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Biomedical subjects

Yuji Itai

Publications and source records attributed to Yuji Itai.

32 records · Page 2Linked to original sources
PubMed2002

A decidualized endometrial cyst in a pregnant woman: a case observed with a steady-state free precession imaging sequence.

Decidual changes of the ectopic endometrial stroma during pregnancy are well known among pathologists and obstetricians. However, they appear very similar to endometrial cysts with malignant transformation when imaged. Balanced fast field echo (BFFE) is a steady-state free precession imaging sequence and its contrast is decided by the T1/T2 ratio. The authors report a case of a decidualized endometrial cyst in which mural nodules were isointense with the nomotopic decidualized endometrium on T1- and T2-weighted images and BFFE. Isointensity with the nomotopic endometrium is an MR characteristic that can differentiate a decidualized endometrial cyst from malignant transformation. BFFE is a good alternative sequence during pregnancy because of its shorter acquisition time and lower radiofrequency absorption.

Adult↗
PubMed2002

Quantification of cerebral metabolites in glioma patients with proton MR spectroscopy using T2 relaxation time correction.

This study was aimed to investigate the significance of absolute concentration of metabolites in glioma patients using proton MR spectroscopy (MRS) with T2 relaxation time correction using three different echo times. The absolute concentrations of metabolites in 7 normal subjects and in 23 gliomas (10 low-grade, 13 high-grade) were obtained by proton MRS using a tissue water signal as an internal standard. The signal intensities of metabolites and tissue water were corrected by T2 relaxation time. In low-grade glioma, the T2 relaxation time of NAA was shorter, and T2 relaxation time of water was prolonged as compared to normal subjects (p < 0.001). In high-grade glioma, the T2 relaxation time of NAA (p < 0.001) and T2 relaxation time of Cr (p < 0.01) were shorter, and T2 relaxation time of water (p < 0.001) was prolonged as compared to normal subjects. Moreover, high-grade gliomas revealed a shorter T2 relaxation time of Cr than low-grade gliomas (p < 0.05). In glioma, NAA and Cr concentration were decreased, and Cho were increased as compared to normal subjects. Moreover, high-grade glioma revealed a significant lower Cr (p < 0.001) and Cho (p < 0.01) concentration compared to low-grade gliomas. Low Cr concentration is the most reliable indicator of malignancy in glioma. Cho concentration did not correlate with malignancy in gliomas.

Adult↗
PubMed2002

[Proton MRS in a case of intracerebellar epidermoid].

We report a case of epidermoid, in which proton MR spectroscopy(MRS) provided additional information to MRI. The tumor revealed high signal intensity on T2-weighted images(WI) and low signal intensity on T1 WI. No enhancement was observed. Proton MRS was acquired with the Proton Regional Imaging of Metabolites(PRIME) method(TR/TE/measurements = 2,000 ms/136,272 ms/128 times). Proton MRS revealed lactate(Lac) peak at 1.33 ppm as negative peak at TE 136 ms and positive peak at TE 272 ms. N-acetylaspartate(NAA), creatine/phosphocreatine(Cr) and choline-containing compounds(Cho) were not visible. Lac peak without other peaks such as NAA, Cr, Cho is a unique finding of proton MRS for epidermoid and this could be useful in the differential diagnosis.

Aged↗
PubMed2002

[Phase-contrast x-ray imaging with x-ray interferometer for medical applications].

Phase-contrast x-ray imaging with x-ray interferometer can depict the minute difference within the biological object, and its sensitivity is about 1000 times higher than that of absorption-contrast method. For biomedical use of this technique, a large monolithic x-ray interferometer and 2 crystal interferometer having a field of view with 25 mm x 25 mm is being developed. Phase-contrast x-ray CT could reveal detail structures within tumor and surrounded tissue, and the vessel imaging of rat liver is also possible using physiological saline at 17.7 keV x-ray energy. Recently, human breast tissues were imaged at 35 keV and the contrast of image was much better than usual absorption contrast x-ray image obtained at 17.7 keV energy.

