Diagnostic performance of ^99mTc-PSMA SPECT/CT in primary prostate carcinoma

⁶⁸Ga (gallium)-PSMA PET-CT (prostate-specific membrane antigen-directed Positron emission tomography-computed tomography) has established its role in prostate cancer management as targeted molecular imaging. However, limited studies are available on the diagnostic accuracy of ^99mTc (Technetium)-PSMA-SPECT/CT. Due to its cost effectiveness and better feasibility, it needs to be explored more extensively for its incorporation into routine clinical practice.

To analyse the diagnostic accuracy of ^99mTc-PSMA-SPECT/CT for detection of primary prostate carcinoma.

As a prospective study in a tertiary hospital, 99mTc-PSMA-SPECT/CT was performed in 29 outpatients with suspected prostate cancer, with a median age of 66 (range: 50-82) years. The findings were compared to histopathology as the gold standard.

Nineteen of twenty-nine patients were positive on ^99mTc-PSMA-SPECT/CT, of which 16 (84.2%) had prostate cancer on histopathology, while the remaining ten were negative on imaging, of which three had prostate cancer, leading to an overall sensitivity, specificity, and accuracy of 84.2%, 70%, and 79.3%, respectively, on visual analysis. Prostate:background and prostate:liver ratios were 37.18 ± 48.85 and 5.35 ± 7.35 in the malignant group, while 6.65 ± 5.17 and 1.14 ± 0.56 in the benign group, respectively. The area under the curve values for prostate:background and prostate:liver ratios were 0.833 (95% confidence interval [CI]: 0.677-0.990, P = 0.005) and 0.767 (95%CI: 0.596-0.937, P = 0.024), respectively, on receiver operator curve analysis. A cut-off value > 10.45 for prostate:background ratio (sensitivity 85% and specificity 88.9%), and > 1.15 for prostate:liver ratio (sensitivity 75% and specificity of 77.8% respectively) was found to be pertinent to differentiate between the malignant vs benign groups.

^99mTc-PSMA-SPECT/CT shows a promising role in the diagnosis of primary prostate cancer.