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Biomedical subjects

M Uetani

Publications and source records attributed to M Uetani.

At least 73 records · Page 4Linked to original sources
PubMed1993

Bone mineral and other bone components in vertebrae evaluated by QCT and MRI.

To evaluate the usefulness of assessing bone components using magnetic resonance imaging (MRI), the contributions of bone components, including mineral, fat and collagen, to bone mineral density (BMD) and T1 relaxation time (T1) were studied using phantoms. Excised human vertebrae were also evaluated by quantitative computed tomography (QCT) and MRI. T1 was shortened with increasing quantities of fat and collagen. In water, T1 was significantly affected by bone density, while in oil, T1 became slightly longer as bone density increased. The presence of fat and collagen caused under- and overestimations of BMD, respectively. There was good correlation between T1 and BMD in osteoporotic vertebrae and the vertebrae with long T1 showed an increased content of hematopoietic marrow and/or abnormally increased bone mineral. It was concluded that the experimental data showed that MRI can contribute to the assessment of bone quality.

Adipose Tissue↗
PubMed1993

The relationship of trabecular and cortical bone mineral density to spinal fractures.

RATIONALE AND OBJECTIVES: The relationships between trabecular, cortical, or integral bone mineral densities (BMD) to spontaneous vertebral fractures was investigated. METHODS: In 360 Japanese women, ranging from 20 to 83 years of age, vertebral trabecular and cortical BMD were measured using quantitative computed tomography (QCT). Among 46 oophorectomized women, BMD was measured using QCT and dual-energy x-ray absorptiometry (DXA). RESULTS: For patients in their sixth and seventh decades, those with fractures could be differentiated from those without fractures by measuring their trabecular BMD using QCT. Cortical BMD of women with fractures and trabecular BMD more than 80 mg/mL was significantly lower than that of women without fractures and trabecular BMD less than 70 mg/mL. CONCLUSIONS: Trabecular BMD can be a good predictor of spinal fracture. Cortical BMD may be important in cases with decreased trabecular BMD.

Absorptiometry, Photon↗
PubMed1993

Relationship of osteophytes to bone mineral density and spinal fracture in men.

PURPOSE: To investigate the relationship of spinal osteophytes to vertebral bone mineral density (BMD) and to spinal fracture. MATERIALS AND METHODS: This relationship was investigated in 203 men. Integral BMD was measured with dual x-ray absorptiometry, and both cortical and trabecular BMD were measured with quantitative computed tomography (QCT). RESULTS: Trabecular BMD was found to decrease with age in subjects with and without large osteophytes, while cortical and integral BMD decreased with age only in subjects without large osteophytes. Trabecular BMD in men without fracture was significantly higher than in those with fracture (P < .05 for BMD measured with single-energy QCT), while there was no significant difference between these groups in cortical or integral BMD. CONCLUSION: Measurement of trabecular BMD with QCT provides information useful in detection of age-related bone loss and of fracture in men with and without osteophytes.

Absorptiometry, Photon↗
PubMed1993

Denervated skeletal muscle: MR imaging. Work in progress.

PURPOSE: To evaluate the change in signal intensity of skeletal muscles after denervation and to determine the clinical usefulness of magnetic resonance (MR) imaging in diagnosis of denervation. MATERIALS AND METHODS: Denervated skeletal muscles associated with various forms of peripheral neuropathy and spinal radiculopathy were studied with MR imaging in 17 patients. RESULTS: On T1-weighted images, signal intensity of denervated muscles was normal in 14 patients and high in three. On T2-weighted images, all denervated muscles showed high signal intensity on at least one MR image. High signal intensity in the denervated muscles on T2-weighted images was observed 15 or more days after onset of paralysis. In two patients, signal intensity of denervated muscles returned to normal after relief of paralysis. CONCLUSION: MR imaging is a noninvasive and accurate method for use in diagnosis of denervation and may ultimately eliminate the need for electromyography.

Adipose Tissue↗
PubMed1991

[Radiologic manifestations of peritoneal mesothelioma].

