Nuclear Medicine

Single-time-point 177Lu‑PSMA dosimetry predicts marrow toxicity and PSA response in mCRPC

In 59 heavily pretreated mCRPC patients on [177Lu]Lu‑PSMA‑617, single-time-point whole-body SPECT/CT quantified bone marrow and total metastatic tumour absorbed dose (TMTAD). Higher bone marrow absorbed dose at cycle 1 correlated with greater red cell and haemoglobin declines, indicating clinically relevant haematologic toxicity risk. PSA change showed a moderate negative correlation with TMTAD at cycle 1 and across cycles 1–4, supporting a dose–response relationship. Response modelling linked increasing TMTAD to higher PSA50 response probabilities, supporting response-guided personalized dosing using limited-time-point dosimetry. 1

Meta-analysis confirms durable efficacy and acceptable toxicity of 177Lu‑PRRT in NETs

This meta-analysis pooled 14 studies with 1,844 NET patients treated with 177Lu-labelled PRRT, mainly 177Lu‑DOTATATE. The pooled disease control rate was 87.6% and objective response rate 32.2%, with median PFS about 31 months and OS about 52 months. Grade 1–2 NETs had higher disease control and objective response rates than grade 3 tumors, indicating grade-dependent benefit. Pancreatic NETs showed longer PFS than gastrointestinal NETs, and grade ≥3 toxicities occurred in about 4% of patients. Overall, 177Lu‑PRRT appears highly effective with a favorable safety profile across NET subtypes, especially well-differentiated disease. 2

18F-fluorocholine PET is reshaping first-line imaging in hyperparathyroidism

This editorial summarizes data showing [18F]fluorocholine PET achieves diagnostic accuracy consistently exceeding 95% in primary and renal hyperparathyroidism, including complex and recurrent cases. FCH PET is increasingly used as first-line preoperative imaging where available, outperforming parathyroid scintigraphy in sensitivity and workflow efficiency. Advantages include lower radiation exposure, particularly with PET/MR, shorter acquisition times, and sustained cost-effectiveness compared with conventional scintigraphy. The authors emphasize remaining unmet needs and call for interdisciplinary efforts to standardize protocols and integrate FCH PET into surgical decision-making. 3

PSMA PET reveals radiographic progression despite undetectable PSA in a substantial subset

In a PSMA PET registry of 2,141 prostate cancer patients, 257 (12%) had radiographic disease progression with undetectable PSA (PSA zero rDP). Most had initially localized disease, and 72% progressed to castration-resistant prostate cancer, indicating aggressive biology despite PSA suppression. Progression sites were mainly bone (57%), followed by lymph nodes, visceral metastases, and local recurrence. Only visceral metastases were significantly associated with worse overall survival on univariate analysis. These findings support considering periodic advanced imaging in selected high-risk patients, even when PSA is undetectable. 4