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

Whole-body CD8⁺ T-cell PET imaging can detect spatial and temporal localization of CD8⁺ T cells. To obtain insight into early CD8⁺ T-cell response to immunotherapy in patients with melanoma, a highly immunogenic tumor, we performed serial PET imaging with the 1-armed CD8 antibody tracer ⁸⁹ZED88082A. Methods: Immunotherapy-naïve adult patients with stage IV melanoma underwent PET scanning 2 d after receiving 10 mg of ⁸⁹ZED88082A intravenously at baseline and 6-8 wk after initiation of standard-of-care immunotherapy. Tracer uptake in lesions, normal lymph nodes, and Waldeyer ring was assessed using SUV_max; other healthy tissue uptake was assessed using SUV_mean Uptake in tumors and healthy lymph nodes was expressed as the geometric mean SUV_max per patient and in healthy tissue as SUV_mean for all patients. Tumor response was evaluated in accordance with iRECIST version 1.1. Tumor tissue was immunohistochemically stained for CD8. Results: Serial imaging was performed for 10 of 11 enrolled patients. The geometric mean tumor SUV_max was 7.2 (95% CI, 5.6-9.4) before treatment and 7.3 (95% CI, 5.7-9.5; P = 0.89) during treatment, with spatial and temporal heterogeneity in tumor uptake. The spleen demonstrated the highest uptake among healthy tissues, and this value remained similar during treatment. After immunotherapy, 2 patients experienced a complete response, 7 a partial response, and 2 progressive disease. Changes in tumor uptake during treatment did occur but did not correlate with tumor response. Nine evaluable pretreatment tumor tissues showed a CD8-inflamed immune phenotype. Conclusion: Lesions demonstrated spatial and temporal heterogeneity in ⁸⁹ZED88082A uptake within and among patients with melanoma.

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.