The role of Ga-68 PSMA PET/BT' for prostate cancer patients

SUMMARY The Role of Ga-68 PSMA PET/CT for Prostate Cancer Patients Burak Sönmezer, Dokuz Eylül University, Faculty of Medicine, Department of Nuclear Medicine Dokuz Eylül University, Faculty of Medicine, Department of Nuclear Medicine, 35340, İnciraltı-İzmir Aim: To compare the findings obtained by Ga-68 PSMA PET/CT imaging with findings obtained from pathology, laboratory and other imaging methods in patients with prostate cancer and to analyze the correlations between them. Method: A total of 123 patients with Ga-68 PSMA PET/CT imaging performed for "staging" and "re-staging" from March 2016 to March 2017 were retrospectively investigated. D'Amico risk classification was performed in patients referred for staging. In both groups, findings obtained on Ga-68 PSMA PET/CT were compared with the results obtained from other imaging methods (thoracoabdominal CT, pelvic/abdominopelvic MR, bone scintigraphy). In all patients the highest SUVmax values were obtained for prostate, lymph nodes, bones and visceral organs. These values were correlated with Gleason score, Gleason grade and laboratory findings.. The Ga-68 PSMA PET/CT studies were subgrouped according to the presence-absence of pathologic findings. These subgroups were statistically analyzed with respect to the pathology and laboratory results. In the re-staging group, the differences in SUVmax values were investigated according to the therapy protocol. Results: In the staging group, the correlations were moderate level between prostate SUVmax and highest SUVmax values with Gleason grade and PSA values (r:0.42, r:0.5, r:0.54, r:0.53, respectively). Ga-68 PSMA PET/CT was compared with other imaging methods. In the staging group 22 patients (67%) had additional 72 lesions were identified. The differences for prostate SUVmax and highest SUVmax values were statistically significant between patients with Gleason grade 2 and below with respect to the patients with Gleason grade above 3 and above (p:0.005, p:0.002, respectively). The prostate SUVmax values of patients with PSA values 20 ng/ml and below were statistically different than patients with PSA values above 20 ng/ml (p:0.045). In the re-staging group, the correlation of the visceral organ SUVmax values and the highest SUVmax value with PSA values were in moderate level (r:0.56, r:0.43, respectively). The compliance rate of Ga-68 PSMA PET/CT with anatomic imaging methods (CT/MR) in identifying malign lesions for prostate gland, lymph nodes, bones and visceral organs were 66.2%, 67.5%, 70.2% and 79.7% respectively. The Ga-68 PSMA PET/CT was 75.2%complient with bone scintigraphy. The patients with pathologic findings on Ga-68 PSMA PET/CT were statistically different for PSA values, PSA velocity, Gleason score/grade and presence-absense of hormonotherapy than patients without pathologic findings on Ga-68 PSMA PET/CT (p:<0.001, p:0.034, p:0.032, p:0.030, p:<0.001, respectively). Additionally, there were significant differences in SUVmax values according to therapy protocol (chemotherapy, hormonotherapy, Lu-177 PSMA)in the re-staging group. In all groups, there were significant differences between patients with and without bone involvement on Ga-68 PSMA PET/CT in terms of ALP and Ca values (p:0.010, p:0.003, respectively). There was a very weak correlation between highest SUVmax values and LDH values (r:0.19). There was a significant difference in highest SUVmax values between patients with and without perineural invasion (p:0.012). Conclusion: Ga-68 PSMA PET/CT imaging can be used as a routinely in staging of the moderate-high risk group prostate cancer patients and can also be used in re-staging of patients with suspected morphologic and/or biochemical recurrence. The SUVmax values obtained on Ga-68 PSMA PET/CT may also be used as a prognostic factor. Key Words: Ga-68 PSMA PET/CT, SUVmax, Gleason Score, Gleason Grade, PSA, PSAdt, PSA velocity, Thoracoabdominal CT, Pelvic MR, Bone Scintigraphy