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Biomedical subjects

I Yamada

Publications and source records attributed to I Yamada.

At least 55 records · Page 3Linked to original sources
PubMed2000

Sjögren's syndrome: comparison of assessments with quantitative salivary gland scintigraphy and contrast sialography.

UNLABELLED: This study compared the quantitative parameters of salivary gland scintigraphy and the sialographic stages in patients with Sjögren's syndrome. METHODS: One hundred sixteen patients suspected of having Sjögren's syndrome were examined with salivary gland scintigraphy and contrast sialography. When contrast sialography was used as the gold standard, Sjögren's syndrome was diagnosed in 50 of these 116 patients; Sjögren's syndrome was not seen in the other 66 patients. After injection of 370 MBq 99mTc-sodium pertechnetate, dynamic salivary gland scintigraphy with lemon juice stimulation was performed for 50 min. Functional parameters for the parotid and submandibular glands were calculated, and scintigraphic and sialographic results were compared. RESULTS: With the progression of sialographic stages from 0 to 4, the quantity of tracer accumulation decreased in the submandibular gland (P < 0.0001), and the quantity of tracer secretion decreased in the parotid gland (P < 0.0001). The sialographic stage in patients with Sjögren's syndrome was correlated with these scintigraphic parameters (P < 0.0001): sialographic stage = 3.243 - 0.337 x (submandibular gland uptake ratio) - 0.026 x (parotid gland maximum secretion). CONCLUSION: The decreased accumulation in the submandibular gland and the decreased secretion in the parotid gland were highly sensitive indicators of salivary gland disease in Sjögren's syndrome. The sialographic stage was correlated with these scintigraphic parameters.

Adult↗
PubMed2000

[A novel adult case of acute necrotizing encephalopathy of childhood with bilateral symmetric thalamic lesions].

This report describes a 46-year-old Japanese woman with bilateral symmetric thalamic necrosis. The unusual radiologic findings are discussed in relation with acute necrotizing encephalopathy (ANE) of childhood, a rare disease proposed by Mizuguchi et al. ANE affects young children and the incidence is highest between 6 and 18 months of ages. There is only one report of an adult case. The acute stage pathology in ANE can be summarized as acute edema and necrosis involving both gray and white matter by local breakdown of the blood-brain barrier. The radiologic findings in our case were similar to those in ANE of childhood. Though the pathogenesis between our adult case and ANE of childhood might be different, severe hypoalbuminea in our case could cause the alteration of permeability of the thalamic vessels, which might accelerate breakdown of the blood-brain barrier in the thalamus.

Albumins↗
PubMed1999

Diagnostic imaging of early gallbladder cancer: retrospective study of 53 cases.

To diagnose early gallbladder carcinoma is difficult but essential to improve the survival of the patients with this cancer. Fifty-three early gallbladder cancers were macroscopically divided into protruding and flat types. The diagnostic devises [ultrasonography (US), computed tomography (CT), and drip infusion cholangiography (DIC)] were compared for their ability of early detection. The specimens were examined cytologically for diagnosis during operation and the p53 protein was investigated. Thirty-three cases were of the protruding type, eighteen of the flat type, and two unclassified. Carcinoma tended to be missed when gallstones were present. Preoperative diagnosis of the flat type was difficult. Tumor location did not always correlate with the preoperative diagnosis. Of the misdiagnosed cases of the protruding type, half were missed with US and CT and were not visualized clearly by DIC. Among the flat type cancers, only three had no abnormal findings by diagnostic imaging. Cytologic examination was effective, and p53 was expressed only in early carcinoma, not in adenoma or dysplasia. Even in the presence of gallstones or cholecystitis, any abnormal findings should make one suspicious of gallbladder cancer. Cytology and p53 expression may be useful for the intraoperative diagnosis, and a combination of diagnostic methods is important.

Adenoma↗
PubMed1999

Head and neck haemangiomas: contrast-enhanced three-dimensional MR angiography.

