Prediction of tumor budding in patients with rectal adenocarcinoma using b-value threshold map.

Abstract

To investigate the feasibility of b-value threshold (b_Threshold) map in preoperative evaluation of tumor budding (TB) in patients with locally advanced rectal cancer (LARC). Patients with LARC were enrolled and underwent diffusion-weighted imaging (DWI). Contrast-to-noise ratio (CNR) between the lesions and normal tissues was assessed using DWI and b_Threshold maps. TB was counted and scored using hematoxylin and eosin staining. Reproducibility for the apparent diffusion coefficient (ADC), b_Threshold values, and region-of-interest (ROI) sizes were compared. Differences in ADC and b_Threshold values with low-intermediate and high TB grades and the correlations between mean ADC and b_Threshold values with TB categories were analyzed. Diagnostic performance of ADC and b_Threshold values was assessed using area under the curve (AUC) and decision curve analysis. Fifty-one patients were evaluated. The CNR on b_Threshold maps was significantly higher than that on DW images (9.807 ± 4.811 vs 7.779 ± 3.508, p = 0.005). Reproducibility was excellent for the ADC (ICC 0.933; CV 8.807%), b_Threshold values (ICC 0.958; CV 7.399%), and ROI sizes (ICC 0.934; CV 8.425%). Significant negative correlations were observed between mean ADC values and TB grades and positive correlations were observed between mean b_Threshold values and TB grades (p < 0.05). b_Threshold maps showed better diagnostic performance than ADC maps (AUC, 0.914 vs 0.726; p = 0.048). In LARC patients, b_Threshold values could distinguish different TB grades better than ADC values, and b_Threshold maps may be a preoperative, non-invasive approach to evaluate TB grades. • Compared with diffusion-weighted images, b_Threshold maps improved visualization and detection of rectal tumors. • Agreement and diagnostic performance of b_Threshold values are superior to apparent diffusion coefficient in assessing tumor budding grades in patients with locally advanced rectal cancer. • b_Threshold maps could be used to evaluate tumor budding grades non-invasively before operation.