Biomedical subjects

J Taki

Publications and source records attributed to J Taki.

At least 163 records · Page 9Linked to original sources

PubMed1991

Dynamic acquisition with a three-headed SPECT system: application to technetium 99m-SQ30217 myocardial imaging.

A method for SPECT data acquisition, "continuous repetitive rotation acquisition," was developed with a high-sensitivity three-headed SPECT system. The method was applied to the dynamic imaging of 99mTc-SQ30217, a new myocardial imaging agent. After acquisition and reconstruction of SPECT data every minute, projection images at arbitrary intervals were used for tomographic reconstruction to determine the best timing of SPECT imaging in 99mTc-SQ30217. Based on a comparison of several possible acquisition intervals, SPECT data acquisition within 9 min after injection is recommended because of high myocardial uptake (myocardium-to-lung ratio, 2.83 +/- 0.42 (mean +/- s.e.m.) at 3-6 min) and relatively low hepatic uptake (myocardium-to-liver ratio, 0.85 +/- 0.13 at 3-6 min). The rate constant of the clearance of 99mTc-SQ30217 from the myocardium obtained by SPECT was: k1 = 0.249 +/- 0.050 per min (average half-life = 2.8 min) and k2 = 0.012 +/- 0.004/min (average half-life = 58 min). The continuous repetitive rotation acquisition SPECT study appears useful for imaging SQ30217 with its rapidly changing myocardial distribution.

Adult↗

PubMed1991

[Myocardial perfusion imaging with 99mTc-SQ30217: application of three-headed SPECT system].

The early dynamic change of a new myocardial imaging agent, 99mTc-SQ30217, was investigated in SPECT study. A three-headed high sensitivity SPECT system was employed to evaluate the serial changes of accumulation pattern in the heart, lung and liver using a "continuous repetitive acquisition" mode. The myocardial activity reached a peak rapidly and decreased with rapid clearance rate. The analysis of myocardial clearance curve showed a T1/2 of 2.8 minutes (k1 = 0.25 +/- 0.12/min) in the rapid phase, and a T1/2 of 57 minutes (k2 = 0.012 +/- 0.011/min) in the slow phase. The tracer clearance in the lung was more rapid, while the hepatic uptake reached a peak approximately 10 to 15 minutes after injection. When the serial SPECT images were reviewed, the early 3-minute acquisition within 10 minutes after injection showed better image quality than the images obtained after 10 minutes. The hepatic activity did not obscure the infero-septal wall in the earlier images, but did in the images 10 minutes after injection. Thus, quick SPECT data acquisition seemed to be desirable for this agent. We concluded that 99mTc-SQ30217 was a promising radiopharmaceutical for myocardial perfusion imaging.

Aged↗

PubMed1990

Temporal relation between left ventricular dysfunction and chest pain in coronary artery disease during activities of daily living.

Forty-three ambulatory patients with angina of increasing frequency underwent continuous monitoring of left ventricular (LV) function for an average of 2.9 +/- 1.9 hours to determine the incidence and temporal sequence of LV dysfunction, ST-segment depression and chest pain. Indicators of ischemia were: a decrease in ejection fraction greater than 5% lasting greater than 1 minute; horizontal or downsloping ST-segment depression of greater than or equal to 1 mm; or onset of the patient's typical chest pain complex, or a combination of these. During the monitoring interval, subjects performed daily activities such as sitting, walking, climbing stairs and eating. In 11 patients, 22 episodes of chest pain or ST-segment depression, or both, were observed. Eighteen episodes were accompanied by a decrease in ejection fraction (9 patients); chest pain accompanied the decrease in ejection fraction during 13 episodes, whereas ST-segment changes occurred during 7. In 12 of 13 episodes the decrease in ejection fraction began earlier than the onset of chest pain, whereas in 1 patient ejection fraction decrease and chest pain onset started at the same time. The average interval from a decrease in ejection fraction to the onset of chest pain was 56 +/- 41 seconds (range 0 to 120). ST changes occurred after the onset of a decrease in ejection fraction in 6 of 7 episodes. The average interval from the onset of ejection fraction decrease and the onset of ST change was 99 +/- 91 seconds. These data suggest that LV dysfunction manifested by a decrease in ejection fraction is an earlier indicator of myocardial ischemia than is angina pectoris or electrocardiographic evidence of ischemia.

