Comparison between conventional imaging (CI) and wholebody 18F-choline (FCH) positron emission tomography/ computed tomography (PET/CT) in patients (pts) with prostate cancer (PCa)

Purpose For T staging of prostate cancer, transrectal ultrasonography and magnetic resonance imaging (MRI) are the established imaging studies in many institutions. The use of CT and MRI for N staging is of limited value because of the low sensitivity in the detection of lymph node metastases. Bone scintigraphy is generally used to exclude the presence of bone metastases. We aimed to compare the diagnostic accuracies of 18F-Choline PET/CT (FCH) and CI in patients with prostate cancer at initial staging and in case of suspicious of biochemical relapse. Methods and Materials A retrospective analysis of 74 patients (age: 72±8 years) with histologically proven prostate cancer was performed at our Institution. All patients underwent FCH PET/ CT and CI including CT, bone scan, radiography and ultrasonography for staging and restaging of disease. Histopathology, imaging or clinical follow-up served as the standard of reference. A patient- and a lesion-based analyses were performed. Results Twenty-two patients had a Gleason score (Gs) <7, 40 had a Gs # 7 while it was not available in 12 subjects. In patients with suspicious of disease relapse, the PSA value ranged between 0.20 and 434 ng/mL (median: 4.6 ng/mL).On a patient base, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy for detecting local and distant metastases were calculated to be 88%, 67%, 77%, 82%, 78% compared with 85%, 97%, 97%, 84%, 91% with CI. In case of initial staging the accuracy of FCH PET/CT was lower than CI (77% vs. 92%), whereas in case of biochemical relapse the sensitivity of FCH PET/CT was slightly higher than CI (89% vs. 82%).On a lesion base more lymph node and more bone metastases were detected by using FCH PET/CT compared with CI. In particular, FCH PET/CT demonstrated lymph node involvement in three patients and bone lesions in two subjects. Moreover, one patient showed a diffuse bone medullary involvement. Conclusion FCH PET/CT demonstrates apparent advantages for the restaging of prostate cancer in case of biochemical relapse compared with CI on a patient base. The advantage of PET/CT in depicting lymph node and bone metastasis in one-step should be further studied in highly-selected subset of patient.