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Biomedical subjects

Y Itai

Publications and source records attributed to Y Itai.

At least 19 recordsLinked to original sources
PubMed1992

[CT of pulmonary dirofilariasis--differential diagnosis from lung cancer].

We present here four cases of pulmonary dirofilariasis in which histological examination of the surgical specimen showed occlusion of the peripheral pulmonary artery by filariae and formation of a necrotic mass surrounded by reactive inflammation and hemorrhage. Radiological examination showed a solitary pulmonary nodule in three cases and a wedge-shaped consolidation in one case. Although pulmonary nodules in dirofilariasis closely mimic bronchogenic carcinoma on radiographs , it is possible to distinguish them from bronchogenic carcinoma on the basis of the following findings: (1) coexistence of subtle satellite lesions, (2) absence of pleural involvement, (3) fine marginal speculations, and (4) lack of concentric marginal speculations (eccentric speculation). In each case of dirofilariasis, CT showed the peripheral pulmonary artery entering the mass. This finding differentiates this disease from metastatic lung tumor, because in tumor metastasis via the pulmonary arteries, visible vessels are not usually involved.

Aged↗
PubMed1992

[The value of frequent positioning of treatment field in radiotherapy of esophageal cancer].

Since 1983 a clinical trial of proton beam radiotherapy has been conducted at the Proton Medical Research Center (PMRC) of the University of Tsukuba. We have made it a rule to do field localization by X-ray pictures before each treatment. For this purpose we have developed a localize-verify system consisting of a fluoroscopic unit and a real time digital image processing device. By using this system as well as X-ray films, field placement errors or corrected distance at field localization were measured in 11 patients with esophageal cancers. Measurements of corrected distances on a total of 177 localization attempts disclosed that correction by > 5 mm was necessary in 30.6% and by > 10 mm in 10.2% of all localization attempts. Corrected distances appeared to increase with age, possibly because the skin becomes looser and ambulatory status tends to be more limited in older patients. Field placement corrections of more than 5 mm were required in 66.7% of 60 localizations in patients > 80 years old. Two patients in whom the anatomical positions of the esophagus were easily movable are presented. The following common characteristics of these patients were considered high risk factors: they were more than 80 years old; lesions were located in the lower esophagus; and they had T1 tumors. These findings suggested that frequent positioning and verification of treatment fields are necessary in the accurate treatment of esophageal cancers, especially those in high-risk patients.

Aged↗
PubMed1992

Rapid T1 estimation using tagged magnetization-prepared gradient-echo MR imaging.

A technique for estimation of the longitudinal relaxation time of a large homogeneous object with an acquisition time of 4 s or less was developed by combining spatially selective rf tagging pulses with a T1-weighted magnetization-prepared gradient-echo sequence. Multiple 5-mm-wide tagged areas are laid orthogonal to the imaging section of interest. The contrast between each tag and the untagged regions differs because each tag is produced at a different time. The T1 value is determined from the nulling time at which tagged and untagged areas have no contrast.

Adipose Tissue↗
PubMed1992

Pseudomyxoma peritonei with progressive calcifications: CT findings.

Development of abdominal calcifications due to pseudomyxoma peritonei is rare. The authors present three cases whereby computed tomographic (CT) studies during or after chemotherapy for pseudomyxoma peritonei demonstrated development and progression of punctate calcifications in the abdomen. The clinical and CT findings of these cases are presented together with a brief review of the pertinent literature.

Adult↗
PubMed1992

MR imaging of malignant mesenchymal tumors of the liver.

Magnetic resonance (MR) features of five primary malignant mesenchymal neoplasms (plasmocytoma, leiomyosarcoma, undifferentiated sarcoma, epithelioid hemangioendothelioma, and angiosarcoma) of the liver were reported. All tumors were hypointense on T1-weighted images and hyperintense on T2-weighted images. No halo and intravenous extension were noted. A target appearance was revealed in epithelioid hemangioendothelioma. MR findings of angiosarcoma were essentially the same as those of cavernous hemangiomas (markedly hyperintense with hypointense linear septa on T2-weighted images). MR findings of these rare hepatic malignancies were nonspecific, although they were quite different from those of typical hepatocellular carcinomas. This study suggested that MR differentiation of primary hepatic mesenchymal tumors from other common benign and malignant neoplasms was difficult; however, the number of studied cases was limited.

