Diffusion-weighted endorectal MR imaging at 3T for prostate cancer: correlation with tumor cell density and percentage Gleason pattern on whole mount pathology.

OBJECTIVE

To determine if tumor cell density and percentage of Gleason pattern within an outlined volumetric tumor region of interest (TROI) on whole-mount pathology (WMP) correlate with apparent diffusion coefficient (ADC) values on corresponding TROIs outlined on pre-operative MRI.

METHODS

Men with biopsy-proven prostate adenocarcinoma undergoing multiparametric MRI (mpMRI) prior to prostatectomy were consented to this prospective study. WMP and mpMRI images were viewed using 3D Slicer and each TROI from WMP was contoured on the high b-value ADC maps (b0, 1400). For each TROI outlined on WMP, TCD (tumor cell density) and the percentage of Gleason pattern 3, 4, and 5 were recorded. The ADC, ADC, ADC, and ADC were also calculated in each case from the ADC maps using 3D Slicer.

RESULTS

Nineteen patients with 21 tumors were included in this study. ADC values for TROIs were 944.8 ± 327.4 vs. 1329.9 ± 201.6 mm/s for adjacent non-neoplastic prostate tissue (p < 0.001). ADC, ADC, and ADC values for higher grade tumors were lower than those of lower grade tumors (mean 809.71 and 1176.34 mm/s, p = 0.014; 10th percentile 613.83 and 1018.14 mm/s, p = 0.009; ratio 0.60 and 0.94, p = 0.005). TCD and ADC (ρ = -0.61, p = 0.005) and TCD and ADC (ρ = -0.56, p = 0.01) were negatively correlated. No correlation was observed between percentage of Gleason pattern and ADC values.

CONCLUSION

DWI MRI can characterize focal prostate cancer using ADC, ADC, and ADC, which correlate with pathological tumor cell density.