Biomedical subjects

A Inugami

Publications and source records attributed to A Inugami.

At least 37 records · Page 2Linked to original sources

PubMed1995

Evaluation of cerebral infarction with iodine 123-iomazenil SPECT.

UNLABELLED: This study evaluates ischemic damage to central benzodiazepine (BZD) receptor binding in the brain with [123]iomazenil SPECT in relation to CT hypodense lesions and blood flow abnormalities. METHODS: Nine patients with middle cerebral artery territory infarction were studied. Iomazenil images obtained 180 min postinjection were analyzed for BZD receptor binding. The cortical infraction, visualized as CT hypodense area on CT, the peri-infarct area, visualized as normodensity surrounding the infarction on CT, the intrahemispheric remote area and the cerebellum were analyzed by taking the ratio of the lesion to contralateral mirror region (L/C ratio). CT during the chronic stage and perfusion images obtained during the smallest time difference between the two studies were used for comparative analysis. RESULTS: The mean L/C ratio of iomazenil uptake was 0.53 +/_ 0.08, 0.79 +/- 0.07, 0.98 +/- 0.03 and 1.00 +/- 0.04 in the infarct, peri-infarct and remote areas and the cerebellum, respectively. The infarct and peri-infarct areas showed significant decrease compared with unity. The corresponding mean L/C ratio for blood flow was 0.52 +/- 0.08, 0.73 +/- 0.07, 0.83 +/- 0.09, and 0.80 +/- 0.07, respectively. In all areas, the ratios were significantly decreased compared with unity. There was significant difference between the L/C ratio for blood flow and iomazenil in the remote area and the cerebellum. CONCLUSION: Iodine-123-iomazenil SPECT imaging may provide new information on ischemic damage to the brain, particularly neurons.

Aphasia, Broca↗

PubMed1995

Carbon-11-methionine PET evaluation of intracerebral hematoma: distinguishing neoplastic from non-neoplastic hematoma.

UNLABELLED: We evaluated whether PET with L-methyl-11C-methionine (11C-methionine) was clinically useful in distinguishing neoplastic from non-neoplastic intracerebral hematoma. METHODS: We examined eight patients with neoplastic (n = 4) or non-neoplastic (n = 4) intracerebral hematomas between 5 and 68 days after the bleeding episode using PET with 11C-methionine (Met-PET). RESULTS: Carbon-11-methionine accumulated in the area surrounding the hematoma in both groups, except in one patient with an acute hypertensive hematoma. Between 22 and 45 days after the ictus, non-neoplastic hematomas showed increased 11C-methionine accumulation largely in accordance with the contrast-enhanced areas on CT or MR images; whereas between 14 and 68 days after bleeding, neoplastic hematomas showed increased 11C-methionine accumulation that extended beyond the contrast-enhanced areas on CT or MR images. The intensity of 11C-methionine accumulation in tumor tissue was greater than that in non-neoplastic hematomas. CONCLUSION: Preliminary results suggest that Met-PET can distinguish neoplastic from non-neoplastic hematomas on the basis of differences in lesion extent compared with CT or MR findings.

Adult↗

PubMed1994

A method to quantitate cerebral blood flow using a rotating gamma camera and iodine-123 iodoamphetamine with one blood sampling.

A method has been developed to quantitate regional cerebral blood blow (rCBF) using iodine-123-labelled N-isopropyl-p-iodoamphetamine (IMP). This technique requires only two single-photon emission tomography (SPET) scans and one blood sample. Based on a two-compartment model, radioactivity concentrations in the brain for each scan time (early: t(e); delayed: td are described as: [formula: see text] respectively, where x denotes the convolution integral; Ca(t), the arterial input function; f, rCBF; and Vd, the regional distribution volume of IMP. Calculation of the ratio of the above two equations and a "table look-up" procedure yield a unique pair of rCBF and Vd for each region of interest (ROI). A standard input function has been generated by combining the input functions from 12 independent studies prior to this work to avoid frequent arterial blood sampling, and one blood sample is taken at 10 min following IMP administration for calibration of the standard arterial input function. This calibration time was determined such that the integration of the first 40 min of the calibrated, combined input function agreed best with those from 12 individual input functions (the difference was 5.3% on average). This method was applied to eight subjects (two normals and six patients with cerebral infarction), and yielded rCBF values which agreed well with those obtained by a positron emission tomography H2(15)O autoradiography method. This method was also found to provide rCBF values that were consistent with those obtained by the non-linear least squares fitting technique and those obtained by conventional microsphere model analysis. The optimum SPET scan times were found to be 40 and 180 min for the early and delayed scans, respectively. These scan times allow the use of a conventional rotating gamma camera for clinical purposes. Vd values ranged between 10 and 40 ml/g depending on the pathological condition, thereby suggesting the importance of measuring Vd for each ROI. In conclusion, optimization of the blood sampling time and the scanning time enabled quantitative measurement of rCBF with two SPET scans and one blood sample.