We report four cases of histologically proved peritoneal mesothelioma and describe the radiographic (mainly CT and angiographic) findings. There were three malignant diffuse tumors and one benign localized tumor. In one case, the lesion extended to the omentum and entrapped the fat tissue, and differentiation from peritonitis carcinomatosa was difficult. In the other three cases, reflecting necrotic change within the tumor, CT showed hypodensity throughout most of the mass. In two cases with hemorrhage, CT showed hyperdensity in the center of the mass. Angiography showed slight or medium neovascularity in the periphery of the tumor, but most of the tumor was avascular. Angiography was helpful for topographic diagnosis, but it was difficult to make a specific diagnosis or differentiate between malignant and benign types. We emphasize that it is important to consider peritoneal mesothelioma in the differential diagnosis when a mass of unknown origin is found in the abdomen, particularly when it is accompanied by necrosis and hemorrhage.

Aged↗
PubMed1990

[CT evaluation of bone mineral density (BMD) of lumbar spine in patients after gastrectomy].

The late postoperative complications in patients after gastrectomy include anemia and metabolic bone disorders. We studied to determine whether gastric surgery is associated with metabolic bone disease. Vertebral BMD was measured in 55 patients after gastric resection by using DEQCT (dual energy quantitative CT). Forty patients were symptomatic, having bone or joint pain, history of bone fracture, or dental caries. The control group consisted of 161 patients without metabolic bone disorders. Forty percent of the patients with either the symptoms or history of bone fracture or dental caries, and 20% of the patients without the symptoms or the history showed decreased BMD. BMD was significantly lower in males in their 60s and in females in their 50s and 70s than BMD in age-matched control groups. When male subjects were grouped according to the years following the operation (1-5, 6-10, 11-15, 16-20 years), BMD was found to be decreased in 27%, 29%, 40% and 50% of the patients after surgery. Higher incidence of decreased BMD was found in the patients after total gastrectomy when compared with those after subtotal gastrectomy. Among the patients with subtotal gastrectomy, the incidence of decreased BMD was higher in patients with Billroth II anastomosis than in those with Billroth I anastomosis. In cases with compression fracture on thoracolumbar radiographs, BMD was significantly lower in comparison with cases with no fracture. It was difficult to differentiate between osteomalacia and osteoporosis only by the thoracolumbar radiographs.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Comparison of digital and conventional musculoskeletal radiography: an observer performance study.

Interpretations of 122 musculoskeletal radiographs were compared with interpretations of their digital counterparts at a resolution of 1,024 X 840 X 12 bits. Images were evaluated by four readers and included subtle and nonsubtle abnormalities and normal findings. Joint receiver operating characteristic (ROC) analysis results were averaged over all readers and demonstrated no statistically significant difference between the two imaging methods. High interobserver variability limited identifiable differences. Review of cases with subtle findings on the digital system at a resolution of 2,048 X 1,680 X 12 bits (2.5 line pairs per millimeter) revealed adequate visualization of the abnormality in every case. It is concluded that a resolution of 1,024 X 840 X 12 bits is adequate for the interpretation of many musculoskeletal abnormalities but that a resolution of 2,048 X 1,680 X 12 bits is needed for visualization of some subtle abnormalities.

Bone Diseases↗
PubMed1989

Problems in applying expert system technology to radiographic image interpretation.

A prototype expert system was developed to study the problems applying expert system technology to radiographic image interpretation. The Radiographic Image Interpretation System (RIIS) was developed on a microcomputer using Turbo Prolog, a low cost implementation of the prolog programming language. The present implementation of RIIS was developed to highlight potential problems in applying expert system technology in the evaluation of radiographic images. It was believed that the evaluation of this prototype expert system should include a large number of users unfamiliar with the program's use as this would probably be the case in clinical use of an image interpretation expert system. At present, the expert system deals with a limited domain of focal bony lesions. Twenty cases of pathologically proven bony lesions of varying difficulty were used to evaluate potential problems in the use of this expert system technology. RIIS, with the 20 sample cases, was presented as an exhibit at the 1987 Radiological Society of North America (RSNA) meeting to evaluate the potential problems with inexperienced users. These results were compared with those of experienced users. When a musculoskeletal radiologist, familiar with the programs use, provided the "proper description," the program averaged the correct diagnosis in the top five 80% of the time. During the program's use at the RSNA meeting, the program selected the correct diagnosis in the top five 22% of the time.

