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Biomedical subjects

K Hisada

Publications and source records attributed to K Hisada.

At least 73 records · Page 4Linked to original sources
PubMed1994

Decreased 123I-MIBG uptake and increased clearance in various cardiac diseases.

123I-metaiodobenzylguanidine (MIBG), a tracer for sympathetic neuron integrity and function, was applied to 155 patients with various types of cardiac disease. The methods for quantification of MIBG and washout were studied as well as normal ranges. Heart-to-mediastinum average count ratio (H/M) correlated well with total heart count divided by injected activity (r = 0.60, P < 0.0001 and r = 0.72, P < 0.0001 for early and delayed images, respectively). Although as a whole left ventricular ejection fraction (LVEF) positively correlated with H/M ratio, decreased H/M ratio could be associated with normal LVEF, which may indicate that the MIBG activity was an independent variable compared with cardiac contractility. High washout rate was seen in various cardiac diseases, such as dilated cardiomyopathy, hypertrophic cardiomyopathy, ischaemic heart disease, hypertension, hypothyroidism and arrhythmia. The increased washout seems to be nonspecific to disease type, but is a common feature of damaged or failing myocardium.

3-Iodobenzylguanidine↗
PubMed1994

Utility of 123I-IMP SPECT brain scans for the early detection of site-specific abnormalities in Creutzfeldt-Jakob disease (Heidenhain type): a case study.

Serial changes in brain imaging of regional cerebral blood flow with single photon emission computed tomography (SPECT) using N-isopropyl-(iodine-123) p-iodoamphetamine (123I-IMP) were observed in a patient with probable Heidenhain type of Creutzfeldt-Jakob disease, which was characterized by the initial onset of visual symptoms. Corresponding to the visual signs and periodic synchronous discharges localized in the bilateral parietal and occipital regions on EEG, focal hypoperfusion images in the occipital lobes were detected on the SPECT scan before brain X-ray computed tomography and magnetic resonance imaging showed any abnormalities. These results suggest that SPECT brain imaging is useful in the early detection of site-specific abnormalities in Creutzfeldt-Jakob disease.

Aged↗
PubMed1994

Correlations between quantitative EEG and regional cerebral blood flow (SPECT) in patients with partial epilepsy.

During interictal periods in 9 patients with partial epilepsy we examined whether there were correlations between the relative power of background EEG (power spectral analysis) and the absolute values of regional cerebral blood flow (rCBF) measured by 99mTc hexamethylpropylene amine oxime (HMPAO) SPECT in each cerebral region. None of the patients had any organic cerebral lesions on X-ray CT examinations, neurological abnormalities or mental retardation. There was an inverse correlation between rCBF and the relative power of the theta band, and a direct correlation between rCBF and that of the alpha band of 10-12.8 Hz, in the right and/or left frontal, parietal and temporal regions. In the occipital regions, there was a direct correlation only between rCBF and the relative power of the beta band. These correlations were noted whether the analyzed regions were epileptic foci or not. These results suggest that background EEG and rCBF changes in epileptic patients are closely coupled.

Adult↗
PubMed1994

Effects of head elevation on intracranial hemodynamics in patients with ventriculoperitoneal shunts.

The present study was performed to investigate the effects of head elevation on intracranial hemodynamics in patients with ventriculoperitoneal (VP) shunts. The series included 35 hydrocephalic patients and five individuals without hydrocephalus who were used as controls. The hydrocephalic patients were divided into three groups: 15 patients who received VP shunts with a differential-pressure valve (DP group); 11 who received VP shunts with a variable-resistance valve (VR group), and 13 hydrocephalic patients (Hyd group) who had not received shunts (four underwent VP shunts later). The cerebral blood flow (CBF) of patients in the supine and upright positions was measured by technetium-99m hexamethylpropylenamine oxide (HMPAO) single-photon emission computerized tomography in each patient, using the subtraction technique. Cerebral perfusion pressure (CPP) was taken as the difference between the mean arterial blood pressure and ventricular fluid pressure, both referenced to the level of the foramen of Mono. The patients' heads were elevated stepwise from supine to upright. Percent changes of the mean CBF in the upright position (% delta mCBFupr) were 24.9% +/- 4.3% (mean +/- standard error of the mean) in the DP group, 6.2% +/- 2.7% in the VR group, 3.5% +/- 2.6% in the Hyd group, and 4.5% +/- 2.2% in the control group. Patients in the DP group showed a pathological increase in CPP with head elevation, whereas those in the Hyd and VR groups showed a physiological decrease in CPP. Three patients with differential-pressure valves, whose % delta mCBFupr was markedly high, developed low-intracranial pressure syndrome. In conclusion, shunted patients with a DP valve showed pathological intracranial hemodynamics in the upright position. This pathological hemodynamic stress in patients with long-standing differential-pressure valve implantation may induce pathological changes in the brain such as subependymal gliosis.