Animals↗
PubMedDate not supplied

Ovarian tumor with functioning stroma.

The authors reported two cases with ovarian tumors with functioning stroma. One was an ovarian carcinoid with testosterone-producing stroma and another was an ovarian mucinous cystadenoma with elevated serum level of estrogen. They appeared as multilocular cystic masses with varying signal on MR. This imaging feature was mimicking both those of Sertoli-Leydig tumors with heterologous elements and granulosa cell tumors, which are well known as functioning tumors. It had been reported in pathological literatures that any type of ovarian tumors can show hormonal activity due to functional stroma, although, it is the first report in the radiological literatures.

Aged↗
PubMedDate not supplied

Contrast-enhanced CT with saline flush technique using two automated injectors: how much contrast medium does it save?

PURPOSE: The purpose of this work was to investigate the volume of contrast medium saved by the saline flush technique. METHOD: Thoracic helical CT was performed by injecting 75 ml of contrast material (Ioversol 320) only (n = 25; Group A) or 75 ml of contrast medium pushed with 6 ml (n = 25; Group B), 12 ml (n = 25; Group C), 25 ml (n = 25; Group D), or 50 ml (n = 25; Group E) of saline at a rate of 2 ml/s. The aortic CT numbers were measured from 30 to 55 s after the beginning of injection. We compared the time to peak aortic enhancement (TPAE) among Groups A-E. RESULTS: The TPAEs of the Groups A-E were 42.6, 45.2, 48.6, 48.4, and 48.3 s, respectively, and there was a statistically significant difference among them (p < 0.0001, analysis of variance). Post hoc test revealed statistically significant differences in TPAE between Groups A and B, C, D, and E and between Groups B and C, D, and E but no differences among Groups C, D, and E. CONCLUSION: The saline flush technique prolongs TPAE by 6 s and saves 12 ml of contrast medium.

Adult↗
PubMedDate not supplied

Postmortem intravascular high-density fluid level (hypostasis): CT findings.

PURPOSE: To evaluate postmortem CT (PMCT) finding of hypostasis. METHODS: PMCT examinations were performed within 2 hours of death in 126 patients who arrived at our institution in nontraumatic cardiopulmonary arrest. RESULTS: PMCT showed hypostasis as high-density fluid level in the lumen of the heart or great vessels in 66 of 126 patients (52%). CONCLUSION: Hypostasis is observed as an intravascular high-density fluid level on PMCT.

Adolescent↗
PubMedDate not supplied

MR imaging of the uterine cervix: imaging-pathologic correlation.

Magnetic resonance (MR) imaging is useful not only for preoperative staging of gynecologic malignancies but also for prediction of the histopathologic features of a variety of intrapelvic tumors. Familiarity with the specific imaging findings that have been reported for the uterine cervix is a goal of radiologists. The typical MR imaging findings of uterine cervical lesions correspond to the histopathologic features. These lesions can be categorized as epithelial neoplasms, nonepithelial neoplasms, and nonneoplastic diseases. Cervical carcinoma accounts for most cases of malignant lesions and is staged by using the classification system established by the International Federation of Gynecology and Obstetrics. MR imaging allows differentiation between endophytic and exophytic growth and between normal and abnormal findings after hysterectomy and irradiation. Other epithelial neoplasms of the uterine cervix include adenoma malignum, which is a special type of cervical adenocarcinoma, as well as carcinoid tumor and malignant melanoma. Nonepithelial neoplasms of the uterine cervix include malignant lymphoma and leiomyoma. Nonneoplastic diseases of the uterine cervix include cervical pregnancy, cervicitis, nabothian cysts, polyps, and endometriosis.

Cervix Uteri↗
PubMedDate not supplied

Radiation-induced liver injury showing low intensity on T2-weighted images noted in Budd-Chiari syndrome.

