Search

Positron Emission Tomography (PET) imaging after 90 Y liver radioembolization is used for both lesion identification and dosimetry. Bayesian penalized likelihood (BPL) reconstruction algorithms are an alternative to ordered subset expectation maximization (OSEM) with improved image quality and lesion detectability. The investigation of optimal parameters for 90 Y image reconstruction of Q.Clear, a commercial BPL algorithm developed by General Electric (GE), in PET/MR is a field of interest and the subject of this study. The NEMA phantom was filled at an 8:1 sphere-to-background ratio. Acquisitions were performed on a PET/MR scanner for clinically relevant activities between 0.7 and 3.3 MBq/ml. Reconstructions with Q.Clear were performed varying the β penalty parameter between 20 and 6000, the acquisition time between 5 and 20 min and pixel size between 1.56 and 4.69 mm. OSEM reconstructions of 28 subsets with 2 and 4 iterations with and without Time-of-Flight (TOF) were compared to Q.Clear with β = 4000. Recovery coefficients (RC), their coefficient of variation (COV), background variability (BV), contrast-to-noise ratio (CNR) and residual activity in the cold insert were evaluated. Increasing β parameter lowered RC, COV and BV, while CNR was maximized at β = 4000; further increase resulted in oversmoothing. For quantification purposes, β = 1000-2000 could be more appropriate. Longer acquisition times resulted in larger CNR due to reduced image noise. Q.Clear reconstructions led to higher CNR than OSEM. A β of 4000 was obtained for optimal image quality, although lower values could be considered for quantification purposes. An optimal acquisition time of 15 min was proposed considering its clinical use., (© 2024. Australasian College of Physical Scientists and Engineers in Medicine.)

Background: PET/MRI is an emerging imaging modality which enables the evaluation and quantification of biochemical processes in tissues, complemented with accurate anatomical information and low radiation exposure. In the framework of theragnosis, PET/MRI is of special interest due to its ability to delineate small lesions, adequately quantify them, and therefore to plan targeted therapies. The aim of this study was to validate the diagnostic performance of [ 68  Ga]Ga-DOTA-TOC PET/MRI compared to PET/CT in advanced disease paragangliomas and pheochromocytomas (PGGLs) to assess in which clinical settings, PET/MRI may have a greater diagnostic yield., Methods: We performed a same-day protocol with consecutive acquisition of a PET/CT and a PET/MRI after a single [ 68  Ga]Ga-DOTA-TOC injection in 25 patients. Intermodality agreement, Krenning Score (KS), SUVmax (Standard Uptake Value), target-to-liver-ratio (TLR), clinical setting, location, and size were assessed., Results: The diagnostic accuracy with PET/MRI increased by 14.6% compared to PET/CT especially in bone and liver locations (mean size of new lesions was 3.73 mm). PET/MRI revealed a higher overall lesion uptake than PET/CT (TLR 4.12 vs 2.44) and implied an upward elevation of the KS in up to 60% of patients. The KS changed in 30.4% of the evaluated lesions (mean size 11.89 mm), in 18.4% of the lesions it increased from KS 2 on PET/CT to a KS ≥ 3 on PET/MRI and 24.96% of the lesions per patient with multifocal disease displayed a KS ≥ 3 on PET/MR, that were not detected or showed lower KS on PET/CT. In 12% of patients, PET/MRI modified clinical management., Conclusions: PET/MRI showed minor advantages over conventional PET/CT in the detection of new lesions but increased the intensity of SSRs expression in a significant number of them, opening the door to select which patients and clinical settings can benefit from performing PET/MRI., (© 2023. The Author(s).)

Objective: To contribute our results to increase the scientific evidence about the use of radioembolization in the management of patients with hepatocellular carcinoma., Material and Methods: This retrospective review included 53 patients with hepatocellular carcinoma treated with radioembolization at our center. Patients were classified according to the BCLC algorithm in detail according to their Child-Pugh functional status. We analyzed survival using the Kaplan-Meier method. We used Cox regression analysis to determine clinically significant parameters, including the doses administered in the parameters studied., Results: Patients ranged in age from 28 to 86 years (mean, 60 years). A total of 61 procedures were done. The mean activity administered was 2.8 GBq (0.7-6.4 GBq), with a mean dose of 229.9Gy (74-425.9Gy) administered in the tumor. Progression-free survival was 6.7 months and overall survival was 12.8 months. Differences in disease-free survival according to BCLC and Child-Pugh classification were not significant (p=0.848 and p=0.252, respectively). The clinical parameters that were significantly different with respect to overall survival were bilirubin levels (p<0.001), pretreatment transaminase levels (AST) (p=0.022), Child-Pugh subclassification (p=0.003), and dose administered in the tumor (p=0.001). Only one patient had a severe adverse reaction, developing posttreatment liver failure resulting in death., Conclusions: Radioembolization is safe and efficacious in the treatment of patients with hepatocellular carcinoma. Liver function and the doses received by the tumor are key parameters for the efficacy of treatment. The increase in the scientific evidence supports the inclusion of this technique in treatment guidelines., (Copyright © 2020 SERAM. Publicado por Elsevier España, S.L.U. All rights reserved.)

Objective: To validate the sentinel lymph node selective biopsy (SLNSB) in the staging of Prostate Cancer with Briganti Index > 5 by comparison with extended lymphadenectomy (ePLND) in a prospective longitudinal study., Methods: SLNSB has been performed in 84 patients, the first 70 by injection of nanocoloids marked with Tc99m and preoperative SPECT-CT, and in the last 14 with mixed radiotracer (99mTc + ICG). After laparoscop ic removal of sentinel nodes all patients underwent an ePLND., Results: SPECT-CT showed radiotracer deposits outside the territory of the ePLND in 76% of patients and laparoscopic gamma probe in 57%. The median number of sentinel nodes removed was 5.2 with a total average number of lymph nodes removed of 22. In all cases with metastatic nodes (28% in the series) there was at least one positive sentinel node but metastatic sentinel nodes outside of the territory of the ePLND were found in 6/24 patients (25%). The sensitivity, specificity, PPV and NPV of 99mTc were 100%, 96.07%, 90.47% and 100%, respectively. In 5 out of 14 patients with mixed radiotracer, lymph node involvement was detected. In all of them there was at least one sentinel node affected with 99mTc, and only 3 showed fluorescence with 100% sensitivity and 100% NPV for 99mTc and 60% sensitivity and 77.77% NPV for ICG., Conclusion: The SLNSB with 99mTc has a high sensitivity and a VPN of 100%, increasing the identification of lymphatic metastases outside the territory of the ePLND. Fluorescence can facilitate the visualization of the sentinel nodes when they have been previously located by the SPECT-CT, although the sensitivity and the NPV of the ICG are lower than that of the 99mTc.