Adolescent↗
PubMed1994

[Quantitative analysis of 123I-BMIPP imaging in relation to exercise-redistribution 201Tl in patients with old myocardial infarction].

Myocardial kinetics of 123I-labeled 15-(p-iodophenyl)3R,S-methylpentadecanoic acid (BMIPP) was evaluated with BMIPP imaging in conjunction with stress-201Tl. We studied 20 patients with old myocardial infarction. BMIPP SPECT was obtained at 20 min and 3 h after injection. On a separate day, exercise stress-201Tl SPECT was performed at 10 min and 3 h after injection. Then, left ventricular myocardium was divided into 20 segments. For quantitative analysis, in each SPECT data, the maximum value (average counts per pixel) of all 20 myocardial segments was taken as 100%; the other values were calculated as a percentage of this maximum (Relative regional uptake, RRU). On the basis of stress-201Tl pattern, the myocardial segments were classified into 4 groups; normal 201Tl uptake, reversible 201Tl defect, fixed 201Tl defect and 201Tl defect with reverse redistribution. The 20 min BMIPP showed reduced activity compared with 3 h-201Tl (p < 0.001), especially in the area of 201Tl redistribution (50/111 segments, 45%), implicating impaired fatty acid utilization at resting condition. The washout rate of the segments with reversible 201Tl defect (-1.6 +/- 13.9%) was significantly lower than that of the segments with normal 201Tl uptake (9.0 +/- 9.8%) and fixed 201Tl defect (3.8 +/- 12.9%). Thus, BMIPP in combination with stress 201Tl imaging provides precise informations of impaired myocardial fatty acid utilization in patients with old myocardial infarction.

Adult↗
PubMed1994

Left ventricular functional reserve in nonobstructive hypertrophic cardiomyopathy: evaluation by continuous left ventricular function monitoring.

UNLABELLED: The cardiac functional response to exercise in patients with nonobstructive hypertrophic cardiomyopathy (HCM) was evaluated using a continuous ventricular function monitor with a cadmium telluride detector (CdTe-VEST). METHODS: Supine ergometric exercise was performed under CdTe-VEST monitoring in 41 patients with nonobstructive HCM (34 men and 7 women, age 18-72 yr, mean 51 yr) and 15 patients without cardiac disease (9 men and 6 women, age 36-56 yr, mean 49 yr). RESULTS: Although 20 of 41 patients with HCM maintained a LVEF above baseline at peak exercise (Group A), 21 did not show an EF increase at peak exercise (Group B). Exercise duration and work load in Group A were longer and higher, respectively, than in Group B. Resting EF in Group B (72 +/- 7.7%) was significantly higher than that in Group A (65 +/- 8.2%) and the control group (62 +/- 5.9%). The EF increase from baseline to EF overshoot during recovery and the time to EF overshoot were lower and longer, respectively, in Group B than in Group A and the control group. Septal wall thickness and the septum-to-posterior-wall-thickness ratio between Groups A and B were not different. ST-segment depression was observed in all 21 Group B patients and in 8 of the Group A patients. CONCLUSION: In patients with nonobstructive HCM, left ventricular dysfunction during exercise and during recovery was frequently observed but was not related to the degree of septal wall hypertrophy. The CdTe-VEST is a useful means to evaluate left ventricular functional reserve to exercise in patients with HCM.

Adolescent↗
PubMed1994

[123I-BMIPP whole-body scintigraphy in relation to left ventricular ejection fraction].

