The value of diffusion kurtosis imaging in assessing pathological complete response to neoadjuvant chemoradiation therapy in rectal cancer: a comparison with conventional diffusion-weighted imaging

// Feixiang Hu 1,* , Wei Tang 1,* , Yiqun Sun 1 , Dang Wan 1 , Sanjun Cai 2 , Zhen Zhang 3 , Robert Grimm 4 , Xu Yan 5 , Caixia Fu 6 , Tong Tong 1 and Weijun Peng 1 1 Department of Radiology, Fudan University Shanghai Cancer Center, Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, P.R. China 2 Department of Colorectal Surgery, Fudan University Shanghai Cancer Center, Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, P.R. China 3 Department of Radiotherapy, Fudan University Shanghai Cancer Center, Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, P.R. China 4 MR Applications Predevelopment, Siemens Healthcare GmbH, Erlangen, Germany 5 MR Collaboration NE Asia, Siemens Healthcare, Shanghai, P.R. China 6 APPL, Siemens Shenzhen Magnetic Resonance Ltd., Shenzhen, P.R. China * These authors have contributed equally to this work Correspondence to: Tong Tong, email: // Weijun Peng, email: // Keywords : diffusion kurtosis imaging, apparent diffusion coefficient, neoadjuvant chemoradiation therapy, locally advanced rectal cancer, pathological complete response Received : February 06, 2017 Accepted : April 11, 2017 Published : April 27, 2017 Abstract Objectives: The aim of this study is to comprehensively evaluate the advantage of diffusion kurtosis imaging (DKI) in distinguishing pathological complete response (pCR) from non-pCR patients with locally advanced rectal cancer (LARC) after neoadjuvant chemoradiation therapy (CRT) in comparison to conventional diffusion-weighted imaging (DWI). Material and Methods: Fifty-six consecutive patients diagnosed with LARC were prospectively enrolled and underwent pre- and post-CRT MRI on a 3.0 T MRI scanner. Apparent diffusion coefficient (ADC), mean diffusion (MD) and mean kurtosis (MK) values of the tumor were measured in pre- and post-CRT phases and then compared to histopathologic findings after total mesorectal excision (TME). Both Mann-Whitney U-test and Kruskal-Wallis test were used as statistical methods. Diagnostic performance was determined using receiver operating characteristic (ROC) curve analysis. Results: For a total of 56 rectal lesions (pCR, n = 14; non-pCR, n = 42), the MK pre and MK post values were much lower for the pCR patients (mean±SD, 0.72±0.09 and 0.56±0.06, respectively) than those for the non-pCR patients (0.89±0.11 and 0.68±0.08, respectively) ( p < 0.001). The ADC post and the change ratio of apparent diffusion coefficient (ADC ratio ) values was significantly higher for the pCR patients (mean±SD, 1.31±0.13 and 0.64±0.34, respectively) than for the non-pCR patients (1.12±0.16 and 0.33±0.27, respectively) ( p < 0.001 and p = 0.001, respectively). In addition, the MD post and the change ratio of mean diffusion (MD ratio ) (2.45±0.33 vs. 1.95±0.30, p < 0.001; 0.80±0.43 vs. 0.35±0.32, p < 0.001, respectively) also increased, whereas the ADC pre , MD pre and the change ratio of mean kurtosis (MK ratio ) of the pCR (0.82±0.11, 1.40±0.21, and 0.23±0.010, respectively) exhibited a neglectable difference with that of the non-pCR ( p = 0.332, 0.269, and 0.678, respectively). The MK post showed relatively high sensitivity (92.9%) and high specificity (83.3%) in comparison to other image indices. The area under the receiver operating characteristic curve (AUROC) that is available for the assessment of pCR using MK post (0.908, cutoff value = 0.6196) were larger than other parameters and the overall accuracy of MK post (85.7%) was the highest. Conclusions: Both DKI and conventional DWI hold great potential in predicting treatment response to neoadjuvant chemoradiation therapy in rectal cancer. The DKI parameters, especially MK post , showed a higher specificity than conventional DWI in assessing pCR and non-pCR in patients with LARC, but the pre-CRT ADC and MD are unreliable.