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Biomedical subjects

Y Itai

Publications and source records attributed to Y Itai.

At least 343 records · Page 19Linked to original sources
PubMedDate not supplied

MR imaging of hepatocellular carcinoma.

Forty-two patients with hepatocellular carcinoma (HCC) were examined by magnetic resonance (MR) imaging. The presence of tumor was suggested in 41 of 42 cases by a high-intensity area on T2 weighted spin-echo (SE) images with a repetition time (TR) of 1.6 s. Specific findings of HCC such as the presence of a capsule, mosaic pattern, and tumor thrombus in major veins were noted in 10, two, and seven cases, respectively. In six cases the tumor pattern changed from a well-defined mass to an irregular, ill-defined one according to pulse sequence (SE: echo time 35 and 70 ms; TR 1.6 and 0.4 s). In our early experience MR was almost equal to conventional X-ray CT in the detection of main or daughter lesions and in the determination of extent and characterization of HCC.

Adult↗
PubMedDate not supplied

MR imaging of hepatoma treated by embolization.

The magnetic resonance findings of two hepatomas treated by embolization are presented. The T2-weighted spin echo images showed an increase in signal intensity in the tumor after embolization. This phenomenon corresponded to a decrease in tumor density on CT and to necrosis observed histologically. Magnetic resonance also demonstrated gas bubbles as low signal foci within the embolized tumor.

Carcinoma, Hepatocellular↗
PubMedDate not supplied

CT demonstration of gas in dilated pancreatic duct.

A case of "innocent" pancreatic gas is reported. The patient had cystic dilatation of the main pancreatic duct limited to the head. Air entered through the patulous ampulla of Vater. Pancreatic gas can be present without abscess or fistula.

Aged↗
PubMedDate not supplied

CT and MR imaging of fatty tumors of the liver.

The presence of fat in hepatic masses narrows the range of differential diagnoses down to hepatic angiomyolipoma, lipoma, adenoma, hepatoma, metastatic fatty tumors of the liver, focal fatty infiltration of the liver, and extrahepatic fatty masses such as intraperitoneal implants from malignant teratomas, and packed omentum. We report six hepatic tumors containing fat (lipoma, hepatocellular carcinoma, and calcified mass with fat-fluid level) with CT and magnetic resonance (MR) imaging. The distribution of fat was diffuse in the lipomas and some hepatocellular carcinomas and localized in other hepatocellular carcinomas and fat-fluid masses. The density ranged from - 100 to 0 HU. High intensity areas on both T1- and T2-weighted MR images corresponded to the hypodense areas on CT.

Adult↗
PubMedDate not supplied

CT demonstration of fluid-fluid levels in nonenhancing hemangiomas of the liver.

A fluid-fluid level was observed in three cases of liver hemangioma and in two cases of liver cancer. The patients with hemangioma of the liver did not show enhancement on dynamic CT and the fluid-fluid levels were not detected by ultrasound in two of these patients. Fluid-fluid levels detected by CT but not by ultrasound strongly suggested the diagnosis of nonenhancing hemangioma of the liver.

Carcinoma, Hepatocellular↗
PubMedDate not supplied

Microcystic adenoma of the pancreas: spectrum of computed tomographic findings.

Fourteen cases of microcystic adenoma (serous cystadenoma) of the pancreas were reviewed and radiological findings were correlated with pathological specimens. Microcystic adenomas appeared grossly either as solid tumors with innumerable tiny cysts or as honeycombed cystic tumors depending on the size and number of cysts and amount of connective tissue. Dynamic enhanced CT of the tumor reflected the amount of connective tissue and appeared as (a) densely enhanced spongy masses (n = 6: classic appearance); (b) cystic masses with (n = 6) or without (n = 1) enhanced septa; or (c) dense diffusely enhanced mass (n = 1). Ultrasound similarly showed a variety of features such as echogenic masses with or without small cystic portions, multilocular cysts, or mixed hyperechoic and hypoechoic masses. The ultrasonic features mainly reflected the dominant sizes of cysts. Angiography almost always showed inhomogeneously hypervascular masses with tumor vessels. The imaging diagnosis is easy and conclusive in classic subtypes, but a correct diagnosis can be made even in other subtypes. However, mucinous cystic neoplasm can be confused with microcystic adenoma with large cysts and a small amount of connective tissue, and islet cell tumors can be mistaken for microcystic tumors with minute cysts.

