Prediction of left lobe hypertrophy after right lobe radioembolization of the liver using a clinical data model with external validation

In cirrhotic patients with hepatocellular carcinoma (HCC), right-sided radioembolization (RE) with Yttrium-90-loaded microspheres is an established palliative therapy and can be considered a “curative intention” treatment when aiming for sequential tumor resection. To become surgical candidate, hypertrophy of the left liver lobe to > 40% (future liver remnant, FLR) is mandatory, which can develop after RE. The amount of radiation-induced shrinkage of the right lobe and compensatory hypertrophy of the left lobe is difficult for clinicians to predict. This study aimed to utilize machine learning to predict left lobe liver hypertrophy in patients with HCC and cirrhosis scheduled for right lobe RE, with external validation. The results revealed that machine learning can accurately predict relative and absolute volume changes of the left liver lobe after right lobe RE. This prediction algorithm could help to estimate the chances of conversion from palliative RE to curative major hepatectomy following significant FLR hypertrophy

Multiparametric quantification by 18F-Choline PET and MRI in prostate cancer

Problématique : Les paramètres fonctionnels extraits en Tomographie par Émission de Positons (TEP) à la 18F-Choline (FCH) et en Imagerie par Résonance Magnétique (IRM) apportent-ils une information supplémentaire par rapports aux informations déjà connues pour caractériser l’agressivité du tissu tumoral ? Objectifs : Notre travail avait pour objectifs tout d’abord (i) de mettre en évidence un éventuel lien entre les paramètres quantitatifs extraits par TEP à la FCH et et les paramètres clinicopathologiques dans le cancer de la prostate. Après cette étude préliminaire, pour quantifier au mieux l’influx de FCH par analyse dynamique de l’acquisition précoce, la deuxième étape avait pour but (ii) d’optimiser cette acquisition. Enfin (iii), le dernier objectif était de mettre en évidence un éventuel lien entre les paramètres quantitatifs extraits par TEP à la FCH et les paramètres quantitatifs extraits par IRM multiparamétrique. Résultats : Pour la première étape (i), nous avons comparé les paramètres quantitatifs extraits par TEP à la FCH et les paramètres clinico-pathologiques de 61 patients venant en TEP à la FCH pour le bilan d’extension initial. L’influx de FCH mesuré par analyse dynamique était plus élevé pour les patients avec un score de Gleason ≥ 4+3 que pour les patients avec un score de Gleason < 4 + 3. Pour la deuxième étape (ii), nous avons tout d’abord voulu optimiser la durée de l’acquisition précoce de TEP à la FCH en comparant le contraste sur bruit de 77 lésions tumorales à 5 minutes et 10 minutes après l’injection de FCH. Le contraste sur bruit à 5 minutes n’était statistiquement pas différent de celui à 10 minutes. La deuxième phase de l’optimisation de l’acquisition précoce de la TEP à la FCH consistait à déterminer quel était le meilleur échantillonnage temporel de ces 5 minutes par la comparaison de 7 échantillonnages temporels différents avec un objectif d’influx de FCH extrait de 37 lésions. L’échantillonnage temporel 12x5”-8x30” a été retenu. Pour la dernière étape (iii), nous avons comparé les paramètres TEP et IRM extraits de 14 lésions tumorales prostatiques. L’influx de FCH et la constante de transfert du gadolinium étaient corrélés, toutefois de manière modérée (r = 0,55). Conclusion : L’influx de FCH mesuré par analyse dynamique de l’acquisition précoce en TEP semble lié à la différenciation des cancers prostatiques. Cet influx semble également lié à la constante de transfert du gadolinium. Ces 2 paramètres d’imagerie semblent toutefois quantifier des processus physiopathologiques différents. Les différents résultats obtenus justifient la poursuite des travaux pour évaluer le rôle de marqueur d’agressivité des cellules cancéreuses prostatiques des différents paramètres quantitatifs obtenus par imagerie fonctionnelle par TEP à la FCH et par IRM multiparamétrique.Research question: Do the functional parameters derived by 18F-Choline (FCH) Positon Emission Tomography (PET) and Magnetic Resonance Imaging (MRI) add informations to characterize the aggressiveness of prostate cancer? Objectives: The first objective of this work was (i) to enhance a potential link between quantitative parameters extracted by FCH PET and clinicopathological parameters in prostate cancer. Then, after this preliminary study, in order to optimize the quantification of the FCH influx with a kinetic analysis, the second objective was (ii) to optimize the exam protocol of the FCH PET early acquisition. Finally, the last objective was (iii) to enhance a potential link between quantitative parameters extracted by FCH PET and quantitative parameters extracted by multiparametric MRI in prostate cancer. Results: For the first step (i), we compared FCH PET quantitative parameters and clinicopathological parameters extracted from 61 patients referred to the nuclear medicine department to perform an FCH PET/ CT with newly histologically proven prostate cancer and before any treatment The FCH influx measured using kinetic analysis was higher for patients with a Gleason score ≥ 4+3 than for patients with a Gleason score < 4 + 3. Concerning the second step (ii), firstly, we compared the contrast to noise ratio of 77 prostatic cancer lesions at 5 minutes and 10 minutes post-injection in order to optimize the length of the early FCH PET acquisition. No significant difference was observed. Secondly, we sought to define an optimal time sampling of the early FCH PET acquisition comparing 7 different time samplings with a FCH influx as objective extracted from 37 prostatic cancer lesions. The 12x5”-8x30” time sampling was selected. For the last step of this work (iii), we compared FCH PET and multiparametric MRI quantitative parameters extracted from 14 prostatic cancer lesions. The FCH influx was moderately correlated to the vessel permeability measured by the volume transfert constant of gadolinium (r = 0.55). Conclusion: The FCH influx extracted from the early FCH PET acquisition using kinetic analysis seems to be linked to the tumoral differentiation of prostatic cancers. This FCH influx seems also linked to the vessel permeability. However, due to the moderate degree of correlation, these two imaging parameters reflect two different processes. To confirm the results obtained in this work, other studies are needed to enhance the role of the functional parameters derived by FCH PET and multiparametric MRI as biomarkers for prostate cancer