Activities of Daily Living↗

PubMed1990

Whole-body distribution of iodine 123 metaiodobenzylguanidine in hypertrophic cardiomyopathy: significance of its washout from the heart.

Whole-body distribution of iodine 123 metaiodobenzylguanidine (123I-mIBG) was evaluated in 27 patients with hypertrophic cardiomyopathy (HCM). At 1 and 4 h after injection, anterior and posterior whole-body images were obtained with a dual-headed, camera-computer system. Patients were classified into three groups based on the septal wall thickness as determined by echocardiography: group 1 consisted of 7 patients with less than or equal to 15 mm septal thickness, group 2 included 12 patients with 16-19 mm septal thickness, and group 3 included 6 patients with greater than or equal to 20 mm septal thickness. Although the myocardial mIBG uptakes at 1 h were similar among these groups (1.84% +/- 0.19%, 1.95% +/- 0.38%, 1.98% +/- 0.57%, respectively; NS), mIBG washout from the heart in group 3 was faster than in groups 1 and 2 (31.5% +/- 13.0% vs. 15.8% +/- 11.0% (group 1, P less than 0.05), 17.6% +/- 7.3% (group 2, P less than 0.01)). There was a significant positive correlation between mIBG washout from the heart and septal thickness, with correlation coefficient r = 0.52 (P less than 0.01). The liver, lung, parotid gland, spleen and skeletal muscle showed similar mIBG uptake and washout among the three groups. We conclude from these data that mIBG washout from the heart in HCM was faster in patients with severe hypertrophy than in patients with mild to moderate hypertrophy, and hence it may be a useful parameter for evaluating the severity of altered adrenergic innervation and activities.

3-Iodobenzylguanidine↗

PubMed1990

Error of uptake in dual energy acquisition with 201Tl and 123I labeled radiopharmaceuticals.

In myocardial scintigraphy, simultaneous injection of two radionuclides and dual energy acquisition are potentially useful in the assessment of regional perfusion and metabolism. The feasibility of dual radionuclide study with 201Tl and 123I labeled radiopharmaceuticals (meta-iodobenzylguanidine I 123, in this study) was investigated in phantoms and patients. The crosstalk of one radionuclide to the other pulse height window was defined as the ratio of the 201Tl count in the 123I and 201Tl windows, R[I/Tl], and the ratio of the 123I count in the 201Tl and 123I windows, R[Tl/I]. The ratios were determined in planar images and SPECT studies. In clinical studies with whole body scintigraphy (n = 8), the value of R differed significantly in various organs. In the SPECT study (n = 13), R was not uniform and varied with time and location, resulting in significant errors in uptake and regional count ratio. Thus, dual energy acquisition with 201Tl and 123I labeled radiopharmaceuticals is generally not recommended because of varying amounts of crosstalk interference. Possible solutions to this problem are discussed. The feasibility of dual radionuclide study must be confirmed in human as well as in phantom studies.

3-Iodobenzylguanidine↗

PubMed1990

Quantitative analysis of 123I-meta-iodobenzylguanidine (MIBG) uptake in hypertrophic cardiomyopathy.

