Biomedical subjects

Toshihide Yamaoka

Publications and source records attributed to Toshihide Yamaoka.

7 recordsLinked to original sources

PubMed2005

Posterior cul-de-sac obliteration associated with endometriosis: MR imaging evaluation.

PURPOSE: To retrospectively evaluate the accuracy of magnetic resonance (MR) imaging in depicting posterior cul-de-sac obliteration in patients with endometriosis. MATERIALS AND METHODS: Institutional review board approval was not required for this retrospective study, but informed consent was obtained from all patients. MR images obtained between January 1989 and December 2000 in 57 women (mean age, 39 years; age range, 26-52 years) with histologically confirmed endometriosis were retrospectively evaluated by four radiologists independently. All patients underwent laparotomy or laparoscopy less than 1 month after MR imaging. MR images were evaluated for the presence and location of endometrial implants and adhesions. MR images were also scored for the presence of five findings: retroflexed uterus, elevated posterior vaginal fornix, intestinal tethering or tethered appearance of rectum in direction of uterus, faint strands between uterus and intestine, and fibrotic plaque or nodule covering serosal surface of the uterus. Interobserver agreement for each of the five findings and for the overall diagnosis of cul-de-sac obliteration was calculated. Sensitivity, specificity, accuracy, positive and negative predictive values, and kappa statistics were determined. RESULTS: Laparotomy or laparoscopy revealed posterior cul-de-sac obliteration in 30 patients. Overall, the four radiologists had mean accuracies of 89.0% and 76.3% for diagnosing endometrial implants and adhesions, respectively, at MR imaging. Overall, the radiologists achieved mean sensitivity, specificity, accuracy, and positive and negative predictive values of 68.4%, 76.0%, 71.9%, 76.6%, and 68.5%, respectively, in diagnosing posterior cul-de-sac obliteration. The best accuracy (mean value, 64.5%) was obtained with the finding of fibrotic plaque in the uterine serosal surface. Readers agreed on the observations 63.2%-91.2% of the time. For the impression of the presence or absence of posterior cul-de-sac obliteration, interobserver agreement varied between substantial and moderate: Mean interobserver agreement was 78.4% (range, 70.2%-84.2%), and mean kappa was 0.57 (range, 0.40-0.67). Mean accuracy of MR imaging for diagnosing posterior cul-de-sac obliteration was 71.9%. CONCLUSION: These results suggest that use of the described MR imaging findings may enable diagnosis of posterior cul-de-sac obliteration.

Adult↗

PubMed2003

Kinematics of the uterus: cine mode MR imaging.

Cine mode magnetic resonance (MR) imaging has allowed evaluation of kinematics of the pelvis. Visualization of dynamic changes under strain facilitates evaluation of prolapses and adhesions between organs. The uterus, an organ of smooth muscle, has an inherent contractility that characterizes it as different from other visceral organs. This sustained contraction has occasionally been shown on static images as a finding masquerading as a leiomyoma or as adenomyosis. Cine mode MR imaging clearly shows the configuration of the myometrium during these dynamic changes, as well as its signal intensity during contractions. Uterine peristalsis, the subtle and rhythmic contractions of the inner myometrium, is also clearly identifiable on cine mode images as a wavy movement of the endometrium and/or inner myometrium. The direction and frequency of uterine peristalsis are different in each of the menstrual cycle phases and are thought to have important roles in uterine function, such as in fertility and menstrual blood discharge. Elucidation of these kinematics of the uterus will help in the evaluation of static MR images and study of the physiology of the uterus. Cine MR imaging is a novel technique for diagnosis and evaluation of the pelvic organs, especially the uterus.

Adult↗

PubMed2003

Uterine peristalsis shown on cine MR imaging using ultrafast sequence.

PURPOSE: To demonstrate and evaluate uterine peristalsis on cine magnetic resonance imaging (MRI) using ultrafast imaging. MATERIALS AND METHODS: Serial MR uterine images (300) were obtained from 15 normal volunteers over four menstrual phases using true fast imaging with steady-state precession (true FISP) technique over 117 seconds and videotaped. Three radiologists independently evaluated videotapes of 59 studies. Uterine peristalsis was defined as wavy movements of subendometrial myometrium or endometrium. Interobserver reliability was evaluated using a Kappa coefficient. Fifty-four studies obtained in appropriate phases were analyzed. RESULTS: Cine MRI displayed uterine peristalsis in 30 of 59 studies; consensus reading showed direction in 23 studies. Reliability between the final consensus of the recognition of uterine peristalsis and those of the three readers was extremely concordant, with a Kappa coefficient of 0.908. Wave direction was cervico-fundal in follicular and periovulatory phases, with frequency of contraction waves being 1.2-2.3 per minute in positive studies. CONCLUSION: Uterine peristalsis was demonstrated on cine MR using ultrafast MRI. Direction and frequency of peristaltic waves are closely related to menstrual cycle phases. Supplementary material for this article can be found on the JMRI website at http://www.interscience.wiley.com/jpages/1053-1807/suppmat/index.html.

