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Biomedical subjects

K Torizuka

Publications and source records attributed to K Torizuka.

At least 217 records · Page 12Linked to original sources
PubMed1984

In vivo estimation of renal volume using a rotating gamma camera for 99mTc-dimercaptosuccinic acid renal imaging.

The in vivo renal volume was determined using SPECT for 99mTc -DMSA renal imaging. The total renal volume was derived by summing the DMSA distribution volumes of the transaxial slices in the whole kidney. In 20 healthy subjects the renal volume in the right kidney was 220 ml for men and 195.2 ml for women, while that in the left kidney was 213 ml for men and 193.7 ml for women. Differences in those values were not statistically significant. A good correlation was found between renal volumes in both kidneys and body surface area. In 106 kidneys including solitary and pathological kidneys, individual renal volume correlated well with individual DMSA renal uptake rate which demonstrates cortical functioning mass, depending on the cortical blood flow. Thus, SPECT enables an accurate noninvasive means of estimating in vivo functioning renal volume.

Adult↗
PubMed1984

Segmental analysis of stress thallium myocardial emission tomography for localization of coronary artery disease.

The value of stress thallium 201 myocardial emission computed tomography (ECT) in the assessment of coronary artery disease (CAD) was analyzed in 75 patients admitted for coronary arteriography. The ECT provided contiguous transaxial, short-axis, and long-axis sections of the myocardium and the myocardial images were divided into nine segments. The sensitivity and specificity in the diagnosis of CAD were 95% and 93%, respectively. Using selected segments, the ECT identified 97 of 111 (83%) major vessels involved: 89% for right coronary artery (RCA), 88% for left anterior descending (LAD), and 70% for left circumflex (LCx). Among the 75 cases, 35 underwent stress conventional planar imaging within 3 months. The planar imaging provided high sensitivity (90%) and specificity (100%) for the detection of CAD patients as well, but it showed lower sensitivity (57%, P less than 0.001) in identifying individual vessels involved: 55% for RCA (P less than 0.01), 70% for LAD, and 36% for LCx (P less than 0.05). Stress ECT detected vessel involvement more in two-vessel disease (85%) and three-vessel disease (78%) than the planar imaging (50%: P less than 0.05 and 44%: P less than 0.01, respectively). Thus, segmental analysis of stress ECT yielded as high sensitivity and specificity in the diagnosis of CAD as the planar imaging. This can improve sensitivity in identifying individual vessels involved in deep myocardial regions, especially in those with multivessel disease.

Adolescent↗
PubMed1984

Clinical evaluation of 99mTc-pyrophosphate myocardial emission computed tomography: comparison with planar imaging.

To depict the three-dimensional distribution of 99mTc-pyrophosphate in the heart, emission computed tomography (ECT) was performed, following the conventional planar imaging, in 32 cases with suspected acute myocardial infarction (AMI). There were 23 cases with evidence of AMI, 7 with unstable angina (UA), and 2 with dilated cardiomyopathy (DCM). While the planar images showed discrete cardiac activity in only 11 of the 23 cases (48%) with AMI, the ECT images delineated focal myocardial uptake clearly in 20 of them (87%). On the other hand, the ECT images revealed cardiac blood-pool activity without significant myocardial uptake in all cases with UA and DCM in which the planar images showed diffuse activity. Thus, the ECT imaging of 99mTc-pyrophosphate seems to be a valuable technique for assessing the presence and localization of myocardial necrosis, especially in cases showing diffuse cardiac activity in the planar imaging.

Adult↗
PubMed1984

A quantitative assessment of scintigraphy of the legs using 201Tl.

201Tl perfusion scintigraphy of the legs was evaluated to define intermittent claudication quantitatively, based on Sapirstein's indicator fractionation principle. After intravenous injection of 201Tl with or without exercise, the distribution of the radiotracer throughout the body was obtained using the whole blood scanner. Regional blood flow of cardiac output for three segments of the leg was estimated as a regional fractional uptake (rFU) distributed in these segments compared with the whole body distribution. The validity of the principle was confirmed by a comparative study with 99mTc-MAA (r = 0.979). Normal rFUs (%) for each section at rest and after stress, respectively, were 5.49 +/- 0.69 and 19.40 +/- 2.04 (whole leg); 3.57 +/- 0.49 and 12.26 +/- 1.91 (thigh); 1.59 +/- 0.34 and 6.58 +/- 0.61 (calf). The rates of rFU change from the state of rest to stress (delta rFU) in normals were 3.41 +/- 0.45 (whole leg), 3.44 +/- 0.61 (thigh), and 4.30 +/- 1.03 (calf). Although rFU was within normal limits in patients with arteriosclerosis obliterans (ASO) and thromboangitis obliterans (TAO), delta rFU of the whole leg was significantly decreased from the normal value of 3.41 +/- 0.45 to 1.95 +/- 0.40 for ASO (P less than 0.001) and 1.82 +/- 0.47 for TAO (P less than 0.001). A defect or decreased activity on the stress scintigraph was well correlated with the angiographic findings.

