Incremental Value of Ga-68 Prostate-Specific Membrane Antigen-11 Positron-Emission Tomography/Computed Tomography Scan for Preoperative Risk Stratification of Prostate Cancer

U N Pallavi; Sanjay Gogoi; Parul Thakral; Vindhya Malasani; Kanchan Sharma; Divya Manda; Subha Shankar Das; Vineet Pant; Ishita Sen

doi:10.4103/ijnm.IJNM_189_19

Incremental Value of Ga-68 Prostate-Specific Membrane Antigen-11 Positron-Emission Tomography/Computed Tomography Scan for Preoperative Risk Stratification of Prostate Cancer

Indian J Nucl Med. 2020 Apr-Jun;35(2):93-99. doi: 10.4103/ijnm.IJNM_189_19. Epub 2020 Mar 12.

Authors

U N Pallavi¹, Sanjay Gogoi², Parul Thakral¹, Vindhya Malasani¹, Kanchan Sharma¹, Divya Manda¹, Subha Shankar Das¹, Vineet Pant¹, Ishita Sen¹

Affiliations

¹ Department of Nuclear Medicine, Fortis Memorial Research Institute, Gurgaon, Haryana, India.
² Department of Urology, Manipal Hospitals, New Delhi, India.

Abstract

Background: Prostate cancer (PC) is the second-most common cause of cancer.⁶⁸Ga-prostate-specific membrane antigen (PSMA)-11 positron-emission tomography/computed tomography (PET/CT) scan help in accurate staging of PC owing to its high PSMA avidity and specificity. The aim of this prospective observational study was to determine the incremental value of Ga-68 PSMA-11 PET/CT over multiparametric magnetic resonance imaging (mpMRI) in the locoregional staging of intermediate- and high-risk PC using histopathology from radical prostatectomy specimens as a gold standard.

Materials and methods: This was a prospective study, including 35 patients with biopsy-proven prostate carcinoma. All the patients underwent whole-body Ga-68 PSMA-11 PET/CT scans along with mpMRI including a dedicated pelvic imaging protocol within a time window of ± 10 days. The reference standard was based on histopathological results, postprostatectomy.

Results: All 35 patients showed Ga-68 PSMA-11-avid disease, of which 29 underwent radical prostatectomy, one underwent radiation therapy, and five did not undergo surgery owing to metastases. A total of 52 PC lesions were detected in 29 patients on histopathology. Of 52 lesions, 29 lesions were identified in prostate parenchyma and 23 were extraprostatic lesions on histopathology. Ga-68 PSMA-11 PET/CT detected a total of 45 lesions, of which 29 lesions were located within the prostate parenchyma and 16 were representative of extraprostatic lesions. mpMRI detected a total of 36 lesions, of which 29 lesions were located within the prostate parenchyma and seven were representative of extraprostatic lesions. The overall sensitivity of ⁶⁸Ga-PSMA PET/CT and mpMRI in the detection of lesions was 86.2% and 68.6%, respectively. However, the overall specificity was 94.7% and 89.1% for ⁶⁸Ga-PSMA and mpMRI, respectively.

Conclusion: Ga-68 PSMA-11 PET/CT provided superior locoregional preoperative staging of PC as compared to mpMRI in intermediate- and high-risk PC patients.

Keywords: Ga-68 prostate-specific membrane antigen-11 positron-emission tomography/computed tomography; prostate cancer; risk stratification.