We evaluated the clinical effectiveness of contrast-enhanced three-dimensional (3D) magnetic resonance angiography (MRA) for diagnosing head and neck haemangiomas. We studied six patients using a magnetization prepared rapid acquisition gradient-echo (MP-RAGE) sequence on a 1.5-T system. Conventional T1- and T2-weighted and contrast-enhanced images were also obtained. The images were compared with histological findings. In four cavernous haemangiomas, a mass was partially visible as an enhancing lesion on the early phase of MRA, and was completely visible as a larger enhancing lesion in the late phase, showing slow blood flow. In two capillary haemangiomas, a mass was completely visible in the early phase showing fast flow. In all patients, MRA clearly showed both the haemangiomas and the external carotid artery branches. MRA allowed assessment of the relationship between the haemangiomas and the feeding arteries, and of the haemodynamics.

Adolescent↗
PubMed1999

Functional magnetic resonance imaging to word generation task in a patient with Broca's aphasia.

We describe the findings of functional magnetic resonance imaging (fMRI) in a patient with Broca's aphasia. The patient was a 45-year-old, right-handed woman who developed Broca's aphasia after infarction in the left frontal lobe. The first fMRI showed no signals in the left frontal lobe during verbal tasks, 2 weeks after the onset of infarction. Four weeks later, when the patient's symptom had improved, the second fMRI showed some increase in the fMRI signals in the left frontal lobe. Seven months later, she had completely recovered the ability to speak. The last fMRI then showed that the increment in signal activity in the left frontal lobe during verbal tasks had recovered to the level seen in normal subjects. There was a good correlation between the increase in task-related signals in Broca's area and the recovery of language function. Our findings show that fMRI has can be important in assessing cognitive functions in patients with Broca's aphasia.

Aphasia, Broca↗
PubMed1999

Quantitative assessment of chronic aortic regurgitation with 3-dimensional echocardiographic reconstruction: comparison with electromagnetic flowmeter measurements.

Two-dimensional echocardiography and color Doppler are useful in the qualitative assessment of aortic regurgitation. However, color Doppler planar methods are not accurate in quantifying regurgitant flow, in part because of the complex geometry of aortic regurgitant flow events. Three-dimensional echocardiographic reconstruction is a new technique that provides dynamic 3-dimensional images of intracardiac color flow jets. We sought to determine whether the measurement of aortic regurgitant jet volume by 3-dimensional echocardiography correlated with the true regurgitant volume, measured by electromagnetic flowmeter in vivo, to accurately reflect the severity of aortic regurgitation. We performed volume-rendered 3-dimensional echocardiography in 6 sheep with surgically induced chronic eccentric aortic regurgitation. We obtained a total of 22 aortic regurgitation states by altering loading conditions. Instantaneous regurgitant flow rates were obtained by aortic and pulmonary electromagnetic flowmeters. The maximum aortic regurgitant jet volume by 3-dimensional echocardiography and the maximum jet area by 2-dimensional echocardiography were measured and compared with electromagnetic flowmeter data. By electromagnetic flowmeter, aortic regurgitant flow rate varied from 0.14 to 3.1 L/min (mean 1. 25 +/- 0.78); aortic regurgitant stroke volume varied from 1 to 34 mL/beat (mean 12 +/- 8), and regurgitant fraction varied from 3% to 42% (mean 25% +/- 12%). The maximum jet volume by 3-dimensional echocardiography correlated very well with the aortic regurgitant stroke volume (r = 0.92; P <.0001), with the mean regurgitant flow rate (r = 0.87; P <.0001), and with the regurgitant fraction (r = 0. 87; P <.0001) derived from electromagnetic flowmeter. Both intraobserver and interobserver variability on the measurement of the jet volume by 3-dimensional echocardiography were excellent (r = 0.98; P <.0001 and r = 0.90; P <.001, respectively). The maximum jet area by 2-dimensional echocardiography did not correlate with the aortic regurgitant stroke volume (r = 0.41; P = not significant) and related poorly with the regurgitant fraction (r = 0.52; P <.05) by electromagnetic flowmeter. Dynamic 3-dimensional echocardiography can allow better determination of the geometry of the aortic regurgitant jet and may assist of quantifying the severity of aortic regurgitation.

Animals↗
PubMed1999

Diffusion coefficients in abdominal organs and hepatic lesions: evaluation with intravoxel incoherent motion echo-planar MR imaging.

