Objectives: To compare the value of Power Doppler Sonography (PDS) and B mode sonography in the diagnosis of prostate cancer and to assess the value of PDS to specify capsular effraction of the cancer.
Patients and methods: 323 patients were investigated: 41 control subjects allowed the establishment of normal vascular semiology and 282 patients with suspected cancer (PSA >4ng/ml). Power Doppler Sonography with 3D reconstruction was used to describe Power Doppler Sonography features of normal or abnormal vessels. Three types of blood supply(a: regular avascular posterior peripheral margin, b: irregular avascular posterior peripheral margin, c: vessels crossing the posterior peripheral margin) were described as a function of the presumed stage of cancer (a: intraprostatic, b: undetermined, c: extraprostatic). Comparison with histology was performed on random biopsies without Doppler (282 cases) (median PSA level = 15.8ng/ml), on second biopsies indicated with PDS (72 cases), and radical prostatectomy specimens (63 cases).
Results: A cancer was diagnosed in 157 of the 282 patients (55.7%) with suspected cancer. The overall sensitivity of PDS in the initial diagnosis of prostatic cancer was 92.4% and its specificity was 72% (versus 87.9% and 57.6% for sonography alone respectively). The negative predictive value of PDS was elevated to 80.6% (p<0.0001). Targeting area presenting abnormal blood flow in any part of the prostate was useful to detect isoechoic or lesions in patients with first negative biopsy results (in 41 of 72 targeted patients with first negative biopsies with PDS a cancer was diagnosed: 58% of these cancers had less than 3 positive biopsies and 34% only one positive biopsy). The 3 vascular types a, b, c were evaluated prospectively in the detection of capsular effraction. The presence or absence of vessels crossing the capsule to determine an extracapsular extension was a significant sign (p<0.0001). Capsular effraction was detected in 3 of the 27 cases (11%) of type a cancer and in 16 of the 18 cases (87%) of type c cancer.
Conclusion: PDS improves the accuracy of echographic imaging in the diagnosis of cancer. Combining first sextant biopsies and targeted areas presenting abnormal blood flow using PDS can increase cancer detection with an optimized number of biopsy cores. The risk of extracapsular involvement can be evaluated by the presence of vessels perforating the capsule.