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Biomedical subjects

K Torizuka

Publications and source records attributed to K Torizuka.

At least 199 records · Page 11Linked to original sources
PubMed1985

Dynamic positron computed tomography of the heart with a high sensitivity positron camera and nitrogen-13 ammonia.

Dynamic positron computed tomography (PCT) of the heart was performed with a high-sensitivity, whole-body multislice PCT device and [13N]ammonia. Serial 15-sec dynamic study immediately after i.v. [13N]ammonia injection showed blood pool of the ventricular cavities in the first scan and myocardial images from the third scan in normal cases (n = 4). In patients with myocardial infarction (n = 8) and mitral valve disease (n = 2), tracer washout from the lung and myocardial peak time tended to be longer, suggesting presence of pulmonary congestion. PCT delineated tracer retention in the dorsal part of the lung. Serial 5-min late dynamic study in nine cases showed gradual increase in myocardial activity for 30 min in all normal segments and 42% of infarct segments, while less than 13% activity increase was observed in 50% of infarct segments. Thus, serial dynamic PCT with [13N]ammonia assessing tracer kinetics in the heart and lung is a valuable adjunct to the static myocardial perfusion imaging for evaluation of various cardiac disorders.

Ammonia↗
PubMed1985

[Evaluation of myocardial viability in myocardial infarction by thallium-201 emission computed tomography].

Stress thallium-201 emission computed tomography (ECT) was performed for 24 patients with myocardial infarction for quantitative evaluation of regional thallium redistribution and washout. ECT was performed using a rotating gamma camera 10 minutes and 2.5 hours after thallium injection during maximal exercise. Three short-axis sections and one central long-axis section were selected for the circumferential profile curves. Redistribution (%) and washout (%) were calculated from the stress and redistribution profile curves in each section. These parameters were evaluated by comparison with regional wall motion on radiographic contrast ventriculography. Forty-eight of the 52 segments (92%) with normal thallium uptake showed normal wall motion. Among the segments with abnormal thallium uptake, normal or hypokinetic wall motion was observed in 12 of 13 segments (92%) with more than 20% redistribution and in 16 of 19 segments (84%) with 10-20% redistribution, while it was observed in only 15 of 36 segments (42%) without redistribution (p less than 0.001). Among 48 infarcted segments, 16 segments (33%) showed significant redistribution on ECT analysis. Normal or hypokinetic wall motion was observed in three of five segments (60%) with more than 20% redistribution, and in 10 of 11 segments (91%) with 10-20% redistribution, while it was seen in only eight of 30 segments (17%) without redistribution (p less than 0.005).

Heart↗
PubMed1985

[Myocardial positron computed tomography using N-13 ammonia for evaluating coronary artery disease: comparison with thallium-201 emission computed tomography].

To assess myocardial perfusion in patients with coronary artery disease (CAD), N-13 ammonia positron computed tomography (PCT) was performed for 32 cases, and the PCT images were compared with those of single-photon emission computed tomography (SPECT) using thallium-201. Myocardial perfusion images were obtained with a whole-body multislice PCT device following the intravenous injection of 10 to 20 mCi N-13 ammonia at rest (32 cases) and during exercise (23 cases). Eleven cases underwent serial 15-20 second dynamic studies immediately following the N-13 ammonia injection. Serial dynamic study showed the blood-pool images in the first scan, and enabled assessment of tracer washout from the blood-pool, and the lung as well as washin into the myocardium. PCT provided clear resting myocardial perfusion images in all cases. PCT images were of higher quality than those of SPECT due to higher spatial resolution with less statistical noise, allowing delineation of the right ventricular myocardium and papillary muscles in many cases. Both PCT and SPECT detected perfusion abnormalities in 18 of the 19 cases with myocardial infarction, without false positive findings. PCT yielded stress myocardial images and permitted comparative evaluations of myocardial perfusions at rest and during exercise in all 23 cases. Perfusion abnormalities were detected in 14 cases (74%) at rest and in 18 cases (95%) during exercise among 19 patients with CAD. No false positives were observed, either by resting or stress PCT imaging. Stress myocardial PCT identified regional perfusion abnormalities in 30 of the 34 regions supplied by stenosed vessels (88%). High resolution PCT images enabled precise evaluation of myocardial perfusions which proved valuable for assessing myocardial perfusions before and after aorto-coronary bypass surgery. The present study proved advantages of N-13 ammonia PCT in creating three-dimensional high resolution images of the myocardium, which facilitates precise evaluation of myocardial perfusions. Furthermore, its potential capabilities in quantifying coronary reserve function will be very useful. This method should provide valuable pathophysiological information for CAD, as well as for metabolic PCT imaging.