Aged↗

PubMed1994

Accumulation of L-[2-(F-18)]fluorophenylalanine in peri-infarct area in a patient with acute cerebral infarction.

We studied the brain uptake of amino acid in a patient with acute cerebral infarction with L-[2-(F-18)]fluorophenylalanine and positron emission tomography. The increased accumulation of the ligand was specifically found in the peri-infarct area where oxygen metabolism was still maintained but decreased later in the 72-day follow-up period. The kinetic analysis revealed that increased accumulation was not due to increased transport from the blood to the brain but delayed washout from the brain to the blood. Although the mechanism is still unknown, abnormally high accumulation of L-[F-18]fluorophenylalanine may predict delayed neuronal changes after ischemic insults of the brain.

Aged↗

PubMed1994

Infratentorial infarction: correlation of MR findings with neurological and angiographical features.

Using magnetic resonance imaging, we reviewed 141 infratentorial infarcts in 81 consecutive cases: 65 infarcts were seen in the paramedian pons, while 18 in the posterior inferior cerebellar artery (PICA) territory and 17 in the watershed area between PICA and superior cerebellar artery. No comparable sign or symptom was observed for 44 (31.2%) infarcts, whereas 66 (46.8%) infarcts appeared symptomatic and 31 (22.0%) infarcts were regarded as equivocal mainly due to the coexisting supratentorial lesions or non-localizing symptoms. The frequent coexistence of basal ganglionic small infarcts in those with infratentorial small (< 15 mm) infarcts implicated their common pathogenetic background. The fact that atrial fibrillation was seen in 33.3% of those with large (> 15 mm) infarcts whereas it was seen in only 6.5% of those with small infarcts may suggest a cardiogenic embolism as a possible cause of infratentorial large infarcts. Major artery occlusive lesion was seen in 15 of 22 cases with cerebellar infarction, whereas no occlusive lesion was seen in the majority of cases with pontine small infarcts. With MR imaging, infratentorial infarcts were detected more frequently than in the previous studies based on X-ray CT, and they can be considered as a benign condition.

Adult↗

PubMed1994

Methionine PET for follow-up of radiation therapy of primary lymphoma of the brain.

Positron emission tomography (PET) with carbon-11 methionine, computed tomography (CT), and magnetic resonance (MR) imaging were performed in 10 patients with histologically verified central nervous system (CNS) lymphoma before and after radiation therapy to compare the radiologic findings and to evaluate the usefulness of PET in monitoring tumor response to radiation therapy. Methionine PET clearly depicted CNS lymphoma before radiation therapy as an increased accumulation of C-11 methionine. The extent of increased accumulation of the radiotracer in tumor tissue markedly decreased after radiation therapy. The area of increased uptake was larger than the enhancing lesions on CT or MR images in most cases. One patient was confirmed to have tumor recurrence at the region of residual increased accumulation on methionine PET images. Methionine PET is useful for the delineation of CNS lymphoma and for monitoring the therapeutic effect of irradiation.

Aged↗

PubMed1994

Comparison of carbon dioxide responsiveness of cerebellar blood flow between affected and unaffected sides with crossed cerebellar diaschisis.

BACKGROUND AND PURPOSE: Concerning vasoreactivity of cerebellar blood flow (CeBF) in patients affected with crossed cerebellar diaschisis (CCD), several controversies have been reported. One is reduced asymmetry of CeBF after acetazolamide administration in 99mTc hexamethylpropyleneamine oxime single-photon emission-computed tomography, and the other is persistent asymmetry with alternation in PaCO2 using the 133Xe clearance method. The purpose of this study is to examine whether CeBF vasoreactivity in the side affected with CCD is the same as that in the unaffected side. METHODS: We analyzed CeBF during hypocapnia, normocapnia, and hypercapnia performed in 27 patients with cerebrovascular disease (age range, 38 to 73 years; mean age, 62.0 +/- 8.5 years) affected by CCD. CeBF was measured using H2(15)O and positron emission tomography. RESULTS: The CeBF ratio of CCD-affected side to CCD-unaffected side was consistent during the perturbation of PaCO2. This ratio was 0.82 +/- 0.08 for PaCO2 elevation and 0.83 +/- 0.07 for PaCO2 lowering. Both were not significantly different from unity. CONCLUSIONS: The percent change of CeBF per millimeter of mercury PaCO2 change was uniform across affected and unaffected sides with CCD. These findings are consistent with our recent findings observed in activated cerebral tissue during photic stimulation.