Adult↗
PubMed1984

Quantitative evaluation of tricuspid regurgitation by digital simulation of cardiac time-activity curves.

To estimate tricuspid regurgitation (TR) quantitatively, a curve fitting method by computer has been employed. Transport in the right cardiac chambers after intravenous bolus injection of macro-aggregated albumin labeled with technetium 99m (99mTc-MAA) was recorded in anterior view by a gammacamera system. Disturbance of the dilution curves from the left heart can be avoided by using 99mTc-MAA injection. To know the radioisotope activity during the transport, time-activity curves are recorded for the superior vena cava, right atrium, and right ventricle. Parametric differential equations, obtained from compartmental analysis, interpret these curves mathematically. The rate of regurgitation is determined by comparison, using an iterative process, between the original and simulated curves. The whole process is performed automatically by computer. The calculated regurgitation value correlated well with the value from the analog simulation. The method clearly separated those with TR from those without TR. This digital simulation for estimating parameters using a compartmental model is a feasible tool in detecting and quantifying TR.

Computers↗
PubMed1984

"Hot spot" on gallium-67-citrate scan in renal cell carcinoma. Clinicopathologic and biochemical correlation.

A frontal tomographic whole-body gallium-67-citrate scan was performed on 30 patients with renal cell carcinoma. Positive gallium uptake by the kidney in 20 patients (66.7%) correlated well with the clinicopathologically higher stage and grade of the tumor and with abnormal values in prognostic indexes in the blood. Thus, a negative gallium uptake may be indicative of an improved clinical course and longer survival in patients with renal cell carcinoma.

Adenocarcinoma↗
PubMed1984

Stress thallium-201 transaxial emission computed tomography: quantitative versus qualitative analysis for evaluation of coronary artery disease.

Stress thallium-201 myocardial distribution was quantitatively evaluated by emission transaxial tomography in 104 patients who underwent coronary arteriography. The initial uptake and percent washout of thallium were assessed by the circumferential profile curves of the three short-axis sections and one middle right anterior oblique long-axis section. This quantitative tomographic analysis showed abnormal distribution in all but two patients (98%) with coronary artery disease, whereas qualitative analysis showed abnormality in 76 of the patients (93%). Quantitative analysis showed better sensitivity (91%) for detecting involved coronary vessels than qualitative analysis (80%, p less than 0.01), especially in three vessel disease (82 versus 67%, p less than 0.05). For localization of individual vessel involvement, quantitative analysis showed high sensitivity (right coronary artery: 96%, left anterior descending artery: 90% and left circumflex artery: 88%) as compared with qualitative analysis (88, 83 and 63%, respectively, p less than 0.05), while similar specificity was observed (92% for quantitative and 93% for qualitative analyses). Furthermore, in the study of patients without infarction, myocardial segments supplied by coronary vessels with moderate stenosis (51 to 75%) revealed abnormality more often with quantitative (81%) than with qualitative (56%) analysis. Thus, quantitative analysis of stress thallium emission tomography provides improved sensitivity for the detection of diseased coronary vessels in patients with three vessel disease and those with moderate stenosis. It is a valuable technique for the evaluation of coronary artery disease.

Cardiac Catheterization↗
PubMed1984

Imaging of soft tissue tumors with Tc(V)-99m dimercaptosuccinic acid. A new tumor-seeking agent.

Tumor scintigraphy, using Tc(V)-99m dimercaptosuccinic acid (Tc(V)-DMS) was performed in 58 patients with soft tissue tumors, and the results were compared with that of Ga-67 citrate. Tc(V)-DMS was found to have a sensitivity of 90% for malignant tumors including aggressive fibromatosis compared to that of Ga-67 citrate, which was 56%. However, the specificity of Tc(V)-DMS for these tumors was 71% but with Ga-67 citrate the specificity was 80%. The imaging accuracy in soft tissue tumors with Tc(V)-DMS and Ga-67 citrate was 78% and 71%, respectively. Although the accumulation of Tc(V)-DMS has been detected in some benign soft tissue tumors, the reduced accumulation in inflammatory lesions compared to Ga-67 citrate was recognized, and Tc(V)-DMS could be of great use in the detection of extension or location of malignant soft tissue tumors.

Abscess↗
PubMed1984

Computed tomography of calcified gastric carcinoma.

The CT findings in a case of calcified gastric carcinoma of the mucin-producing type are described. These findings include localized thickening of the gastric wall and multiple tiny calcific nodules within it.

