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Biomedical subjects

K Hisada

Publications and source records attributed to K Hisada.

At least 163 records · Page 9Linked to original sources
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

Characteristics of the binding of N-isopropyl-p-[125I]iodoamphetamine in the rat brain synaptosomal membranes.

N-isopropyl-p-[125I]iodoamphetamine (125I-IMP) binding to crude synaptosomal membranes of rat brain was saturable and pharmacologically displacable. Scatchard analysis of binding data revealed an apparent dissociation constant, KD of 56.2 +/- 5.2 microM, and the estimated maximum number of binding sites, Bmax of 7.5 +/- 1.1 nmoles mg-1 protein; and competition studies demonstrated structure activity relationships among structural analogues of arylalkylamines. These findings suggest that the retention mechanism of IMP in the brain is probably associated with saturable binding of IMP to extreme high-density, relatively low-affinity binding sites rather than any of the well-known amine receptors.

Amphetamines↗
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

Imaging of propagated sites of epileptic discharges in repeated 123I-IMP SPECT scans.

Single-photon emission computed tomographic (SPECT) brain scans with N-isopropyl-(iodine-123-p-iodoamphetamine (123I-IMP) were performed twice at an interval of about 2.5 years in the interictal period in an adult patient with occipital-lobe epilepsy. The first SPECT scan showed an abnormal image of decreased 123I-IMP uptake in the right occipital lobe. This abnormal image was regarded as the primary focus of his epilepsy on the basis of its regional agreement with right-occipital spikes consistently seen in interictal electroencephalographic recordings throughout his clinical history. In the second scan, he showed multiple abnormal images of decreased uptake in the right frontotemporal lobes and left occipital lobe together with the right occipital lobe. These additional abnormal images were considered to be propagated sites of epileptic discharges.

Adult↗
PubMed1990

[Washout rate in patients with hypertrophic cardiomyopathy and hypertensive cardiac hypertrophy].

The present study was performed to clinically clarify the pathogenesis of hypertensive cardiac hypertrophy (HT) and hypertrophic cardiomyopathy (HCM). Exercise thallium-201 (Tl-201) myocardial scintigraphy using a bicycle ergometer was performed for controls, HT and HCM. The scintigrams were evaluated by the circumferential profile analysis. Furthermore, the changes in Tl-201 dynamics in exercise Tl-201 scintigraphy with verapamil injections were examined in these three groups. Analysis of exercise Tl-201 scintigraphy without verapamil injections showed that the initial uptake did not differ among the three groups, but the washout rate three hours after the Tl-201 injections (WR3) did differ among the three groups. Although the WR3 of HT did not differ from that of the controls, the WR3 of HCM was lower than that of the controls. The WR3 with and without verapamil were compared. Although the WR with verapamil injections equalled that without verapamil injections in the controls and HT, the WR3 with verapamil injections decreased more than did that without verapamil injections in HCM. As an index of great and rapid changes in circulation, the washout rate one hour after the Tl-201 injection (WR1) was calculated. The WR1 without verapamil did not differ among the three groups and did not differ from that with verapamil injections in each group. These results suggest that Tl-201 dynamics of HT differ from those of HCM and lowering of the WR3 in HCM may not be caused by disturbance in the microcirculation, but rather by disturbance of Tl-clearance through the cell membrane and its cytoplasm.

Cardiomegaly↗
PubMed1990

[201T1 single photon emission computed tomography in the diagnosis of lung cancer].

201T1 SPECT was performed in 84 patients with suspected lung cancer. Both early and delayed scans demonstrated abnormal accumulation in 67 of 68 malignant pulmonary lesions and in nine of 18 benign conditions. All of 64 lung cancer were clearly visualized. Delayed ratio (uptake ratio of the lesion to the normal lung on delayed scan) and retention index (degree of retention in the lesion) were helpful to differentiate malignant from benign lesions. This method was also useful to evaluate mediastinal involvement from lung cancer.

Adenocarcinoma↗
PubMed1990

[Fundamental study on nuclear medicine imaging of cholinergic innervation in the brain: changes of neurotransmitter and receptor in animal model of Alzheimer's disease].

A fundamental study was performed on the nuclear medicine imaging of cholinergic innervation in the brain. In a cholinergic denervation model prepared by producing an unilateral basal forebrain lesion in the rat, which is reported to be one of animal models of Alzheimer's disease, quantitative determination of acetylcholine in parietal cortices revealed statistically significant 31% decrease on an average in the ipsilateral side relative to the contralateral side to the lesion. In vitro receptor autoradiography showed no significant differences in total, M1 and M2 muscarinic acetylcholine receptors between the ipsilateral and contralateral cortices to the lesion. Simultaneous mapping of presynaptic cholinergic innervation using 3H-2-(4-phenylpiperidino) cyclohexanol (AH5183) demonstrated significant 14% decrease of AH5183 binding on an average in the ipsilateral relative to the contralateral fronto-parieto-temporal cortices to the lesion. These results suggest that AH5183 is a promising ligand for mapping cholinergic innervation in nuclear medicine imaging.

