Biomedical subjects

T Momose

Publications and source records attributed to T Momose.

204 records · Page 12Linked to original sources

PubMedDate not supplied

Computer simulation of ventricular wall motion using the finite element method.

To investigate how changes in the mechanical characteristics of the myocardium caused by cardiac diseases affect ventricular wall motion, a new computer program to simulate wall motion using the finite element method has been developed. A simple two-dimensional finite element model of the left ventricle is designed with an idealized tension-length curve applied to each element. Pathological changes in the ischemic process are induced in a certain portion of the model to make it possible to evaluate the relationship between the type and degree of changes and abnormal ventricular wall motion (i.e., hypokinesis, akinesis, and dyskinesis). Assumption of plastic deformation at the affected site of the model reproduced the genesis of a ventricular aneurysm. The model is then transformed into a three-dimensional wire frame structure, and the results can viewed from any perspective. These simulations enable the semiquantitative comprehension of cardiac wall motion without need for complicated physiological experiments and may be applied to human cardiac motion in combination with data obtained from cardiac scintigraphy, echocardiography, ventriculography, or cine-CT.

Computer Simulation↗

PubMedDate not supplied

N-isopropyl I-123 p-iodoamphetamine brain scans with single photon emission computed tomography: mental sweating and EEG abnormality.

We studied a patient with hyperhidrosis and electroencephalographic (EEG) abnormality using N-isopropyl I-123 p-iodoamphetamine (I-123 IMP) with single photon emission computed tomography (SPECT). EEG abnormality was found predominantly in the frontal area, and sharp wave bursts were induced by hyperventilation. Ictal and nonictal scans were obtained with simultaneous EEG recordings. Ictal scans revealed increased uptake of IMP in the frontal cortex, reflecting hyperperfusion to the frontal area. The ratio of IMP uptake of the frontal to the parietal cortex (F/P ratio) was calculated both in the ictal and nonictal phase. In the ictal phase, the F/P ratio was 1.23, compared with 0.91 in the nonictal phase. The data indicated altered regional cerebral blood flow with EEG abnormality and hyperventilation load. Although the relationship between sweating and cortical function is not fully understood, our study indicates that excessive mental sweating is related to frontal cortical dysfunction. I-123 IMP-SPECT seems valuable for topographical demonstration of epileptogenic lesions and understanding the pathophysiological process of mental sweating.

Adult↗

PubMedDate not supplied

MRI of callosal disconnection due to cerebral infarction.

Magnetic resonance imaging (MRI) was performed to study two cases of callosal disconnection due to cerebral infarction. Both cases had pure alexia and right homonymous hemianopsia. Midsagittal inversion recovery (IR) images demonstrated that the corpus callosum was completely intact, and coronal IR images revealed involvement of the lingual gyrus, fusiform gyrus, forceps major, inferior longitudinal fascicle, and optic radiation in the dominant cerebral hemisphere in both cases. Midline sagittal images provided direct visualization of the corpus callosum but did not provide sufficient information for the study of callosal disconnection syndromes. Coronal reconstructions aided in visualizing the relationship of lesions to the adjacent structures of cerebral white and gray matter. MRI may be one of the most useful tools for understanding the process of interhemispheric transference of information.

Aged↗

PubMedDate not supplied

Assessment of the cerebrovascular response to acetazolamide using 99mTc-DTPA-HSA: methodological considerations.

We have reported methods of assessing the cerebrovascular response to acetazolamide using 99mTc-DTPA-HSA and their usefulness in evaluating cerebral hemodynamics. Several problems of this technique were investigated in 10 normal subjects. Following 99mTc-DTPA-HSA injection, dynamic imaging of the anterior head view was performed for 25 to 50 minutes, and 10 minutes after the beginning of imaging, 1,000 mg of acetazolamide was infused intravenously. Venous blood samples were obtained during the imaging period to estimate the blood retention of 99mTc-DTPA-HSA. Radioactivity in the head increased for about 10 minutes following acetazolamide infusion, then decreased slowly. The declining phase almost disappeared after correction for the blood clearance of 99mTc-DTPA-HSA, indicating stability of the vasodilatory effect of acetazolamide. Dilatation index, the percent increase in activity, was a little smaller after correction, but was closely correlated with the index without correction. There was a high correlation between dilatation indices obtained by two analyses, including ROI setting and visual determination of the peak, of the same data. In conclusion, neither blood clearance of 99mTc-DTPA-HSA nor subjective analysis considerably impairs the reliability of the dilatation index, and blood volume in the head from about 15 to 40 minutes after acetazolamide injection is stable and suitable for SPECT.

Acetazolamide↗

PubMedDate not supplied

SPECT measurements of cerebral blood volume before and after acetazolamide in occlusive cerebrovascular diseases.

Cerebral blood volume before and after acetazolamide was measured by SPECT to evaluate cerebral vasodilatory capacity in eight patients with cerebrovascular disease and five control subjects. Two SPECT measurements were performed serially, and acetazolamide was administered between them. The ratio of increase in hemispheric blood volume was calculated, and it was compared with the results of cerebral blood flow and cerebral blood volume measurements. A cerebral vasodilatory capacity map, the image after acetazolamide minus the baseline image, was also produced. Acetazolamide increased hemispheric blood volume in all unilateral carotid disease than in the uninvolved hemispheres of the patients and control subjects. The ratio of concordance with blood flow and blood volume measurements was approximated at 80%. Cerebral vasodilatory capacity mapping revealed three defects compatible with the clinical data. SPECT measurements of cerebral blood volume after acetazolamide can be performed following baseline SPECT with no additional radiotracer, and may be helpful to assess hemodynamic status.

Acetazolamide↗

PubMedDate not supplied

Delayed imaging of Tc-99m-DTPA-HSA SPECT in subacute cerebral infarction.

Cerebral blood volume measurement by Tc-99m-DTPA-HSA SPECT was performed in a patient with subacute cerebral infarction to evaluate compensatory vasodilatation. Additional delayed imaging revealed focal increased radioactivity that was not found on the early images, indicating leakage of radioactive agents due to blood-brain barrier breakdown. Delayed SPECT may be helpful to detect areas unsuitable for estimating regional blood volume.

Acute Disease↗