Mitigating bladder signal in 68Ga-PSMA-11 PET/CT for prostate cancer: a clinical comparative study of dynamic whole-body parametric imaging
摘要
The pharmacokinetics of 68Ga-PSMA-11 leads to intense bladder accumulation, obscuring adjacent lesions. This study evaluated the feasibility of dynamic whole-body 68Ga-PSMA-11 PET/CT Patlak parametric imaging to reduce bladder signal interference, and compared the difference between the long axial field of view (LAFOV) PET/CT and short axial field of view (SAFOV) PET/CT.
ResultsA total of 18 patients with prostate cancer were prospectively enrolled in this study, 9 patients were scanned on the uMI Panorama GS (FOV = 148 cm), and the other 9 patients were scanned on the uMI Panorama 35 C (FOV = 35 cm). The V images demonstrated a significant reduction in bladder TBR [LAFOV: TBR_SUV: 26.71 (14.50-34.83) vs. TBR_V: 0, P < 0.001; SAFOV: TBR_SUV: 14.56 (12.64–17.97) vs. TBR_V: 0.08 (0-1.42), P < 0.001] and SV [LAFOV: TBR_SUV: 154.06 ± 86.64 cm3 vs. SV_V: 0.94 ± 2.83 cm3, P < 0.001; SAFOV: SV_SUV: 174.33 ± 95.48 cm3 vs. SV_V: 12.90 ± 11.41 cm3, P < 0.001], achieving a 99.5% and 91.0% volume reduction in LAFOV and SAFOV PET, respectively. Prostatic base obscuration occurred in 33.3% (3 + 3/18) of SUV images (score = 2) but was absent in V images. All primary prostate lesions (15/15) and 96.7% (58/60) metastases were detected on V images in LAFOV PET. All primary prostate lesions (10/10) and 90.9% (20/22) metastases were detected on V images in SAFOV PET. In LAFOV PET, whether it is a primary or metastatic lesion, TBR_SUV is higher than TBR_V, but lower than TBR_Ki, all of which differ significantly. In SAFOV PET, lymph node metastases exhibited higher, while bone metastases showed no significant TBR difference, and primary prostate TBR_V was lower than TBR_SUV but remained above background. Compared with SAFOV PET, TBR_SUV, TBR_V, TBR_Ki of LAFOV PET were significantly higher (all P < 0.01).
ConclusionsPatlak V imaging significantly reduces bladder signal intensity and obscuration in 68Ga-PSMA-11 PET/CT while preserving lesion TBR, enabling improved visualization of prostatic base lesions. Whether LAFOV or SAFOV PET, dynamic whole-body Patlak parametric imaging is feasible for mitigating bladder interference. Our results indicate that parametric imaging contributes to improved clinical evaluation of prostate cancer lesions.