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

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 ϭ 7) and patient (N ϭ 19) groups. The spin-echo images comprised 96 ϫ 96 pixels (field of view of 16 cm, TR/TE ϭ 4000/120 msec) with six b-factor values ranging from 64 to 786 seconds/mm 2 . Results:The ADC values averaged over all patients in noncancerous and malignant peripheral zone (PZ) tissues were 1.82 Ϯ 0.53 ϫ 10 -3 (mean Ϯ SD) and 1.38 Ϯ 0.52 ϫ 10 -3 mm 2 /second, respectively (P ϭ 0.00045, N ϭ 17, paired t-test). The ADC values were found to be higher in the non-cancerous PZ (1.88 Ϯ 0.48 ϫ 10 -3 ) than in healthy or benign prostatic hyperplasia central gland (BPH-CG) region (1.62 Ϯ 0.41 ϫ 10 -3 ). For the normal group, the mean values were 1.91 Ϯ 0.46 ϫ 10 -3 and 1.63 Ϯ 0.30 ϫ 10 -3 mm 2 /second for the PZ and CG, respectively (P ϭ 0.011, N ϭ 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.

Combined diffusion‐weighted and dynamic contrast‐enhanced MRI for prostate cancer diagnosis—Correlation with biopsy and histopathology

“…The ADC values measured in our study in the normal PZ and CG, and PCa generally correspond well with previously published values (21,23,33,34). The only exception is a study by Gibbs et al (20), which reported much higher ADC values compared to other studies.…”

“…The ADC maps were reconstructed by calculating ADC values in each pixel of each slice. The average ADC values of the tumors were calculated from regions of interest (ROIs) defined as the hypointense areas in the PZ on ADC maps, since previous studies showed lower ADC values in tumors as compared to normal PZ (21,22,(27)(28)(29). The mean diffusivity was calculated as an average of ADCx, ADCy, and ADCz.…”

Apparent diffusion coefficient: Prostate cancer versus noncancerous tissue according to anatomical region

“…Most studies have conducted a simple comparison of ADC between prostate cancer and adjacent noncancerous tissue (16 -19). Studies that compared the ADC in the nonprostatic tissues divided the prostate into peripheral and central glands or into peripheral and transitional zones but did not consider the ADC in the prostatic base (12)(13)(14)(15)20,21). However, our results suggest that the prostatic base may be the most confusing region in which to differentiate prostate cancer from noncancerous tissue.…”

“…However, investigators have also suggested the wide variability of ADC in noncancerous tissue, which causes a considerable overlap of ADC between cancer and noncancerous tissue (12)(13)(14)(15). As the microscopic structure of the prostate varies according to the anatomical compartment, we suggest that structural variability by anatomical region may cause a wide range of ADC in the prostate.…”

“…This extended application is based on the fact that cancer tissue generally tends to have more restricted diffusion than noncancerous tissue because of its highcell densities and abundant intra-and intercellular membranes (5,(7)(8)(9)(10)(11)(12).…”