Diffusion Tensor Imaging (DTI) of the Cesarean-Scarred Uterus in vivo at 3T: Comparison Study of DTI Parameters Between Nonpregnant and Pregnant Cases.

<bold>Background: </bold>Fiber architecture of the human uterus can be depicted in vivo using 3T MR-DTI (diffusion tensor imaging).<bold>Purpose: </bold>To investigate the differences in fibrous structure and DTI-related parameters between nonpregnant and pregnant cases in vivo.<bold>Study Type: </bold>Prospective case-control study.<bold>Subjects: </bold>Thirty-one subjects were divided into two groups; 18 nonpregnant volunteers with previous cesarean deliveries (Group 1) and 13 patients in early pregnancy also with previous cesarean section (Group 2).<bold>Field Strength/sequence: </bold>3T Ssh-EPI (single-shot echo planar imaging) fast sequence with b values of 0 and 600 s/mm2 along 30 directions.<bold>Assessment: </bold>Fiber density, fiber length, apparent diffusion coefficient (ADC) value, and the fractional anisotropy (FA) value measured in the mid-sagittal plane of the uterus were obtained from the outer myometrium (OM), junctional zone (JZ), and the cesarean section scar (CSS). Fiber architecture in vivo was depicted by 3D diffusion tensor tractography (DTT).<bold>Statistical Tests: </bold>A t-test of independent sample or Wilcoxon rank sum test were used for comparison.<bold>Results: </bold>Pregnant scarred-uterus (Group 2) showed a decrease in fiber density, FA value, and an increase in fiber length, ADC value than the nonpregnant scarred-uterus (Group 1) on OM, JZ, and CSS. Among the above parameters between the two groups, for OM, significant differences were found in fiber density (P < 0.001), length (P = 0.0306), and ADC (P = 0.0039). For JZ, significant differences were found in fiber density (P = 0.0093), FA (P = 0.0002), and ADC (P < 0.001). The scar's fiber density (P = 0.0794), length (P = 0.6167), FA (P = 0.6305), and ADC value (P = 0.1865) showed no statistically significant difference during early pregnancy.<bold>Data Conclusion: </bold>Our results indicate considerable diffusional changes in uterine fiber architecture during pregnancy. The microenvironment of scar tissue appears to change little during early pregnancy.<bold>Level Of Evidence: </bold>2 Technical Efficacy Stage: 2 J. Magn. Reson. Imaging 2020;51:124-130. [ABSTRACT FROM AUTHOR]