Adult↗

PubMed2002

Immature teratoma of the ovary: correlation of MR imaging and pathologic findings.

The objectives of this study were to describe MR imaging findings of immature teratoma and to correlate imaging findings with histopathologic findings. The MR findings of ten patients (age range 12-29 years, mean age 19.0 years) with pathologically proven immature teratoma were retrospectively reviewed for tumor size, presence and characteristics of fatty content, presence and characteristics of solid components, and presence of ascites and implants. The MR findings were compared with gross (n=3) and microscopic (n=10) findings. Comparisons between relative amounts of solid components and histologic grades were evaluated by Spearman rank-order correlation. On MR images all lesions appeared to be fat-containing tumors with solid components consisting of numerous cysts of various sizes. Solid tissue exhibited a wide variety of signal intensities on T2-weighted images. Punctate foci of fat were identified in all lesions, whereas fatty fluid was observed only in two. Predominant fluid content exhibited signal intensities similar to simple fluid in nine lesions. Ascites was observed in six lesions, and peritoneal dissemination in three. Pathologic studies confirmed scattered foci of adipose tissue in the solid portions of all cases, and revealed numerous cystic structure formations in these solid components. The correlation coefficient between the amount of solid tissue and the tumor grade was not significant (r(s)=0.266). The MR images of immature teratoma tended to show aqueous fluids and the solid components consisting of numerous cysts with punctate foci of adipose tissue, whereas predominant fluid is sebaceous fluid in the vast majority of mature cystic teratomas.

Adolescent↗

PubMed2002

[A case of giant perirenal malignant lymphoma: a case report].

We report a case of malignant lymphoma arising as a giant perirenal mass in a 62-year-old woman who presented with an enlarging abdominal mass. Computed tomography (CT) revealed a large homogeneous mass with a diameter of 20 cm arising in the retroperitoneum. It surrounded the left kidney without renal infiltration and accompanied with para-aortic lymph node enlargement. Compared with the renal cortex, the tumor showed a homogeneous isodense mass by plain CT and only slight enhancement by the contrast-enhanced CT. On the basis of these imaging studies, the tumor was diagnosed as lymphoma. Then, a US guided percutaneous biopsy was performed and the tumor was diagnosed as malignant B-cell lymphoma by the histopathological analysis. This patient was treated by systemic chemotherapy since tumor cells were also disseminated in the bone marrow. The tumor responded well to the chemotherapy and about 70% of regression was achieved after six courses of chemotherapy.

Female↗

PubMedDate not supplied

MR imaging of müllerian mucinous borderline tumors arising from endometriotic cysts.

This report describes MR findings of müllerian mucinous borderline tumors, pathologically proven to have arisen from endometriotic cysts, in three patients. They were unilocular or paucilocular masses with mural nodules. Cystic components showed hyperintensity on both T1- and T2-weighted images, simulating clear cell or endometrioid carcinomas arising from endometriotic cysts. Mural nodules showed prominent high signal intensity on T2-weighted images. Correlation with pathologic findings suggests that this hyperintensity reflects intraluminal mucinous material and stromal edema.

Adult↗

PubMedDate not supplied

Diffusely enlarged uterus: evaluation with MR imaging.

Diffuse uterine enlargement is a common clinical finding. Because this abnormality can represent a physiologic manifestation, benign tumor, or malignancy, the diagnostic dilemma of a diffusely enlarged uterus can be challenging. Clinical findings can provide valuable information in regard to physiologic effects, pregnancy-related changes, and hormonal causes. Cytologic examination is essential for identification of cervical and endometrial malignancies. However, since preoperative histologic examination of myometrial lesions is not possible, preoperative distinction between benign and malignant conditions is frequently difficult. Imaging thus plays an important role in evaluation of myometrial lesions. In particular, magnetic resonance (MR) imaging allows specific diagnosis of several different lesions. Signal voids and prominent vessels at MR imaging are characteristic of vascular lesions. Adenomyosis and leiomyomas can be distinguished from other lesions with MR imaging, although a variety of unusual manifestations can be seen. MR imaging findings that allow distinction between leiomyoma and leiomyosarcoma have yet to be clearly established; however, invasion, hemorrhagic necrosis, or rapid growth is suggestive of malignancy. Endometrial stromal sarcoma tends to have distinct MR imaging features that allow differentiation from benign lesions.

Adult↗