Histographic Analysis of Magnetic Resonance Imaging for the Evaluation of Ovarian Endometrial Invasion

ABSTRACT

Purpose@#The purpose of this study was to evaluate the effectiveness of histographic analysis for the perfusion map of pelvic magnetic resonance imaging (MRI) in predicting remnant ovarian tissue in patients with ovarian endometriosis. @*Materials and Methods@#To generate the perfusion map, subtracted T1-weighted image (T1-WI) was divided by contrast enhanced T1-WI with using image analysis software ImageJ. Each region of interest (ROI) was quantified by outlining of the affected ovaries with endometrioma at the level with the largest area of normal ovary tissue and normal contralateral ovaries using the measurement tool on the software. Consequently, the number of ratios per each pixel comprising the perfusion map was scored from 0 (not perfused) to 1 (totally perfused). The pixel information, including area within ROI, mean with standard deviation of signal intensity, as well as integrated density of affected ovary with endometrioma, were compared with that of the normal ovary. Additionally, we compared the histogram according to the severity of the ovarian invasion. @*Results@#In comparison between the affected ovary with endometrioma and the normal ovary, the perfusion ratio of the normal ovary was higher than that of the affected ovary (0.48 ± 0.07 vs. 0.20 ± 0.12, p < 0.001), whereas the area within the ROI and the perfusion ratio was higher in the affected ovary. According to the severity of the endometrial invasion of the ovary based on the surgical findings, the area with the perfusion ratio between 0.4 and 0.8 (199.17 ± 163.15 vs. 528.00 ± 154.43, p = 0.003), perfusion ratio (0.11 ± 0.07 vs.0.27 ± 0.11, p = 0.012), and, and integrated density (187.33 ± 106.32 vs. 427.125 ± 132.24, p = 0.003) was lower in the group of severe invasion than those of the mild group and moderate invasion group. @*Conclusion@#The histographic analysis for the perfusion map of the pelvic MRI could be valuable in revealing the extent of the endometrial invasion and viable remnant ovarian tissue.