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K Torizuka

Publications and source records attributed to K Torizuka.

At least 19 recordsLinked to original sources
PubMed1992

[Phase I clinical study of 99mTc-ECD].

A phase I clinical study of 99mTc-L,L-ethyl cysteinate dimer (99mTc-ECD) was carried out in 3 normal volunteers. There was no significant change in vital signs and laboratory parameters attributing to the radiopharmaceutical. 99mTc-ECD was rapidly taken up by the brain, reaching the maximum peak activity within 1 min after the injection and remained relatively constant over several hours. The brain uptake of 99mTc-ECD at 5 min was 5.4 +/- 0.5% which decreased to 5.0 +/- 0.3% by 65 min. 99mTc-ECD cleared rapidly from other organs. The primary excretion route was through the kidneys. Cumulative 99mTc activity in the urine at 90 min and 24 hr were 60.2 +/- 7.3% and 88.5 +/- 10.3%, respectively. The critical organ was the bladder wall with an estimated radiation dose of 0.073 mGy/MBq, which was acceptable value. Clear SPECT images were obtained at 30, 90 and 150 min postinjection. In conclusion, 99mTc-ECD is a safe and promising radiopharmaceutical for the evaluation of regional cerebral blood flow.

Adult↗
PubMed1992

[Phase 2 clinical study of 99mTc-ECD--a multicenter study].

A phase 2 clinical study of a newly developed brain perfusion agent, 99mTc-ECD, was performed in 166 cases of cerebrovascular diseases and impairment of brain function to evaluate effectiveness, usefulness, optimum dose and optimum timing of imaging as a multi-center study involving 10 institutions in Japan. All cases were judged as no problems on safety and any side effects due to the administration of the compound were not observed. Out of 163 cases evaluated for the clinical usefulness, valuable information for clinical diagnosis was obtained in 160 cases (98.3%), and 154 cases (94.5%) were judged as "extremely useful" or "useful". Although SPECT imaging was possible from 5 min after injection, images obtained between 60 and 90 min after injection showed relatively better image quality in many cases. Regarding standard administration dose, 400 to 800 MBq were considered to be appropriate. 99mTc-ECD is considered to be a promising radiopharmaceutical as a brain perfusion agent.

Adolescent↗
PubMed1992

[Metabolite of 15-p-iodophenyl-3(R,S)-pentadecanoic acid (123I) in blood and urine].

We analyzed metabolites of 123I-BMIPP in blood and urine using rats, rabbits and human, while human samples were obtained from normal volunteers of Phase I clinical study. We estimated metabolic pathway of 123I-BMIPP as a myocardial metabolic imaging agent. Radioactivity accumulated in heart after administration gradually decreased and was mainly excreted to bladder via kidneys. The main radioactive component in blood was 123I-PIPA for any species and the urinary components were metabolic conjugates of 123I-PIPA. As results of these studies, we considered that 123I-BMIPP was metabolized to 123I-PIPA by alpha-oxidation process for the first step, follow by beta-oxidation process, then 123I-PIPA was released to blood from tissues. Moreover, 123I-PIPA in blood was conjugated with other compounds and excreted to the bladder.

Animals↗
PubMed1992

[Phase III multi-center clinical study on 99mTc-GSA, a new agent for functional imaging of the liver].

