Abstract
ObjectivesTo investigate the performance of the mean parametric values and texture features based on intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI) on identifying pathological complete response (pCR) to neoadjuvant chemoradiotherapy (nCRT) in locally advanced rectal cancer (LARC).MethodsPretreatment IVIM-DWI was performed on 41 LARC patients receiving nCRT in this prospective study. The values of IVIM-DWI parameters (apparent diffusion coefficient, ADC; pure diffusion coefficient, D; pseudo-diffusion coefficient, D* and perfusion fraction, f), the first-order, and gray-level co-occurrence matrix (GLCM) texture features were compared between the pCR (n = 9) and non-pathological responder (non-pCR, n = 32) groups. Receiver operating characteristic (ROC) curves in univariate and multivariate logistic regression analysis were generated to determine the efficiency for identifying pCR.ResultsThe values of IVIM-DWI parameters and first-order texture features did not show significant differences between the pCR and non-pCR groups. The pCR group had lower Contrast and DifVarnc values extracted from the ADC, D, and D* maps, respectively, as well as lower CorrelatD value. Higher CorrelatD*, Correlatf, SumAvergADC, and SumAvergD values were observed in the pCR group. The area under the ROC curve (AUC) values for the individual predictors in univariate analysis ranged from 0.698 to 0.837, with sensitivities from 43.75% to 87.50% and specificities from 66.67 to 100.00%. In multivariate analysis, CorrelatD* (P < 0.001), DifVarncADC (P = 0.024), and DifVarncD (P < 0.001) were the independent predictors to pCR, with an AUC of 0.986, a sensitivity of 93.75%, and a specificity of 100.00%.ConclusionPretreatment GLCM analysis based on IVIM-DWI may be a potential approach to identify the pathological response of LARC.
Highlights
Neoadjuvant chemoradiotherapy combined with subsequent total mesorectal excision (TME) is the current standard of care for locally advanced rectal cancer (LARC) because of its great performance on decreasing the chance of local recurrence and increasing overall survival rate [1, 2]
This study focused on the utility of texture features based on IVIM-diffusion-weighted imaging (DWI), together with mean parametric values, to identify pathologic complete response (pCR) from non-pathological complete response (non-pCR) to preoperative chemoradiotherapy of LARC
Our study found that the pCR and nonpCR groups differed significantly from each other in the baseline gray-level co-occurrence matrix (GLCM) features related to IVIM-DWI, which demonstrated the potential of GLCM analysis to discriminate the pathological response status for LARC
Summary
Neoadjuvant chemoradiotherapy (nCRT) combined with subsequent total mesorectal excision (TME) is the current standard of care for locally advanced rectal cancer (LARC) because of its great performance on decreasing the chance of local recurrence and increasing overall survival rate [1, 2]. Pathological examination is the gold standard to evaluate the therapy response to nCRT of LARC. The pathologic response to nCRT is variable across LARC individuals, of which 15–27% achieve a pathologic complete response (pCR) [3]. These patients may need no further anti-tumor treatment and benefit from this “wait-and-watch” strategy [4], while alternative therapy should be considered for those without pCR. Functional MRI approaches such as diffusion-weighted imaging (DWI) [9] and dynamic contrast-enhanced MRI [10] have advantages in evaluating the treatment effect of LARC. Based on a mono-exponential decay model, traditional DWI report shows the potential to predict treatment response of LARC, but its performance remains controversial across previous reports [11, 12]
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