Value of diffusion kurtosis imaging in predicting and assessing response to neoadjuvant chemoradiotherapy in locally advanced rectal cancer

Abstract

Objective To investigate the applicable value of diffusion kurtosis imaging(DKI)-derived parameters and apparent diffusion coefficient(ADC) values in predicting and assessing the response to neoadjuvant chemoradiotherapy (CRT) in locally advanced rectal cancer (LARC). Methods A total of 108 patients with rectal cancer who were admitted to the Shanxi Province Tumor Hospital for diagnosis and treatment from December 2016 to May 2018 were treated with neoadjuvant chemoradiotherapy, and all imaging and clinical data were reviewed. Among them, 42 cases were females and 86 cases were males, with an average age of 60 (42-81) years. According to pathology results, tumor regression grading(TRG)1-2 levels was neoadjuvant therapy curative effect good, TRG 3-5 was poor. Mean diffusion(MD), mean kurtosis(MK) and ADC values of the tumor were measured with relevant software in pre-CRT and post-CRT phases. Student's t-test, Paired sample t-test, receiver operating characteristic(ROC) curves, and interclass correlation coefficient (ICC) were used for statistical analysis. Results There were 27 patients(25%) with good postoperative pathological evaluation (including 5 TRG1 patients and 22 TRG2 patients), and 81 patients(75%) with poor efficacy (including 41 TRG3 patients, 26 TRG4 patients and 12 TRG5 patients). The ADCpre and MDpre values of good responder group were lower than those with poor responder group, while the MKpre was higher than those with poor responder group. However, there was no significant difference of these index between the two groups (all P values>0.05). MKpost value in patients with good responders was significantly lower than that of patients with poor responder (P<0.05). The ADCpost and MDpost values in patients with good responder were significantly higher than those with poor responder (all P values<0.05), and the differences in MDratio, ADCratio and MKratio values between the two groups were also statistically significant (all P values<0.05). MKpost showed the highest area under the curve(0.823) of ROC among all the DKI and ADC index for response to CRT in LARC. When the cutoff of MKpost was 0.635, the corresponding sensitivity and specificity were 76.5% and 63.0%, respectively. Conclusions DKI-derived parameters and ADC values, especially MKpost, can aid in predicting treatment response to neoadjuvant CRT in patients with LARC. Key words: Rectal neoplasms; Locally advanced; Chemotherapy, adjuvant; Diffusion magnetic resonance imaging; Apparent diffusion coefficient; Mean diffusivity; Mean kurtosis