Personalised Dosimetry in Radioembolisation for HCC Impact on Clinical Outcome and on Trial Design

International audienceSelective internal radiation therapy (SIRT) of hepatocellular carcinoma (HCC) has been used for many years, usually without any specific dosimetry endpoint. Despite good clinical results in early phase studies or in cohort studies, three randomized trials in locally advanced HCC available failed to demonstrate any improvement of overall overall survival (OS) in comparison with sorafenib. In recent years, many studies have evaluated the dosimetry of SIRT using either a simulation-based dosimetry (macroaggregated albumin (MAA)-based) or a post-therapy-based one (Y-based). The goal of this review is to present the dosimetry concept, tools available, its limitations, and main clinical results described for HCC patients treated with Y-loaded resin or glass microspheres. With MAA-based dosimetry, the threshold tumor doses allowing for a response were between 100 and 210 Gy for resin microspheres and between 205 and 257 Gy for glass microspheres. The significant impact of the tumor dose on OS was reported with both devices. The correlation between Y-based dosimetry and response was also reported. Regarding the safety, preliminary results are available for both products but with a larger range of normal liver doses values correlated with liver toxicities due to numerous confounding factors. Based on those results, international expert group recommendations for personalized dosimetry have been provided for both devices. The clinical impact of personalized dosimetry has been recently confirmed in a multicenter randomized study demonstrating a doubling of the response rate and an OS of 150% while using personalized dosimetry. Even if technical dosimetry improvements are still under investigation, the use of personalized dosimetry has to be generalized for both clinical practice and trial design

Trans-arterial Radioembolization Dosimetry in 2022.

International audienceTrans-arterial radioembolization is currently performed using 90Y-loaded glass or resin microspheres and also using 166Ho-loaded microspheres. The goal of this review is to present dosimetry and radiobiology concepts, the different dosimetry approaches available (simulation-based dosimetry and post-treatment dosimetry), main confounding factors as main clinical dosimetry results provided during the last decade for both hepatocellular carcinoma (HCC) and metastases of colorectal carcinoma (mCRC). Based on the different number of microspheres or different isotope used, radiobiology of the three devices is different, meaning that tumouricidal doses and maximal tolerated doses are different. Tumouricidal doses described for HCCs were 100-120 grays (Gy) with 90Y resin microspheres and 205 Gy with 90Y glass microspheres. For mCRC, it is 39-60 with 90Y resin microspheres, 139 Gy with 90Y glass microspheres and 90 Gy with 166Ho microspheres. An impact of tumoural doses with overall survival has also been reported. Personalised dosimetry has been developed and is now recommended by several international expert groups. Level-one evidence of the major impact of personalised dosimetry on response and overall survival in HCC is now available, bringing a new standard approach for TARE in clinical practice as well as for trial design

Tumoural thrombosis extended into the right atrium revealed by 18F-flurodeoxyglucose positron emission tomography/computed tomography

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FDG PET in Diffuse Spinal Carcinomatous Meningitis

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F-18-FDOPA PET/CT of Paraganglioma in the Spermatic Cord

International audienceA 53-year-old man with chronic kidney failure was referred to perform an F-18-FDOPA PET/CT to characterize a mass located on the right spermatic cord. Previously, the pathological analysis of CT-guided biopsies suggested paraganglioma or metastatic lesion of pheochromocytoma. Serum normetanephrine and serum metanephrine values were respectively 2- and 1.5-fold greater than the normal upper limit, which could be explained by the chronic kidney failure. PET/CT images revealed intense F-18-FDOPA uptake of the mass without any other pathological findings, suggesting the diagnosis of paraganglioma. Pathological examination of surgical specimen confirmed the diagnosis of paraganglioma of the spermatic cord, which is exceptional

18F-Choline Uptake in Acute Ischemic Stroke

International audienceA 75-year-old man with a history of prostate cancer was referred to our department to perform F-choline (FCH) PET/CT. FCH PET/CT showed a markedly increased uptake in the right temporoparietal junction brain. Three weeks earlier, acute ischemic stroke was diagnosed in the right temporoparietal junction brain on diffusion-weighted sequence and thrombosis in a distal branch of the right middle cerebral artery on MR angiography. Choline precursors promote repair and growth of cell membranes in neurologic diseases, so FCH PET/CT uptake could be explained by repair processes during early outcome of acute ischemic stroke

Asymmetric muscle activity on (18)F-FDG PET/CT.

International audienceA 51-year-old man referred to our department to undergo an F-FDG PET/CT to detect primary tumor 7 days after diagnosis of one left brain metastasis on MRI in the aftermath of acute right-sided hemiparesis. F-FDG PET/CT was performed without sufficient fasting period. It showed abnormal uptake in the left apical lung nodule, suspicious for primary tumor. Moreover, F-FDG PET/CT showed extensive skeletal muscle accumulation which was more significant as expected but concerning only the left side of the body. So, acute right-sided hemiparesis was responsible for no muscle uptake, probably explained by denervation and altered muscle energetics