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

High specific-activity ¹³¹I-metaiodobenzylguanidine ([¹³¹I]MIBG) therapy is approved for patients with pheochromocytoma or paraganglioma. As [¹³¹I]MIBG is not effectively cleared through dialysis, the 2008 European Association of Nuclear Medicine guidelines list renal insufficiency requiring dialysis as a contraindication for [¹³¹I]MIBG treatment. Methods: We describe the clinical and dosimetry findings of a hemodialysis-dependent patient with metastatic paraganglioma who was treated with [¹³¹I]MIBG. Results: The patient tolerated the treatment with acceptable radiation doses to normal organs and effective treatment doses. Radiation safety precautions were followed, and radiation exposures stayed below safe limits for staff. Conclusion: Dosimetry-guided treatment with [¹³¹I]MIBG in patients requiring hemodialysis is feasible. With appropriate dose reduction, the treatment can be effective with limited side effects.

Quantitative assessment of rheumatoid arthritis (RA) activity using [¹⁸F]fluoro-polyethylene glycol (PEG)-folate PET/CT scans may prove a useful noninvasive therapeutic response assessment tool to evaluate antitumor necrosis factor therapy in RA patients. This study aims to assess [¹⁸F]fluoro-PEG-folate kinetics through a metabolite-corrected plasma input model and to investigate comparisons with simplified quantitative PET outcome measures. Methods: Dynamic [¹⁸F]fluoro-PEG-folate PET/CT scans were obtained for 6 patients for a total of 11 scans, 6 before and 5 after treatment. These scans were analyzed using conventional pharmacokinetic models. In addition, SUVs were calculated at intervals of 10-40, 20-50, 30-60, and 40-60 min after injection for comparison and imaging window optimization. Results: [¹⁸F]fluoro-PEG-folate kinetics in joints of RA patients were best described using the reversible pharmacokinetic 2-tissue compartment model with a volume of distribution (V_T ) mean of 1.0 (±0.5). V_T values correlated between arterial and venous samples at both baseline (P < 0.001, r ² = 0.96) and 4 wk after antitumor necrosis factor treatment (P < 0.001, r ² = 0.75), both at intervals of 30-60 and 40-60 min. Changes in V_T behavior during treatment could not be accurately assessed because of limited available data, but observed changes in the linear association slope may indicate changed kinetic behavior. Conclusion: The most optimal kinetic model for [¹⁸F]fluoro-PEG-folate uptake in joints of RA patients was the reversible 2-tissue compartment model. The associations between V_T and a simplified SUV interval of 30-60 min allow us to quantify tracer uptake without the need for a full cross-sectional pharmacokinetic evaluation at the time of imaging. Further research will be required to accurately assess the change in tracer behavior between time points and the use of simplified assessment of changes of tracer uptake in joints over time.

Although there is strong evidence for the prognostic value of myocardial flow reserve (MFR), there are fewer data on the prognostic implications of its constituents: myocardial blood flow at rest (MBF_rest) and stress (MBF_stress). Methods: Consecutive patients undergoing ⁸²Rb PET imaging with regadenoson stress testing at a tertiary care center between August 2019 and August 2024 were included in this study. The 2 coprimary outcomes were a composite of death or heart failure (HF) hospitalization and a composite of myocardial infarction (MI) or late revascularization. Multivariable Andersen-Gill Cox models with robust variance estimators were used to incorporate recurrent events. Outcomes were modeled as a smooth function of MBF_stress and MBF_rest, with restricted cubic splines to allow nonlinearity. Results: The analysis included 8,131 consecutive patients (median age of 68 y; 46.1% were women; median follow-up of 520 d (interquartile range, 186-921 d), among whom 471 deaths, 828 HF hospitalizations, 164 MIs, and 429 late revascularizations occurred. After adjusting for the relevant covariates, an MFR of 2 achieved through a lower MBF_rest was associated with a significantly lower incidence of death and HF hospitalization, whereas an MFR of 2 achieved through a greater MBF_stress was associated with a significantly lower incidence of MI and late revascularization. Assessments of the partial χ² statistic, which measures the importance of predictors, similarly confirmed that MBF_rest was more important for predicting death or HF hospitalization whereas MBF_stress was more important for predicting MI or late revascularization. Conclusion: Measurements of absolute myocardial blood flow offer complementary prognostic value to MFR. A diminished MBF_stress may signal a greater risk of future ischemic outcomes, whereas an elevated MBF_rest may signal a greater risk of future death or HF hospitalization.

The prognostic significance of metabolic response by posttreatment ¹⁸F-FDG PET in esophageal squamous cell carcinoma (ESCC) treated with chemoradiotherapy remains unclear, particularly regarding metabolic response after induction chemotherapy versus after chemoradiotherapy. This study aimed to evaluate and compare their prognostic impact. Methods: This retrospective study analyzed 604 patients with localized ESCC who received induction chemotherapy followed by chemoradiotherapy, with or without surgery, at Asan Medical Center between 2006 and 2018. Metabolic responses after induction chemotherapy (before chemoradiotherapy) and after chemoradiotherapy were evaluated using European Organisation for Research and Treatment of Cancer-based criteria adapted for prognostic assessment. Results: In patients treated with definitive chemoradiotherapy (bimodality therapy), metabolic response after both induction chemotherapy and chemoradiotherapy was significantly associated with progression-free survival (PFS) and overall survival (OS). Complete metabolic response after induction chemotherapy correlated with the longest survival (PFS, 58.9 mo; OS, 90.8 mo), whereas progressive metabolic disease predicted poor prognosis (PFS, 3.7 mo; OS, 7.0 mo; P < 0.001). A similar pattern was observed for postchemoradiotherapy metabolic response. In patients who underwent surgery (trimodality therapy), metabolic response after induction chemotherapy did not significantly impact survival. However, in patients for whom surgery was initially planned, it remained prognostic, suggesting its prognostic relevance in the preoperative setting. Postchemoradiotherapy metabolic response was a strong independent prognostic factor in both bimodality therapy and trimodal therapy. Patients with diffuse esophagitis after chemoradiotherapy had intermediate survival outcomes, among complete metabolic response and partial metabolic response groups, indicating a distinct prognostic pattern. Conclusion: Postchemoradiotherapy metabolic response is a strong prognostic marker in localized ESCC, supporting its use for risk stratification. Early metabolic response after induction chemotherapy may also inform treatment decisions, particularly in surgery-intended patients.