Objective:To investigate the MRI manifestation of the uterus in nulliparous healthy women at childbearing age and its changes during different menstrual cycles. Methods:Siemens 1.5T MRI was used to scan the pelvis of 100 healthy nulliparous females at childbearing age;the thickness of the myometrial and endometrial in mid-sagittal of the uterus was measured and the relationship between the thickness and the menstrual cycle was analyzed by the ANOVA;the uterus tilt direction and bending direction were measured at the same time. Results:The thickness of myometrial of the uterus fundus was(1.18±0.22) cm

the thickness of anterior wall of the uterus corpus was(1.44±0.24) cm

the thickness of posterior wall was(1.37±0.32) cm;and the thickness of the former was thinner than that of the latter two parts

but the thickness of the latter two parts had no significant difference. The thickness of the myometrial did not change with the menstrual cycle

but the endometrial was progressively thicker from the follicular phase to the luteal phase. During the follicular phase

the thickness of the endometrial was(0.58±0.19) cm

(0.92±0.25) cm in the periovulatory phase

and(1.21±0.26) cm in the luteal phase. Among 100 volunteers

the uterus of 62 cases was anteverted

of 27 cases was upright and of 11 cases was retroverted;the uterus of 62 cases was anteflexion

of 6 cases was straight and of 32 cases was retroflexion.Conclusion:Confirming the thickness and the position of the uterus in nulliparous women will contribute to the comparison with females uterus after childbirth and it also provides basis for setting the volume of interest in magnetic resonance spectroscopy studies.