Evaluating Prostate Cancer Using Fractional Tissue Composition of Radical Prostatectomy Specimens and Pre-Operative Diffusional Kurtosis Magnetic Resonance Imaging

BACKGROUND: Evaluating tissue heterogeneity using non-invasive imaging could potentially improve prostate cancer assessment and treatment. METHODS: 20 patients with intermediate/high-risk prostate cancer underwent diffusion kurtosis imaging, including calculation of apparent diffusion (D(app)) and kurtosis (K(app)), prior to radical prostatectomy. Whole-mount tissue composition was quantified into: cellularity, luminal space, and fibromuscular stroma. Peripheral zone tumors were subdivided according to Gleason score. RESULTS: Peripheral zone tumors had increased cellularity (p<0.0001), decreased fibromuscular stroma (p<0.05) and decreased luminal space (p<0.0001). Gleason score ≥4+3 tumors had significantly increased cellularity and decreased fibromuscular stroma compared to Gleason score ≤3+4 (p<0.05). In tumors, there was a significant positive correlation between median K(app) and cellularity (ρ = 0.50; p<0.05), and a negative correlation with fibromuscular stroma (ρ = -0.45; p<0.05). In normal tissue, median D(app) had a significant positive correlation with luminal space (ρ = 0.65; p<0.05) and a negative correlation with cellularity (ρ = -0.49; p<0.05). Median K(app) and D(app) varied significantly between tumor and normal tissue (p<0.0001), but only median K(app) was significantly different between Gleason score ≥4+3 and ≤3+4 (p<0.05). CONCLUSIONS: Peripheral zone tumors have increased cellular heterogeneity which is reflected in mean K(app), while normal prostate has a more homogeneous luminal space and cellularity better represented by D(app).