PURPOSE: Although it is documented that radiation can cause density or intensity changes on computed tomography or MR imaging in the irradiated hepatic parenchyma, few researchers have reported or understood the MR presentation of changes in hepatic parenchyma following radiotherapy in the patient with Budd-Chiari syndrome. The purpose of this study was to investigate the MR appearance of hepatic radiation injury in Budd-Chiari syndrome and to consider the underlying pathophysiology. MATERIALS AND METHODS: The MR examinations of two patients with Budd-Chiari syndrome were compared with those of 11 patients without Budd-Chiari syndrome. The two groups, both of which suffered from hepatocellular carcinoma, underwent 50-72 Gy of proton-beam irradiation during a period of 14-43 days. Examinations including T1- and T2-weighted imaging, superparamagnetic iron oxide-enhanced imaging, and dynamic study were performed 3-10 weeks after the end of irradiation. RESULTS: Radiation-induced hepatic injury was observed as a low-intensity area on T2-weighted images and on delayed phase images of dynamic study in the Budd-Chiari patients, and as iso- or high-intensity areas on both images in the patients without Budd-Chiari syndrome. US-guided needle biopsy from the irradiated area in one patient with Budd-Chiari syndrome revealed mostly necrotic tissue and fibrous tissue. CONCLUSION: These MR features of hepatic radiation injury in Budd-Chiari syndrome were considered to be due to severe hepatic fibrosis.

Acute Disease↗
PubMedDate not supplied

Hyperattenuating aortic wall on postmortem computed tomography (PMCT).

PURPOSE: To quantitatively evaluate the finding of hyperattenuating aortic wall on postmortem computed tomography (PMCT) and investigate its causes. MATERIALS AND METHODS: Our subjects were 50 PMCT of non-traumatic deaths and 50 CT of living persons (live CT). The ascending aorta at the level of the carina was visually assessed regarding the presence or absence of hyperattanuating aortic wall and hematocrit effect on PMCT and live CT. The diameter, thickness of the aortic wall, and CT number (HU) of the aortic wall and the lumen were also measured. RESULTS: Hyperattenuating aortic wall was detected in 100% of PMCT and 2% of live CT. The diameter of the aortic wall was 2.9 +/- 0.5 cm on PMCT and 3.5 +/- 0.5 cm on live CT, showing a significant difference. The thickness of the aortic wall was 2 mm on PMCT. Hematocrit effect was observed in 46% of PMCT and in none of live CT. With PMCT, there was a significant difference between the CT numbers of the upper and lower half portions of the lumen (19.6 +/- 11.7/30.9 +/- 12.9), whereas, with live CT, there was no such significant difference (37.4 +/- 7.6/38.9 +/- 6.7), with the overall value of 38.2 +/- 6.7. The CT number of the aortic wall was 49.9 +/- 10.9 on PMCT. CONCLUSION: The causes of hyperattenuating aortic wall on PMCT are considered to be increased attenuation due to contraction of the aortic wall, a lack of motion artifact, and decreased attenuation of the lumen due to dilution of blood after massive infusion at the time of cardiopulmonary resuscitation.

Adult↗
PubMedDate not supplied

Dilatation of the heart on postmortem computed tomography (PMCT): comparison with live CT.

PURPOSE: To delineate cardiac structures on postmortem computed tomography (PMCT) and quantitatively to prove dilatation of the heart after death. MATERIALS AND METHODS: Our subjects were 50 PMCT of non-traumatic deaths and 50 CT of living persons (live CT). We measured maximal and minimal diameters of the superior vena cava (SVC) at three levels (upper, middle, and lower), the inferior vena cava (IVC), pulmonary artery (PA), pulmonary vein (PV), right atrium (RA), and left atrium (LA). Then the product of maximal by minimal diameter and the eccentricity were calculated. RESULTS: The maximal and minimal diameters of the heart were significantly longer than those on live CT except for 1) the maximal diameter of the SVC at the upper level and 2) the maximal diameter of the PA. All of the products of maximal by minimal diameter on PMCT were significantly larger than those on live CT. All of the eccentricities decreased significantly after death except LA. CONCLUSION: The heart is dilated on PMCT, and the right side of it dilates toward a round shape.

Adult↗