Adolescent↗
PubMed1992

Quantitative phase analysis of myocardial wall thickening by technetium-99m 2-methoxy-isobutyl-isonitrile SPECT.

Regional wall thickening was assessed by ECG-gated SPECT using technetium-99m 2-methoxy-isobutyl-isonitrile (99mTc-MIBI). For myocardial segments with an optimal short axis, regional count changes from end-diastole to end-systole were used to calculate the regional wall thickening. Functional images displaying amplitude, % wall thickening (% WT), and phase were generated by a fundamental Fourier analysis. In the control subjects, % WT analysis showed heterogeneous contraction among the left ventricular wall segments. The amplitude values showed a similar pattern to the %WT values. Phase images demonstrated that the timing of ventricular contraction was almost homogenous between the various wall segments. In the CAD patients, regional decreases in amplitude and %WT corresponding to zones of reduced perfusion were shown in the ischemic segments. Phase images also indicated asynchronous contraction in these segments. Phase analysis of regional wall thickening in 99mTc-MIBI scintigraphy seems to be useful for understanding regional myocardial function in combination with perfusion scanning.

Aged↗
PubMed1992

Ameloblastoma in the maxillomandibular region: MR imaging.

Nine patients suspected of having primary ameloblastoma of the mandible or maxilla and five patients with clinical and/or radiologic indications of postoperative recurrence of ameloblastoma were examined with magnetic resonance (MR) imaging. In the former, results were compared with those of conventional radiography, computed tomography (CT), and pathologic analysis. Seven tumors were multilocular; two were unilocular. MR imaging showed a mixed pattern of solid and cystic components (n = 9), irregularly thick walls (n = 9), and papillary projections (n = 6). MR imaging was superior to conventional radiography and CT in demonstrating these findings. However, shell-like bulgings of the bone cortex were demonstrated more effectively with conventional radiography and/or CT in six cases, and soft-tissue invasion was overestimated with MR imaging in four cases. All tumors except one showed strong enhancement of solid components including papillary projections, walls, and septa at enhanced MR imaging. In the latter group of patients, MR imaging correctly demonstrated recurrence in two and no recurrence in three.

Adolescent↗
PubMed1992

Gastric tumors: radiologic-pathologic correlation and accuracy of T staging with dynamic CT.

Incremental dynamic computed tomography (CT) was prospectively performed in 89 patients with gastric tumors (78 gastric cancers, five malignant lymphomas, and six submucosal tumors) after the intake of 400 mL of water, and findings were compared with those obtained at pathologic examination. Dynamic CT of healthy control subjects (15 patients without gastric lesions) showed the gastric wall as a two- or three-layered structure (multilayered pattern): a markedly enhanced inner layer; an intermediate layer of low attenuation; and (sometimes) an outer layer of slightly high attenuation, which corresponded histologically to the mucosal layer, submucosal layer, and muscular-serosal layer, respectively. In 68 lesions that were removed at surgery, the detectability of early and advanced gastric cancers and the accuracy of classification of gross appearance and serosal invasion as determined with CT were 53%, 92%, 80%, and 80%, respectively. All detected advanced gastric cancers were seen as enhanced areas with the destruction of the multilayered pattern. Differentiation between infiltrating gastric cancer (n = 5) and malignant lymphoma (n = 5) was successful. Five of six submucosal tumors were demonstrated as having an overlying intact mucosal layer.

Female↗
PubMed1992

Muscle energetics during exercise by 31P NMR.

Previous studies have shown that a decrease in muscle tension is not proportional to decrease in the ATP concentration and free energy for ATP degradation but is proportional to the decrease in ATP consumption during muscle contraction, and that the free ADP concentration in the cell can be estimated using the Pi/PCr ratio obtained by 31P NMR. From this view, we discuss findings on muscle energetics during exercise that have been clarified by 31P NMR and its future problems.