PURPOSE: To determine the true diffusion coefficients of abdominal organs and hepatic lesions with intravoxel incoherent motion (IVIM) echo-planar magnetic resonance (MR) imaging. MATERIALS AND METHODS: Seventy-eight patients suspected of having hepatic lesions were examined with IVIM echo-planar MR imaging at 1.5 T. There were 77 hepatic masses (27 hepatocellular carcinomas, 10 metastatic tumors, eight hemangiomas, and 32 cysts) in the 78 patients. The true diffusion coefficient D and the perfusion fraction f were calculated and compared with the apparent diffusion coefficient (ADC). RESULTS: Specific values of D were found for abdominal organs (liver, 0.72 x 10(-3) mm2/sec; spleen, 0.80 x 10(-3) mm2/sec; kidney, 1.38 x 10(-3) mm2/sec; gallbladder, 2.82 x 10(-3) mm2/sec) and for hepatic lesions (hepatocellular carcinoma, 1.02 x 10(-3) mm2/sec; metastasis, 1.16 x 10(-3) mm2/sec; hemangioma, 1.31 x 10(-3) mm2/sec; cysts, 3.03 x 10(-3) mm2/sec). The ADCs of solid organs and solid lesions were significantly higher than their D values, indicating a high contribution of perfusion to the ADCs. CONCLUSION: Perfusion contributes to the ADCs of abdominal organs and hepatic lesions. The D and f values are useful for the characterization of hepatic lesions.

Abdomen↗
PubMed1999

Moyamoya disease: evaluation with diffusion-weighted and perfusion echo-planar MR imaging.

PURPOSE: To determine the clinical efficacy of diffusion-weighted and perfusion echo-planar magnetic resonance (MR) imaging in the evaluation of moyamoya disease. MATERIALS AND METHODS: Seventeen patients with moyamoya disease were examined prospectively with diffusion-weighted and perfusion echo-planar MR imaging and conventional angiography. The change in the effective transverse relaxation rate (delta R2*) peak value, delta R2* peak time, and delta R2* integral were calculated to assess regional cerebral perfusion. The MR images were compared with angiographic images. RESULTS: Of the 34 posterior cerebral arteries (PCAs) of the 17 patients, 14 PCAs (41%) in 11 patients showed stenosis or occlusion. The delta R2* peak value ratio in the cerebral hemispheres decreased significantly, and the delta R2* peak time ratio increased significantly, with PCA stenosis and occlusion. However, no correlation was apparent between perfusion and extent of the stenotic or occlusive lesions of the internal carotid artery bifurcation. The frequency of cerebral infarctions was significantly increased in patients with stenotic or occlusive PCA lesions. For three acute infarctions, a decrease in the apparent diffusion coefficient was significantly correlated with a decrease in the delta R2* peak value, an increase in the delta R2* peak time, and a decrease in the delta R2* integral. CONCLUSION: Regional cerebral perfusion in moyamoya disease is decreased and delayed with PCA stenosis, with greater decrease and delay with PCA occlusion. Diffusion-weighted and perfusion imaging are useful for evaluating cerebral ischemia in moyamoya disease.

Adult↗
PubMed1999

Correlations between the apparent diffusion coefficient, water content, and ultrastructure after induction of vasogenic brain edema in cats.

OBJECT: The authors examined the correlation between changes in the apparent diffusion coefficient, regional water content, and tissue ultrastructure after vasogenic brain edema. METHODS: Vasogenic edema was induced in the white matter of six cats by cortical cold lesioning. The trace of diffusion tensor (Trace[D]) obtained from magnetic resonance imaging to measure the orientationally averaged water diffusibility was compared with the corresponding tissue water content determined by gravimetric studies and with ultrastructural water localization. Edema fluid had spread to the subcortical and deep white matter by 4.5 hours postlesioning. The increase in Trace(D) showed a significant linear correlation with the increase in tissue water content, both in the subcortical and deep white matter as follows: y = 45.5x - 2367 (r = 0.94) and y = 37.0x - 1769 (r = 0.93), respectively, where x is the water content (gram water/gram tissue) and y the Trace(D) (x 10(-6) mm2/second). On histological examination, nerve fibers were found to be dissociated in the white matter and the extracellular space was markedly enlarged with protein-rich fluid. No noticeable hydropic swelling of the cellular components was observed. CONCLUSIONS: A linear correlation was observed between increases in Trace(D) and increases in extracellular water volume in in vivo vasogenic brain edema. A similar correlation between the subcortical and deep white matter showing different arrangements of nerve fibers (parallel compared with intermingled, respectively) indicated that measurement of Trace(D) is a suitable parameter for the evaluation of vasogenic brain edema.

