Gallium 68 (68Ga)-labeled prostate-specific membrane antigen (PSMA) positron emission tomography (PET)/computed tomography (CT) and PET/magnetic resonance imaging (MRI) used for staging before prostatectomy are both accurate for detecting lymph node involvement in prostate cancer, according to a study published online May 16 in Einstein (São Paulo).
Álan Roger Gomes Barbosa, from Hospital Israelita Albert Einstein in São Paulo, Brazil, and colleagues conducted a retrospective study of 91 patients diagnosed with prostate cancer between 2016 and 2020 who underwent 68Ga-PSMA PET/CT or PET/MRI for staging before prostatectomy. The patients were divided into two groups: 65 patients with satisfactory pathological lymph node analysis (group 1) and 91 patients representing the sum of patients with pathological lymph node analysis (group 2). The accuracy of the predictive capacity of imaging exams for lymph node involvement was assessed.
The researchers found that the groups showed similar results for local clinical staging, and 50% were classified as staging T2a. For prostate cancer lymph node staging, the accuracy of 68Ga-PSMA PET/CT was 86.5 percent, with sensitivity and specificity of 58.3% and 95%, respectively. The corresponding accuracy of 68Ga-PSMA PET/MRI was 84.6%, with sensitivity and specificity of 40% and 100%. The accuracy was 85.7% considering both 68Ga-PSMA PET/CT and PET/MRI, with sensitivity and specificity of 50% and 97%, respectively.
“Both 68Ga-PSMA PET/CT and PET/MRI showed high specificity; however, as expected, because of the principle of the radiological method per se, the CT was much less sensitive than MRI for such diagnoses,” the authors write.