Abstracts—sessions 1–3

Objectives : To evaluate diffusion-weighted imaging (DWI) with low b factors of the peripheral zone (PZ) of patients with prostatic cancer. Materials and methods : An EPI diffusion MR sequence (TE = 75 ms, TR = 4000 ms, slice thickness = 4 mm), with low diffusion factors incremented by 10 s/mm2, has been developed on a 1.5 T magnet. Axial T2-weighted images of the prostate were performed on 21 consecutive patients with biopsy-proven prostate cancer. An EPI diffusion sequence with low b factors for the middle part of the prostate was performed at the level showing the lowest T2 signal intensity of the PZ. In both low and normal T2 signal intensity PZ, ADC were computed. A bi-exponential adjustment was performed to extract the slow and fast component values of the apparent diffusion coefficient (ADCslow and ADCfast) as well as the respective fractions of these two compartments (fslow and ffast). Results : The decrease in signal intensity was bi-exponential for all patients. The mean ADCfast values were 25.70×10−3 mm2/s (DS = 20.62 × 10−3) in the low T2 signal intensity PZ and 5.87 × 10−3mm2/s (DS = 2.07 × 10−3) in normal signal intensity PZ (t-test, p = 0.0002). Conclusion : The significant increase in ADCfast in low T2 signal intensity areas of the PZ when compared to normal signal intensity areas may reflect a difference in microvascular perfusion.