Yoshiaki Tazaki

Regional Cerebral Blood Volume and Hematocrit Measured in Normal Human Volunteers by Single-Photon Emission Computed Tomography

Single-photon emission computed tomography (SPECT) was used for the measurement of regional cerebral blood volume (CBV) and hematocrit (Hct) in normal healthy human volunteers (mean age 30 ± 8 years). Regional cerebral red blood cell (RBC) volume and plasma volume were determined separately and their responses to carbon dioxide were investigated. Ten right-handed healthy volunteers were the subjects studied. SPECT scans were performed following intravenous injection of the RBC tracer (99mTc-labeled RBC) and plasma tracer (99mTc-labeled human serum albumin) with an interval of 48 h. Regional cerebral Hct was calculated as the regional ratio between RBC and plasma volumes and then was used for calculating CBV. Mean regional CBV in the resting state was 4.81 ± 0.37 ml/100 g brain, significantly greater in the left hemisphere compared with the right by 3.8% (p < 0.01). Mean regional RBC volumes (1.50 ± 0.09 ml/100 g brain) were less than mean regional plasma volumes (3.34 ± 0.28 ml/100 g brain), and mean regional cerebral Hcts were 31.3 ± 1.8%, which was 75.9 ± 2.1% of the large-vessel Hct. During 5% CO2 inhalation, increases in plasma volume (2.48 ± 0.82%/mmHg Paco2) were significantly greater than for RBC volume (1.46 ± 0.48%/mmHg Paco2). Consequently, the cerebral-to-large-vessel Hct ratio was reduced to 72.4 ± 2.2%. Results emphasize the importance of cerebral Hct for the measurement of CBV and indicate that regional cerebral Hcts are not constant when shifted from one physiological state to another.

Magnetic Resonance Imaging of the Brain in Patients with Migraine

Magnetic resonance imaging (MRI) was studied in 91 patients with migraine and in 98 controls. Risk factors known to cause MRI lesions were carefully examined. In 36 patients with migraine (39.6%), small foci of high intensity on T2-weighted and proton-density-weighted images were seen in the white matter. Of patients with migraine who were less than 40 years old and without any risk factor, 29.4% showed lesions on MRI; this was significantly higher than the 11.2% for the group of age-matched controls (n = 98). The lesions were distributed predominantly in the centrum semiovale and frontal white matter in young patients, but extended to the deeper white matter at the level of basal ganglia in the older age group. The side of the MRI lesions did not always correspond to the side of usual aura or headache. Migraine-related variables such as type of migraine, frequency, duration or intensity of headache or consumption of ergotamine showed no significant correlation with the incidence of MRI abnormalities. Our data indicated that migraine may be associated with early pathologic changes in the brain.

Cerebral blood flow and cerebral hematocrit in patients with cerebral ischemia measured by single-photon emission computed tomography

Abstract– Single‐photon emission computed tomography (SPECT) was used for the measurement of regional cerebral blood flow (CBF), cerebral blood volume (CBV) and cerebral hematocrit (Hct). CBF was measured using N‐isopropyl‐p‐I‐123‐Iodoamphetamine. CBV was measured by both RBC tracer (Tc‐99m RBC) and plasma tracer (Tc‐99m human serum albumin) and cerebral hematocrit (Hct) was calculated. In normals, the cerebral‐to‐large vessel Hct ratio was 75.9%. Isovolemic hemodilution in patients with high Hct tended to increase the cerebral‐to‐large vessel Hct ratio. Low CBF, high CBV and slow cerebral blood mean transit time (MTT by dynamic CT scanning) was seen during the acute stage of completed infarction and during the symptom‐free interval of TIA. Cerebral Hct was increased in the ischemic region of poor prognosis.

Regional cerebral blood flow during an attack of vertebrobasilar insufficiency.