A multi-center clinical study was performed in patients with hepatic disorders to evaluate the clinical usefulness of 99mTc-DTPA-galactosyl serum albumin (99mTc-GSA), a new radiopharmaceutical which binds to asialoglycoprotein receptors on hepatocytes. The blood clearance and hepatic accumulation were evaluated on the basis of the dynamic data and serial hepatic images obtained for 20 min after 99mTc-GSA injection. The blood clearance and hepatic accumulation indices of 99mTc-GSA demonstrated the followings. 1) In acute liver diseases, these indices reflected the clinical features of the disease and correlated with the laboratory test indices for the blood coagulation system. 2) In chronic liver diseases, these indices changed in direct proportion to the progression of the hepatic disorder and correlated well with the conventional laboratory test results. 3) In obstructive jaundice, these indices aided evaluation of the liver function despite the high serum bilirubin level. 4) The indices reflected the change in the number of hepatocytes before and after hepatectomy. The scintigraphic findings with 99mTc-GSA permitted both functional and morphological evaluations of the liver and provide additional information compared with conventional liver scintigraphy. These results suggest that 99mTc-GSA scintigraphy may be useful for evaluating both the function and morphology of the liver from a new viewpoint of receptor-mediated accumulation.

Drug Evaluation↗
PubMed1992

[Phase II clinical study on 99mTc-GSA, a new agent for functional imaging of the liver].

Phase II study of 99mTc-DTPA-galactosyl human serum albumin (99mTc-GSA), a new radiopharmaceutical which binds to the asialoglycoprotein receptors on the hepatocytes, was performed in 81 patients with liver diseases to validate its safety and possibility for the evaluation of hepatic function. None of adverse reactions, abnormal clinical laboratory findings and anti-99mTc-GSA antibody production due to 99mTc-GSA was recognized. Immediately after the injection of 99mTc-GSA, the dynamic data and serial hepatic images were obtained for 60 min. The indices for blood clearance and liver accumulation were calculated based on the counts in the regions of interest on the hearts and livers. In 54 patients with chronic hepatic disorders such as liver cirrhosis, the blood clearance and liver accumulation of 99mTc-GSA were retarded according to the progress of the hepatic disorders. The findings of 99mTc-GSA scintigraphy also reflected the hepatic functions of the patients with large hepatic tumors, obstructive jaundice and acute hepatitis. These results suggest that 99mTc-GSA has the clinical potentials to evaluate the liver functions in the patients with hepatic disorders.

Adult↗
PubMed1992

[Phase 2 study of beta-methyl-p-(123I)-iodophenyl-pentadecanoic acid, a myocardial imaging agent for evaluating myocardial fatty acid metabolism].

A phase 2 study of beta-methyl-p-(123I)-iodophenyl-pentadecanoic acid (123I-BMIPP), a myocardial imaging agent developed for evaluating myocardial fatty acid metabolism, was performed in 197 patients with various heart diseases. The myocardial distribution of 123I-BMIPP did not change from early to late images in 88% of 91 patients with ischemic heart disease (IHD), while washout and/or fill-in were observed in 45% of 55 patients with hypertrophic cardiomyopathy (HCM). In comparison with 201Tl in 165 patients with various heart diseases, the decrease in uptake was more profound with BMIPP in 56% and with 201Tl in only 4%. 123I-BMIPP showed more severely decreased uptake in 83% of the patients with subacute myocardial infarction (15 to 30 days after the onset) and in 73% of the patients with HCM. High-quality SPECT images were obtained with 123I-BMIPP in 93% of 194 patients analyzed. However, the image quality in cardiomyopathy was inferior to that in IHD. The optimal injection dose range and standard dose of 123I-BMIPP were considered to be 74-148 MBq and 111 MBq, respectively. These findings suggest that 123I-BMIPP myocardial imaging is safe and useful for evaluating myocardial fatty acid metabolism in various heart diseases.

Adolescent↗
PubMed1992

[Phase 3 study of beta-methyl-p-(123I)-iodophenyl-pentadecanoic acid, a myocardial imaging agent for evaluating fatty acid metabolism--a multi-center trial].

