Diffusion Kurtosis Imaging Study of Rectal Adenocarcinoma Associated with Histopathologic Prognostic Factors: Preliminary Findings

Purpose: To determine the correlation between diffusion kurtosis imaging (DKI)-derived parameters and prognostic factors for rectal adenocarcinoma. Materials and Methods: This study was approved by the local institute review board, and written informed consent was obtained from each patient. Data from 56 patients (median age, 59.5 years; age range, 31-86 years) with rectal adenocarcinoma between April 2014 and September 2015 were involved in this prospective study. DKI (b = 0, 700, 1400, and 2100 sec/mm(2)) and conventional diffusion-weighted imaging (b = 0, 1000 sec/mm(2)) were performed. Kurtosis and diffusivity from DKI and apparent diffusion coefficients (ADCs) from diffusion- weighted imaging were measured by two radiologists. Student t test, receiver operating characteristic curves, and Spearman correlation were used for statistical analysis. Results: Kurtosis was significantly higher in high-grade than in low-grade rectal adenocarcinomas on the basis of both the number of poorly differentiated clusters (PDCs) (1.136 +/- 0.086 vs 0.988 +/- 0.060, P < .05) and World Health Organization (WHO) grades (1.103 +/- 0.086 [standard deviation] vs 1.034 +/- 0.103, P < .05). In PDC grading, the diffusivity and ADC were significantly lower in high-grade tumors than in low-grade tumors (1.187 +/- 0.150 vs 1.306 +/- 0.129 and 1.020 +/- 0.113 vs 1.108 +/- 0.097, respectively; P < 05) and showed similar correlations with histologic grades (r = -0.486 and r = -0.406, respectively; P >.05). Compared with both diffusivity and ADC, kurtosis showed significantly higher sensitivity (83.3% [20 of 24] vs 70.8% [17 of 24] and 70.8% [17 of 24], respectively) and specificity (96.8% [31 of 32] vs 84.4% [24 of 32] and 81.3% [26 of 32], respectively). Kurtosis showed a better correlation with PDC grades than with WHO grades (r = 0.797 vs r = 0.293, P < 05). Kurtosis was significantly higher in pN1-2 than in pN0 tumors (1.086 +/- 0.103 vs 1.009 +/- 0.086, P < 05). Conclusion: Kurtosis derived from DKI demonstrated a higher correlation with histologic grades compared with diffusivity and ADC. It also showed better performance in differentiating between high-and low-grade rectal adenocarcinomas and between pN1-2 and pN0 tumors. (C) RSNA, 2016