Adult↗
PubMedDate not supplied

CT and MR imaging of postnecrotic liver scars.

Four cases of postnecrotic liver scar were examined by dynamic CT or MR imaging or both. Postnecrotic scars appeared as low-density areas on plain CT, showed marked and prolonged enhancement on single level dynamic CT, and became isodense on postcontrast scan. On T2-weighted images, postnecrotic scar were as hyperintense as the spleen. Postnecrotic liver scar is an example of localized attenuation or intensity difference not corresponding to mass lesion. It should be distinguished from mass lesions associated with lobar or segmental attenuation (or intensity) difference of the liver as well as nonmass lesions such as irregular fatty infiltration, radiation hepatitis, and hepatic infarction.

Adult↗
PubMedDate not supplied

Fat intensity within the hypointense zone on MR imaging of avascular necrosis of the femoral head.

In some patients with avascular necrosis of the femoral head (ANFH), an area of signal intensity similar to that of subcutaneous fat tissue is found within or proximal to the hypointense zone of spin echo MR images. We refer to these MR findings as the "fat intensity" sign. This fat intensity sign was positive in 62 (47%) of 133 MR examinations of femoral heads with radiographically proven ANFH; this sign was negative in all hips with other diseases including degenerative joint disease, transient osteoporosis, rapidly destructive coxoarthrosis, and rheumatoid arthritis.

Adipose Tissue↗
PubMedDate not supplied

MR study of normal joint function using a low field strength system.

A functional MR study was performed using a 0.064 T permanent magnet MR system. The shoulder joints, elbow joints, hip joints, and knee joints of three volunteers (mean height and weight, 176 cm and 71 kg, respectively) were examined at incremental joint angles in three to eight stages during flexion-extension, abduction-adduction, or pronation-supination movement. Each set of 16 images was obtained in 4 min, 49 s using three-dimensional Fourier transformation methods with gradient echo pulse sequences. The images were evaluated in static mode and sometimes in cine mode. The findings obtained about the physiology of these normal joints was generally compatible with findings previously accumulated in the field of kinesiology. The study suggests that this method can be useful for in vivo study of kinesiology and pathogenesis of diseases and that patients with most types of contracture or deformity can be examined by MR imaging.

Adult↗
PubMedDate not supplied

CT and MR appearances of splenic hamartoma.

The MR and CT appearances of two cases of splenic hamartoma are presented. Computed tomography showed a well demarcated low-density mass without calcification. Dense spreading enhancement was seen in one case on dynamic CT, and prolonged enhancement was noted in both. The masses were demonstrated as areas of isointensity on T1-weighted MR images and of high intensity on T2-weighted images. On gadolinium-enhanced T1-weighted images they were shown as areas of high intensity. Prolonged enhancement on postcontrast CT and MR imaging was a useful finding in differentiation of splenic hamartoma from malignant lesions of the spleen, especially from nodular lesions of malignant lymphoma.

Adult↗
PubMedDate not supplied

Improved CT fat detection in small kidney angiomyolipomas using thin sections and single voxel measurements.

OBJECTIVE AND METHODS: Seven echogenic renal masses < 1.0 cm in size were studied by CT to make the diagnosis of angiomyolipoma by identifying the presence of fat. RESULTS: In four of six lesions, initial 5 mm section CT failed to detect fat, although repeat 3 and/or 1.5 mm section CT was successful in demonstrating fat. In one patient who underwent 3 and 1.5 mm section CT, attenuation values of four voxels were low enough to indicate the presence of fat only on the 1.5 mm sections. CONCLUSION: Measuring single voxel values in the hypoattenuating areas on nonenhanced thin (3 or 1.5 mm) sections is essential for CT diagnosis of small (< 1.0 cm) renal angiomyolipomas.

Adipose Tissue↗
PubMedDate not supplied

Paroxysmal nocturnal hemoglobinuria: MR findings.

