To evaluate the changes of regional cerebral blood flow (CBF) in artificial hypertensive state, we investigated vascular responses to changes of arterial carbon dioxide tension (PCO2) and blood pressure by means of positron emission tomography (PET). The subjects were eight brain tumors which were histologically proven. We calculated CBF changes in hypercapnic and hypocapnic state, and then using those results, CBF changes in hypertensive state were corrected. Every patient represented a selective increase of tumor blood flow in hypertensive state induced by angiotensin II, demonstrating a loss of autoregulation in tumor. Our results suggested the possibility of enhancement of chemotherapy for brain tumors.

Adult↗

PubMedDate not supplied

Changes of cerebral blood flow, and oxygen and glucose metabolism following radiochemotherapy of gliomas: a PET study.

The effects of radiochemotherapy on blood flow, blood volume, and consumption of oxygen and glucose in tumor tissue and normal brain were studied by positron emission tomography. Thirteen patients with cerebral gliomas were included, and they were examined before, during, and within approximately 1 month after the therapy. The 15O-labeled gas steady state inhalation and the 18F-fluorodeoxyglucose methods were used. After the therapy, glucose consumption and blood volume decreased (p less than 0.03) in the tumoral tissue. In the structurally (CT) normal gray matter, blood flow, blood volume, and oxygen consumption did not show any significant changes; oxygen extraction fraction, glucose consumption, and glucose extraction fraction, however, decreased significantly (p less than 0.05, less than 0.02, and less than 0.03, respectively).

Brain↗

PubMedDate not supplied

Anatomical adjustments in brain positron emission tomography using CT images.

We have developed a method that allows us to place regions of interest on X-ray CT (XCT) images that are automatically adjusted to positron emission tomography (PET) images from the same patient. A face mask with landmarks was used during PET and XCT studies for matching slice positions between PET and XCT. Anatomical locations in different images of the same slice can be accurately adjusted using the landmarks and a video system. In our clinical experience misadjustments of the slice position are on the average less than 2 mm in axial distance and 1.0 degrees in slice angle. The method is easily applicable to any PET or XCT device.

Brain↗

PubMedDate not supplied

Differentiation between cerebral embolism and thrombosis on sequential CT scans.

A differentiation between embolic versus thrombotic infarction has been attempted on the basis of sequential CT of 32 patients fulfilling our clinical and angiographic criteria for embolic or thrombotic cerebral infarction of the middle cerebral arterial distribution. In the 20 patients of the embolic group, a large homogeneous low attenuation area was seen in every case. In 18 of these 20 patients, the low attenuation area extended from the deep brain to the cortex. In the 12 patients of the thrombotic group, 10 had an inhomogeneous low attenuation area that did not involve the cortices in 8 cases. The frequency of hemorrhagic transformation in the embolic group was higher than in the thrombotic group. Computed tomography showed discrete areas of increased attenuation corresponding to an angiographically occluded artery in 7 of the 20 patients in the embolic group. Sequential CT can assist in differentiating between embolic and thrombotic infarction.

Aged↗

PubMedDate not supplied

PET evaluation of spinal cord tumor using 11C-methionine.

A cervical cord tumor was examined with positron emission tomography using L-methyl-[11C]methionine. The radioactive tracer accumulated in the solid parts (but not in the associated cysts) of the neoplasm, which at histology was found to be an ependymoma.

Carbon Radioisotopes↗

PubMedDate not supplied

High L-methyl-[11C]methionine uptake in brain abscess: a PET study.

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Brain↗

PubMedDate not supplied

Reduction in regional cerebral metabolic rate of oxygen during human aging.

To investigate changes in cerebral circulation and oxygen metabolism during aging, regional cerebral blood flow (rCBF), regional oxygen extraction fraction (rOEF), regional cerebral metabolic rate of oxygen (rCMRO2) and regional cerebral blood volume (rCBV) were measured using the 15O labelled gas inhalation technique and a multi-slice positron emission tomograph (PET) in 22 healthy volunteers, aged from 26 to 64 years old. The measurements were performed with subjects at rest, without sensory deprivation. The values of rCBF, rOEF, rCMRO2 and rCBV in more than 40 anatomical structures of the brain were evaluated by studying a large series of scans in each region of interest after the functional PET image had been anatomically identified using x-ray computed tomographic images corresponding to the PET. In mean gray values, only CMRO2 showed significant reduction with age. rCMRO2 significantly decreased with age only in the supratentrium, and much more in the left hemisphere. Especially remarkable was rCMRO2 reduction in the left caudate region. Both CBF and OEF were variable and less age-dependent. It was concluded that CMRO2 could be reflecting healthy brain aging most properly.

Adult↗

PubMedDate not supplied

Anomalous origin of the posterior inferior cerebellar artery from the posterior meningeal artery.

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Adult↗

PubMedDate not supplied

Remote effects in MCA territory ischemic infarction: a study of regional cerebral blood flow and oxygen metabolism using positron computed tomography and 15O labeled gases.

Using positron computed tomography (PCT) and the 15O labeled gas steady-state inhalation technique, regional cerebral blood flow (rCBF), cerebral oxygen consumption (rCMRO2), and oxygen extraction fraction (rOEF) can be measured quantitatively in humans. We quantitatively examined the relationship between focal ischemic lesions and intact regions as detected by X-ray CT in such areas as the territory of the contralateral middle cerebral artery (MCA), thalami, pons, and cerebellar hemispheres. Twenty-three PCT measurements in 13 patients with unilateral ischemic infarction in the MCA territory as detected by X-ray CT were performed. Remote effects from cerebral infarction of the MCA territory were observed in the contralateral MCA territory, ipsilateral thalamus, brainstem, and contralateral cerebellar hemisphere. Slight depression of rCBF and rCMRO2 was also observed in the contralateral thalamus and ipsilateral cerebral hemisphere; rOEF was normal in these areas. Though the depression of rCBF and rCMRO2 due to remote effects was detected in all periods, it was mildly observed 0 to 6 days after onset. The reduction of rCBF and rCMRO2 due to remote effects was less than the morphological as well as the functional threshold. The phenomenon is probably caused by neuronal deactivation, and the regions with depressed blood flow and metabolism may be in a "resting" state.

Adult↗

PubMedDate not supplied

Unusual widening of Virchow-Robin spaces: MR appearance.

MR in two patients with unusual widening of the Virchow-Robin spaces showed multiple cystic foci up to 2 cm in diameter along the perforating medullary arteries in the cerebral white matter, mainly in one cerebral hemisphere. These areas were of the same signal intensity as cerebrospinal fluid on all pulse sequences. In one patient, the cystic foci in the white matter were biopsied and histologically confirmed to be large Virchow-Robin spaces.

Aged↗