Adult↗

PubMed1994

[Circulation time determined by carotid angiography in patients with chronic internal carotid artery occlusion: comparison with cerebral blood flow and oxygen metabolism measured by PET].

The degree of collateral circulation in patients with unilaterally chronic internal carotid artery occlusion was estimated by mean transit time of contrast material in rapid sequence carotid angiography (Angiographic MTT), and compared with cerebral blood flow and oxygen metabolism measured by PET. In normal density region on X-ray CT, a significant negative correlation was observed between Angiographic MTT and cerebral blood flow (CBF). This indicates that cerebral blood flow can be estimated by Angiographic MTT. It has been reported that the ratio of cerebral blood volume (CBV) to CBF (CBV/CBF), i.e., mean transit time determined by PET well agreed with OEF, and is good indicator for brain circulation reserve. In this study, no significant correlation was observed between Angiographic MTT and CBV/CBF. However, a significant positive correlation was observed between Angiographic MTT and oxygen extraction fraction (OEF), and no significant correlation was observed between Angiographic MTT and oxygen consumption rate (CMRO2). These indicates that Angiographic MTT may be indicator for brain circulation reserve.

Aged↗

PubMed1994

MR of acute subarachnoid hemorrhage: a preliminary report of fluid-attenuated inversion-recovery pulse sequences.

We report preliminary results applying fluid-attenuated inversion-recovery (FLAIR) sequences to three patients with acute subarachnoid hemorrhage. Acute subarachnoid hemorrhage could be clearly demonstrated as areas of high signal intensity on FLAIR sequences in all patients. These preliminary results suggest that with FLAIR sequences one could reliably diagnose acute subarachnoid hemorrhage.

Acute Disease↗

PubMed1994

Cerebral infarction within six hours of onset: prediction of completed infarction with technetium-99m-HMPAO SPECT.

UNLABELLED: Technetium-99m-HMPAO can be used to evaluate abnormal brain perfusion in the hyperacute stage of stroke. METHODS: We investigated cerebral blood flow using 99mTc-HMPAO SPECT in 31 patients within 6 hr after the onset of cerebral infarction and analyzed the relationship between abnormal perfusion and morphological changes on follow-up CT scans. Patients were classified into an infarct group and a noninfarct group, and the lesions on SPECT images were divided into infarct and peri-infarct regions. RESULTS: Among a total of 30 infarct regions, three lesions studied at 1.5, 2.5 and 5 hr after the ictus showed local hyperperfusion suggestive of early postischemic hyperemia, while the other 27 lesions demonstrated local hypoperfusion. All of the peri-infarct regions showed moderate hypoperfusion. The noninfarct group consisted of five patients, four of whom showed no perfusion abnormalities. The lesion-to-contralateral radioactivity ratios for the infarct and peri-infarct regions were respectively 0.48 +/- 0.14 and 0.75 +/- 0.10 in the patients with hypoperfusion, while the right-to-left ratio in the noninfarct group was 0.97 +/- 0.10. CONCLUSION: This SPECT study of cerebral blood flow demonstrates that local hyperperfusion occurs in some infarcts even within 6 hr of onset and that infarcted and morphological viable brain can be distinguished by a lesion-to-contralateral radioactivity ratio of 0.6 within this time range.

Adult↗

PubMed1994

Cerebral uptake of 99mTc-bicisate in patients with cerebrovascular disease in comparison with CBF and CMRO2 measured by positron emission tomography.

The regional brain uptake of 99mTc-N,N'-(1,2-ethylenediyl)bis-L-cysteine diethyl ester (99mTc-bicisate) measured by single photon emission computed tomography (SPECT) was compared with the regional CBF and CMRO2 measured by positron emission tomography in patients with cerebrovascular disease. Nine patients with the diagnosis of cerebral ischemic disorders (n = 7) or cerebral hemorrhage (n = 2) were studied. 99mTc-Bicisate brain uptake correlated with CBF and CMRO2. However, 99mTc-bicisate uptake did not reflect CBF in the single lesion showing luxury perfusion, which seemed to resemble a CMRO2 image. Though quantitative analysis showed the nonlinear correspondence of 99mTc-bicisate brain uptake with CBF and CMRO2, this correspondence could be corrected into a more linear relationship using a correction factor. 99mTc-Bicisate washout from the brain had no correlation to CBF and CMRO2. This diffuse decreasing washout rate was approximately 15% during the first hour after injection. By using the lipophilic fraction of arterial blood and a linearized correction of 99mTc-bicisate SPECT images, the feasibility of obtaining a factor-related CBF and CMRO2 was suggested from our data. These results suggested that 99mTc-bicisate had good characteristics for routine clinical use with SPECT to display the brain function in patients with neurological disorders.