OBJECTIVE: Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired hemolytic disorder, characterized by hemosiderin deposition in the proximal renal tubules. MATERIALS AND METHODS: We examined six cases of PNH with MRI including gradient echo imaging. RESULTS: On T2- and T2*-weighted imaging a characteristic hypointense pattern was noted in five of six patients with PNH. The extent of the hypointense area roughly correlated with the time elapsed from the latest hemolytic attack. CONCLUSION: T2*-weighted imaging (gradient echo imaging) is superior to T2-weighted imaging in the detection of hemosiderin in the renal cortex because of the higher sensitivity to magnetic susceptibility effect and shorter examination times. On the other hand, reversal of the normal cortical-to-medullary intensity ratio on T1-weighted imaging was not seen in our cases in which we used echo delay times short enough to neglect T2 effects.

Aged↗
PubMedDate not supplied

Systemic arterial supply to normal basal segments of left lower lobe: CT findings.

OBJECTIVE: The purpose of this study was to evaluate the usefulness of CT in making a diagnosis of systemic arterial supply to normal basal segments of the left lower lobe. MATERIALS AND METHODS: We retrospectively reviewed chest radiography (three cases), CT (three cases), and angiography (two cases). RESULTS: An anomalous systemic artery arising from the descending aorta was shown as a retrocardiac density on posteroanterior radiography and as a nodular density behind the heart on lateral radiography. Contrast enhanced CT revealed the vascular nature of the density adjacent to the descending aorta. Dynamic CT in one patient demonstrated that the nodular density was composed of an anomalous systemic artery and a prominent inferior pulmonary vein. High-resolution CT showed the interlobar artery distal to the origin of the superior segmental artery to be absent. The bronchial system of the left basal segments was normal as was the pulmonary parenchyma on CT. CONCLUSION: Characteristic CT findings consist of absence of the interlobar artery distal to the origin of the superior segmental artery and origination of an anomalous artery from the descending aorta that gives off branches to normal left basal segments. With a constellation of these CT findings, angiography would be obviated for definite diagnosis of this anomaly.

Aorta, Thoracic↗
PubMedDate not supplied

High spatial resolution CT with a synchrotron radiation system.

OBJECTIVE: We describe a monochromatic X-ray CT system using synchrotron radiation, which has been constructed employing a vertical wiggler beam line at the National Laboratory for High-Energy Physics in Tsukuba, Japan. This CT system was produced to facilitate examination of the microstructures of material and biological specimens. MATERIALS AND METHODS: The system provides excellent contrast and has a spatial resolution capacity ranging from 2 to 100 mm. In this preliminary experiment, the images of the rat were obtained at 36-mm slice thickness and 33.2-keV X-ray energy. RESULTS: The nasal cartilage, skull, and teeth of a live rat were clearly demonstrated with 36-mm spatial resolution. CONCLUSION: Using a monochromatic X-ray CT system with synchrotron radiation, detailed structures of rat skull were imaged clearly.

Animals↗
PubMedDate not supplied

MRI of muscle strain injuries.

OBJECTIVE: The purpose of our study was to evaluate (a) the characteristics of muscle strain injuries on MRI and (b) the potential of a frequency-selective fat suppression technique for diagnosing such injuries. MATERIALS AND METHODS: Muscle strain injuries in seven athletes were examined by MRI. Spin echo sequences were obtained with and without fat suppression sequences. The absolute values of the contrast-to-noise (C/N) ratios for lesion versus muscle or fat were then compared for both types of images. RESULTS: We obtained two types of characteristic findings for muscle strain. Lesions of the fascia and adjacent muscles showed a characteristic spray-like or fan-like appearance, extending longitudinally from a shared tendon to the muscle belly in five athletes. This finding was better displayed on coronal images. In contrast, lesions inside a muscle showed a diffuse and inhomogeneous appearance in two athletes. The absolute C/N ratios for lesion versus fat and lesion versus muscle were not significantly different for images with and without fat suppression according to the sign test. However, fat-suppressed images revealed subtle abnormalities that were not seen on conventional images. CONCLUSION: Magnetic resonance can provide detailed information on muscle strain injuries, especially when coronal fat-suppressed images are obtained.

Adolescent↗