Animals↗
PubMed1999

Quantitative evaluation of salivary gland scintigraphy in Sjörgen's syndrome.

UNLABELLED: This study compared the quantitative characteristics of salivary gland scintigraphy in patients with Sjogren's syndrome with the histopathologic grading of labial biopsy. METHODS: Thirty-nine patients with Sjögren's syndrome were studied by salivary gland scintigraphy and labial biopsy. Twelve normal volunteers were also studied as a control group for scintigraphic parameters. After injection of 370 MBq 99mTc sodium pertechnetate, dynamic salivary scintigraphy with lemon juice stimulation was performed for 50 min. Functional parameters for the parotid and submandibular glands were calculated, and scintigraphic and histopathologic results were compared. RESULTS: With the progression of histopathologic grades 1-4, the velocity of tracer secretion decreased in the parotid gland (P < 0.05), and the quantity of tracer accumulation decreased in the submandibular gland (P < 0.05). The histopathologic grade in patients with Sjögren's syndrome was correlated with these scintigraphic parameters (P < 0.05): Histopathologic grade = 2.304 - 0.014 x (submandibular gland maximum accumulation) + 0.196 x (parotid gland time interval of tracer secretion). CONCLUSION: Decreased secretion velocity in the parotid gland and decreased accumulation in the submandibular gland were sensitive indicators of salivary gland disease in Sjögren's syndrome. The histopathologic grade was correlated with these scintigraphic parameters.

Adult↗
PubMed1998

What is the validity of continuous wave Doppler grading of aortic regurgitation severity? A chronic animal model study.

Continuous wave Doppler methods have been widely used clinically for evaluating the severity of aortic regurgitation; however, there have been no studies comparing these continuous wave Doppler methods with a strictly quantifiable reference for regurgitant severity. The purpose of this study was to test the applicability of continuous wave Doppler methods (deceleration slope and pressure half-time) for evaluation of chronic aortic regurgitation in an animal model. Eight sheep were studied 8 to 20 weeks after surgery to create chronic aortic regurgitation. Twenty-nine hemodynamically different states were obtained pharmacologically. A Vingmed 775 system was used for recording continuous wave Doppler traces with a 5 MHz annular array transducer directly placed on the heart near the apex. The aortic regurgitation was quantified as peak and mean regurgitant flow rates, regurgitant stroke volumes and regurgitant fractions determined with pulmonary and aortic electromagnetic flow probes and meters balanced against each other. Peak regurgitant flow rates varied from 1.8 to 13.6 L/min (6.3 +/- 3.2 L/min) (mean +/- SD), mean regurgitant flow rates varied from 0.7 to 4.9 L/min (2.7 +/- 1.3 L/min), regurgitant stroke volume varied from 7.0 to 48.0 ml/beat (26.9 +/- 12.2 ml/beat), and regurgitant fraction varied from 23% to 78% (53% +/- 16%). Only marginal correlations were obtained between reference indexes and continuous wave Doppler deceleration slope and pressure half-time (r = 0.55 to 0.74). A deceleration slope greater than 3 m/sec2 and pressure half-time less than 400 msec did, however, provide 100% specificity for detecting severe AR (regurgitant fraction > 50%). Our study shows that the continuous wave Doppler deceleration slope and pressure half-time methods have limited use for quantifying aortic regurgitation.

Animals↗
PubMed1998

Temporal variability of vena contracta and jet areas with color Doppler in aortic regurgitation: a chronic animal model study.

