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Biomedical subjects

H Toyama

Publications and source records attributed to H Toyama.

At least 145 records · Page 8Linked to original sources
PubMed1989

[The relationship between N-isopropyl-p-[123I]iodoamphetamine accumulation in the brain and its dynamics in other organs].

Single photon emission computed tomography of the brain and dynamic scintigraphy of the lung and liver with N-isopropyl-p-[123I]iodoamphetamine (IMP) were performed in 21 patients with and without cerebrovascular diseases to determine the relationship between IMP accumulation in the brain and its dynamics in other organs. The D/E ratios of the lung, liver and brain were calculated dividing the counts of the delayed image by that of the early image. The brain D/E ratio in the normal hemisphere was well correlated with the lung D/E ratio. So cases which showed more rapid lung washout tended to washout faster from the brain. We thought that this fact was affected by the systemic circulation. And the values of the brain D/E ratio of the cerebrovascular disease group were larger than that of the non-cerebrovascular disease group. This suggest the frequent existence of arteriosclerotic changes in patients of the cerebrovascular disease. Because the local brain washout was depended on the amount of the cerebral blood flow there. On the other hand, the lung D/E ratio was inversely correlated with the liver D/E ratio. In other words, more washout from the lung caused more accumulation of IMP in the liver. Also the brain D/E ratio was inversely correlated with the liver D/E ratio. In conclusion, there was a close relationship between IMP dynamics in the brain and that in other organs.

Adolescent↗
PubMed1989

[Crossed cerebellar diaschisis in hydrocephalus--a case report].

A case of hydrocephalus in which a crossed cerebellar diaschisis with single photon emission CT (SPECT) using 123I-iodoamphetamine (123I-IMP) disappeared by a ventriculo-peritoneal shunting operation, was reported. A 54-year-old female had a clipping surgery for a aneurysm of the left middle cerebral artery on April 9, 1987. Post-operatively, she had a transient mild aphasia. Cerebral blood flow (CBF) study with 123I-IMP-SPECT had showed low perfusion in the left frontal and temporal lobe. But after a month, clinical symptom and CBF findings had improved. She had been doing well after the discharge until October, 1987, when she developed disorientation. CT on re-admission showed the ventricular dilatation with periventricular low density (left greater than right). 123I-IMP-SPECT study showed the crossed cerebellar diaschisis which was a low perfusion in the left frontal, temporal, parietal, thalamus, basal ganglionic area and in the opposite cerebellum. A ventriculo-peritoneal shunting operation was performed which brought the disappearance of the crossed cerebellar diaschisis and the clinical improvement. The phenomenon of crossed cerebellar diaschisis has been reported in a lot of literatures. However, those diseases were located in unilateral supratentorium. It has been speculated that crossed cerebellar diaschisis is the transneural metabolic change through the cortico-ponto-cerebellar pathway by supratentorial lesion. Crossed cerebellar diaschisis in hydrocephalus has not been reported so far.(ABSTRACT TRUNCATED AT 250 WORDS)

Amphetamines↗
PubMed1989

[Evaluation of cerebral hemodynamics by 123I-IMP in cerebral AVMs before and after operation by using SPECT].

To evaluate cerebral hemodynamics by N-isopropyl-p-[123I]-iodoamphetamine (123I-IMP) preoperative and postoperative (after 1 day, and after 7-10 days) regional cerebral blood flow scan, 6 arteriovenous malformations (AVMs) which performed total removal operations were studied by using a ring type SPECT "HEADTOME". We performed the dynamic scan just after the intravenous injection of 222 MBq (6 mCi) of 123I-IMP, then the static scan 20 minutes after the intravenous injection. In preoperative dynamic scans of all cases, only the first frame image showed the increased activity on the nidus probably because of the blood pool. Preoperative static scans of all cases showed the remarkable decreased activity on the nidus, and decreased activity surrounding the nidus probably because of the peripheral steal phenomenon. In postoperative scan of the next day, 4 out of 6 cases showed the transient decreased peripheral steal, particularly 2 out of those 4 cases showed the transient hyperperfusion probably because of the normal perfusion pressure breakthrough (NPPB). And, 2 out of 6 cases showed transient peripheral low perfusion on much larger area than those of the preoperative scans probably because of the focal brain damages and edemas. We conclude that 123I-IMP SPECT on AVM is very useful to decide the indication of the removal operation, and to estimate the postoperative risk, and to evaluate the preoperative and postoperative cerebral hemodynamic changes in the peripheral area of AVM.