Aged↗

PubMed1993

Cerebral glioma: evaluation with methionine PET.

The authors examined 50 patients with cerebral glioma with use of positron emission tomography (PET) and L-[methyl]-[11C]methionine to assess the grade of malignancy and the extent of cerebral glioma. Carbon-11 methionine was highly accumulated in the lesion in 31 of 32 patients with high-grade glioma and 11 of 18 patients with low-grade glioma. The rate of uptake of C-11 methionine in high-grade glioma was significantly higher than in low-grade glioma (P < .001). However, in individual cases it was difficult to evaluate the grade of malignancy only from the degree of C-11 methionine accumulation. In most cases, the area of increased accumulation of C-11 methionine did not correspond to the abnormalities seen at computed tomography (CT). Surgical intervention confirmed that methionine PET delineated the extent of cerebral glioma more clearly than did CT. The authors concluded that methionine PET has greater utility in assessing the extent rather than the grade of malignancy of cerebral glioma.

Adolescent↗

PubMed1993

Subarachnoid hemorrhage: evaluation with MR imaging.

Thirty-seven magnetic resonance (MR) examinations were performed at 0.5 T in 33 patients with subarachnoid hemorrhage (SAH) caused by a ruptured aneurysm. Images were obtained 2 hours to 75 days after the ictus. Twenty-four proton-density-weighted (long repetition time [TR], short echo time [TE]) images were obtained in the acute stage (< 72 hours after the ictus) of SAH; SAH was hyperintense to brain parenchyma and cerebrospinal fluid in all cases. The detectability of acute SAH on T1- (short TR, short TE) and T2- (long TR, long TE) weighted images was 36% and 50%, respectively. In the subacute and chronic stages (> 3 days after the ictus), the detectability of SAH on T1-, T2-, and proton-density-weighted images was 73%, 31%, and 83%, respectively. Although computed tomography is still the modality of choice for evaluating acute SAH, the authors emphasize that even acute SAH can be reliably demonstrated with MR imaging with the appropriate parameters.

Adult↗

PubMed1993

Embolic cerebral infarction: MR findings in the first 3 hours after onset.

OBJECTIVE: MR imaging has a high sensitivity for detecting ischemic brain parenchyma. The aim of this study was to evaluate the changes in the signal intensity of infarcted brain parenchyma on MR images obtained within the first 3 hr after the onset of signs and symptoms in patients with embolic cerebral infarction. MATERIALS AND METHODS: We studied MR images of 16 patients who had a diagnosis of embolic cerebral infarction (highly probable according to criteria of the National Institute of Neurological and Communicative Disorders and Stroke). T1-weighted, T2-weighted, and proton density-weighted MR images were obtained within 3 hr after the onset of symptoms. Two neuroradiologists who had no knowledge of the diagnoses reviewed the MR images of these 16 patients and 20 control subjects in random order and evaluated signal-intensity changes in the gray and white matter. RESULTS: On proton density-weighted images, the central and cortical gray matter showed increased signal intensity in 63-69% and 88-94% of the patients, respectively. No abnormalities of the brain parenchyma were apparent on T1-weighted and T2-weighted images obtained within 3 hr after the onset of symptoms. The adjacent white matter appeared hyperintense on long TR images in only a few cases. CONCLUSION: An increased signal intensity in the gray matter on proton density-weighted images was the most characteristic parenchymal change seen on MR images of the brain obtained within 3 hr after embolic cerebral infarction.

Aged↗

PubMed1993

[A technique for a rapid imaging of regional CBF and partition coefficient using dynamic SPECT and N-isopropyl-p-[123I]iodoamphetamine (123I-IMP)].

