Motonobu Kameyama

Magnetic resonance imaging of C2 segmental type of vertebral artery

Two cases with C2 segmental type of vertebral artery (VA) were reported. One case was a 64-year-old man, who was referred to our hospital suffering from vertigo, ataxia, and right facial palsy. Computed tomography (CT) scan showed multiple lacunae in the basal ganglia bilaterally. Another case was a 47-year-old man, complaining of left hemiparesthesia. A small high density area with a little enhancement was seen in the right parietal region in CT scan, and the lesion was diagnosed as cavernous angioma. Angiography of both cases depicted the vertebral artery not passing through the transverse foramen of the Atlas, but running medioposterior to it, and magnetic resonance imaging (MRI) and CT findings showed the vertebral artery running between the Atlas and Axis, and entering into the spinal canal. In our experience of 1669 sides in 1436 cases, such anomaly of the vertebral artery was found in ten cases including the two abovementioned. Six cases of such anomaly have previously been reported, but demonstration of the VA coursing between Atlas and Axis by MRI has not been published in the literature. During surgical therapy on the upper cervical spine, especially when using a posterior approach, or C1-C2 lateral puncture, the possibility of an anomalous vertebral artery, as in our cases, should be taken into consideration.

Metabolic fate of L-[methyl-11C] methionine in human plasma

The metabolites of L-[methyl-11C]methionine in the plasma of 8 patients with tumor were measured for 60 min after injection. In the plasma, after a rapid clearance, the total radioactivity remained constant, and protein-bound radioactivity increased rapidly. Non protein metabolites detected by HPLC as at least two components besides methionine, increased with time. Significant individual variations for the metabolism were observed. AT 60 min after injection, 36.5% (range: 16%–72%) and 45.3% (range: 13%–74%) of the 11C was measured as methionine and labeled proteins, respectively.

The accumulation of11C-methionine in cerebral glioma patients studied with PET

SummaryFourteen patients with cerebral gliomas were studied with positron emission tomography (PET) using L-[methyl-11C]methionine (11C-MET). Positive images of tumour were obtained in all cases regardless of histological grades. The analysis of differential absorption ratio (DAR) showed the higher accumulation of11C-MET in high grade gliomas than in low grade gliomas. PET study with11C-MET will be of great value not only in delineating the location of gliomas, but also in making a qualitative diagnosis from the view point of the biological properties of gliomas.

Cerebral blood flow and oxygen metabolism in infants with hydrocephalus

In this study, regional cerebral blood flow (rCBF) and the cerebral metabolic rate of oxygen (rCMRO2) were measured using positron emission tomography (PET) with oxygen-15 radiopharmaceuticals to clarify the pathophysiology of ventriculomegaly in the developing brain. Four hydrocephalic infants without severe neurological deficit were studied. Hypoperfusion was observed in the frontal, parietal, and visual association cortices which surrounded dilated anterior or posterior horns of the lateral ventricle. Lower rCMRO2 values than adult rates were observed in all cases. In the infants with markedly enlarged anterior or posterior horns, the surrounding cortices showed relatively lower rCMRO2 values with the fall of rCBF. Postoperative studies were performed in two infants. rCMRO2 increased in every region after ventriculoperitoneal shunting, but little change was observed in rCBF. These results indicate that metabolic deterioration occurs in the developing brain with hydrocephalus.

Evaluation of cerebral blood flow and metabolism in childhood moyamoya disease: an investigation into “re-build-up” on EEG by positron CT

The cerebral blood flow and cerebral metabolic rate of oxygen (CBF and CMRO2) of three cases of childhood moyamoya disease were examined by positron-emission-computed tomography for the purpose of investigating the mechanism of the “re-build-up” phenomenon on EEG. Decrease in both CBF and CMRO2 were observed following hyperventilation. However, dissociation between the decrease in CBF and CMRO2 was also observed. Arterial blood-gas analysis disclosed hypocapnea during hyperventilation and hypoxia following hyperventilation. These results clearly indicate that the re-build-up seen on EEG is the manifestation not only of ischemic hypoxia but also of hypoxic hypoxia characteristically seen in moyamoya disease.

