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

Abstract

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.

Predictive significance of intraprostatic volumetric parameters derived from early and standard time 68Ga-PSMA PET/CT images in newly diagnosed prostate cancer patients

“…In our study, we observed that SUVmax and SUVmean values obtained from standard time images were higher, consistent with their findings. Notably, our study did not identify a clear advantage for routine early imaging, similar to recent observations [13]. While early imaging may assist in clarifying certain suspicious lesions, it lacks additional contribution for routine practice.…”

“…Some centers opt for early pelvic imaging, acquired before bladder activity to prevent urinary artifacts. While early images have contributed to the detection and evaluation of primary tumors and lymph node metastases in some studies [10][11][12][13][14][15], our study seeks answers to questions not adequately addressed in English literature. These include whether various parameters obtained from standard time 68 Ga-PSMA PET images can also be obtained from early images, whether these parameters can substitute those from standard images, and whether early imaging provides an advantage over standard time imaging.…”

What a difference a methylene makes: replacing Glu with Asp or Aad in the Lys-urea-Glu pharmacophore of PSMA-targeting radioligands to reduce kidney and salivary gland uptake

“…Most of the reported PSMA-targeting radioligands including [ 18 F]DCFPyL, [ 68 Ga]Ga-PSMA-11, [ 177 Lu]Lu-PSMA-617, [ 177 Lu]Lu-PSMA-I&T, [ 225 Ac]Ac-PSMA-617, and [ 225 Ac]Ac-PSMA-I&T are derived from the Lys-urea-Glu pharmacophore, and all of them show significant uptake in kidneys and salivary glands. The high kidney uptake of PSMA-targeting ligands reduces the sensitivity for detecting prostate cancer lesions adjacent to kidneys due to the signal extinction artifact 8 . In addition, the high kidney and salivary gland uptake of PSMA-targeting radiotherapeutic agents can cause xerostomia and impaired renal function especially when 225 Ac-labeled therapeutics such as [ 225 Ac]Ac-PSMA-617 and [ 225 Ac]Ac-PSMA-I&T are used 7 , 9 .…”

Distinguishing Physiological Ureter Uptake From an Involved Lymph Node in Staging Prostate-Specific Membrane Antigen (PSMA) Scans: Implications for Radiation Planning

“…Potential approaches to reducing the impact of urine activity include​ prophylactic​ diuretic administration, large delays in scanning and/or multiple scan times, or as ​in​ this study, additional imaging (CT urography and/or MRI). ​However, these approaches may not adequately address the problem ​as well as ​add unnecessary costs and delays in management [ 19 ].…”