OBJECTIVE: The purpose of our study was to determine the temporal variability of regurgitant color Doppler jet areas and the width of the color Doppler imaged vena contracta for evaluating the severity of aortic regurgitation. METHODS: Twenty-nine hemodynamically different states were obtained pharmacologically in 8 sheep 20 weeks after surgery to produce aortic regurgitation. Aortic regurgitation was quantified by peak and mean regurgitant flow rates, regurgitant stroke volumes, and regurgitant fractions determined using pulmonary and aortic electromagnetic flow probes and meters balanced against each other. The regurgitant jet areas and the widths of color Doppler imaged vena contracta were measured at 4 different times during diastole to determine the temporal variability of this parameter. RESULTS: When measured at 4 different temporal points in diastole, a significant change was observed in the size of the color Doppler imaged regurgitant jet (percent of difference: from 31.1% to 904%; 233% +/- 245%). Simple linear regression analysis between each color jet area at 4 different periods in diastole and flow meter-based severity of the aortic regurgitation showed only weak correlation (0.23 < r < 0.49). In contrast, for most conditions only a slight change was observed in the width of the color Doppler imaged vena contracta during the diastolic regurgitant period (percent of difference, vena contracta: from 2.4% to 12.9%, 5.8% +/- 3.2%). In addition, for each period the width of the color Doppler imaged vena contracta at the 4 different time periods in diastole correlated quite strongly with volumetric measures of the severity of aortic regurgitation (0.81 < r < 0.90) and with the instantaneous flow rate for the corresponding period (0.85 < r < 0.87). CONCLUSIONS: Color Doppler imaged vena contracta may provide a simple, practical, and accurate method for quantifying aortic regurgitation, even when using a single frame color Doppler flow mapping image.

Animals↗
PubMed1998

Simultaneous Doppler and catheter transvalvular pressure gradients across St Jude bileaflet mitral valve prosthesis: in vivo study in a chronic animal model with pediatric valve sizes.

A mixture of valve types has been used in previous in vivo studies to assess the accuracy of Doppler echocardiography compared with catheter-measured pressure gradients across prosthetic mitral valves. However, limited data exist regarding the most commonly used bileaflet mechanical valve. We studied 14 sheep with St Jude Medical mechanical mitral valves. Continuous wave Doppler data were obtained across each of the 3 valve orifices. Hemodynamic data were obtained simultaneously by direct measurements with catheters. Valve sizes commonly used in the pediatric population in the mitral position (23 mm, 25 mm, and 27 mm) were studied. Linear regression analyses of Doppler-predicted versus catheter-measured gradients provided correlation coefficients ranging from 0.75 to 0.91. Agreement analysis demonstrated a scatter of Doppler data about the regression line. Although a reasonably good correlation of Doppler-predicted peak and mean pressure gradients across bileaflet mechanical valves exists in the mitral position, caution is needed when this method is applied to patients. Doppler overestimation was greatest across the 23-mm valves. Analyses of the specific orifice interrogated demonstrated higher estimated pressure gradients across the central orifice compared with the side orifices.

Animals↗
PubMed1998

Tl-201 myocardial SPECT in patients with systemic arterial diseases.

We compared the results of Tl-201 myocardial SPECT of patients with arteriosclerosis obliterans (ASO), abdominal aortic aneurysm (AAA), and Takayasu arteritis (TA), so that coronary artery disease could be evaluated in them. Twenty-three patients (ASO, 9; AAA, 8; TA, 6) had Tl-201 myocardial SPECT with stress testing, and SPECT data was assessed qualitatively and quantitatively. Qualitative analysis showed that myocardial perfusion was decreased most in patients with ASO, followed by patients with AAA, and was minimally decreased in patients with TA. Quantitative analysis indicated that segmental uptake was significantly less in four segments in ASO compared with TA, less in two segments in AAA compared with TA, and less in two segments in ASO compared with AAA. Thus patients with ASO and AAA were found to have a marked abnormality in Tl-201 myocardial SPECT, indicating that this procedure should be performed in these patients. In patients with TA, however, because of minimal abnormality in myocardial perfusion, the role of SPECT is limited.

Aged↗
PubMed1998

Takayasu arteritis: evaluation of the thoracic aorta with CT angiography.