Acetylcholine↗
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 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

Autoradiographic analysis of iodoamphetamine redistribution in experimental brain ischemia.

The pathophysiologic significance of iodoamphetamine (IMP) redistribution was analyzed using a double radionuclide autoradiography technique in experimental brain ischemia in the rat. Within 4 hr after unilateral arterial occlusion, IMP almost completely redistributed at 150 min postinjection in the affected areas. At 2 min postinjection, both a remarkable decrease of IMP accumulation and histopathologic change of diminished staining were observed in these areas. The redistribution amplitude was higher in the affected hemisphere, especially in the regions surrounding the ischemic core than in the unaffected hemisphere. These findings were consistent with computer simulation studies of the time course of brain activity based on the standard diffusible tracer model. The results suggest that IMP redistribution in the ischemic area is due to differences of the temporal changes of the brain activity between the unaffected and affected areas and that it is a "physical" phenomenon (only flow related) rather than a "biologic" one.

Amphetamines↗
PubMed1990

[Brain perfusion SPECT imaging before and during the acetazolamide test using 99mTc-HMPAO].

A new method using brain perfusion 99mTc-HMPAO SPECT imaging was developed for evaluating cerebral perfusion reserve by the acetazolamide test with a short period. The first SPECT study was carried out for 13.5 min to obtain SPECT images at the resting state after 3 min postinjection of 555 MBq (15 mCi) of 99mTc-HMPAO. At the same time as the start of the first SPECT study, 1 g of acetazolamide was intravenously injected. Immediately after the stop of the 1st SPECT study, 925 MBq (25 mCi) of 99mTc-HMPAO from the same vial as in the first study was additionally injected. Three minutes later the second SPECT study was carried out for 10 min. After reconstruction the tomographic images in the first study were subtracted from the images in the second study to obtain those during the acetazolamide test after correction of the time differences in data acquisition between the two studies. This subtraction technique gives independent brain perfusion SPECT images before and during the acetazolamide test. Besides, the regional flow changes during the test were quantitatively analyzed. In conclusion this method seems to be practically useful for evaluating regional brain perfusion before and during drug treatments as a consecutive study with a short period of approximately 30 min.

Acetazolamide↗
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

Determination of the lysosomal role in tumor accumulation of 67Ga by dual-tracer studies.

The lysosomal role in tumor accumulation of 67Ga was determined by dual-tracer (67Ga and 46Sc) studies. It became clear that 67Ga essentially did not accumulate in the tumor lysosome, and that the lysosome did not play a major role in tumor accumulation of 67Ga. In addition, it was revealed that tumor lysosome was hardly disrupted at all in some phases of fractionation procedures.

Animals↗
PubMed1989

Relation between the location of elements in the periodic table and various organ-uptake rates.

Fifty four elements and 65 radioactive compounds were examined to determine the organ uptake rates for rats 3, 24 and 48 h after i.v. injection of these compounds. They were prepared as carrier free nuclides, or containing a small amount of stable nuclide. Generally speaking, behaviors of K, Rb, Cs and Tl in all the organs were very similar to one another, but they differed from that of Na. Bivalent hard acids were avidly taken up into bone; therefore, uptake rates in soft tissues were very small. Hard acids of tri-, quadri- and pentavalence which were taken up into the soft tissue organs decreased more slowly from these organs than other ions. Soft acids such as Hg2+ were bound very firmly to the component in the kidney. Anions (with few exceptions), GeCl4 and SbCl3 were rapidly excreted in urine, so that the uptake rates in organs were low.

Animals↗
PubMed1989

Scintigraphic demonstration of intracranial communication between arachnoid cyst and associated subdural hematoma.

An arachnoid cyst found to have a communication to an associated subdural hematoma was demonstrated with the Tc-99m DTPA brain scintigraphy. Although arachnoid cysts are known to be silent, when a patient with an arachnoid cyst develops signs of increased intracranial pressure or neurological deficits, the presence of a complication, including subdural hematoma, intracystic hemorrhage or subdural hygroma, is highly suspected. In the present case, the patient with an arachnoid cyst had a subdural hematoma following minor head injury. Tc-99m DTPA brain scintigraphy showed abnormal accumulation of the tracer not only in the hematoma but in the arachnoid cyst. This observation suggested communication of the two lesions, which was confirmed at surgery.

Adolescent↗