A multi-center trial of beta-methyl-p-(123I)-iodophenyl-pentadecanoic acid (123I-BMIPP) was performed to assess its clinical usefulness in the evaluation of myocardial fatty acid metabolism in 587 patients with various heart diseases. 123I-BMIPP showed relatively decreased uptake compared with 201Tl in the myocardial lesions of 62% of patients with ischemic heart disease (IHD), 39% of those with cardiomyopathy and 32% of those with other heart diseases. In case of myocardial infarction, less uptake of 123I-BMIPP (Type B) than 201Tl was more frequently seen in patients with successful recanalization than in those without recanalization. The patients with matched distribution of the two tracers (Type E) increased in the direct proportion to the interval between the onset of myocardial infarction and the radionuclide studies. The uptake of 123I-BMIPP correlated well with myocardial viability evaluated by 201Tl exercise-redistribution studies. Type B was frequently seen in the areas with 201Tl redistribution, while Type E was seen in the fixed defect areas. In the other heart diseases studied, Type E was observed in approximately 60% of patients with dilated or secondary cardiomyopathies. Type B was seen in about 45% of patients with valvular heart diseases and myocarditis. Various types of mismatch between the two tracers were demonstrated in hypertrophic cardiomyopathy and hypertensive heart disease. It is concluded that 123I-BMIPP is a safe and useful agent for the diagnosis of various heart diseases, since it reflects myocardial fatty acid metabolism.

Adolescent↗
PubMed1991

[Clinical trial of color-hybrid images for assessment of Gd-DTPA contrast enhancement].

Gd-DTPA (Gd) has been shown to provide effective contrast enhancement in MR imaging. However, it is sometimes impossible to evaluate Gd contrast enhancement (C.E.) in high intensity tissues like fat and bone marrow. To solve this problem, color-hybrid images (hybrid images) were generated by the use of an RGB mixing method. A total of 54 lesions, including 30 bone and soft tissue lesions and 24 gynecological lesions, were studied. In most cases, the hybrid images were superior to the original ones in terms of both morphologic and temporal evaluation of Gd C.E. The hybrid images helped to define the localization and extent C.E., by providing better visualization through the use of color display.

Adult↗
PubMed1991

Functional hepatic imaging with receptor-binding radiopharmaceutical: clinical potential as a measure of functioning hepatocyte mass.

Asialoglycoprotein receptor (ASGP-R) is a hepatic cell surface receptor specific for galactose-terminated glycoproteins. Technetium-99m diethylenetriaminepentaacetic acid-galactosyl human serum albumin (TcGSA) is a newly developed analog ligand to ASGP-R. Fourteen human subjects were studied: three normal volunteers, one with chronic hepatitis, 6 with liver cirrhosis, and 4 with hepatocellular carcinoma associated with liver cirrhosis. The receptor index parameter (LHL15), was obtained from the liver and heart time-activity data as the ratio of radioactivity of the liver over that of the liver plus heart at 15 min after intravenous injection of 1 mg of TcGSA. Means +/- standard deviations of LHL15 in normal volunteers (3 cases), patients with mild (4 cases), moderate (2 cases), and severe liver damage (5 cases) were 0.933 +/- 0.006, 0.789 +/- 0.045, 0.723 +/- 0.033, and 0.488 +/- 0.094, respectively. The difference between the mean values of each group was statistically significant (P less than 0.05). LHL15 correlated well with classical indicators for hepatic functional capacity such as serum albumin level, serum bilirubin level, prothrombin time, ICG R15 or Child-Turcotte criteria score. Our preliminary experiences of high correlations of TcGSA functional imaging data with clinical data suggest that the dynamic data using this receptor-binding radiopharmaceutical provides invaluable information with regard to liver function, and thus, the TcGSA study is potentially a noninvasive practical tool to measure functioning hepatocyte mass.

Asialoglycoprotein Receptor↗
PubMed1991

[Phase I clinical study on 99mTc-GSA, a new agent for functional imaging of the liver].

