Abstract
ObjectivesThe 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 MethodsFifty-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.ResultsFor a total of 56 rectal lesions (pCR, n = 14; non-pCR, n = 42), the MKpre and MKpost 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 ADCpost and the change ratio of apparent diffusion coefficient (ADCratio) 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 MDpost and the change ratio of mean diffusion (MDratio) (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 ADCpre, MDpre and the change ratio of mean kurtosis (MKratio) 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 MKpost 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 MKpost (0.908, cutoff value = 0.6196) were larger than other parameters and the overall accuracy of MKpost (85.7%) was the highest.ConclusionsBoth DKI and conventional DWI hold great potential in predicting treatment response to neoadjuvant chemoradiation therapy in rectal cancer. The DKI parameters, especially MKpost, 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.
Highlights
Magnetic resonance imaging (MRI) has been widely used to evaluate the neoadjuvant chemoradiation therapy (CRT) response in rectal cancer because of its classical morphological MR evaluation [1,2,3]
The area under the receiver operating characteristic curve (AUROC) that is available for the assessment of pathological complete response (pCR) using MKpost (0.908, cutoff value = 0.6196) were larger than other parameters and the overall accuracy of MKpost (85.7%) was the highest
It is reported that diffusion kurtosis imaging (DKI) was more applicable and appropriate for assessing early response to neoadjuvant chemotherapy (NAC) in patients with locally advanced nasopharyngeal carcinoma (NPC) than Apparent diffusion coefficient (ADC) [30].The results showed that ∆D was more sensitive in predicting the treatment results (P = 0.006)
Summary
Magnetic resonance imaging (MRI) has been widely used to evaluate the neoadjuvant CRT response in rectal cancer because of its classical morphological MR evaluation [1,2,3]. Quantitative biomarkers of functional magnetic resonance imaging could objectively reflect the response to therapy [4,5,6,7,8] and play an essential role in identifying patients with good prognosis. Patients with no response to the treatment (non-responders [NRs]) that were identified at an early stage (2-3 weeks after the start of neoadjuvant CRT) might have chance to choose alternative treatment [15, 16]. The current lack of reliable non-invasive diagnostic tools to identify complete responders remains a major challenge [17]. A non-Gaussian diffusion model called as diffusion kurtosis imaging was proposed by Jensen and his co-workers in 2005 [22]. This model calculates the kurtosis coefficient (K) that signifies the deviation of tissue diffusion from a Gaussian model, and the diffusion coefficient(D) with the correction of non-Gaussian bias
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
