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

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Abstract
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 non‐cancerous 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. J. Magn. Reson. Imaging 2002;16:196–200.