IMP is a flow tracer due to a large first pass extraction fraction and high affinity in the brain, but significant clearance from the brain causes change of distribution when the scan start time is delayed. The purpose of the present study is to develop a new method to rapidly calculate a quantitative CBF image by taking into account for the clearance effects. A dynamic SPECT scan was performed on 5 subjects (4 patients with cerebral infarction and 1 normal volunteer) following slow intravenous infusion of 123I-IMP. The arterial input function was obtained by frequent blood sampling and by measuring an octanol extraction ratio for each sample. Firstly, non-linear least square fitting (NLS) was performed to investigate the tracer kinetics of 123I-IMP. The 3 compartment model analysis yielded negligibly small k3 (retaining rate constant) (0.0056 +/- 0.0128 (ml/ml/min)), and consistent k1 (transport rate constant) with those determined by 2 compartment model (2CM) analysis (r = 0.96, p < 0.001). In addition, k1 was consistent with CBF measured by 15O water PET technique. These observations suggested validity of using 2CM for describing the IMP tracer kinetics. Secondly, a weighted integration (WI) technique has been implemented to calculate rapidly images of CBF and partition coefficient (Vd). The WI technique yielded values of CBF (k1) and Vd (k1/k2). They were confirmed to be consistent with those determined by NLS technique (CBF; r = 0.99, p < 0.001, Vd; r = 0.99, p < 0.001), and calculated k1 agreed well with PET CBF (r = 0.91, p < 0.001). We observed changed Vd in infarcted patients. This supports an importance for calculating of Vd image. Vd image will provide additional clinical information because 123I-IMP binding mechanism may be related to cell viability.

Adult↗

PubMed1992

Age-related decline of cerebral oxygen metabolism in normal population detected with positron emission tomography.

Using positron emission tomography (PET), cerebral blood flow (CBF) and cerebral metabolic rate of oxygen (CMRO2) were measured in 32 healthy volunteers aged from 27 to 67 years. In bilateral putamen, left supratemporal, left infrafrontal and left parietal cortices, CMRO2 showed a significant decline during aging. The age-related decline of CBF was seen only at the left superior temporal cortex. The mean CMRO2 was significantly lower in the elder group (over 51 years old) than in the younger group (under 50 years old), whereas no significant difference in mean CBF between the two groups. The poor correlation of CBF to the age could be explained partly by the fact that CBF is easily influenced by the physiological, psychological and/or environmental factors. The age-related changes of CMRO2 were more marked in the association cortices of the left hemisphere than in that of the right hemisphere.

Adult↗

PubMed1992

[A method for measurement of regional cerebral blood flow using N-isopropyl-p-[123I]iodoamphetamine (123I-IMP) SPECT; two scans with one point blood sampling technique].

We have developed a new method to quantitate regional cerebral blood flow (CBF) using 123I-IMP and SPECT. This technique requires two SPECT scans and one blood sampling. Based on the 2 compartment model (influx; k1 and outflux; k2), a table between k2 and ratio of 1st scan counts/2nd scan counts was calculated, and a table look up procedure yielded a unique pair of k1 (CBF) and distribution volume (Vd = k1/k2) for each region of interest (ROI). The arterial input function was obtained by one point blood sampling to calibrate the standard input function, which has been obtained from the previous study on 12 subjects. This method was applied to 5 subjects including 1 healthy volunteer and 4 patients with cerebral infarction, and the regional CBF results were compared with those measured by H2(15)O PET technique. Optimized scan time combination was 40, 180 min which provided the best correlation with H2(15)O-CBF. The Vd values obtained in infarcted regions were significantly smaller than those in normal regions, suggesting the importance of measuring Vd for each ROI.

Aged↗

PubMed1992

Cerebral blood flow and glucose metabolism measurements in a patient surviving one year after carbon monoxide intoxication.

A 29-yr-old woman was studied for 1 yr after acute carbon monoxide intoxication following an attempted suicide by inhalation of automobile exhaust fumes. The patient demonstrated impaired responsiveness to stimuli without any specific neurological deficits for 1 yr after carbon monoxide intoxication. Repeated brain magnetic resonance imaging consistently displayed only bilateral globus pallidus lesions, but no lesions in either deep white matter or cerebral cortex. Position emission tomography measurements of regional cerebral blood flow, and glucose utilization rate were made in this patient at 6 mo and 1 yr following carbon monoxide intoxication. Impairment of both blood flow and glucose metabolism were found not only in the basal ganglia but also in morphologically normal frontal cortex. The decrease in glucose utilization in the frontal cortex was greater than that in the basal ganglia. During the period of 6 mo to 1 yr, blood flow and glucose metabolism in the basal ganglia recovered to the normal range. In the frontal cortex, however, blood flow and glucose metabolism remained approximately 20% lower than the normal mean values. This prolonged dysfunction in the frontal cortex may therefore be responsible for the impaired responsiveness of the subject.

Adult↗