Journal of nuclear medicine : official publication, Society of Nuclear Medicine最新文献

The extravasation of therapeutic radiopharmaceuticals presents a risk of radiation-induced injury. The recent rise in the use of therapeutic radiopharmaceuticals has highlighted the need for a better understanding of the consequences of extravasation and different treatment approaches, which are summarized in this systematic review. Here, we propose a standardized, step-by-step management guide with the aim of integrating this approach into future guidelines. Methods: A search of MEDLINE and Embase databases was conducted. The first search string contained synonyms of extravasation The second search string contained the names of therapeutic radiopharmaceuticals. Case reports on extravasation of therapeutic radiopharmaceuticals were included in the analysis. Extracted data were standardized for nomenclature and absorbed dose units. Reported absorbed doses, side effects, and treatment approaches were grouped by radiopharmaceutical. Proposed management strategies were summarized chronologically by author. Results: After screening 3,033 abstracts, conducting a full-text review of 75 publications, and screening all references of included publications and European Association of Nuclear Medicine guidelines on therapeutic radiopharmaceuticals, 28 publications remained, involving 39 case reports of extravasation of therapeutic radiopharmaceuticals. The severity of side effects varied widely, from mild and quickly resolving to severe, depending on the radiopharmaceutical used. The most frequent acute side effects were transient swelling, pain, and redness. In cases of radiation injury, the degree of severity, ranging from erythema and dry or moist desquamation to necrosis, was related to the absorbed dose. The most frequently reported intervention after extravasation was mobilization of the affected limb, which included massage, elevation of the arm, stress ball use, or hand-pumping exercises. Management strategies to prevent extravasation focused mainly on ensuring adequate vascular access. Conclusion: Extravasation of therapeutic radiopharmaceuticals is a rarely reported complication, with its severity determined by the activity infiltrated, retention time, and energy of the particulate radiation. Severe radiation-induced injuries were observed after radiosynoviorthesis or extravasation of large molecules (e.g., [⁹⁰Y]Y-ibritumomab tiuxetan). To date, there have been no reported cases of radiation-induced damage after extravasation during peptide receptor radionuclide therapy or prostate-specific membrane antigen-targeted radiopharmaceutical therapy. This systematic review highlights the consequences of 39 documented cases of extravasation of therapeutic radiopharmaceuticals and offers a step-by-step management guide.

We developed and evaluated an artificial intelligence (AI)-powered approach for easier quantification of tau PET uptake without requiring structural MR to aid earlier tracking of Alzheimer disease (AD). Methods: We implemented a deep neural network model that normalizes ¹⁸F-AV1451 (tau) PET images to a standard template without requiring MR, using transfer learning from a model pretrained on amyloid PET. This model was integrated into an MR-free pipeline for tau PET quantification and validated on external dataset (Alzheimer Disease Neuroimaging Initiative). We examined correlations between model-derived tau uptake estimates and cognitive measures, including AD stage and episodic memory performance (n = 666). Longitudinal analyses were conducted to assess whether baseline tau deposition predicted future cognitive decline (n = 168). Results: The AI-powered pipeline achieved robust performance with intraclass correlation coefficients exceeding 0.97 for regional uptake estimation compared with MR-based ground truth. We also showed that the tau deposition in metatemporal regions was significantly correlated with Mini-Mental State Examination and Montreal Cognitive Assessment scores. Elevated tau PET uptake in the entorhinal cortex and inferior temporal gyrus predicted future cognitive decline. Conclusion: The proposed AI-powered pipeline enhances the clinical accessibility of tau PET by reducing scan costs and streamlining the uptake quantification, achieving high performance without requiring structural MR. We further demonstrated that the pipeline yields cognitively relevant outcome measures for early diagnosis and monitoring of AD progression to aid more personalized treatment strategies targeting AD biomarkers.

Reactive fibrosis is a complex response to chronic myocardial insults, contributing to heart failure progression. Fibroblast activation protein inhibitor (FAPI) PET shows promise in distinguishing active from established fibrosis. Although antifibrotic therapies may improve left ventricular (LV) function in preclinical studies, their clinical application is limited by the lack of noninvasive imaging methods to assess fibrosis regression. This study investigates the potential of FAPI PET to track the therapeutic transition of activated fibroblast activation protein (FAP)-positive fibroblasts toward a FAP-negative phenotype. Methods: Mice were implanted with minipumps, infused with angiotensin-II/phenylephrine (Ang-II/PE) for 6 wk and scanned with ⁶⁸Ga-FAPI-46 PET/CT longitudinally. Control mice received saline. ⁶⁸Ga-FAPI-46 biodistribution studies were conducted at preselected time points, and FAPI uptake in the major organs was measured ex vivo. To assess the potential reversibility of the FAPI PET signal in the myocardium and liver, Ang-II/PE infusion was discontinued in a group of animals at 1 and 2 wk, respectively. LV structural and functional changes were assessed via echocardiography, tissue fibrosis via histology, and FAP expression via immunohistochemistry. Results: Significant ⁶⁸Ga-FAPI-46 uptake in the myocardium of treated mice peaked at 1 wk. An increase of ⁶⁸Ga-FAPI-46 uptake was also observed in the liver, peaking at 2 wk, and decreased significantly at 4 wk. The PET signal declined to an indiscernible level in the heart and liver early after Ang-II/PE withdrawal. Three weeks after the removal of the minipumps, the hearts of mice previously exposed to Ang-II/PE for 1 wk exhibited a significant reduction in fibrosis compared with mice that were sacrificed immediately after 1 wk of Ang-II/PE infusion, without the 3-wk recovery period. Coinjection with excess unlabeled FAPI-46 reduced uptake in the heart, liver, and kidneys. Despite an increase in LV wall thickness at 1 wk, the ejection fraction remained stable initially but dropped significantly by 4 wk. Conclusion: The rapid decline in PET signal after Ang-II/PE withdrawal shows that FAPI PET effectively visualizes dynamic changes in FAP expression, making it a valuable tool for quickly assessing treatment responses targeting activated fibroblasts. The cardiac FAPI signal precedes functional myocardial changes, indicating that FAPI PET could detect early fibrosis in cardiac remodeling leading to heart failure. FAPI PET may also visualize cardiac cirrhosis, a serious complication of cardiac disorders.

