99mTc-PSMA SPECT/CT Versus 68Ga-PSMA PET/CT in the Evaluation of Metastatic Prostate Cancer. (February 2021)

• Record Type: Journal Article
• Authors: Fallahi, Babak; Khademi, Niloufar; Karamzade-Ziarati, Najme; Fard-Esfahani, Armaghan; Emami-Ardekani, Alireza; Farzanefar, Saeed; Eftekhari, Mohammad; Beiki, Davood
• Is Part Of: Clinical nuclear medicine. Volume 46:Number 2(2021)
• Publication Date: 2021-02
• Subjects: 99mTc-PSMA SPECT/CT -- 68Ga-PSMA PET/CT -- prostate cancer; Nuclear medicine -- Periodicals; Radioisotope scanning -- Periodicals; Nuclear Medicine -- Periodicals; 616.07575
• DOI: 10.1097/RLU.0000000000003410
• Languages: English
• ISSNs: 0363-9762

Abstract

Abstract : Background: 99m Tc–prostate-specific membrane antigen (PSMA) SPECT/CT is less expensive and readily available modality compared with 68 Ga-PSMA PET/CT for imaging prostate cancer (PC). The aim of this study is to compare the value of these 2 modalities in patients confirmed or suspicious to have metastatic prostate cancer. Patients and Methods: Twenty-two patients with the mean age of 66.6 ± 10.1 years were studied using 99m Tc-PSMA SPECT/CT and 68 Ga-PSMA PET/CT, with less than 7 days interval between the 2 imaging procedures. Whole-body PET/CT was done 60 minutes after IV injection of 185 MBq (5 mCi) of 68 Ga-PSMA. 99m Tc-PSMA SPECT/CT was performed 3 hours after IV injection of 555 to 740 MBq (15–20 mCi) of 99m Tc-PSMA. The images of each modality were interpreted independently, and the results were compared according to patient-based as well as region-based analyses. Results: In patient-based evaluation, both 99m Tc-PSMA SPECT/CT and 68 Ga-PSMA PET/CT scans were positive in 95.45% (21/22). In region-based evaluation, 68 Ga-PSMA PET/CT detected 53 regions (median of 2 regions per patient; range, 0–5), whereas 43 (median of 2 regions per patient; range, 0–5) were detected by 99m Tc-PSMA SPECT/CT. Most of these differences could be explained by lower detection rate of 99m Tc-PSMA SPECT/CT in prostate bed (n = 6). PET/CT detected more involved regions than SPECT/CT ( P = 0.007), whereas similar frequency of extraprostatic lesions were diagnosed in both modalities ( P = 0.102). Significant correlation was also demonstrated between serum prostate-specific antigen level and imaging parameters of disease extension detected by 2 modalities. Conclusions: 99m Tc-PSMA SPECT/CT could be a potential substitute for 68 Ga-PSMA PET/CT in high-risk patients, except when evaluation of prostate bed is of major concern.