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

Abstract

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.

Keywords: Fertility preservation; Internal Os of cervix; Localization; Magnetic resonance imaging; Surgery.

Figure 1

L1, L3, and L5 shows the length of the cervix starting from the cross-section showing enhancement differences between the uterus and cervix on dynamic contrast-enhanced scanning images, and starting from the cross-section where the physiological curvature of the uterus is formed, and the length of cervical stroma on T2WI images. L2, L4, and L6 shows the corresponding cervix length on gross uterine specimens.

Figure 2

The sagittal T2WI image, the uterus is in an anteverted position, with the thickened endometrium protruding into the cervical canal. The patient had a history of cesarean section surgery and a scar formed in the muscle layer of the lower part of the anterior uterine wall. This is accompanied by deep endometriosis and adenomyosis of the posterior cervical wall, affecting the formation of the physiological curvature of the uterus, and the distinction between the lower part of the uterine body and the cervical stroma is unclear (a). The sagittal dynamic enhanced scan image, the enhancement degree of the uterine body and the cervix is different, the uterine body is stronger than the cervix, and the cross-section formed by the difference in enhancement degree can be used to locate the internal os of the cervix (b).

Figure 3

Sagittal T2WI, measure the cervical length from the start of the low signal of the cervical stroma (a). Sagittal T2WI, measures the cervix length starting from the cross-section where the physiological curvature of the uterus is formed (b). Sagittal dynamic enhancement scanning image, measure the cervix length beginning from the uterine and cervical enhancement junction (c).