Endometrial carcinoma: Evaluation using diffusion‐tensor imaging and its correlation with histopathologic findings

<jats:sec><jats:title>Background</jats:title><jats:p>Although the prognosis of endometrial carcinoma (EMC) patients strictly depends on tumor invasion depth and its histologic grade, accurate preoperative assessment of these prognostic factors is often difficult.</jats:p></jats:sec><jats:sec><jats:title>Purpose</jats:title><jats:p>To determine the usefulness of diffusion‐tensor imaging (DTI) as a noninvasive method for evaluating tumor invasion depth and its histologic grade in patients with EMC.</jats:p></jats:sec><jats:sec><jats:title>Study Type</jats:title><jats:p>Prospective.</jats:p></jats:sec><jats:sec><jats:title>Population</jats:title><jats:p>Twenty‐five consecutive patients with histologically confirmed EMC who were surgically treated at our institution.</jats:p></jats:sec><jats:sec><jats:title>Field Strength/Sequence</jats:title><jats:p>DTI was performed with a 1.5T MRI system using a single‐shot echo‐planar imaging sequence with b values of 0 and 1000 s/mm<jats:sup>2</jats:sup> and motion‐probing gradients in nine noncollinear directions.</jats:p></jats:sec><jats:sec><jats:title>Assessment</jats:title><jats:p>Fractional anisotropy (FA), mean diffusivity (MD), and axial diffusivity (AD) maps were analyzed by three observers and compared with histopathologic findings.</jats:p></jats:sec><jats:sec><jats:title>Statistical Tests</jats:title><jats:p>Dunnett's test, Spearman's rank correlation coefficient, and receiver operating characteristic (ROC) curve analyses.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>FA maps from all patients distinctly identified the junctional zone as a high‐FA zone (0.864 ± 0.037) that was significantly different from the endometrium and outer myometrium (0.251 ± 0.030 and 0.471 ± 0.091, respectively; <jats:italic>P</jats:italic> < 0.001). All EMCs were clearly depicted as hypointense areas on all DTI maps. AD maps provided the best tumor‐to‐uterus contrast, and EMCs (0.977 ± 0.120 × 10<jats:sup>−3</jats:sup> mm<jats:sup>2</jats:sup>/s) had significantly lower AD values than all other layers of the normal uterine wall (2.166 ± 0.408, 2.010 ± 0.289, and 2.655 ± 0.203 × 10<jats:sup>−3</jats:sup> mm<jats:sup>2</jats:sup>/s, respectively; <jats:italic>P</jats:italic> < 0.001). EMCs were clearly demarcated from the normal uterine wall, and DTI maps and histopathologic data yielded identical findings regarding tumor invasion depth. FA values showed a significant inverse correlation (<jats:italic>r</jats:italic> = –0.818; <jats:italic>P</jats:italic> < 0.001) with histologic grades 1, 2, and 3 of endometrioid adenocarcinomas.</jats:p></jats:sec><jats:sec><jats:title>Data Conclusion</jats:title><jats:p>In patients with EMC, DTI may be useful for evaluating tumor invasion depth and its histologic grade.</jats:p><jats:p><jats:bold>Level of Evidence:</jats:bold> 1</jats:p><jats:p><jats:bold>Technical Efficacy:</jats:bold> Stage 2</jats:p><jats:p>J. Magn. Reson. Imaging 2019;50:250–260.</jats:p></jats:sec>