Adenocarcinoma, Mucinous↗
PubMed1984

Emission computed tomography with technetium-99m pyrophosphate for delineating location and size of acute myocardial infarction in man.

Emission computed tomography with technetium-99m pyrophosphate was used to delineate the location and estimate the size of myocardial infarcts in 20 patients with documented acute myocardial infarction. Tomography was performed after planar imaging within 2-5 days after the onset of infarction. A series of transaxial, frontal, and sagittal tomograms were reconstructed from 32 views imaged from the left side of the patient's chest with a rotating gammacamera. Infarct volume was measured from the tomographic images by computerised planimetry and was compared with the cumulative release of creatine kinase MB isoenzyme. The planar images showed discrete myocardial uptake in 13 of the 20 patients and diffuse uptake throughout the cardiac region in the remaining seven. In contrast, the tomographic images clearly delineated discrete myocardial uptake by avoiding confusion of myocardial activity with that of surrounding structures, particularly bones, in all patients. For the 10 patients whose infarct size was assessed by analysis of the creatine kinase MB curve there was a close correlation between infarct volume estimated by tomography and by cumulative creatine kinase MB release. Thus emission computed tomography can provide a three dimensional map of technetium-99m pyrophosphate distribution within the heart and is thus able accurately to localise and estimate the size of myocardial infarcts in man.

Adult↗
PubMed1984

Improved detection of myocardial infarction by emission computed tomography with thallium-201. Relation to infarct size.

Emission computed tomography with thallium-201 was compared with planar imaging in its ability to detect myocardial infarctions of various sizes four weeks after the onset. Tomography was performed after planar imaging at rest in 160 patients with a first myocardial infarction, in whom infarct size was prospectively estimated by the peak value of creatine kinase activity at the time of the acute episode and in 39 patients without infarction. The planar images and the transaxial, short axial, and long axial tomograms were interpreted qualitatively. Tomography was significantly more sensitive than planar imaging in detecting anterior (87% v 96%), inferior (73% v 97%), and non-transmural (47% v 87%) infarcts. The increased sensitivity was confined to detecting small infarcts as assessed by the peak creatine kinase value (44% v 89% when peak creatine kinase activity was less than or equal to 1000 IU/l). The overall sensitivity was 96% for tomography and 78% for planar imaging. The specificity was similar (92%) with the two techniques. Thus emission computed tomography can improve the detection rate of small infarcts that cannot be identified on planar images, by showing the three dimensional distribution of thallium-201, and increases the diagnostic value of thallium-201 scintigraphy.

Adult↗
PubMed1984

Altered balance of immunoregulatory T lymphocyte subsets in autoimmune thyroid diseases.

Three monoclonal antibodies recognizing cell surface antigens of total peripheral (OKT3), helper/inducer (OKT4) and suppressor/cytotoxic (OKT8) T lymphocytes were used by an indirect immunofluorescence technique to enumerate peripheral T lymphocytes in 25 patients with Graves' disease (including 4 euthyroid Graves' patients), 16 patients with Hashimoto's thyroiditis and 22 normal controls. Total lymphocyte count and percentages of overall T and helper/inducer T cells among peripheral lymphocytes in these conditions showed no significant difference from those of the controls. Percentage of suppressor/cytotoxic T cells, however, was decreased in Graves' disease patients with or without hyperthyroidism. The ratio of helper/inducer T cells to suppressor/cytotoxic T cells was increased in Graves' disease population and slightly increased in hypothyroid Hashimoto's thyroiditis patients. The ratio correlated with the mitogenic response of peripheral mononuclear cells to phytohaemagglutinin, but not with the serum levels of thyroid hormones nor with the titres of thyroid autoantibodies. These findings are in accordance with the results of previous functional studies and indicate possible defects in suppressor T lymphocytes in autoimmune thyroid disease.

Adolescent↗
PubMed1984

Procurement and biological significance of pure 11C-glucose.

Biological significance of 11C-glucose purity has been a controversial matter. In order to understand the contribution of impurities contained in the photosynthetic 11C-glucose, its analysis and biodistribution in mice was studied. Studies indicated the interference of impurities, particularly 11C-fructose in the injectate, with the quantitative evaluation of glucose metabolic rate in brain. Furthermore, results obtained offered a good basis for search of simpler and easier separation methodology. Namely, good selection and combination of commercially available high performance liquid chromatography (HPLC) column provided 11C-glucose with high radiochemical purity. The radiochemical yield achieved was 6-10% at 75 min after the end of bombardment including the HPLC purification. The imaging study by positron computed tomography in a rabbit showed the suitability of 11C-glucose as a radiopharmaceutical for the diagnosis of the brain function.

Animals↗