Myocardial scintigraphy with 123I-meta-iodobenzylguanidine (MIBG) and thallium-201 (201Tl) was performed in 29 patients with hypertrophic cardiomyopathy (HCM) using whole-body scintigraphy and single-photon emission computed tomography (SPECT). Nonhypertensive patients were classified into three groups according to the septal thickness determined by ultrasonography; group 1 (wall thickness less than 16 mm, n = 5), group 2 (from 16 to 20 mm, n = 12) and group 3 (greater than 20 mm, n = 4). The regional myocardial uptakes of both 201Tl and 123I-MIBG (percent of injected dose/cm3 myocardium) were higher in the more hypertrophic septa. However, when regional MIBG uptake at 3 hours was divided by the 201Tl uptake to calculate the MIBG uptake per unit of blood flow, the hypertrophic septa showed lower mean values--0.39 +/- 0.23 and 0.50 +/- 0.10 in groups 3 and 2, respectively (p less than 0.1 compared with 0.69 +/- 0.20 in group 1). The regional MIBG clearance rate in the septum was significantly higher in group 3 compared with group 1 (13.4 +/- 8.0%/hr versus 1.5 +/- 6.2%/hr, p less than 0.05). The uptake and 123I-MIBG clearance rate in the lateral wall showed a similar tendency. Myocardial uptake determined by whole-body scintigraphy was slightly increased in group 2 (3.5 +/- 0.6%, p less than 0.05) compared with group 1 (2.7 +/- 0.8%); however, it was lower in group 3 (2.7 +/- 0.4%). Myocardial 123I-MIBG distribution demonstrated various patterns in comparison with 201Tl distribution, suggesting that flow-independent changes in sympathetic innervation or activity may exist in patients with HCM.(ABSTRACT TRUNCATED AT 250 WORDS)

3-Iodobenzylguanidine↗

PubMed1990

Tc-99m MDP bone imaging in inflammatory enthesopathy.

A case is presented in which uptake of Tc-99m MDP was noted at the sites of tendon and ligament attachments to the calcaneus in inflammatory enthesopathy. Following successful treatment with corticosteroids, the uptake was markedly decreased in accordance with subsidence of clinical manifestations and normalization of laboratory data. Radionuclide bone imaging may be useful in evaluating the response to treatment with corticosteroids as well as revealing the active disease sites in inflammatory enthesopathy.

Bone and Bones↗

PubMed1990

Shunt between right subclavian vein and the left heart in superior vena cava obstruction due to lung cancer.

A case in which there was a shunt between systemic veins and the left heart in superior vena cava syndrome due to lung cancer is reported. Superior vena cava syndrome developed one and a half years after right upper lobectomy with combined resection of thoracic wall. Radionuclide venography from the right antecubital vein showed immediate visualization of the left ventricle and aorta, before the right atrium and right ventricle were seen. In the superior vena cava syndrome due to a malignant tumor, this rare pathway as well as usual collaterals should be considered.

Carcinoma, Squamous Cell↗

PubMed1990

Cardiac sarcoidosis demonstrated by Tl-201 and Ga-67 SPECT imaging.

Ga-67 and Tl-201 SPECT was performed to evaluate cardiac sarcoidosis in a 15-year-old boy. Tl-201 SPECT imaging showed decreased uptake in the inferior to lateral wall and Ga-67 accumulation in the area of decreased Tl-201 uptake. These findings suggested cardiac sarcoidosis, and cardiac biopsy confirmed this diagnosis. After corticosteroid therapy, myocardial uptake of Ga-67 disappeared and myocardial TI-201 uptake became more homogeneous.

Adolescent↗

PubMed1990

Estimation of right ventricular pressure by 201Tl scintigraphy in paediatric cardiac disease.

