Ki-67. Results. Benign nodules of NONRESPONDERS (n = 19) did not express CK-19 ( p = 0.03 ), as compared to RESPONDERS (n = 26). We combined the absence of CK-19 and the presence of Ki-67 to obtain a composite biomarker of resistance to TA, which discriminated between likelihood of retreatment and no retreatment with an AUC of 0.68 (95%CI: 0.55-0.81) and a sensitivity, specificity, PPV, and NPV of 29%, 91%, 71%, and 64%, respectively. Conclusion. In benign thyroid nodules, the absence of CK-19 was associated with resistance to TA, while the presence of CK-19 was predictive of response to TA. If confirmed, this finding could provide rapid and inexpensive information about the potential outcome of TA on benign thyroid nodules. In addition, as CK-19 can be expressed in adenomatous hyperplasia, it could be speculated that these nodules, rather than follicular adenomas, might be better candidates for TA.

Thermal ablation (TA) for benign thyroid nodules (BTNs) is widely accepted as an effective and safe alternative to surgery. However, studies on the long-term outcomes of TA have reported problems with nodule regrowth and symptom recurrence, which have raised the need for adequate control of regrowth. Therefore, a more complete TA with a longer-lasting treatment effect may be required. In this study, we review and discuss long-term outcomes and regrowth of BTNs following TA and evaluate factors affecting the long-term outcomes. We also discuss the management of regrowth based on long-term outcomes.

’IRM (imagerie par résonance magnétique) est l’examen d’imagerie de référence de la prostate. L’IRM de prostate est devenue l’examen de référence afin de rechercher des cibles tumorales, grâce à un protocole multiparamétrique, incluant les séquences T2, diffusion et T1avec injection de gadolinium Un score pronostique PIRADS est réalisé à partir des différentes séquences et, si les lésions à haute probabilité de malignité (PIRADS 4 et 5), une biopsie ciblée est réalisée. Les ablations mini-invasives, dites traitements focaux, se développent de plus en plus : HIFU (High-Intensity Focused Ultrasound), cryothérapie, laser, etc. Pour le guidage de ces thérapies, l’échographie reste la technique la plus répandue du fait de sa disponibilité,mais avec une sensibilité moindre que l’IRM. C’est pourquoi, les ablations sont maintenant réalisées sous échographie avec fusion des images IRM. Afin de mieux couvrir le volume lésionnel, la mesure des variations de température pendant tout le traitement s’avère nécessaire ; or, l’IRM est capable de mesurer ces variations, ce qui permet d’anticiper l’efficacité de l’ablation. L’obtention de cartographies de température est possible, comme cela a été démontré en IRM cardiaque durant les procédures d’ablation par radiofréquence à l’IHU de Bordeaux. La thermométrie en IRM repose sur le principe du changement de fréquence de résonance magnétique des protons d'eau en fonction de la température.Lorsque des tissus sont soumis à une augmentation de température, les mouvements moléculaires des protons d'eau s'intensifient, entraînant un élargissement des raies de résonance magnétique nucléaire (RMN). Cela se traduit par un déplacement de la fréquence de résonance des protons d'eau, qui est mesurée par l'IRM.En pratiquant cette séquence de thermométrie et en analysant les variations de fréquence de résonance des protons d'eau au fil du temps, il est possible d'estimer la température des tissus environnants. Cette méthode de thermométrie en IRM offre une résolution spatiale élevée,permettant une cartographie précise des changements de température en temps réel au seindes tissus ciblés.L’objectif de cette thèse est de mettre en application une séquence ce thermométrie pour améliorer la prise en charge des traitements focaux sous guidage IRM. Pour cela 3 grands axe sont été développés. Dans une première partie, nous avons évalués la séquence de thermométrie sur le foie des cochons durant des ablations micro-ondes. Dans notre deuxième partie nous avons évalué la séquence de thermométrie sur la prostate de patients réalisés dans le cadre d’un dépistage de tumeur prostatique ou de bilan d’adénome prostatique. Dans notre troisième et dernière partie nous avons réalisé une méta-analyse sur le traitement par laser du cancer de la prostate guidé sous IRM
Magnetic Resonance Imaging (MRI) is the reference imaging modality for the prostate.Prostate MRI has become the gold standard for detecting tumor targets, using a multiparametric protocol that includes T2-weighted, diffusion-weighted, and gadoliniumen hancedT1-weighted sequences. A PI-RADS (Prostate Imaging-Reporting and Data System)score is established from these different sequences. If high-probability malignant lesions (PIRADS4 and 5) are identified, targeted biopsies are performed. Minimally invasive ablation therapies, known as focal treatments, such as HIFU (High-Intensity Focused Ultrasound),cryotherapy, and laser, are increasingly being developed. For guiding these therapies,ultrasound remains the most widely used technique due to its availability, but it has lower sensitivity than MRI. Therefore, ablations are now often performed using ultrasound with MRI image fusion. To better cover the lesion volume, measuring temperature variations throughout the treatment is necessary; MRI can measure these variations, allowing for anticipation of the ablation's effectiveness.Temperature mapping is possible with MRI, as demonstrated during radiofrequency ablation procedures in cardiac MRI at the IHU of Bordeaux. MRI thermometry is based on the principle that the magnetic resonance frequency of water protons changes with temperature. When tissues are exposed to increased temperature, the molecular movement of water protons intensifies, leading to a broadening of nuclear magnetic resonance (NMR) lines. This results ina shift in the resonance frequency of water protons, which is measured by MRI.By performing this thermometry sequence and analyzing the resonance frequency variations of water protons over time, it is possible to estimate the temperature of the surrounding tissues. This MRI thermometry method offers high spatial resolution, enabling precise realtime mapping of temperature changes within targeted tissues.The objective of this thesis is to apply a thermometry sequence to improve the management of focal treatments under MRI guidance. To achieve this, three main areas have been developed. In the first part, we evaluated the thermometry sequence on the liver of pigs during microwave ablations. In the second part, we assessed the thermometry sequence on the prostate of patients under going screening for prostate tumors or evaluation of benign prostatic hyperplasia. In the third and final part, we conducted a meta-analysis on MRI-guided laser treatment of prostate cancer