Animals↗
PubMed1991

[Computed tomographic evaluation of thickness of perirectal fascia in rectal cancer treated by preoperative radiotherapy--diagnostic value for prediction of local recurrence].

Perirectal fascia was examined by computed tomography before and after preoperative radiotherapy in thirty-six patients with rectal cancer. CT measurement showed that perirectal fascia tend to increase in thickness during preoperative radiotherapy in proportion to tumor extension into perirectal fat tissue. The fascial thickening more than 7 mm after preoperative radiotherapy was suggestive of local recurrence to develop. Preoperative or intraoperative boost irradiation would be recommended for such high-risk patients.

Adenocarcinoma↗
PubMed1991

[Iron oxide-enhanced MR imaging of hepatocellular carcinoma of woodchuck].

To determine the utility of iron oxide-enhanced MR imaging for primary hepatocellular carcinoma (HCC), MR imagings of an adult woodchuck with two nodules of HCC was obtained before and after an injection of iron oxide. On postcontrast images, signal intensity decreased in one nodule and did not change in the other. Pathologically, the former was well-differentiated HCC with trabecular pattern and the latter was with pseudograndular and scirrhous pattern. Iron oxide particles were noted within the former. Iron oxide-enhanced MR imaging is a promising method for differentiation of pathological subtypes of HCC, however well-differentiated one with reticuloendothelial cells might be overlooked.

Animals↗
PubMed1991

CT and MR appearance of focal nodular hyperplasia of the liver in children with biliary atresia.

Two children with biliary atresia are described in whom focal nodular hyperplasia of the liver occurred following portoenterostomy. The lesions were low-or iso-dense on unenhanced CT and became hypodense post-contrast enhancement. There was normal 99mTc phytate on hepatic colloid scintigraphy. On T2-weighted spin echo MR images, there was increased signal intensity within the masses, and the surrounding liver parenchyma was divided by linear septa in one of the two cases.

Biliary Atresia↗
PubMed1991

MR differentiation of hepatic haemangioma and hepatocellular carcinoma: value of delayed-phase Gd-DTPA enhanced images.

The efficacy of three different approaches (precontrast and delayed-phase postcontrast T1-weighted (T1-W) images, measurement of T2 value, and dynamic FLASH imaging) for differentiation between hepatic haemangiomas and hepatocellular carcinomas, was compared. Most haemangiomas (89%) showed iso- or hypointensity on precontrast T1-W images and hyperintensity on delayed-phase postcontrast T1-W images. By using both pre/postcontrast T1-W images and T2 measurement, 30 out of 32 lesions (94%) were correctly differentiated. The dynamic FLASH imaging did not significantly improve the overall accuracy although it played a critical role in a few problematic cases. It is concluded that the combination of pre/postcontrast T1-W images is a promising approach for differentiation of small hepatic tumours, and plays a complementary role with T2 measurement.

Adult↗
PubMed1991

Malignancy associated with chronic empyema: radiologic assessment.

Radiologic findings of six cases of malignancy associated with chronic empyema 5-39 years in duration were reviewed. Pathologic examination confirmed three B-cell non-Hodgkin lymphomas, one round-cell sarcoma, one mesothelioma, and one adenocarcinoma. Retrospective findings on plain chest radiographs suggested the occurrence of malignancy: increased radiopacity in the thoracic cavity, soft-tissue bulgings and/or unsharpness of fat planes in the chest walls, destruction of bone near the empyema, and extensive medial deviation of the calcified pleurae. Computed tomography delineated masses with soft-tissue attenuation more clearly than radiography in all cases. Magnetic resonance images of three cases were informative because empyema cavities were surrounded by low-intensity rims, and two of them showed a signal intensity different from that of necrotic tumors. Scintigraphy revealed increased uptake of gallium in all cases. Ultrasonography was useful for biopsy guidance. Every radiologist should know this entity in observation of chest radiographs obtained in patients with chronic empyema, and further radiologic assessment and aggressive biopsy are recommended if malignancy is suspected.

Adenocarcinoma↗