To estimate right ventricular overload in paediatric cardiac disease, 201Tl scintigraphy was used to quantify right ventricular uptake. Six methods for calculating the 201Tl right-to-left ventricular uptake ratio (TRL) were compared, based on the location of regions of interest (ROIs), use of total count or mean count density, and the ROI-based method or profile method. When the TRL was compared with the right-to-left ventricular peak systolic pressure ratio (RVP/LVP), the mean count density method using entire right and left ventricular ROIs seemed to be appropriate, considering its simplicity, reproducibility and regression line. The linear regression line was RVP/LVP = 1.15 x TRL - 0.13 (n = 15, P = -0.0001), and RVP(mm Hg) = 162 x TRL - 33 (n = 15, P = 0.0001). In four patients with pulmonary stenosis, the changes of TRL were in good agreement with the right ventricular pressure changes after percutaneous balloon valvuloplasty. Thus, evaluation of thallium scintigraphy using this quantitative method can be a simple and effective way to evaluate patients with right ventricular pressure overloading.

Adolescent↗

PubMed1990

Redistribution of regional and organ blood volume and effect on cardiac function in relation to upright exercise intensity in healthy human subjects.

To determine the effect of relative exercise intensity on organ blood volume and its relation to cardiac function, changes in relative blood volume and cardiac function were monitored with radionuclide techniques in 14 healthy volunteers. After labeling the subject's red cells with technetium 99m, we acquired data at rest, zero-load cycling, and at 50%, 75%, and 100% of maximal oxygen uptake. From rest to zero-load cycling, leg blood volume decreased 32 +/- 2% (mean +/- SEM), whereas relative end-diastolic blood volume increased 9.6 +/- 1.2%, and lung blood volume increased 18 +/- 2%, suggesting that the lungs may act as a blood volume buffer during periods of acutely increased venous return. With relative increasing exercise, leg blood volume stabilized, and then the blood volume in the abdominal organs decreased, further augmenting cardiopulmonary blood volume; leg blood volume and abdominal blood volume decreased by 23 +/- 2% and 19 +/- 2% from baseline, respectively, whereas thoracic blood volume increased 38 +/- 4%. In the abdomen, large decreases in blood volume were observed in the spleen (46 +/- 2%), kidney (24 +/- 4%), and liver (18 +/- 4%). In contrast, lung blood volume increased 50 +/- 4%, with the upper lung fields increasing more than the lower. Blood sampling revealed an increase in the hematocrit level by 4.3 +/- 0.4 units at peak exercise that paralleled the decrease in splenic blood volume (r2 = -0.64, p less than 0.001), suggesting a role for the spleen in augmenting cardiovascular performance by the release of concentrated red blood cells into general circulation. We conclude that upright exercise results in marked blood volume shifts from the legs and abdominal organs to the heart and lungs in a dynamic process correlating closely with oxygen consumption.

Adult↗

PubMed1990

Evaluation of inferior mesenteric vein blood flow circulation with per-rectal administration of thallium-201 and technetium-99m pertechnetate.

We administered both per-rectal thallium-201 (201Tl) and technetium-99m pertechnetate (99mTc) to patients with liver diseases in order to understand the abnormalities of inferior mesenteric vein (IMV) blood flow circulation. As 201Tl heart-to-liver uptake ratio (H:L), reflecting the degree of portal-systemic shuntings (PSS), increased, the visualization of IMV in general became poor on 99mTc scintigrams. 201Tl H:L in the group with no visualization of IMV on 99mTc scintigrams was significantly higher than in the group with clear visualization of IMV (p less than 0.001). However, there were patients who showed IMV visualization among those with high 201Tl H:L. In these patients, it was considered that IMV blood flowed in the normograde direction, escaping mainly through PSS at the upper part of the portal system, and resulting in elevated H:L. In the patients without IMV visualization, IMV blood flowed in the retrograde direction, escaping mainly through collaterals at the lower part of IMV. Inferior vena cava (IVC) was visualized on 99mTc scintigrams in some patients without IMV visualization, indicating the presence of collaterals from the distal part of IMV to IVC. Per-rectal studies using these two radiotracers can afford us useful informations on the abnormalities of IMV blood flow hemodynamics in patients with liver diseases.

Adult↗

PubMed1990

[Evaluation of factor analysis and other functional images in exercise gated blood-pool study].