Using technetium-99m-labeled hexamethylpropyleneamineoxime [( 99mTc]HM-PAO) and single-photon emission computed tomography, we measured changes in regional cerebral blood flow in a 58-year-old man during an attack of vertebrobasilar insufficiency. Angiography demonstrated compression of the left vertebral artery by the osteophytes of cervical spondylosis when the patient turned his head to the left. Measured in the orthostatic position while turning his head to the left during a typical attack of vertebrobasilar insufficiency, regional cerebral blood flow was significantly reduced in the left cerebellum and the right occipital region. Our study illustrates the capability of [99mTc]HM-PAO single-photon emission computed tomography to measure transient reductions in regional cerebral blood flow and to relate these changes to the pathophysiology of vertebrobasilar insufficiency.

Ataxic hemiparesis with reductions of ipsilateral cerebellar blood flow.

Regional cerebellar blood flow was measured in a patient with left-sided ataxic hemiparesis, using single-photon emission computed tomography and N-isopropyl-p-[123I]Iodoamphetamine. X-ray computed tomography revealed a small infarct in the paramedian portion of the right upper basis pontis. Blood flow was markedly reduced in the contralateral cerebellar hemisphere corresponding to the side of ataxia. The present study emphasizes the value of the three-dimensional functional imaging of the cerebellum to investigate the responsible lesion for ataxia and to study function of the cerebro-cerebellar circuits.

Clinical Effect of Encephabol (Pyritinol) in the Treatment of Cerebrovascular Disorders

The results of a series of multicentre, controlled, double-blind trials of the clinical efficacy of Encephabol compared with placebo in patients with a variety of cerebrovascular disorders are reported.

Increase in cerebrospinal fluid and plasma levels of 3-methoxy-4-hydroxyphenylglycol in acute stroke.

BACKGROUND AND PURPOSE 3-Methoxy-4-hydroxyphenylglycol is known to be a principal metabolite of brain norepinephrine and to be released into the blood and cerebrospinal fluid in association with activation of the central noradrenergic system. We examined changes in plasma and cerebrospinal fluid levels of 3-methoxy-4-hydroxyphenylglycol during acute stroke to see if there might be a correlation between these and the patients clinical state. METHODS We measured plasma levels of 3-methoxy-4-hydroxyphenylglycol in 32 control subjects and in 50 patients with brain hemorrhage and 57 patients with brain infarction who were admitted to the hospital within 72 hours after onset. In addition, we estimated 3-methoxy-4-hydroxyphenylglycol concentrations in the cerebrospinal fluid of 37 patients with brain infarction and eight control patients. RESULTS Mean +/- SEM values for plasma 3-methoxy-4-hydroxyphenylglycol in the patients with brain hemorrhage and those with brain infarction were 7.3 +/- 0.5 and 6.6 +/- 0.5 ng/ml, respectively. Both values were significantly higher than that obtained in the 32 control subjects (4.6 +/- 0.3 ng/ml, p less than 0.01). Plasma levels of 3-methoxy-4-hydroxyphenylglycol correlated well with state of consciousness and prognosis. The mean +/- SEM level of 3-methoxy-4-hydroxyphenylglycol in the cerebrospinal fluid of the 37 patients with brain infarction (10.9 +/- 0.6 ng/ml) was also significantly higher than that in the eight control patients (7.9 +/- 0.6 ng/ml, p less than 0.01). CONCLUSIONS The observed increase in plasma and cerebrospinal fluid levels of 3-methoxy-4-hydroxyphenylglycol implies that the activity of the central noradrenergic neurons may be enhanced at the onset of stroke, and these levels may be related to some extent to the clinical state and prognosis of stroke patients.

SPECT Measurements of Regional Cerebral Blood Flow, Blood Volume, and Hematocrit in Stroke

In the present study, single-photon emission computed tomography (SPECT) was used for the measurement of regional cerebral blood flow (CBF), blood volume (CBV), and cerebral hematocrit (Hct) in normal subjects and patients with occlusive cerebral vascular diseases. Using these three cerebral hemodynamic parameters, regional pathophysiology during the acute stages of cerebral infarction and transient ischemic attack (TIA) was investigated.