In vivo measurement of the apparent diffusion coefficient in normal and malignant prostatic tissues using echo-planar imaging

Purpose: To measure for the first time the apparent diffusion coefficient (ADC) values in anatomical regions of the prostate for normal and patient groups, and to investigate its use as a differentiating parameter between healthy and malignant tissue within the patient group. Materials and Methods: Single-shot diffusion-weighted echo-planar imaging (DW-EPI) was used to measure the ADC in the prostate in normal (N = 7) and patient (N = 19) groups. The spin-echo images comprised 96 × 96 pixels (field of view of 16 cm, TR/TE = 4000/120 msec) with six b-factor values ranging from 64 to 786 seconds/mm². Results: The ADC values averaged over all patients in noncancerous and malignant peripheral zone (PZ) tissues were 1.82 ± 0.53 × 10^-3 (mean ± SD) and 1.38 ± 0.52 × 10^-3 mm²/second, respectively (P = 0.00045, N = 17, paired t-test). The ADC values were found to be higher in the non-cancerous PZ (1.88 ± 0.48 × 10^-3) than in healthy or benign prostatic hyperplasia central gland (BPH-CG) region (1.62 ± 0.41 × 10^-3). For the normal group, the mean values were 1.91 ± 0.46 × 10^-3 and 1.63 ± 0.30 × 10^-3 mm²/second for the PZ and CG, respectively (P = 0.011, N = 7). Significant overlap exists between individual values among all tissue types. Furthermore, ADC values for the same tissue type showed no statistically significant difference between the two subject groups. Conclusion: ADC is quantified in the prostate using DW-EPI. Values are lower in cancerous than in healthy PZ in patients, and in BPH-CG than PZ in volunteers.