Bone Neoplasms↗
PubMed1987

Vascular compromise in chronic volvulus with midgut malrotation.

Three cases of chronic volvulus of the small bowel in midgut malrotation are presented, all of whom manifested similar angiographic findings: proximal occlusion of the superior mesenteric artery and vein and development of collateral vessels. These findings may indicate the pathophysiology of chronic volvulus in midgut malrotation; the volvulus is progressive and eventually results in the twisting of the mesenteric root itself, but because of its chronic nature collateral circulation develops, eliminating bowel necrosis. Computed tomography (CT), performed in two cases, revealed dilated, tortuous vessels in the mesentery in addition to the known CT finding of a whirl-like pattern of the volvulated small bowel loops. Sonography, performed in one case, showed an unique feature of whirling sonolucent layers probably representing the volvulated small bowel loops intermixed with dilated mesenteric collateral vessels. We would like to emphasize the usefulness of CT and sonography in the early diagnosis of those cases with vague and nonspecific clinical manifestations.

Adolescent↗
PubMed1987

High-attenuation recent thrombus of the portal vein: CT demonstration and clinical significance.

Attenuation characteristics of portal vein thrombi on nonenhanced computed tomographic (CT) scans were assessed in 122 patients with proved portal vein thrombosis. Portal vein thrombi of high attenuation were found in four patients with hepatocellular carcinoma. From pathologic and radiologic studies, it was concluded that the high attenuation was caused by blood clots of recent onset formed at the tip of tumor thrombus. Differentiation from choledocholithiasis, hematobilia, and calcification of thrombi could be easily made by means of ultrasonography (US). Although plain CT is usually considered noncontributory in the diagnosis of venous thrombosis, it enabled the differentiation of recent thrombus in these four patients. Tumor thrombus in the major branches or main trunk of the portal vein is indicative of poor prognosis. When hepatic mass and high-attenuation portal vein thrombi are demonstrated with plain CT and substantiated by US, enhanced CT and angiography may be unnecessary for treatment of patients with advanced hepatocellular carcinoma.

Aged↗
PubMed1987

[Digital subtraction angiography of the coronary artery: evaluation of morphological aspects].

The usefulness of digital subtraction angiography (DSA) in coronary angiography was evaluated in terms of its ability to delineate the coronary artery and aortocoronary (A-C) bypass grafts. First, 59 intra-arterial injections of contrast media were made for 23 patients with ischemic heart disease. With aortic root injection, the proximal coronary artery was moderately well visualized, but visualization of the peripheral arteries was inadequate. By selective coronary injection, good images of the coronary arteries were obtained using small quantity of contrast media; however, detailed evaluations of the degrees of stenosis and collateral circulation were difficult, because of limitations in spatial resolution and misregistration artifacts due to cardiac pulsations. In addition, the patencies of 12 A-C bypass grafts were evaluated using intravenous (IV-) DSA for three cases and intraaortic (IA-) DSA for five cases. Ten grafts were shown to be patent. With IV-DSA, the graft was imaged as superimposed on the ascending aorta. In IA-DSA, a small (4F) catheter was introduced via the right brachial artery and advanced to the ascending aorta where an aortic root injection was performed. With aortic root injection, not only the anastomotic portion but also the distal native coronary artery were visualized. Lateral and severe left anterior oblique projections were best to visualize the grafts. IA-DSA using 4F catheter could be performed for outpatients without complications. The patency of a graft can be evaluated with the time density curve between two points in the graft, and the coronary blood flow can be calculated using the time density curve measurements and the diameter of the artery.(ABSTRACT TRUNCATED AT 250 WORDS)

Aorta↗