Adolescent↗
PubMed1989

[SPECT measurement of cerebral hemodynamics in transient ischemic attack patients--evaluation of pathogenesis and detection of misery perfusion].

To evaluate the cerebral hemodynamics and the pathogenesis by regional cerebral blood flow (rCBF) and regional cerebral blood volume (rCBV), 42 transient ischemic attack (TIA) patients and 9 normal volunteers were studied using SPECT. We classified these patients into Group A (n = 23: no occlusion or stenosis of the internal carotid or middle cerebral artery; non large vessel disease) and Group B (n = 19: chronic occlusion or severe stenosis of the internal carotid or middle cerebral artery; large vessel disease). We obtained rCBF with 133Xe inhalation and rCBV with 99mTc-red blood cells. Of 9 normal volunteers aged 43-70 yr (mean age 59.8 +/- 8.3 yr), the mean rCBF was 45.8 +/- 5.1 (ml/100 g brain/min), the mean rCBV was 4.0 +/- 0.4 (ml/100 g brain). The examination was done by comparing the values of the affected hemispheres of Group A and Group B patients with the mean rCBF and the mean rCBV of normal volunteers. Eleven out of Group A patients and 15 out of Group B patients showed decreased rCBF. But of those patients, no patients of Group A showed increased rCBV and 6 out of 19 Group B patients showed increased rCBV. Thromboembolic mechanism which is of Group A patients and Group B patients without increased rCBV, and hemodynamic mechanism which is of Group B patients with increased rCBV were considered as the main cause of TIA. Decreased rCBF and increased rCBV in Group B patients can be assumed as the misery perfusion as reported in PET studies.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Isoproterenol stress thallium scintigraphy for detecting coronary artery disease.

The value of exercise thallium scintigraphy in detecting coronary artery disease is well established. However, there are at times situations in which the exercise test cannot be readily used. Isoproterenol (ISP) stress ECG (ISP-ECG) is reportedly a useful method in diagnosing coronary artery disease. In the present study, we assessed the diagnostic value of ISP thallium scintigraphy, comparing it with those of ISP-ECG and exercise thallium scintigraphy. The study population consisted of 24 patients who had histories of chest pain without previous myocardial infarction. ISP was given at increasing doses of 0.02, 0.04, 0.08 micrograms/kg/min at 3-minute intervals, and was terminated for any of the following reasons: angina, significant arrhythmia, significant ST segment depression (greater than or equal to 0.1 mV) or target heart rate. Thallium scintigrams were obtained immediately after terminating ISP infusion, and after a 3-hour delay, redistribution scans were obtained. Scintigrams were considered positive when a reversible defect was present. In nine patients who underwent exercise tests, exercise thallium scintigraphy was also performed. After the stress tests, coronary angiography was performed. According to the presence or absence of significant coronary artery stenosis (greater than or equal to 75%), all subjects were divided into two groups: coronary artery disease (CAD) group (n = 12) and so-called normal coronary (NC) group (n = 12). 1. Among 12 patients in the CAD group, ISP induced anginal pain in six (50%), and ISP-ECG and ISP thallium scintigraphy were positive in 10 (83%) and in 11 (92%), compared with four (33%), four (33%) and two (17%) in the NC group.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1989

[Clinical usefulness of physiologic components obtained by factor analysis--application to 99mTc-DTPA renography].

