DWI and T2-Weighted MRI Volumetry in Resectable Rectal Cancer: Correlation With Lymphovascular Invasion and Lymph Node Metastases

Abstract

<b>OBJECTIVE.</b> The purpose of this study was to assess whether MR volumetric data on DW and T2-weighted MR images are correlated with lymphovascular invasion and lymph node metastases in resectable rectal cancer. <b>MATERIALS AND METHODS.</b> This retrospective study consisted of 50 consecutive patients with rectal cancer who underwent radical surgery within 1 week of MRI. The gross tumor volume was determined on both diffusion-weighted and T2-weighted MR images and correlated with pathologic lymphovascular invasion and lymph node metastases using univariate, multivariate, and ROC curve analyses. <b>RESULTS.</b> Both gross tumor volume values showed correlations with lymphovascular invasion (<i>r</i> = 0.750 vs <i>r</i> = 0.710; <i>p</i> < 0.0001) and lymph node metastases (<i>r</i> = 0.780 vs <i>r</i> = 0.755; <i>p</i> < 0.0001). Both values were associated with lymphovascular invasion and lymph node metastases in univariate analysis (all <i>p</i> < 0.0001), whereas only the DWI-based value was an independent risk factor for lymphovascular invasion (odds ratio = 1.207; <i>p</i> = 0.005) and lymph node metastases (odds ratio = 1.420; <i>p</i> = 0.005) in multivariate analysis. Both values could distinguish between N0 and N1, N0 and N1-N2, and N0-N1 and N2 disease (all <i>p</i> < 0.0001) in the Mann-Whitney <i>U</i> test. The area under the ROC curve was higher for the DWI-based value in lymphovascular invasion (0.899 vs 0.877), N0 vs N1 (0.865 vs 0.827), N0 vs N1-N2 (0.934 vs 0.911), and N0-N1 vs N2 (0.932 vs 0.927). <b>CONCLUSION.</b> Tumor volumetry data correlated with both lymphovascular invasion and lymph node metastases in resectable rectal cancer. In particular, the DWI-based gross tumor volume showed the most potential for noninvasive preoperative evaluation of lymphovascular invasion and lymph node metastases.