Ammonia↗
PubMed1985

Immunohistological phenotyping of thyroid infiltrating lymphocytes in Graves' disease and Hashimoto's thyroiditis.

Subsets of lymphocytes in the thyroid were immunophenotyped by their surface antigens in frozen tissues of Hashimoto's thyroiditis and Graves' disease. Using triple layer immunoperoxidase staining (IP), monoclonal antibodies (T3, Leu 3, T8, anti-Tac and Leu 7) were employed to detect markers of T cell subsets, activated T cells, and a natural killer associated antigen. B cells were identified by 2 step IP with anti-IgD antisera. Excluding those cells forming lymphoid follicles, the density of lymphocytes infiltrating between thyroid epithelial cells was much higher in Hashimoto's thyroiditis than in Graves' disease. However, relative proportions of subsets were similar in both diseases. Most of the infiltrating cells were T3 positive T cells (T3+), with more T8+ (suppressor/cytotoxic T) than Leu 3+ (inducer/helper T). Some Leu 7+ were occasionally seen, but surface IgD positive mature B cells (IgD+) were almost absent. In contrast, IgD+ cells were densely aggregated in primary lymphoid follicles and mantle zones of secondary follicles. In these regions, Leu 3+ cells were about twice as frequent as T8+ cells. Some Leu 7+ and scarce Tac+ cells were also found. The present study indicates a major involvement of immunoregulatory T cells in autoimmune thyroid disease, and also suggested intrathyroidal maturation of B cells.

Adult↗
PubMed1985

[Recent advance in diagnostic imaging: NMR].

Application of NMR, whether in imaging or in spectroscopy, is evolving rapidly and its clinical feasibility is to be fully assessed. It is not clear if speculation today will hold true tomorrow, but here present status of NMR in medicine, especially in its roles in research of the central nervous system are discussed as follow; NMR imaging in brain tumors, cerebrovascular diseases, degenerative diseases, trauma, spinal cord diseases, Imaging by surface coil, Contrast material in NMR imaging, Blood flow measurement by NMR, Chemical shift imaging, Studies of metabolism by 31P NMR spectroscopy, Recent advances and possible future role of NMR in medicine.

Brain↗
PubMed1984

Stress scintigraphy using single-photon emission computed tomography in the evaluation of coronary artery disease.

Twenty-seven patients with angina pectoris, 24 with postmyocardial infarction angina and 7 with normal coronary arteries were examined by exercise thallium-201 emission computed tomography (SPECT) and planar scintigraphy. Exercise SPECT was compared with the reperfusion imaging obtained approximately 2 to 3 hours after exercise. The sensitivity and specificity of demonstrating involved coronary arteries by identifying the locations of myocardial perfusion defects were 96 and 87% for right coronary artery, 88 and 89% for left anterior descending artery (LAD) and 78 and 100% for left circumflex artery (LC). These figures are higher than those for planar scintigraphy (85 and 87% for right coronary artery, 73 and 89% for LAD and 39 and 100% for LC arteries). In patients with 3-vessel disease, sensitivity of SPECT (100, 88 and 75% for right coronary artery, LAD and LC, respectively) was higher than planar imaging (88, 63 and 31%, respectively), with a significant difference for LC (p less than 0.05). In 1, 2 and 0-vessel disease the sensitivity and specificity of the 2 techniques were comparable. Multivessel disease was more easily identified as multiple coronary involvement than planar imaging with a significant difference in 3-vessel disease (p less than 0.05). In conclusion, stress SPECT provides useful information for the identification of LC lesions in coronary heart disease, including 3-vessel involvement.

Coronary Disease↗