Edward Malnor Lawrence BS, Abstract Co-Author: Nothing to Disclose

Debra A. Goldman MS, Abstract Co-Author: Nothing to Disclose

Ferdia Aidan Gallagher PhD, FRCR, Abstract Co-Author: Research support, General Electric Company

Andrew N. Priest, Abstract Co-Author: Nothing to Disclose

Tristan Barrett MBBS, BSc, Abstract Co-Author: Nothing to Disclose

Anne Warren, Abstract Co-Author: Nothing to Disclose

Vincent Gnanapragasam, Abstract Co-Author: Nothing to Disclose

Evis Sala MD, PhD, Presenter: Nothing to Disclose

To investigate the relationship between diffusional kurtosis imaging (DKI), Gleason score (GS), and the tissue composition of peripheral zone (PZ) tumors.

Twenty patients underwent magnetic resonance imaging (MRI) at 3 T, including DKI (b-values: 150,650,1050,1500 s/mm^2) for this prospective study. Axial T1W images and high-resolution T2W images of the pelvis in axial, sagittal and coronal planes were acquired. Maps of apparent diffusion (Dapp) and apparent kurtosis (Kapp) were calculated from these b-values, and PZ tumor location was marked on these maps using whole-mount histopathology slides as a reference. These hematoxylin & eosin slides were digitalized at 20x resolution and percentage areas of cellularity, fibromuscular stromal matrix (FSM), and luminal space were measured by using color based image segmentation (ImageScope v11.2; Aperio Technologies, Vista, CA). PZ tumors were divided into 2 groups: (1) GS ≤ 3+4 (low grade); (2) GS ≥ 4+3 (high grade). Correlations between DKI and histopathology were assessed using Wilcoxon Rank Sum test and Spearman's correlation.

Twenty patients were included (median age, 64; median prostate specific antigen- 8.2 ng/mL). Twelve patients had low grade and 8 had high grade PZ tumors. Kapp was significantly increased in high grade compared to low grade PZ tumors (0.85 v. 0.66, respectively; p=0.035); Dapp was decreased, but the change was not significant (p=0.193). Higher grade PZ tumors had both a significant increase in the percentage area of cellularity (p=0.041) and a decrease in the percentage area of FSM (p=0.011). Kapp had a significant positive correlation with cellularity using Spearman’s correlation (ρ = 0.48, p=0.034) and a moderate negative correlation with FSM (ρ = -0.43, p = 0.057). Dapp only had a weak negative correlation with percentage area of cellularity (ρ= -0.40) (p=0.078). Tumor GS, Kapp, and Dapp all had an insignificant correlation with luminal space.

There is a significant positive relationship between diffusional kurtosis, measured with Kapp, and the percentage area of cellularity. Kapp also shows improved performance over Dapp in assessing tumor grade.

Diffusional kurtosis is related to the increasing cellularity and architectural distortion seen in PZ tumors and provides additional biological information compared to standard diffusion weighted MRI.

Lawrence, E, Goldman, D, Gallagher, F, Priest, A, Barrett, T, Warren, A, Gnanapragasam, V, Sala, E, Evaluating the Relationship between Gleason Score, Tumor Tissue Composition, and Diffusion Kurtosis Imaging in Intermediate/High-risk Prostate Cancer Whole-mount Specimens.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14003112.html