Volumetric histogram analysis of amide proton transfer-weighted imaging for predicting complete tumor response to neoadjuvant chemoradiotherapy in locally advanced rectal adenocarcinoma

To investigate the potential of histogram analysis applied to pre-treatment amide proton transfer-weighted (APTw) imaging in predicting complete pathological regression (pCR) in patients with locally advanced rectal cancer (LARC) undergoing neoadjuvant chemoradiotherapy (nCRT). This retrospective study enrolled LARC patients who underwent preoperative rectal magnetic resonance imaging (MRI). Based on histologic assessment, the patients were divided into a pathological complete response (pCR) group or a non-pCR group. APTw histogram features, apparent diffusion coefficient (ADC), and clinical parameters were analyzed. Mann-Whitney U-test, Spearman rank correlation, and univariate and multivariate logistic regression were used for statistical analysis. The predictive performances of different models were evaluated by the receiver operating characteristic curve (ROC). One-hundred forty-five patients were included (mean age, 61.6 years ± 11.8 [SD]; 87 men). pCR patients exhibited lower pre-treatment ADC value, higher pre-treatment APTw-10%, APTw-90%, minimum, maximum, median, mean, range, and root mean square (RMS) of the primary tumor compared to non-pCR patients (all p