PURPOSE: To determine the diagnostic accuracy of computed tomographic (CT) angiography in the evaluation of Takayasu arteritis. MATERIALS AND METHODS: Twenty-five patients with clinical symptoms suggestive of Takayasu arteritis underwent CT angiography and conventional angiography. Takayasu arteritis was diagnosed in 20 patients on the basis of conventional angiography. CT angiography was performed with a helical CT scanner after injection of a bolus of contrast material, and images were generated for three-dimensional display, multiplanar reformation, and maximum intensity projection. For vascular assessment, all images from CT angiography were used, and the results were compared with those from conventional angiography. RESULTS: CT angiography clearly depicted various luminal changes, including stenosis, occlusion, dilatation, and aneurysm, in the thoracic aorta and its major branches. CT angiography accurately depicted 190 (95%) of 200 arteries, although the extent of the steno-occlusive lesions was overestimated in five (2%) and underestimated in five (2%). Furthermore, CT angiography depicted mural changes, including wall thickening, calcification, and mural thrombi, not seen with conventional angiography. The sensitivity and specificity of CT angiography in the diagnosis of Takayasu arteritis were 95% and 100%, respectively. CONCLUSION: CT angiography clearly depicts both luminal and mural changes in the thoracic aorta and its major branches and has a high accuracy in the diagnosis of Takayasu arteritis.

Adolescent↗
PubMed1998

Sjögren syndrome: comparison of assessments with MR sialography and conventional sialography.

PURPOSE: To compare the diagnostic accuracy of magnetic resonance (MR) sialography with that of conventional sialography in the assessment of salivary gland disease in Sjögren syndrome. MATERIALS AND METHODS: Thirty-five patients (32 women, three men; age range, 18-69 years) suspected of having Sjögren syndrome were examined with MR sialography and conventional sialography. Gradient and spin-echo MR sialography was performed with a 1.5-T system. MR sialographic findings were compared with conventional sialographic findings. RESULTS: In 31 (89%) patients, the stage of salivary gland disease determined with MR sialography accurately correlated with that determined with conventional sialography. However, the stage at MR sialography was higher in two patients: They had stage I disease but were determined to have stage II disease. In two other patients, the stage at MR sialography was lower: A patient with stage II disease and a patient with stage III disease were determined to have stage I and stage II disease, respectively. The correlation between the stage at conventional sialography and that at MR sialography (P < .001) can be estimated with the following equation: conventional sialographic stage = 0.021 + 0.982 x (MR sialographic stage). Both the sensitivity and the specificity of MR sialography in the diagnosis of Sjögren syndrome were 100%. CONCLUSION: MR sialography is highly accurate in the evaluation of salivary gland disease in Sjögren syndrome.

Adolescent↗
PubMed1998

Different apparent diffusion coefficient: water content correlations of gray and white matter during early ischemia.

BACKGROUND AND PURPOSE: Early and accurate diagnosis of brain edema in stroke patients is essential for the selection of appropriate treatment. We examined the correlations between the changes in the apparent diffusion coefficient (ADC), regional water content, and tissue ultrastructure during early focal cerebral ischemia. METHODS: The left middle cerebral arteries of cats were occluded with an intramagnet occlusion/recirculation device. T2-weighted, diffusion-weighted, and perfusion imaging were performed repeatedly during the initial 3 hours after occlusion. The ADCs obtained from ADC maps were compared with the corresponding tissue water content values determined by gravimetry and electron microscopic water localization. RESULTS: ADC reduction was detected in areas of low perfusion 15 minutes after occlusion and thereafter. The water content increase correlated linearly with the ADC decreases in both the gray and white matter. However, both the water content corresponding to an ADC value and the rate of ADC change of the gray and white matter differed significantly (P<.05) as follows: y = -10105x + 8533 (r=.86) and y = -6174x + 4611 (r=.67), respectively, where x is the water content (grams water per gram tissue) and y is the ADC (x 10(-6) mm2/s). Hydropic astrocytic swelling was seen in both structures, and in the white matter, oligodendroglial and myelinated axonal swelling and periaxonal space enlargement were observed. CONCLUSIONS: When early ischemic edema in experimental focal cerebral ischemia is evaluated with ADC mapping, the different slopes and intercepts of the water content and ADC correlation lines for the gray and white matter, which probably reflect different ultrastructural localization of water, should be taken into account.

Analysis of Variance↗