Factor analysis, a new method of functional imaging, has been applied to cardiovascular nuclear medicine. Because of the difficulty of its interpretation, it has not been popular as a method for detecting abnormal wall motion. The purpose of this study was to evaluate the usefulness of factor analysis in exercise gated blood-pool study in patients with ischemic heart disease. In our factor analysis, left ventricular region of interest (LVROI) was extracted to exclude the surrounding radioactivities. The new method was compared with 1) the conventional factor analysis using whole region (whole ROI method), and with 2) the other functional images, i.e. stroke volume, ejection fraction and phase images. At first we tried 3-factor analysis of the LVROI method, which resulted in many uninterpretable factors. Whereas in 2-factor analysis no uninterpretable factors were extracted. In comparison with cine-mode display, the LVROI method with 2-factor analysis showed the best sensitivity (85%) and specificity (100%). In exercise gated blood-pool study, it became easier to detect abnormal wall motion by comparing the factor image at exercise with resting image. In conclusion, the 2-factor analysis using the LVROI method greatly improved the limitation of conventional factor analysis, and will be useful in detecting wall motion abnormality in patients with ischemic heart disease.

Adult↗

PubMed1990

Evaluation of postoperative flow capacity of internal mammary artery.

The internal mammary artery has been advocated for use in coronary artery bypass grafting because of its excellent long-term patency. We compared the flow capacities of internal mammary artery and saphenous vein grafts under exercise conditions by means of radionuclide angiocardiography. Fifty-two patients were divided according to the type of bypass graft done to the left anterior descending artery: group 1 comprised 27 patients with the internal mammary artery graft, and group 2 included 25 patients with the saphenous vein graft. Saphenous vein grafts were placed into the right and circumflex systems. Before the operation, global and regional ejection fractions decreased similarly in both groups with exercise. After the operation, the global ejection fraction measured in groups 1 and 2 increased significantly from 54% +/- 2% to 57% +/- 2% and from 54% +/- 1% to 60% +/- 2%, respectively, the anteroseptal ejection fraction from 29% +/- 1% to 32% +/- 2% and from 29% +/- 1% to 35% +/- 1%, respectively, and the apical ejection fraction from 75% +/- 3% to 82% +/- 2% and from 77% +/- 2% to 86% +/- 2%, respectively. There were no differences in exercise-induced increases in the global and regional ejection fractions between groups 1 and 2. Six patients in group 1 had exercise-induced wall motion abnormalities at the anteroseptal and/or apical segments. In contrast, patients in group 2 had no exercise-induced wall motion abnormalities at these segments (p less than 0.05, group 1 versus group 2). Results of this study show that internal mammary artery grafts respond to the increased blood flow demand of exercise in essentially the same way as saphenous vein grafts. However, there seems to be a slightly greater potential for inadequate flow in patients with the internal mammary artery graft, as evidenced by the small group of patients with exercise-induced wall motion abnormalities.

Coronary Artery Bypass↗

PubMed1990

[Evaluation of hypertrophic cardiomyopathy with 123I-metaiodobenzylguanidine].

Single-photon emission computed tomography was performed in 29 patients with hypertrophic cardiomyopathy (HCM) using 123I-metaiodobenzylguanidine (MIBG). Segmental myocardial uptake of MIBG and 201T1 was calculated in 21 patients with primary HCM without history of hypertension. Septal thickness was measured by echocardiography and the relationship to septal MIBG uptake was studied. Initial MIBG uptake and 201T1 uptake showed positive correlation with the septal thickness (R = 0.581, p = 0.0058 and R = 0.677, p = 0.0007). When the septal MIBG uptake was divided by the corresponding 201T1 uptake (MIBG/T1), both the early and delayed MIBG/T1 showed negative correlation with the septal thickness (R = -0.485, p = 0.0255 and R = -0.535, p = 0.0125). Significant positive correlation was observed between septal MIBG clearance and the thickness (R = 0.510, p = 0.0182). In patients with severe septal hypertrophy (greater than 20 mm), the MIBG clearance was significantly higher compared with less hypertrophic (less than or equal to 20 mm) group (13.4 +/- 8.0%/hr vs. 3.2 +/- 4.7%/hr, p = 0.0028). Thus, MIBG was useful for the evaluation of sympathetic innervation and activity in HCM. The MIBG clearance and uptake in conjunction with 201T1 study seemed to reflect the severity of hypertrophy in HCM.

