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±249 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.