Anger SPECT monitoring of [¹⁷⁷Lu]Lu-prostate-specific membrane antigen (PSMA) therapy provides significant prognostic information about patients with metastatic castration-resistant prostate cancer (mCRPC) but with 36- to 90-min recording times and partial body coverage. This study assesses the prognostic information from a comprehensive analysis of tumor changes from the first to the last [¹⁷⁷Lu]Lu-PSMA therapy injections, as provided by whole-body [¹⁷⁷Lu]Lu SPECT recordings from a high-speed 360° cadmium-zinc-telluride (CZT) camera of mCRPC patients. Methods: We included mCRPC patients treated by [¹⁷⁷Lu]Lu-PSMA-617 injections who underwent [⁶⁸Ga]Ga-PSMA-11 PET before treatment, whole-body 360° [¹⁷⁷Lu]Lu CZT SPECT recordings of only 18 min obtained 24 h after each [¹⁷⁷Lu]Lu-PSMA therapy injection, and plasma prostate-specific antigen (PSA) measurements before each injection. We used Cox proportional hazards models to predict overall survival (OS) according to PSA evolution during treatment, as well as tumor SUV_max, SUV_mean, total uptake volume, and total lesion activity (TLA; total uptake volume × SUV_mean) extracted from [⁶⁸Ga]Ga-PSMA-11 PET and the first and last [¹⁷⁷Lu]Lu SPECT scans. Results: We included 72 patients with a median age of 71 y (interquartile range, 64-77 y), treated with up to 6 [¹⁷⁷Lu]Lu-PSMA injections. Among 57 patients with at least 2 [¹⁷⁷Lu]Lu-PSMA treatment cycles, 35 (61%) died during a follow-up of 12.0 mo (range, 4.9-17.5 mo) from the last [¹⁷⁷Lu]Lu-PSMA injection. Most PSA, PET, and SPECT variables were significant univariate predictors of OS. However, only 2 [¹⁷⁷Lu]Lu SPECT variables were selected as multivariate predictors: SPECT detection of new bone lesions during treatment (P < 0.0001) and final SPECT TLA (P = 0.0007). Means of survival times were 19.7 mo (95% CI, 16.6-22.8 mo) in the 19 patients who showed no new bone lesions and final TLA lower than the median of 750 mL·SUV, 14.4 mo (95% CI, 10.9-18.0 mo) in the 19 patients with only 1 of these 2 criteria, and 6.9 mo (95% CI, 4.5-9.6 mo) in the 19 patients with neither criterion. Conclusion: A comprehensive analysis of tumor changes from the first to the last [¹⁷⁷Lu]Lu-PSMA injections, obtained with fast whole-body 360° [¹⁷⁷Lu]Lu CZT SPECT recordings, provides strong prognostic information about mCRPC patients, outperforming conventional OS predictors such as PSA evolution and [⁶⁸Ga]Ga-PSMA-11 PET variables before treatment.

Prostate-specific membrane antigen (PSMA) PET has the potential to monitor the response to taxane-based chemotherapy in patients with prostate cancer and shows promise for predicting outcomes and improving response evaluation. This retrospective study aimed to determine the prognostic value of [⁶⁸Ga]Ga-PSMA-11 PET (PSMA PET)-derived quantitative tumor burden parameters for overall survival (OS). Methods: Databases from 6 institutions were screened for patients with prostate cancer who underwent PSMA PET and whose serum prostate-specific antigen (PSA) measurements were recorded at baseline and after completing taxane-based chemotherapy. Tumor segmentation was performed using artificial intelligence-based software, and PSMA PET whole-body quantitative parameters were obtained, including PSMA-positive tumor volume (PSMA-VOL), SUV_max, and SUV_mean Univariate Cox regression analyses were used to evaluate the association of whole-body quantitative PSMA parameters and PSA levels with OS. The Harrell concordance index (C-index) was used to determine prognostic accuracy. Optimal cutoffs were determined by maximizing the log-rank statistic. Results: In total, 128 patients were included in the study; 62 (48%) had hormone-sensitive prostate cancer, and 66 (52%) had castration-resistant prostate cancer. At baseline, PSMA-VOL had the highest prognostic value for OS compared with serum PSA, SUV_max, and SUV_mean (C-index of 0.88, 0.80, 0.69, and 0.29, respectively), whereas the percentage change in PSA levels had the highest prognostic value during treatment compared with percentage change in PSMA-VOL, SUV_max, and SUV_mean (C-index of 0.94, 0.85, 0.90, and 0.85, respectively). Conclusion: Baseline and posttherapeutic PSMA PET quantitative parameters are prognostic for OS after taxane-based chemotherapy in patients with metastatic prostate cancer. Baseline PSMA-VOL had the highest prognostic value for OS, whereas changes in PSA levels outperformed changes in quantitative PSMA PET parameters during treatment.