The clinical usefulness of physiological components obtained by factor analysis was assessed in 99mTc-DTPA renography. Using definite physiological components, another dynamic data could be analyzed. In this paper, the dynamic renal function after ESWL (Extracorporeal Shock Wave Lithotripsy) treatment was examined using physiological components in the kidney before ESWL and/or a normal kidney. We could easily evaluate the change of renal functions by this method. The usefulness of a new analysis using physiological components was summarized as follows: 1) The change of a dynamic function could be assessed in quantity as that of the contribution ratio. 2) The change of a sick condition could be morphologically evaluated as that of the functional image.

Adult↗
PubMed1989

[Bone dynamic study--evaluation for factor analysis of hip joint].

Factor analysis was applied to dynamic study of Tc-99m MDP for the evaluation of hip joint disorders. Fifteen patients were examined; eight were normal, six were osteoarthritis in which one accompanied synovitis was included, and one was aseptic necrosis on the head of the femur. In normals, according to the Tc-99m MDP kinetics, three factor images and time-activity curves were obtained which were named as blood vessel, soft tissue, and bone factor images and curves. In the patient with osteoarthritis, increased accumulation of the hip joint was shown in bone factor image only. But in one patient, who took osteoarthritis with synovitis, marked accumulations of the Tc-99m MDP appeared not only on the bone factor image but also on the soft tissue. Operation revealed thickening synovial tissue around the hip joint, caused by inflammatory process. In follow-up studies of the patient with aseptic necrosis on the head of the left femur, excessive accumulations, which were seemed in his left hip joint on both bone and soft tissue factor images at first, were decreased respondently to the treatment of this lesion. In conclusion, the factor analysis was useful for differencial diagnosis of the hip joint disorders and observation of the clinical course of the hip joint disorders.

Adult↗
PubMed1989

[Development of a new quantitative analysis for thallium myocardial SPECT images--quantitative STEREO-VIEW method and evaluation of its clinical usefulness].

We have developed a three-dimensional quantitative display method, Quantitative STEREO-VIEW method (STEREO-VIEW method), for analysis of thallium (Tl) myocardial SPECT images and have evaluated its clinical usefulness. SPECT data were obtained immediately and 4 hours after the exercise, and contour lines for outer edges of left ventricular (LV) myocardium were detected from 10 slices of short axial images in delayed scan. LV wall was divided into 510 segments by dividing each slice into 51 sectors and LV myocardium was three-dimensionally reconstructed. Mean Tl counts, %T1 uptake and washout rate (WR) of each segment were calculated and these values were represented such as infarcted area display, redistribution display and WR display on STEREO-VIEW. Furthermore, extent index (EI), severity index (SI) and intensity index (II) were defined to express the degree of perfusion abnormality using WR value of each segment. In the 25 patients with coronary revascularization, improving rate of these indices correlated well with that of double product significantly. STEREO-VIEW method resembled in the original shape of left ventricle of each patient, so STEREO-VIEW method has made it easier to discriminate the accurate extent of ischemic lesion. In addition, EI, SI and II using WR were good indices for coronary perfusion and these were thought to be useful on clinical study.

Aged↗
PubMed1988

Analysis of thallium-201 myocardial SPECT images using fuzzy set theory.

Using the fuzzy set theory, a method was developed for analyzing the extent and severity of ischemia by comparing the exercise and delayed SPECT images with Thallium-201. For each short axial image (slice) for exercise and delayed study, a defect probability matrix (DPM) is created so that it shows the severity of ischemia of myocardium in that slice. Each slice is divided into 8 equi-angle sectors, and the left ventricle (LV) also is divided into 8 equi-angle vertical sectors from apex to base. Using DPMs, the defect probability is calculated for each slice, sectors of each slice and vertical sectors of the LV. The results are displayed on a CRT by means of images, curves and histograms. They show what percentage of the area of each slice and that of the lateral, anterior, septum and inferior portions have how much defect. They provide comprehensive and easily understood information about the condition of the LV in exercise and delayed stages. Persistent and transient ischemia can be diagnosed by visual comparison of patients' curves and histograms with their corresponding normal limits.

