Izumi Imaoka

Proton two-dimensional chemical shift imaging for evaluation of prostate cancer: External surface coil vs. endorectal surface coil

To compare the diagnostic ability of proton magnetic resonance spectroscopy (MRS) using an external surface coil with that using an endorectal surface coil in patients with prostate cancer.

MRI Evaluation of the Uterine Structure after Myomectomy

Myomectomy is a good indication for women with uterine leiomyoma who desire to preserve their child-bearing potential. However, there are still no reports about how long it takes the uterus to reach a stable state after myomectomy. We evaluated the changes in uterine structure during the recovery process after myomectomy by MR images. MR images were used to analyze the time-dependant changes in the length of the uterine cavity, the volume of the uterus, recovery of the junctional zone, prevalence of modification of the endometrium, and uterine structure in the region of the enucleated myoma. The cavity length and the volume of the uterus, and the myometrium were stabilized at six weeks after the myomectomy. With regard to the endometrium, 12 weeks were required for it to achieve a stable state after myomectomy. However, even at 12 weeks postoperatively, 14.2% of the cases showed an unusual view near the uterine incision on MR images. We concluded that the recovery process is complete at 12 weeks after the operation if there are no clear findings of hematoma or edema formation in the myometrium on MR images.

ABNORMAL UTERINE CAVITY: DIFFERENTIAL DIAGNOSIS WITH MR IMAGING

The objective of the study was to assess the usefulness of magnetic resonance (MR) imaging in distinguishing malignant from benign conditions in patients with an abnormal uterine cavity. Fifty-four patients that were suspected of having abnormal uterine cavities were retrospectively evaluated by using MR imaging. The diagnosis of an abnormal uterine cavity included a thickened endometrium, and/or a endometrial mass, and/or a submucosal mass. Threshold values to classify the uterine cavity as abnormal on sagittal T2-weighted images were >10 mm for premenopausal women and >5 mm for postmenopausal women. Malignancy was diagnosed when lesions invaded the myometrial/junctional zone, and/or lesion enhancement was lower than that of the adjacent myometrium. The results found that histology confirmed 18 malignant and 37 benign lesions. Twelve of 15 endometrial carcinomas and 3 malignant mixed mesodermal tumors (MMMT) were correctly characterized as malignant on enhanced T1-weighted images; whereas 6 of 15 endometrial carcinomas and 3 MMMT were correctly characterized on T2-weighted images. Thirty-four of 37 benign cases were correctly characterized as not malignant on enhanced T1-weighted images. One of 14 submucosal leiomyomas, one endometrial stromal metaplasia, and one of ten pathologically normal endometria were misdiagnosed on enhanced T1-weighted images but were correctly diagnosed on T2-weighted images. The overall sensitivity, specificity, and accuracy for distinguishing malignant from benign central uterine masses were 83%, 92%, and 89% for enhanced T1-weighted image, and 50%, 97%, and 82% for T2-weighted image, respectively. We came to the conclusion that in diagnosing patients with abnormal uterine cavity, MR imaging may help differentiate malignant from benign disorders.

Studies on the detection of small endometrial implants by magnetic resonance imaging using a fat saturation technique

To assess the usefulness of fat-saturated magnetic resonance (MR) imaging in detecting small endometrial implants, 258 pigmented lesions of endometriosis from 80 consecutive patients with histopathologically diagnosed pelvic endometriosis were compared using fat-saturated and conventional MR imaging. MR imaging was performed with a 1.5-tesla superconducting magnet with spin echo T1-, T2-, and fat-saturated T1-weighted images. Both conventional MR images and fat-saturated MR images permitted identification of almost all endometriomas > 10 mm in diameter. With conventional MR imaging, 29 endometrial implants measuring < 10 mm in diameter were detected. One hundred and seven lesions were detected by fat-saturated MR imaging. However, conventional MR images demonstrated only 4 lesions among these 111 small endometrial implants that measured < 5 mm in diameter. The addition of fat-saturated MR imaging increased the detection rate to 55 of 111 lesions. Fat-saturated MR imaging can, therefore, be useful in detecting small endometrial implants.

Inflammatory pseudotumor of the bladder: MR findings.

We report a case of inflammatory pseudotumor of the bladder in a 29-year-old woman with gross hematuria that was considered as embryonal rhabdomyosarcoma on biopsy specimens. MRI demonstrated a polypoid tumor covered by clot, which disrupted the low intensity of the bladder wall. The lesion exhibited an intermediate signal on T1-weighted images and prominent high intensity on T2-weighted images and was markedly enhanced. A pathologic study revealed a tumor of myxoid stroma invading into the deep muscular layer of the bladder wall.

MRI in predicting the response of ovarian endometriomas to hormone therapy

OBJECTIVE Our goal was to investigate the usefulness of MRI in predicting the response of endometriomas to hormone therapy. MATERIALS AND METHODS MRI and laparoscopy at the onset of treatment and follow-up MRI after 6 months of hormone therapy were performed in 21 patients with 49 endometriomas. T1- and T2-weighted images were obtained with a 1.5 T apparatus using a body coil. The lesions were divided into a responder group and a nonresponder group according to whether the lesion size decreased by > or = 50% or not. RESULTS With MRI, shading was seen in 25 of 27 lesions (93%) from the nonresponder group, but in only 6 of 22 (27%) from the responder group. Low SI rim was seen in 59% of the responders and 89% of the nonresponders. Multiplicity in 68% of the responders and in 85% of the nonresponders and irregularity in 41% of the responders and in 78% of the nonresponders were shown. Multiple logistic analysis revealed shading was the most important factor in prediction of the response to hormone therapy. CONCLUSION Shading was an important sign in evaluating the response of endometriomas to hormone therapy. MRI may assist in selecting the appropriate therapy for endometriomas.