Study on the value of MRI in locating the internal OS of the cervix and influencing factors.

The position of the internal os of the cervix reported in the literature was inconsistent on MRI images. Additionally, the practical impactful data influencing the internal os located by MRI is limited. We aimed to confirm the position of the internal os of the cervix on MRI images, and the influencing factors locating the the internal os by MRI. A single-center retrospective study was conducted. Data from 175 patients who underwent total hysterectomy for stage I endometrial cancer were collected. The internal os of the cervix is positioned as the starting point for measuring the length of the cervix on MRI images. On dynamic contrast-enhanced MRI (DCE-MRI), the section formed by the enhancement difference between the uterus and cervix, and on T2-weighted imaging(T2WI), the section formed by the physiological curvature of the uterus and the low signal intensity of the cervical stroma were used as starting points. The results showed no statistically significant difference compared with the removed uterus specimens (p = 0.208, p = 0.571, p = 0.804). A history of cesarean section(p < 0.001), irregular vaginal bleeding for more than three months(p < 0.001), cervical adenomyosis(p = 0.043), and premenopause(p = 0.001) were not conducive to locating the internal os of the cervix by MRI. Our findings provide valuable information and confirm the position of the internal os of the cervix on MRI images, and the several important infuencing factors. We hope that some patients will benefit from our study.