Comparison of Early Imaging and Imaging 60 min Post-Injection after Forced Diuresis with Furosemide in the Assessment of Local Recurrence in Prostate Cancer Patients with Biochemical Recurrence Referred for 68Ga-PSMA-11 PET/CT

Background: 68Ga-PSMA-11 PET/CT is a promising method for the assessment of local recurrence (LR) in prostate cancer (PCa) patients. The aim of this study was to evaluate the diagnostic performance of early 68Ga-PSMA-11 PET imaging in comparison to 68Ga-PSMA-11 PET imaging 60 min post-injection (p.i.) in the detection of LR in patients with biochemical recurrence (BR) of prostate carcinoma. Materials and Methods: 190 image sets of patients with BR in PCa who underwent 68Ga-PSMA-11 PET/CT were assessed retrospectively (median prostate specific antigen (PSA) value, 0.70 ng/mL (range, 0.1–105.6 ng/mL)). Patients received an early static scan of the pelvic area (median, 248 s p.i. (range, 56–923 s)) and a whole-body scan 60 min p.i. (median, 64 min p.i. (range, 45–100 min)) with intravenous administration of 20 mg furosemide i.v. at the time of tracer application, followed by intravenous hydration with 500 mL of sodium chloride (NaCl 0.9%). Assessment was based on visual analysis and calculation of the maximum standardized uptake value (SUVmax) of the pathologic lesions present in the prostate fossa found in the early PET imaging and 60 min PET scans. The scans were characterized as negative, positive, or equivocal. The results were compared, and the combination of early and 60 min p.i. imaging was evaluated. Results: Image assessment resulted in 30 (15.8%) positive, 17 (8.9%) equivocal, and 143 (75.3%) negative findings in early scans, and 28 (14.7%) positive, 25 (13.2%) equivocal, and 137 (72.1%) negative findings of LR in 60 min p.i. images. For combined image analysis, 33 (17.4%) cases were positive and 20 (10.5%) were equivocal. There was no statistical significance between the number of positive (p = 0.815), negative (p = 0.327), and equivocal (p = 0.152) findings. Furthermore, the combination of both scans showed no statistically significant differences for the positive and negative findings (p = 0.063). The median SUVmax was 4.9 (range, 2.0–55.2) for positive lesions in the early scans and 8.0 (range, 2.1–139.9) in the scans 60 min p.i. The median SUVmax for bladder activity was 2.5 (range, 0.9–12.2) in the early scans and 8.2 (range, 1.8–27.6) in the scans 60 min p.i. Conclusion: Early static imaging additional to 68Ga-PSMA-11 PET images acquired 60 min p.i. has limited value in patients prepared with furosemide and hydration, and showed no statistically significant change in the detection rate (DR) of LR and the number of equivocal findings. Based on our results, in departments following a protocol with forced diuresis, including furosemide, additional early static imaging cannot be routinely recommended for the assessment of BR in PCa patients.

Comparing the Relative Glomerular Filtration Rate with the Relative Renal Function Calculated by 99mTc-DMSA Static Scintigraphy

Objective: To compare whether there is a statistical difference between the relative glomerular filtration rate (RGFR) obtained from renal dynamic imaging using 99mTc-DTPA and the relative renal function (RRF) obtained from renal static imaging using 99mTc-DMSA for children with urinary tract infection. Methods: We retrospectively analyzed 52 children with urinary tract infections, [31 females and 21 males, age: 3~168 months]. All patients underwent renal dynamic imaging with 99mTc-DTPA and renal static imaging with 99mTc-DMSA within one week period. RGFRs and RRFs were calculated for left and right kidneys. Wilcoxon Rank Sum Test is used for comparing the RGFR and RRF. Results: For 99mTc-DTPA renal dynamic imaging, the median and interquartile ranges of RGFRs are 52.55 (49.50, 57.98) for left kidneys and 47.45 (42.02, 50.50) for right kidneys. For 99mTc-DMSA renal static imaging, the values of RRFs are 52.20 (47.92, 57.31) for left kidneys and 47.80 (42.69, 52.08) for right kidneys. The RGFRs were statistically different from the RRFs in the groups of patients (Z =—2.377, P = 0.017). Conclusion: There exists statically difference between the relative glomerular filtration rate (RGFR) measured by renal dynamic imaging using 99mTc-DTPA and the relative renal function (RRF) measured by the renal static imaging using 99mTc-DMSA for the children with urinary tract infections.