Quantitative MRI of the prostate and uterus in monkeys

Quantitative MRI has been carried out in the prostate, seminal vesicles, uterus, and ovaries in the pig-tailed monkey, Macaca nemestrina. T2-weighted, fat-suppressed, multislice experiments were performed at 2.35 T. Eight males, 14 ovariectomized females, and 20 intact females were studied. In the prostate, the caudal and cranial lobe were readily distinguished since the latter had a longer T2 value. For all tissues and organs, interanimal variations were large (up to 12-fold variation in volume), but reproducibility was excellent in the prostate and in the ovariectomized monkey uterus with coefficients of variation (CV) of 3 and 5%, respectively. In the intact monkey uterus, cycle-cycle reproducibility was good with CVs of 6-10% in the myometrium and 14-18% in the endometrium. In the follicular phase, endometrial growth (+3.8% day-1, P < 0.001) was accompanied by myometrial shrinkage (-1.6% day-1, P < 0.001), while in the luteal phase, growth was seen in both tissues (+4.3% day-1, P < 0.001 and +1.4% day-1, P < 0.001, respectively). The great value of these MRI techniques in obtaining data in pharmacological efficacy studies of endocrine drugs, and in limiting the number of animals used, is discussed.