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Biomedical subjects

A Muranaka

Publications and source records attributed to A Muranaka.

At least 19 recordsLinked to original sources
PubMed1999

[Development of a simple method for the washout correction of 123I-IMP SPECT and its application to a quantitative rCBF method].

We have developed a simple method to correct the washout of tracer from the brain based on the two-compartment model in brain early SPECT using N-isopropyl-p-[123I]iodoamphetamine (123I-IMP). This correction was applied to a new quantitative method of regional cerebral blood flow (rCBF) in combination with the microsphere method by continuous arterial sampling previously reported. Data acquisition of 123I-IMP early SPECT was started from 35 min after 123I-IMP i.v. injection, and the time activity curve of whole brain on anterior head planar images was monitored immediately after 123I-IMP i.v. injection for the correction of washout of tracer from the brain. The usefulness of this method was evaluated in 12 patients with various brain diseases by comparison with the results obtained from the super-early SPECT at 7-10 min after 123I-IMP i.v. injection. The washout rates in cases of early SPECT corrected by this method ranged from 16.91% to 39.34% with a mean +/- SD of 27.72 +/- 5.44%. The contrast of hypo- to hyperperfusion regions on early SPECT was improved by the correction of the washout, and its intracerebral distribution was similar to the simultaneously obtained super-early SPECT images. These results indicated that the present correction method for the washout was useful for more correct quantification of rCBF.

Brain↗
PubMed1997

[Compartment analysis of 123I-iomazenil brain on early and delayed SPECT].

We investigated the characteristics of 123I-Iomazenil (IMZ) SPECT images in 12 adults (six males and six females, with a mean age of 56.1 years). The washout rate of 123I-IMZ from the brain was estimated from two SPECTs done 15 min and 3 hr after injection. Although the washout was relatively slow, the rates differed in each intracerebral region, suggesting that the distribution of 123I-IMZ was gradually changing. Furthermore, assuming 123I-IMZ kinetics in the brain for the three-compartment, two-parameter model, the transition rate constant (K1) from the blood to the brain and the binding potentials (BP) of benzodiazepine to the receptor were calculated. The BP and K1 values were compared with 123I-IMZ SPECT counts and CBF values by 123I-IMP. The BP values correlated more closely with the counts on the delayed SPECT than those on the early SPECT. It was confirmed that delayed SPECT images reflect better the distribution of the benzodiazepine receptor than early images do. On the other hand, the K1 values correlated highly with CBF obtained by 123I-IMP, and this finding suggested that super-early SPECT images might be remarkably influenced by the distribution of CBF.

Adult↗
PubMed1993

A survey of ciguatera: assessment of Puako, Hawaii, associated with ciguatera toxin epidemics in humans.

A survey for the assessment of the ciguatera problem has been determined in Puako, South Kohala, on the Island of Hawaii. This is in the area of persistent ciguateric outbreaks during the months of January through March, caused by a specific species of fish (Cheilinus rhodochrous, red rose wrasse, or po'ou). Analyses of algae, Gambierdiscus toxicus, and various species of fish, including herbivores and carnivores, gave positive indications of Puako as a potential ciguateric area. Algae associated with Gambierdiscus toxicus blooms and the dinoflagellate itself were found in transects A and D. Transects A and D showed 291 G. toxicus per gram of Tolycarpidia glomurata and 9 G. toxicus per gram of Turbinaria sp. with epiphytic Jania sp., respectively. No G. toxicus was found in transects B and C. This may be attributed to the low salinity from intrusion of freshwater in this vicinity. Examinations of the fish, kole, manini, Hawaiian kole, roi, and po'ou by the solid-phase immunoassay showed 89% of fish in the borderline and positive categories from all transects. Extracts of viscera and flesh showed high levels of toxicity in mouse (13 of 23 deaths), particularly in the viscera (gut) of both herbivores and carnivores. The guinea pig atrial analysis generally showed a few ciguatoxin-like, but most were nonciguateric type responses. The data presented in this Puako survey showed evidence of toxic fish associated with ciguatoxin-like and most probably other toxins, either polyethers or non-polyethers as yet unidentified.

Animals↗
PubMed1992

[A fundamental study of 99mTc-ethyl cysteinate dimer (99mTc-ECD)].

In vitro fundamental studies of 99mTc-ethyl cysteinate dimer (99mTc-ECD), a newly developed radiopharmaceutical for cerebral perfusion scintigraphy, were performed, and were compared with those of 99mTc-HM-PAO, which has been widely applied to clinical use. 99mTc-HM-PAO should not only be injected soon after reconstitution, but also be avoided mixture with saline or drugs such as Diamox, because of its radiochemical purity decreases with the passage of time and the addition of saline and Diamox. On the other hand, the radiochemical purity of 99mTc-ECD reached a constant level of 94-96% at 30 to 180 min after reconstitution, and it remained stable against the addition of saline and Diamox. Therefore, it was suggested that 99mTc-ECD could be injected from an already saline-infused venous-line or mixed with Diamox. However, early injection after reconstitution should be avoided, because 99mTc-ECD did not become stable enough to maintain sufficient radiochemical purity until 30 min after reconstitution. The present studies are suggested that the red blood cell component is largely related to the metabolism of 99mTc-ECD in blood. Furthermore, from study of the metabolic rate using rabbit blood, it was suggested that a species difference existed in esterase activity in blood.