Technetium-99m-DTPA-galactosyl human serum albumin (99mTc-GSA) is a new radiopharmaceutical which binds to the asialoglycoprotein receptors located specifically on the hepatocytes. Phase I study of 99mTc-GSA was performed on seven normal volunteers, who were intravenously injected with 185 MBq (5 mCi) and 1-10 mg of 99mTc-GSA. None of adverse reactions, abnormal findings of laboratory test and anti-99mTc-GSA antibody production was recognized. The livers were clearly visualized in all subjects. In the pharmacokinetic analyses on five subjects, 99mTc-GSA was rapidly taken up by the livers immediately after the injection and was slowly excreted through the biliary tracts and the urinary tracts. Dose-dependency which is a specific feature for the receptor-mediated agents was observed; the blood clearances of 99mTc-GSA were prolonged in proportion to the injected ligand doses. These results suggest that 99mTc-GSA may be a potential agent for evaluating hepatic functions based on the hepatic receptor quantities.

Adult↗
PubMed1991

[Clinical evaluation of 99mTc-hexakis 2-methoxy isobutyl isonitrile (MIBI): multicenter phase III clinical trial].

Multicenter Phase III clinical trial on a new myocardial imaging agent, 99mTc-hexakis 2-methoxy isobutyl isonitrile (99mTc-MIBI), was carried out in 464 patients with various cardiac disorders. Both planar and tomographic images provided high-quality regional myocardial perfusion images which correlated well with 201TlCl images. The positive ratios of myocardial infarction and angina pectoris by the agent were as high as that of 201TlCl. In addition, ventricular function and wall motion could be assessed with first-pass and ECG gated studies. There was no serious adverse reaction which were attributed to 99mTc-MIBI in any of patients studied. A transient metallic taste was observed immediately after the injection in approximately 64% of the patients. Based on its safety and efficacy, the clinical usefulness of 99mTc-MIBI was observed in 562 (93.1%) of 604 injections. In conclusion, 99mTc-MIBI was useful as a imaging agent of myocardial blood flow.

Adolescent↗
PubMed1991

[Phase I clinical study on 99mTc-MIBI].

A phase I clinical study on 99mTc-hexakis 2-methoxy isobutylisonitrile (99mTc-MIBI) was carried out in 6 normal volunteers. There was no significant change in vital signs and laboratory parameters attributing to the reagent other than complaint of slight and transient metallic taste immediately after the injection in 4 volunteers. The highest dosimetry was calculated as 1.1 mGy/37 MBq at lower large intestine, which was within the acceptable range. 99mTc-MIBI was rapidly cleared from the blood and accumulated in the heart immediately after the injection with 1.4% dose and 1.8% dose at 5 min at rest and at stress, respectively. The retention of radioactivity in the heart well continued for at least several hours. The heart-to-lung ratio was over 2.00 at 5 min and heart-to-liver ratio was over 1.00 at 60 min. Myocardial planar and SPECT images were obtained with high quality. In conclusion, 99mTc-MIBI is a useful myocardial perfusion imaging agent.

Adult↗
PubMed1991

[A Phase 1 study of beta-methyl-p-(123I)-iodophenyl-pentadecanoic acid (123I-BMIPP)].

Phase 1 study of beta-methyl-p-(123I)-iodophenylpentadecanoic acid (123I-BMIPP), a new radiopharmaceutical developed for the evaluation of myocardial fatty acid metabolism, was performed in six normal volunteers to evaluate its biodistribution and safety. After intravenous injection of 111 MBq of 123I-BMIPP, the agent accumulated to the myocardium rapidly (5.4 +/- 0.6% at 1.5 hr after injection) and was washed-out slowly (5.1 +/- 0.4% at 3.0hr). 123I-BMIPP demonstrated no significant accumulation to any specific organs other than myocardium, liver and muscle. Myocardium was clearly visualized in the planar and SPECT images obtained 30 min and 3 hrs after injection. The absorption doses from 123I-BMIPP estimated by MIRD method were lower than those from 201Tl in all organs. Neither adverse reactions nor abnormal clinical laboratory findings were found in the safety evaluation. These results suggest 123I-BMIPP is a promising agent for evaluating myocardial fatty acid metabolism.