3-Iodobenzylguanidine↗

PubMed1990

[A three-headed SPECT system with high resolution and high sensitivity: application to myocardial imaging].

A three-headed single-photon emission computed tomography (SPECT) system was developed, and the fundamental SPECT performance and clinical applications were investigated. The full width at half maximum (FWHM) of the SPECT system is 10.8 mm at the center of rotation with a radius of 20 cm. In clinical applications, 201Tl myocardial images with the three-headed system demonstrated a distincter and thinner myocardium compared to those with the dual-headed system. The right ventricular wall was observed even in patients without right ventricular overload. Owing to both the increased sensitivity and resolution, the three-headed system has high performance capability in clinical use such as ECG-gating and dynamic studies.

Coronary Disease↗

PubMed1989

Cellular differentiation in the embryonic rat pancreas, with special reference to the co-existence of substances immunoreactive to both insulin and glucagon antibodies in the same cells.

We used light and electron microscopy and immunohistochemistry to examine the pancreas primordium in 11- to-20-day-old rat embryos. Cells that were immunoreactive to glucagon-like antibodies (G-like cells) first appeared under light microscopy on day 11, and those immunoreactive to insulin-like antibodies (I-like cells) appeared on day 13. All the I-like cells also reacted to G-like substance antibody. From the 13th to the 17th day of gestation, the G-like cells proliferated rapidly while the I-like cells increased in number very slowly. All the I-like cells continued to react with G-like substance antibody as well. The I-like cells began increasing rapidly on the 18th day and soon occupied about half of the islet-constituting cells. They no longer reacted with G-like substance antibody. Using double-label immunostaining with protein A-colloidal gold, the pancreatic endocrine cells became visible in 15-day-old embryos as large polygonal cells containing numerous secretion granules 180-200 nm in diameter. Some of these cells reacted to both I-like and G-like substance antibodies. These findings show the co-existence of G-like and I-like substances in rat embryo pancreatic endocrine cells between the 13th and 17th days of gestation, after which the I-like cells proliferate rapidly, and undergo definitive differentiation from the G-like cells.

Animals↗

PubMed1989

[Evaluation of ischemia by exercise stress Tl-201 myocardial SPECT in silent and symptomatic ischemia].

Forty patients with ischemic heart disease confirmed by coronary arteriography were performed Tl-201 stress myocardial scintigraphy using SPECT. Fifteen patients had anginal attack during exercise Tl-201 myocardial perfusion study (symptomatic group), and 25 patients had horizontal or downsloping ST segment depression more than 0.1 mV without angina (asymptomatic group). The washout maps were derived from circumferential profile analyses of tomographic short-axis slices, and the data were plotted as a bull's eye map. The patient's washout map was compared with the lower limit of normal (mean--2 SD), and the extent and severity scores were calculated. On visual analysis 87% (13/15) of symptomatic patients showed redistribution, while only 56% (14/25) of asymptomatic patients showed redistribution (p less than 0.05). The extent score was significantly higher in the symptomatic group than in asymptomatic group (37.2 + 23.6 vs. 19.6 + 20.8, p less than 0.05), but severity score was slightly higher in symptomatic group (56.1 + 59.4 vs. 30.0 + 54.8, NS). In conclusion, symptomatic ischemia may be more severe than asymptomatic one and the degree of ischemia may be one of the factors that determine the presence of angina during ischemia.

Adult↗