Heart uptake and clearance of 123I-15-(p-iodophenyl)-3(R,S)-methylpentadecanoic acid (BMIPP) by whole-body scintigraphy in relation to left ventricular injection fraction (LVEF) was evaluated in 19 patients with myocardial infarction. At 45 and 210 min after injection, anterior whole-body images were obtained with a single-headed gamma camera system. In each patient, gated blood pool scintigraphy was also performed, and LVEF was calculated. Percent washout from the heart from the 45 to the 210 min imaging positively correlated with LVEF (r = 0.61, p < 0.01), although percent uptake and count density of the heart at 45 min imaging did show any positive correlation with LVEF (r = -0.10 and r = 0.35, respectively). The count density did not correlated with the percent washout (r = 0.32, p = 0.18). Thus, some relationship between LVEF and washout rate of BMIPP from the heart was suggested by analysis of BMIPP whole-body scintigraphy in patients with myocardial infarction.

Adult↗
PubMed1994

Kinetics of iodine-123-BMIPP in patients with prior myocardial infarction: assessment with dynamic rest and stress images compared with stress thallium-201 SPECT.

UNLABELLED: Myocardial kinetics of 123I-labeled 15-(p-iodophenyl)3R, S-methylpentadecanoic acid (BMIPP) were evaluated with dynamic SPECT, and stress and rest BMIPP images were directly compared in conjunction with stress 201Tl. METHODS: We studied 26 patients with prior myocardial infarction. Two minutes after injection of BMIPP, dynamic data acquisition with a three-headed SPECT was started and continued for 12 min. Conventional SPECT images were obtained at 20 min and 3 hr after injection. On a separate day, exercise, stress 201Tl SPECT was performed at 10 min and 3 hr after injection. Exercise stress-BMIPP imaging was performed in 15 of the patients, and static SPECT images were obtained. RESULTS: With dynamic SPECT, early clearance of BMIPP from the myocardium was observed in the segments with reversible 201Tl defects, suggesting enhanced contribution of backdiffusion from BMIPP. In myocardial segments with reversible 201Tl defects, 20-min BMIPP images showed a higher frequency of reduced uptake when compared to 3-hr 201Tl (90/163) imaging. CONCLUSION: With BMIPP dynamic SPECT, an enhanced contribution of backdiffusion in the early phase from ischemic myocardium was suggested. When exercise stress BMIPP images were obtained, a more severe defect was observed than on rest BMIPP and stress 201Tl imaging, possibly due to decreased coronary blood flow and impaired fatty acid uptake induced by ischemia during exercise.

Exercise Test↗
PubMed1993

[67Ga SPECT in the evaluation of orbital and ocular mass-like lesions].

We evaluated 67Ga SPECT in the differentiation of mass-like lesions in the orbital and ocular areas. A two-headed SPECT system equipped with parallel-hole collimator was used. 67Ga SPECT demonstrated three dimensionally the extent of tumors found by CT and MRI. 67Ga SPECT was especially useful in the assessment of localized lesions in and around the lacrimal gland. In a total of 43 patients studied, the overall accuracy of 67Ga SPECT in diagnosing orbital and ocular lesions was 72%. Sixteen of 21 malignant lesions (76%) showed true positive findings and 15 of 22 benign lesions (68%) showed true negative findings. All seven malignant lymphoma lesions showed true positive findings. One of four cases of malignant melanoma was not visualized. This lesion was less than 15 mm in diameter. None of the three cases of retinoblastoma was visualized, regardless of tumor size. Four of seven cases of pseudotumor or pseudolymphoma showed false positive findings. The differentiation of pseudotumor and pseudolymphoma from malignant lymphoma seemed to be difficult. We conclude that 67Ga SPECT is useful in the differentiation of lesions in the orbital and ocular areas and that evaluation of the extent of malignant lesions can be improved by comparing the findings obtained by morphological diagnostic modalities.

Adult↗
PubMed1993

Regional uptake of iodine-125-metaiodobenzylguanidine in the rat heart.