Adult↗
PubMed1989

Glucose metabolism and rate constants in Alzheimer's disease examined with dynamic positron emission tomography scan.

Glucose metabolic rate constants in patients with Alzheimer's disease were analyzed using dynamic positron emission tomography with [18-F] fluoro-2-deoxyglucose (FDG). The cerebral metabolic rate of glucose (CMRG) was calculated using obtained rate constants, as well as the autoradiographic method. The half-life and distribution volume of FDG between the blood and the brain tissue were also calculated from obtained metabolic rate constants. The most severely affected metabolic step was the phosphorylation of glucose in the parietotemporal regions. The distribution volume of FDG showed no remarkable deviation from normal controls, while the half-life of FDG was found to be longer in the parietal and temporal regions. The CMRG from rate constants and that from the autoradiographic method showed no remarkable differences.

Alzheimer Disease↗
PubMed1989

Value of stress thallium-201 emission tomography for predicting improvement after coronary bypass grafting and assessing graft patency.

To examine the value of stress and redistribution thallium-201 single photon emission computed tomography (SPECT) for predicting improvement after coronary artery bypass grafting (CABG) and for assessing graft patency, 17 patients underwent SPECT before and after CABG. Preoperatively, 16 patients (94%) showed reversible ischemia with redistribution, and defect score decreased from 16.4 +/- 7.6 to 8.3 +/- 5.8 (p less than 0.001) on 2 hour delayed images. Stress electrocardiography was positive in 15 cases (88%). The stress defect score was reduced postoperatively (7.8 +/- 6.3) as compared to the preoperative score (16.4 +/- 7.6) (p less than 0.001). Postoperatively, 7 cases (41%) showed reversible ischemia and the defect score decreased from 11.3 +/- 6.5 to 6.1 +/- 4.7 (p less than 0.05), while 4 cases (23.5%) showed positive stress electrocardiograms (ECG). Resting left ventricular (LV) ejection fraction (EF) improved in 6 cases (48.3 +/- 5.4% preoperatively to 56.8 +/- 7.4% postoperatively, p less than 0.05) and showed a reduction in 11 (58.2 +/- 10.5% to 47.5 +/- 9.4%, p less than 0.01). Grafts were occluded in 6 cases, and redistribution was evident on the delayed thallium images in all cases (100%), while stress ECG was positive in only 3 (50%). Thus, stress and redistribution SPECT is valuable for identifying patients who will improve after surgery and assessing graft patency more accurately than stress ECG. Resting LVEF was less useful for assessing improvement in LV function.

Adult↗
PubMed1989

[Study on determination of the imaginary axis of the tooth crown in anterior teeth: 1].

1. The state of inclination and the change under various conditions of the imaginary axis of the tooth crown of upper jaw anterior teeth can be determined by the image measuring system and method of this study. 2. The measurement error of this system was not more than 0.3 degree. This value was sufficient for the purpose of this study. 3. The imaginary axis of the tooth crown of anterior teeth was determined on the study cast with 1 to 3 degrees in mesiodistal direction and 2 to 4 degrees in labiopalatal direction as standard deviation. 4. The imaginary axis of the tooth crown of anterior teeth was determined toward labial in the random position and toward patient's right and palatal in Standing Posture. 5. It was confirmed that the determination of the imaginary axis of tooth crown was effected by the position of the patient relative to the operator, limitation or direction of view, and approach direction.

Humans↗
PubMed1989

[Study on determination of the imaginary axis of the tooth crown. 1. Measuring procedure].

The state of inclination and the change under various conditions of the imaginary axis of the tooth crown of upper jaw and lower jaw right and left first molar can be determined by the measuring apparatus and method of this study. 2. The measurement error of this method was not more than 0.1 degree. This value was sufficient for the purpose of this study.

Molar↗