Coronary Disease↗
PubMed1988

[Evaluation of the system performance and clinical images of the single photon emission computed tomography for head using ring arranged detector].

To evaluate the system performance, several preoperational fundamental tests of single photon emission computed tomography (SPECT) were carried out. Spatial resolutions (FWHM) measured with the point-spread functions of a 99mTc line source were 12.5 mm with a high resolution (HR) collimator and 17.2 mm with a high sensitivity (HS) collimator respectively. Slice thicknesses (FWHM) obtained from the profile curves of slice images were 17.5 mm (HR) and 29.0 mm (HS) at the center of rotation. System sensitivities were 5.4 kcps/slice (HR) and 27.8 kcps/slice (HS). Uniformities calculated from the SPECT images of a pool phantom were 4.7% (HR) and 2.7% (HS) at the condition of 3,000 kcounts to be acquired. SPECT images of the HEADTOME SET-031 were considered very useful to diagnose the cerebrovascular disease.

Brain↗
PubMed1987

[99mTc-DMSA renal uptake in urological diseases measured from renal tomographic images using single photon emission computed tomography (SPECT)].

To determine renal function, 99mTc-DMSA renal uptake was measured from renal tomographic images obtained by single photon emission computed tomography (SPECT). A total of 77 tests was conducted on 73 patients with various diseases in the kidneys and urinary tract to determine renal uptake. The correlation coefficient(r) between total renal volume and total renal uptake was 0.3509 and that between renal volume and uptake of 143 kidneys was 0.5433. In 62 patients whose creatinine clearance could be measured, the correlation coefficient between creatinine clearance and total renal volume was 0.2352, and that between creatinine clearance and total renal uptake was 0.8854, that is, creatinine clearance correlated well with renal uptake. Renal volume and uptake determined in 10 normal male and 10 normal female adults were 220 ml and 26.8% for the right kidney and 239 ml and 27.6% for the left kidney for the males and 206 ml and 26.4% (right) and 237 ml and 27.9% (left) for the females. This method, which requires no blood or urine collection, is very useful as an individual kidney function test to evaluate individual kidney function and to understand kidney function before and after operation in patients with renal and urinary diseases.

Adolescent↗
PubMed1987

Evaluation of regurgitant fraction of the left ventricle by gated cardiac blood-pool scanning using SPECT.

Regurgitant fraction (RF) of patients with and without mitral regurgitation (MR) and/or aortic regurgitation (AR) was evaluated by gated cardiac blood-pool scanning using single photon emission computed tomography (SPECT). Using the stroke count image of a short-axis tomogram to separate the right atrium and ventricle, the left ventricular stroke count (LVSC) and right ventricular stroke count (RVSC) were determined. The RF equaled (LVSC - RVSC)/LVSC. Calculated RF in 14 subjects without significant regurgitation by contrast angiography was 5.8 +/- 5.9% (mean +/- s.d.), RF of 17 cases with angiographic regurgitation was 42.5 +/- 16.8% (p less than 0.001). The sensitivity of the radionuclide method compared to angiography was 94% (16/17 cases), and specificity was 100% (14/14 cases). RF of mild Re (1+ or 2+) was 26.0 +/- 8.9% (n = 6) and RF of severe Re (3+ or 4+) was 51.5 +/- 12.7% (n = 11) (p less than 0.001). Correlation between the RF determined with the radionuclide method and with cardiac catheterization was good (y = 5.85 + 0.700 x, r = 0.821, n = 17). We conclude that RF of MR and/or AR can be accurately evaluated by gated cardiac blood-pool scanning using SPECT.

Cardiac Catheterization↗