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

The Highlights Lecture, presented at the closing session of each SNMMI Annual Meeting, was originated and presented for more than 30 y by Henry N. Wagner, Jr., MD. Beginning in 2010, the duties of summarizing selected significant presentations at the meeting were divided annually among 4 distinguished nuclear and molecular medicine subject matter experts. The 2024 Highlights Lectures were delivered on June 11, 2024, at the SNMMI Annual Meeting in Toronto, Canada. Presented here is the lecture by Richard Carson, PhD, Professor of Radiobiology and Biomedical Imaging and of Biomedical Engineering at Yale School of Medicine (New Haven, CT), who spoke on neuroscience topics presented at the meeting. Note that in the following presentation summary, numerals in brackets represent abstract numbers as published in The Journal of Nuclear Medicine (2024;65[suppl 2]).

Data are emerging on the prognostic significance of quantitative changes on posttherapy SPECT/CT in patients with metastatic castration-resistant prostate cancer (mCRPC) receiving [¹⁷⁷Lu]Lu-PSMA-617. Our objective was to assess quantitative and visual changes on posttherapy SPECT/CT as prognostic biomarkers for overall survival (OS) among patients in 3 clinical trials: LuPSMA Phase 2 (ANZCTR12615000912583), LuPARP (NCT03874884), and PRINCE (NCT03658447)]. Methods: We segmented the total tumor burden on posttherapy [¹⁷⁷Lu]Lu-PSMA-617 SPECT/CT using an SUV threshold of 3 to measure SUV_max, SUV_mean, metabolic tumor volume (MTV), and total lesion activity (TLA). We assessed the prognostic value of changes in these quantitative parameters and new lesions identified visually on SPECT/CT after cycle 2 for OS using the Cox proportional hazards model, with age, Gleason score, and change in prostate-specific antigen (PSA) as covariates. Results: Eighty-five patients with mCRPC were analyzed (46 from LuPSMA Phase 2, 25 from PRINCE, and 14 from LuPARP). Patients eligible for inclusion had received at least 2 cycles of [¹⁷⁷Lu]Lu-PSMA-617 with a follow-up time of at least 12 mo. Among these patients, 18 (21.2%) had new metastases visible on cycle 2 SPECT/CT, and this was prognostic for OS in univariate (hazard ratio [HR], 2.38; 95% CI, 1.36-4.18; P = 0.002) and multivariate (HR, 2.85; 95% CI, 1.36-5.98; P = 0.01) analyses. Seven (8.2%) patients with PSA reductions had new lesions on posttherapy SPECT/CT. Reductions in TLA (HR, 0.98; 95% CI, 0.97-1.00; P = 0.016) and MTV (HR, 0.98; 95% CI, 0.96-1.00; P = 0.009) (per 10% increase for both) were associated with OS on univariate analysis but not on multivariate analysis. Changes in SUV_max and SUV_mean were not associated with OS. There was moderate correlation among changes in PSA from cycle 1 to cycle 2 and MTV (correlation coefficient = 0.55; 95% CI, 0.39-0.69; P < 0.001) and TLA (correlation coefficient = 0.56; 95% CI, 0.40-0.69; P < 0.001). Conclusion: The presence of new metastases on posttherapy SPECT/CT after cycle 2 is an independent prognostic biomarker for OS in patients with mCRPC and could guide future prospective research to improve treatment strategies for patients with poor prognoses.

This study aimed to test and validate a dual-time-window (DTW) protocol for 6-(fluoro-¹⁸F)-3-(¹H-pyrrolo[2,3-c]pyridin-1-yl)isoquinolin-5-amine ([¹⁸F]MK6240) dynamic PET imaging in experimental datasets acquired in human subjects. Methods: DTW protocols were tested and validated in datasets previously collected in 25 participants: 13 were cognitively normal, 10 had mild cognitive impairment, and 2 had Alzheimer disease. Participants underwent full 120-min [¹⁸F]MK6240 dynamic PET scans as well as structural MRI. Intermediary 3-dimensional volumes were removed from the acquired dynamic PET images to emulate DTW acquisitions consisting of an early phase and a late phase. Five break durations (30, 40, 50, 60, and 70 min) were investigated to determine the optimal break for 2 study durations (120 and 110 min). Regional brain time-activity curves were extracted using atlases available in the Montreal Neurologic Institute template space and using the FreeSurfer parcellation. Interpolation strategies were tested to recover the missing time points. Distribution volume ratio (DVR) estimates obtained from the DTW time-activity curves were compared with those obtained from the full time-activity curves as reference. Parametric maps were generated for the selected protocol and evaluated. Results: The correlation and agreement between DVR values obtained from the DTW method and the full time-activity curves were overall very good. The DTW protocol with a 60-min break using a biexponential model fit as the interpolation method provided the best compromise between practicality and quantitative accuracy. The mean differences between this DTW and the full acquisition, averaged across brain regions and all subjects, were less than 1% with a corresponding SD of less than 4%, and DVR estimates were not statistically different from those obtained from the full acquisition (P > 0.05). DVR parametric images were visually and quantitatively consistent with those obtained from the full acquisition. Conclusion: This study presents strong support for the use of a DTW protocol with [¹⁸F]MK6240. Such a protocol would be well suited to allow for both quantification of tau and derivation of an index of cerebral perfusion while reducing patient discomfort and increasing scanning efficiency in comparison to a full dynamic acquisition.

The PSMA-PET Registry for Recurrent Prostate Cancer study was initiated in Ontario, Canada, to provide access to and characterize the performance of ¹⁸F-prostate-specific membrane antigen (PSMA) PET/CT among men with recurrent prostate cancer. Methods: Between October 2018 and September 2022, 4,135 men were enrolled in PREP. Eligibility included suspected prostate cancer recurrence after prior definitive treatment (radical prostatectomy or radiotherapy). Men were enrolled in 1 of 6 predefined clinical cohorts and imaged with ¹⁸F-DCFPyL at 1 of 6 participating sites. Standardized reports delineated sites of recurrence and changes in disease management after PET/CT. Linkage to provincial databases allowed estimation of overall survival (OS) and use of salvage radiotherapy after PET/CT. Results: The median follow-up was 1.8 y. Significant predictors of a positive PET/CT scan on multivariate analysis included a higher prostate-specific antigen level at the time of PET/CT and cohort (highest for cohort 4, whose cancer had progressed during salvage hormone therapy). Significant predictors of management change were type of recurrence (highest for isolated locoregional disease) and higher prostate-specific antigen level. Significant predictors of worse OS included cohort (worst for cohort 4) and extent and type of metastases (worst for mixed bone, lymph, and visceral or extensive metastases). A change in disease management after PET/CT was a significant independent predictor of improved OS rates. Conclusion: PREP facilitated access to ¹⁸F-PSMA PET/CT and demonstrated high rates of disease detection. Significant factors associated with survival were clinical scenario, pattern of metastases, and change in disease management after ¹⁸F-PSMA PET/CT.