A New Method for Producing Temporary Complete Cerebral Ischemia in Rats

A new model of temporary complete cerebral ischemia was developed and tested in 64 rats. With use of microsurgical techniques, both pterygopalatine and external carotid arteries were occluded and the basilar artery was coagulated to reduce potential collateral CBF during ischemia. After this preliminary five-vessel occlusion, temporary global ischemia was induced by occluding the common carotid arteries (CCAs) with microclips. To validate the method, CBF was measured autoradiographically in 24 anatomical regions at death after 5 min of ischemia or after 15 min of ischemia followed by 5 min of reperfusion. Mean arterial blood pressure and arterial blood gases remained stable under controlled endotracheal ventilation and anesthesia (halothane, 70% N2O, and 30% O2) throughout the CBF experiments, except for a 10–15% increase in mean arterial blood pressure for 1–5 min after bilateral CCA occlusion. After the initial five-vessel occlusion, the EEG did not change, and local CBF levels were comparable to those in anesthetized nonsurgical controls. When the CCAs were occluded, the EEG flattened rapidly; after 5 min of ischemia, autoradiography showed no detectable blood flow in the forebrain and cerebellum. The local CBF levels measured after 15 min of temporary global ischemia and 5 min of reperfusion demonstrated relatively homogeneous postischemic hyperperfusion; only two of eight rats had several 1- to 3-mm areas of no-reflow. Survival studies showed increasing motor impairment after 10, 15, 30, and 60 min of temporary CCA occlusion. Ischemic neuronal damage was observed histologically in the hippocampus and basal ganglia 24 h after 10 min of temporary ischemia. This model consistently produces reversible complete cerebral ischemia in the rat without the use of intracranial hypertension, systemic hypotension, hypoxia, or a neck tourniquet.

Potential radiopharmaceuticals labeled with titanium-45

The potential of some compounds labeled with cyclotron-produced titanium-45 (45Ti) as radiopharmaceuticals was studied. Properties of colloid formation of 45TiOCl2 or 45TiO-phytate in vivo resulted in the highest radioactivity uptake in the rat liver, followed by the spleen, suggesting potential for imaging the reticuloendothelial system. Three 45TiO-complexes with diethylenetriaminepentaacetic acid, citric acid and human serum albumin showed the highest radioactivity levels in the blood over 6 h. The binding of the 45Ti with plasma transferrin in vitro and in vivo suggested that these compounds can be used for estimating the blood volume. Also, potential as an indicator representing the breakdown of the blood-brain barrier in the rat was demonstrated by autoradiography.

A distal anterior cerebral artery aneurysm in infant: disappearance and reappearance of the aneurysm.

The incidence of intracranial aneurysms in childhood is rare, especially in infancy. Spontaneous thrombosis of a cerebral aneurysm in a child is very rare, particularly in a non-giant aneurysm. We report a case of a 1-month-old girl with a distal anterior cerebral artery aneurysm which disappeared spontaneously after subarachnoid hemorrhage and reappeared 6 months later. Surgical resection of the aneurysm was performed and she discharged uneventfully 10 days later. Histological examination revealed an aneurysm with a fibrous muscular layer, absence of the internal elastic lamina and partial hypertrophy of the intimal layer. Though the pathogenesis of this aneurysm is uncertain, two hypotheses are discussed.

Metabolic changes of glioma following chemotherapy: an experimental study using four PET tracers

SummaryTo shed light on the metabolic changes in glioma following therapy, uptake changes among 18F-fluoro-2′-deoxyuridine (18FUdR), 14C-thymidine (dThd),14C-methionine (Met) and 3H-deoxyglucose (DG) in glioma model after chemotherapy were studied, as a means for interpreting clinical PET results, together with the changes in the bromodeoxyuridine (BUdR) labeling index. 1-(4-amino-2-methyl-5-pyrimidinyl)methyl-3-(-2 chloroethyl)-3-nitrosourea hydrochloride (ACNU) was administered intraperitoneally in the tumor-bearing rats and uptake of the tracers or BUdR labeling index in tumor tissue were measured. The metabolic response following chemotherapy was a sharp fall immediately for 14C-dThd and 18FUdR and a moderate fall for 14C-Met whereas there was a fall in 3H-DG from 1 week after chemotherapy. The changes of BUdR labeling index paralleled that in the uptake for dThd and FUdR. These result indicate that PET scans using a variety of tracers in conjunction could be used for clinical diagnosis and evaluation of therapy in glioma cases. 18FUdR is a promising tracer of nucleic acid metabolism to evaluate the proliferative potential of brain gliomas.

Clinical application of18F-FUdR in glioma patients — PET study of nucleic acid metabolism

SummaryPositron emission tomography was used to investigate the metabolism of nucleic acids by18F-fluoro-2′-deoxyuridine (18F-FUdR) in 22 patients with gliomas. Sixteen cases of high grade glioma clearly demonstrated a region of high activity with a differential absorption rate (DAR) of 0.64 ± 0.34. Six cases of low grade glioma failed to reveal a positive image of the tumor and the DAR in tumor was 0.21 ± 0.042 (p < 0.01). This PET-18F-FUdR study succeeded in differentiating high and low grade gliomas from the view point of nucleic acid metabolism.