Regional uptake of iodine-125-metaiodobenzylguanidine ([125I]MIBG) was evaluated in normal (n = 12) and reserpinized (n = 12) rat hearts. At 15 min and 1, 3 and 6 h after injection of [125I]MIBG, tissue activities were calculated for the right ventricular myocardium (RV), the whole left ventricular myocardium (whole LV), the epicardial layer of the left ventricular myocardium (Ep LV), the endocardial layer of the left ventricular myocardium (En LV), the basal segment of the left ventricular myocardium and the apical segment of the left ventricular myocardium. The uptake of [125I]MIBG at 6 h after injection in the normal rat heart was higher in RV than in whole LV (0.45 +/- 0.09% vs 0.30 +/- 0.06% kg dose/g), and in Ep LV than in En LV (0.32 +/- 0.07% vs 0.25 +/- 0.05%). In the reserpinized rat heart, the difference in the uptake between Ep LV and En LV was smaller. This suggests that the difference in the regional [125I]MIBG uptake might reflect different intravesicular uptake in the layers of the heart. To our knowledge, the low uptake in the endocardial layer was a new finding which seems to indicate a difference in innervation between the epicardial and endocardial layers of the left ventricle in the rat heart. Autoradiographic study also showed the low uptake of [125I]MIBG in the endocardial layer, while homogeneous perfusion was observed with thallium-201, supporting the tissue uptake study. Thus, the endocardial and epicardial layers of the left ventricle in the rat heart were considered to be differently innervated.

3-Iodobenzylguanidine↗
PubMed1993

Noninvasive measurements of regional cerebral blood flow using technetium-99m hexamethylpropylene amine oxime.

The previously reported method for quantitative measurements of whole-brain or hemispheric-brain perfusion using technetium-99m hexamethylpropylene amine oxime (HMPAO) radionuclide angiography is now further developed so that regional cerebral blood flow (rCBF) can be measured. Lassen's correction algorithm is used for the linearization of a curve-linear relationship between the radioactivity in the brain and blood flow as seen with single-photon emission tomography (SPET) images. In this algorithm, the cerebral hemisphere was chosen as the reference region and the correction factor alpha was adapted to rCBF in the reference region. This new method of measuring CBF from SPET has been validated in 33 normal subjects and 22 patients with cerebrovascular disease. Regional CBF values in 20 brain regions of the normal subjects were in good agreement with reported values measured by other methods. Regional CBF in the frontal cortex was greater than that in the temporal, parietal or occipital cortex for the entire age range. This hyperfrontal perfusion tended to be less pronounced with advancing age. Seventeen patients with unilateral brain infarction showed significantly lower rCBF than normal subjects. The infarct core showed a low rCBF value of 11.1 ml/100 g/min on average. An increase in rCBF after acetazolamide administration was observed and measured with this method in five patients with unilateral occlusive vascular pathology. These results suggest that this non-invasive method (without any blood sampling) permits the routine measurement of rCBF from HMPAO SPET tomograms of blood flow.

Acetazolamide↗
PubMed1993

Visualization of the thymus with therapeutic doses of radioiodine in patients with thyroid cancer.

Two cases of papillary carcinoma of the thyroid are presented in which whole-body scans following therapeutic doses of iodine-131 revealed intense anterior mediastinal uptake. In both cases, the mediastinal uptake was absent from scans obtained after removal of the entire thymus. Histologically, the resected thymus glands showed hyperplasia and contained neither thyroid tissue nor metastatic foci of thyroid carcinoma. We therefore concluded that anterior mediastinal uptake of radioiodine may be caused by hyperplasia of the thymus.

Adult↗
PubMed1993

SPECT analysis of regional cerebral blood flow changes in patients with schizophrenia during the Wisconsin Card Sorting Test.

Single photon emission computed tomography (SPECT) images were obtained in 10 right-handed neuroleptic-treated schizophrenic patients and 10 healthy volunteers using Tc-99m-hexamethyl-propylenamine oxime (Tc99m-HMPAO) during performance of the Wisconsin Card Sorting Test (WCST) and at rest. None of the patients showed severe impairment on the WCST. The patient group showed a statistically insignificant trend to incur more unique errors. In both the patient and control groups, the left lateral prefrontal blood flow significantly increased during the WCST, as compared to during resting conditions. Only during the WCST, the patient group showed a significant regional cerebral blood flow (rCBF) decline in the left medial prefrontal cortex, as well as in the right side under both the test and resting conditions. This left medial prefrontal rCBF during the WCST correlated positively with the number of unique errors, although this correlation was statistically insignificant. The right fronto-parietal rCBF was significantly increased in the patient group under both the test and resting conditions. Moreover, in the left hippocampal region, the patient group showed a significant rCBF increase under resting conditions.

