Correlation of diffusion-weighted magnetic resonance data with cellularity in prostate cancer

Abstract

Objective: To assess the relationship between the apparent diffusion coefficient (ADC) on magnetic resonance imaging (MRI) and cell density (CD) obtained from radical prostatectomy (RP) specimens.

Patients and methods: In all, 36 patients with prostate cancer were recruited; T2-weighted and diffusion-weighted MRI was obtained axially using a 3.0 T scanner. Patients then proceeded to RP; the prostate was whole-mounted and sectioned axially. Slices (3 microm) were cut from the surface of each section and stained with haematoxylin and eosin (H&E). Five randomly positioned areas from the tumour and normal peripheral zone (PZ) were examined by light microscopy at x 200, then digitally photographed and analysed to obtain automatic CD. ADC values were determined from the MRI data using the H&E slides as a reference. ADC and CD values were measured in both malignant lesions and the PZ, and the correlation between ADC and CD assessed.

Results: ADC values were lower (P <or= 0.001) in regions pathologically determined as tumour, with a mean (sd) of 1.45 (0.26) x 10(-3) mm(2)/s, vs normal PZ, of 1.90 (0.33) x 10(-3) mm(2)/s. Similarly, the mean CD over the five fields was higher (P <or= 0.001) in tumour than in normal PZ, with values of 18.89 (4.93)% vs 9.22 (3.23)%. There was a significant correlation between the ADC values and CD (r = -0.50, P < 0.001) regardless of tissue type. CD values were high in cancer which had lower ADC values than normal PZ.

Conclusions: ADC values were correlated successfully with CD; this information cannot be obtained with conventional MRI and is useful in characterizing prostate cancer.