Date Published: February 4, 2019
Publisher: Public Library of Science
Author(s): Qiang Feng, Hong Yu, Shihang Sun, Zhijun Ma, Pascal A. T. Baltzer.
To determine the correlation between the parameters of MR diffusion kurtosis imaging (MR-DKI) and mismatch repair gene expression (MMR) for rectal carcinomas.
Data from 80 patients with rectal carcinoma were analyzed in this prospective study. High-resolution T2WI and DKI (b = 0, 800 and 1600 s/mm2, respectively) were performed. Mean kurtosis (MK) and mean diffusivity (MD) from DKI were measured. MMR-positive expression and HER-2 expression were classified into two groups. For comparison between different grades, the Mann-Whitney U test, receiver operating characteristic curve, and Spearman’s correlation analysis were used for statistical analyses.
The MK values in identifying positive MMR expressions (MLH1, MSH2, and MSH6) were more reliable than the MD values (rs value: 0.772 vs. 0.448, 0.733 vs. 0.499, and 0.828 vs. 0.633 respectively, P<0.01). Receiver operating curve analysis showed that the performances of the MK values were better than those of the MD values (z = 2.835, 2.000, and 2.827, respectively, P<0.05), while the performances of the MK and MD-MK values were not statistically significant (z = 0.808, 1.557, and 0.596, respectively, P>0.05). Similarly, MK values were better than MD values in identifying HER2 expression (z = 2.795, P<0.05). MK derived from DKI demonstrated a greater correlation than MD with MMR expression. It also showed better performance in differentiating between high- and low-grade positive MMR expression and HER2 expression. Thus, DKI may be valuable for the prognoses and evaluation of non-invasive therapies.
Rectal carcinoma is one of the most common malignant tumors [1,2], with an increasing occurrence. The treatment of rectal carcinoma includes surgery and neoadjuvant chemoradiotherapy (CRT). For locally advanced rectal cancer (LARC), CRT is the most commonly treatment, which may reduce the ratio of local recurrence  and improve the results of resection. Because of individual differences, the CRT of some patients shows poor or even no treatment response , while others show good treatment responses. Early detection and assessment of treatment response before the onset of CRT would be helpful to identify appropriate patients to avoid ineffective and potentially toxic therapy .
We assessed the feasibility of a DKI model for assessment of mismatch repair gene expression of rectal carcinoma, to determine whether DKI could be involved in clinical implementation.