Animals↗
PubMed1992

[Usefulness of 99mTc-ECD SPECT in diseases of the central nerve system: special reference to a comparison with 123I-IMP and 99mTc-HM-PAO SPECT].

The usefulness of a new cerebral perfusion imaging radiopharmaceutical, 99mTc-ethyl cysteinate dimer (ECD), was clinically evaluated. The subjects of this study were 14 patients with neurological disorders including 10 patients with cerebral infarction and 4 patients with other diseases. A total of 15 examinations was performed. 99mTc-HM-PAO or 123I-IMP SPECTs were performed simultaneously, and the findings from those examinations were compared with 99mTc-ECD. As to the count ratio of lesions to normal area (L/N), the L/N ratio in severe ischemic patients was lower in 99mTc-ECD than in 99mTc-HM-PAO or 123I-IMP. In mild ischemic patients, on the other hand, the L/N ratio was the lowest in 123I-IMP. When the relationship between rCBFs obtained from 123I-IMP and the values of L/N in 99mTc-ECD or 99mTc-HM-PAO was compared, the values of L/N in 99mTc-ECD or 99mTc-HM-PAO were found to have decreased linearity with increasing rCBF. In a patient showing luxury perfusion, the accumulation pattern of 99mTc-ECD was different from that of the other two radiopharmaceuticals, and focal defect was revealed in 99mTc-ECD SPECT. On the dynamic SPECT of 99mTc-ECD in a patient with meningioma, the tumor showed a change from high to low perfusion with the passage of time. This finding indicated that care should be taken in the evaluation of accumulation of 99mTc-ECD. Therefore, 99mTc-ECD was found to be useful as a cerebral perfusion agent. In addition, as accumulation of 99mTc-ECD might somehow reflect metabolism in some cases, further careful investigation of many cases should be carried out.

Adult↗
PubMed1989

[A case of Creutzfeldt-Jakob disease followed up by N-isopropyl-[123I]-p-iodoamphetamine and 99mTc-hexamethylpropyleneamine oxime SPECT].

N-isopropyl-[123I]-p-iodoamphetamine (123I-IMP) and 99mTc-hexamethylpropyleneamine oxime (99mTc-HM-PAO) SPECT were performed in a 66 yrs-old female patient with Creutzfeldt-Jakob disease (CJD). The decreased accumulation of both radiopharmaceuticals, which localized initially in the focal regions and progressed eventually to the whole brain, were observed in the early stage of CJD, when no abnormal findings were obtained on X-CT. Although the redistribution of 123I-IMP was recognized in the relatively early stage in which the accumulation was significantly decreased, it disappeared with the progression of the disease. The accumulation of both radiopharmaceuticals which decreased remarkably in the early stage of CJD was sustained in low level during the chronic stage. The accumulation ratio of 99mTc-HM-PAO, after second examinations, to that on first SPECT was lower than those of 123I-IMP. It was suggested, as this cause, that the difference of the accumulation mechanism of both agents might be concerned. Thus, it is interested to follow up a patient with CJD by using 123I-IMP and 99mTc-HM-PAO SPECT, and this modality will provide a useful information to clarify the pathogenesis of CJD.

Aged↗
PubMed1989

[Single photon emission computed tomography by using N-isopropyl-p-[123I]-iodoamphetamine and 99mTc-hexamethyl propyleneamine oxime in a patient with herpes simplex encephalitis].

Single photon emission computed tomographies (SPECTs) by using N-isopropyl-p-[123I-IMP]-iodo-amphetamine (123I-IMP) and 99mTc-hexamethyl propyleneamine oxime (99mTc-HM-PAO) were serially performed in a 70 yrs. old male with herpes simplex encephalitis (HSE), and the chronological changes of accumulations were studied. Accumulations of both 123I-IMP and 99mTc-HM-PAO increased initially, and then decreased with the stage of HSE being advanced. The sequential appearance of the lesion in HSE with 123I-IMP and 99mTc-HM-PAO SPECTs was as same as that reported previously by X-CT; beginning at the temporal lobe with eventually being spread to the occipital and frontal lobe. Furthermore, it was shown that findings of both SPECTs could reflect considerably the clinical features, and the laboratory data in central spinal fluid. Thus, 123I-IMP and 99mTc-HM-PAO SPECTs seemed to be a useful tool in the diagnosis, deciding of whether the treatment was suspended or continued, and clarifying the pathophysiology in HSE.

Aged↗
PubMed1988

[Clinical usefulness of a dual photon absorptiometry system using X-ray for peripheral bone--comparison with a single photon absorptiometric system].

A newly developed dual photon absorptiometry system (DCS-600, ALOKA Co., LTD.) using two monochromatic X-rays for the determination of bone mineral in the peripheral bone was fundamentally studied, in comparison to single photon absorptiometry system (SPA). The accuracy and precision in DCS-600 were equal to or better than SPA system. Furthermore, in DCS-600 the forearm could be imaged, and the manipulation was easy. Thus DCS-600 was found to be a good instrument as a quantifying system of bone mass.

Bone and Bones↗