Color Doppler quantitative measures to predict outcome of biopsies in prostate cancer

Purpose: The aim was to correlate the color Doppler flow activity pre- and postradiotherapy, using transrectal color Doppler ultrasonography (CDUS) and the 2 year positive biopsy rate after radiotherapy in patients with prostate cancer. Methods and materials: Analysis was carried out in 69 out of 160 patients who had undergone treatment with 3D-conformal radiotherapy (3D-CRT) to prostate and seminal vesicles. Patients were randomized to receive 80 Gy in 40 fractions in 8 weeks (arm A) and 62 Gy in 20 fractions in 5 weeks, 4 fractions per week (arm B). Color Doppler flow activity (CDFA) was evaluated calculating the vascularization index (VI), defined as the ratio between the colored and total pixels in the whole and peripheral prostate, delineated by a radiation oncologist on CDUS images, using EcoVasc a home-made software. The difference between the 2 year post- and pre-3D-CRT maximum VI (VImax), named Δ VImax, was calculated in the whole and peripheral prostate for each patient. Then, Δ VImax and the detected 2 year biopsy outcome were analyzed using the receiver operating characteristics (ROC) technique. Results: The VImax increased or decreased in patients with positive or negative biopsies, respectively, compared to the value before RT in both arms. The area under the ROC curve for Δ VImax in the whole and peripheral prostate is equal to 0.790 and 0.884, respectively. Conclusion: The Δ VImax index, comparing CDFA at 2 years compared to that before RT, allows the 2 year postradiotherapy positive biopsy rate to be predicted.