Relaxation time changes of the uterus during the menstrual cycle: correlation with hormonal status

Magnetic resonance imaging relaxation times of female reproductive organs

BACKGROUND

Relaxation time of female reproductive organs affects the tissue contrast of magnetic resonance image (MRI), and is used for quantitative analysis.

PURPOSE

To evaluate the relaxation times of normal female reproductive organs in the luteal phase of the menstrual cycle.

MATERIAL AND METHODS

On a 1.5-T MRI, relaxation times were measured in pelvic tissues (endometrium, junctional zone, myometrium, follicle, and stroma) of 32 female healthy volunteers (33.5 ± 6.8 years). The Look-Locker sequence was used to measure T1 relaxation times. Furthermore, a multiple spin-echo method with 32 different echo times was used to measure T2 relaxation times. The images were obtained in the luteal phase of each volunteer's menstrual cycle.

RESULTS

The measured relaxation times (means ± standard deviations) were as follows: endometrium (T1, 1703 ± 147 ms; T2, 214 ± 35 ms), junctional zone (T1, 1168 ± 63 ms; T2, 72 ± 12 ms), myometrium (T1, 1314 ± 103 ms; T2, 138 ± 20 ms), follicle (T1, 2267 ± 49 ms; T2, 603 ± 68 ms), and stroma (T1, 1481 ± 129 ms; T2, 126 ± 29 ms).

CONCLUSION

Reliable MRI measurements of T1 and T2 relaxation times of normal female reproductive organs in the luteal phase of the menstrual cycle are useful as references to recognize the normal value.

Does the phase of menstrual cycle affect MR-guided focused ultrasound surgery of uterine leiomyomas?

PURPOSE

To determine whether the phase of menstrual cycle at the time of MR-guided focused ultrasound surgery (MRgFUS) treatment for uterine leiomyomas affects treatment outcome.

METHODS

We enrolled all patients participating in a prospective phase III clinical trial from our center who completed 6 months of clinical and imaging follow-up. Patients with irregular cycles and those on oral contraceptives were excluded. Data prospectively documenting the date of the last menstrual period (LMP) at the time of treatment, length and duration of cycle, and raw symptom severity score (SSS) from the Uterine Fibroid Symptom and Quality of Life questionnaire, at baseline and 6 months were collected. Proliferative phase patients were determined retrospectively as those who were treated within less than 14 days from LMP; secretory phase patients were classified as those who were treated greater than 14 days from LMP.

RESULTS

A total of 58 patients were enrolled. There was no significant difference in the mean SSS at baseline and mean SSS at 6 months between patients treated in the proliferative versus secretory phase of the cycle. No significant difference in the SSS change from baseline to 6 months was seen between the two groups.

CONCLUSIONS

Menstrual cycle phase does not influence MRgFUS treatment outcome. Symptomatic improvement occurs with treatment during either phase of the menstrual cycle. Thus, the scheduling of MRgFUS treatment need not be based upon the phase of the menstrual cycle.

In vivo perfusion, T1, and T2 measurements in the female pelvis during the normal menstrual cycle: A feasibility study

PURPOSE

To quantify T(1), T(2), and regional tissue perfusion in uterine tissues, with MR imaging in clinically feasible imaging times, using echo planar imaging (EPI) techniques over a single menstrual cycle.

MATERIALS AND METHODS

A total of 24 healthy ovulating women were scanned; however, complete data sets through the menstrual cycle were not obtained from all women. Three scans were performed to coincide prospectively with the follicular, periovulatory, and luteal phases of the cycle. T(1) and perfusion were measured simultaneously using flow alternating inversion recovery (FAIR), while T(2) was measured using a single Hahn spin-echo (SE) EPI sequence.

RESULTS

Between the follicular and periovulatory phases, statistically significant increases (P < 0.05) were seen for the T(2) of the endometrium and perfusion of the myometrium as well as the T(2)/T(1) ratio for both endometrium and myometrium. A statistically significant decrease was seen in the endometrial T(2) between the periovulatory and luteal phases of the cycle. Tissue differentiation was achieved using the parameters measured, with T(1) and T(2) being statistically greater for the endometrium than for the myometrium, and endometrial perfusion being statistically lower than myometrial perfusion.

CONCLUSION

These results show the feasibility of using these techniques to measure T(1), T(2), and perfusion in uterine tissues and of extending this work to study pathological conditions.