Nuclear Medicine

When is a second 18F‑flotufolastat PSMA PET worthwhile after a negative scan in post‑prostatectomy BCR?

In 101 men with BCR after radical prostatectomy and a prior negative 18F‑flotufolastat PET, 57% had a positive repeat scan. Detection on the second scan rose with higher PSA level, greater absolute and relative ΔPSA, faster PSA velocity, and shorter PSA doubling time. ROC analysis suggested optimal thresholds of PSA >0.82 ng/mL, absolute ΔPSA >0.50 ng/mL, relative ΔPSA >100%, PSA velocity >0.30 ng/mL/year, and PSA doubling time ≤17 months. These data support deferring repeat PSMA PET until PSA levels or kinetics cross these thresholds, improving yield and resource use. 1

PSMA-PET unmasks metastases in EMBARK-like high-risk biochemical recurrence

Among 587 men with first BCR after radical treatment, 29% met EMBARK high‑risk criteria. High‑risk patients had far higher PSMA‑PET positivity for any disease than others (82% vs 39%). They also had more metastatic disease on PSMA‑PET (46% vs 15%), despite conventional nonmetastatic staging in EMBARK. These findings imply many EMBARK‑eligible patients actually harbor PSMA‑detectable metastases, informing intensification and metastasis‑directed strategies. 2

Pre-listing FDG PET predicts microvascular invasion and early HCC recurrence after liver transplant

In 143 patients transplanted for HCC, 28% showed intrahepatic FDG PET positivity before listing. Early post‑transplant recurrence within 24 months occurred in a subset and was independently associated with microvascular invasion on explant pathology. Pre‑transplant intrahepatic FDG positivity independently predicted microvascular invasion with an odds ratio of 3.90. Incorporating FDG PET into candidate assessment could refine selection, risk counseling, and post‑transplant surveillance intensity. 3

Global comparison of radiation dose across noninvasive CAD imaging modalities

This worldwide cross‑sectional study evaluated 19 302 adults undergoing noninvasive CAD imaging at 742 centers in 101 countries. Median effective doses were 2.0 mSv for PET, 6.5 mSv for SPECT, 1.2 mSv for calcium scoring, and 7.4 mSv for CCTA. Eighty‑one percent of nuclear cardiology centers versus 56% of CCTA centers achieved median doses ≤9 mSv. Doses were higher in low‑ and middle‑income countries, with nuclear cardiology doses about 20% higher than in high‑income settings. The findings highlight substantial international variability and emphasize dose optimization, especially where equipment and protocols lag. 4