Magnetic Resonance Imaging of the pelvis has lead to a new radioanatomical description of the uterus. Variations in the anatomical zones of the uterus were noted with different sequences used in MRI. There was also structural and signal variation depending on hormonal impregnation. Twenty seven MRIs of pelvices were carried out on 16 female volunteers. Eight of them were on oestroprogesterone as the method of contraception (Group I) and had a single MRI. Six were not taking contraceptives (Group II) and had different MRI's during the same cycle. Two women already had already gone through the menopause (Group III). Results showed differences in the size of the uterus (uterine height, length of the uterine body and cervix, diameter of the cervix) between groups I and II but no cyclic changes were observed within group II. The myometrium was found to be thicker in group I and in the luteal phase of group II females in comparison to the follicular phase in the same group. The endometrial cavity was seen in 40% of cases on T1 weighted sequences; on T2 weighted sequences it was seen in all the cases. It was thicker during the second phase in group II than in group I and III. The myometrial signal compared to that of the bladder content (urine) showed a significant increase between early and late echoes on T2 weighted sequences in group I and during the second phase of the menstrual cycle in group II. No variations, or at times a decrease in signal, were observed during the first phase of the cycle in group II.(ABSTRACT TRUNCATED AT 250 WORDS)
PIP: 16 healthy 20-71 year old women underwent magnetic resonance imaging (MRI) in Marseille, France so the radiologists could better understand the anatomy of the uterus under various hormonal states. Group I included 8 women who were taking oral contraceptives (OCs) and underwent only 1 MRI. Group II were 6 women who did not take OCs and underwent 2-4 MRIs during 2 phases of the same menstrual cycle. Group III included 2 postmenopausal women. Uterine height, cervix diameter, and uterine body length were greater in group II than group I (76.9 mm vs. 80 mm; 25.6 mm vs. 28.3 mm; and 49.1 mm vs. 46.25 mm respectively). Cervix length was greater in group I than group II (30.6 mm vs. 29.7 mm). The radiologists did not notice any cyclic changes within group II. The myometrium was thicker in group I (16.9 mm) and in the luteal phase of group II (15.8 mm) compared to the follicular phase of group II (13.75 mm). T2 weighted sequences revealed the endometrial cavity of all cases, but T1 weighted sequences revealed the cavity in 40% of cases. The endometrial cavity was thicker in group II women (6.5 mm [1st phase] and 9.9 mm [2nd phase]) than either group I (2.4 mm) or group II (1 mm) women. T2 weighted sequences in group I and during the 2nd phase of the menstrual cycle in group II showed a great increase in the myometrial signal compared to bladder content between early and late echoes. Further only T2 weighted sequences uncovered the junctional zone. The junctional zone was thickest during the 1st phase of the cycle of group II women than during the 2nd phase. T2 weighted sequence could only reveal the junctional zone in only 1 woman in group III. Knowing the zonal anatomy of the uterus and its changes is helpful in diagnosing adenomyosis, myometrial extension of endometrial carcinomas, extension of cervical carcinomas.