Adult↗
PubMed1993

High resolution Tc-99m HMPAO SPECT in a patient with transient global amnesia.

This is a report of a patient who underwent high-resolution brain perfusion SPECT studies during and after an episode of transient global amnesia. During the attack, SPECT imaging showed increased perfusion in the left medial temporal region involving the amygdala and hippocampus. After recovery from amnesia, a follow-up SPECT examination showed slightly decreased perfusion in this region. These findings support the hypothesis that transient global amnesia is associated with transient hyperperfusion in the medial temporal brain structures, and confirm the utility of high-resolution SPECT imaging for the evaluation of the fine details of functional brain anatomy.

Adult↗
PubMed1993

Renal perfusion with Tc-99m DTPA--simple noninvasive determination of extraction fraction and plasma flow.

A simple, noninvasive method for the determination of extraction fraction and renal plasma flow in Tc-99m DTPA studies is presented. This method could be performed in conjunction with the measurement of glomerular filtration rate, providing additional information about renal plasma flow. Graphic analysis of the Patlak plot was employed for the determination of the unidirectional influx rate constant (ku) of Tc-99m DTPA from the blood to the kidney and the initial nonspecific distribution volume (Vn) in the kidney. The first pass extraction fraction was estimated from Ku and Vn, assuming a bolus input to the kidney. The glomerular filtration rate was measured by renal counting corrected for depth and dose. Using the estimated extraction fraction (EF) and glomerular filtration rate (GFR), the renal plasma flow (RPF) was calculated using the formula of RPF = GFR/EF. In a total of 76 kidneys in 38 patients (including 9 patients with normal renal function and without evidence of nephrourologic disease), the value of renal plasma flow showed good correlation with that of effective renal plasma flow measured by renal counting with I-131 orthoiodohippuran. There was a characteristic tendency for the extraction fraction to show a larger value as the renal plasma flow decreased. These results indicate that this method is valid for renal plasma flow estimation and the determinations of extraction fraction and renal plasma flow in Tc-99m DTPA studies is helpful as an adjunct to the measurement of glomerular filtration rate in order to adequately assess the pathophysiologic changes of renal disorders.

Adult↗
PubMed1993

Comparative SPECT study of stroke using Tc-99m ECD, I-123 IMP, and Tc-99m HMPAO.

Brain perfusion SPECT imaging using Tc-99m ethyl cysteinate dimer (ECD) was carried out in 12 patients with chronic cerebrovascular disease. The sensitivity of lesion detection and lesion-to-normal tissue contrast was compared with those of I-123 IMP and Tc-99m HMPAO. Eight patients underwent all three studies and the remaining four patients had Tc-99m ECD and I-123 IMP scans. The sensitivity of lesion detection and lesion contrast was analyzed quantitatively using an asymmetric index determined by the equation: 100 x [right - left[/(right + left). In the cerebral cortex, cerebellum, and white matter, I-123 IMP showed higher lesion sensitivity than Tc-99m ECD and Tc-99m HMPAO. In the striatum and thalamus, Tc-99m ECD and I-123 IMP showed higher lesion sensitivity than Tc-99m HMPAO. I-123 IMP showed the highest lesion contrast in cerebral cortex and cerebellum, whereas Tc-99m ECD showed the highest contrast in thalamus and striatum. In all regions, Tc-99m ECD showed higher lesion contrast than Tc-99m HMPAO. These results suggest regional variation in the sensitivity of lesion detection and lesion contrast of Tc-99m ECD compared to I-123 IMP, and the superiority of Tc-99m ECD to Tc-99m HMPAO.

Adult↗
PubMed1993

Intense gallium-67 uptake in ovarian dysgerminoma.

In a patient with an ovarian dysgerminoma, intense uptake of gallium-67 citrate was demonstrated. This report indicates that dysgerminoma should be added to the list showing abnormal accumulation of gallium-67 citrate in the abdomen.

Adolescent↗