Tetsuhiro Kitahara

The effect of sodium bicarbonate on CBF and intracellular pH in man: Stable Xe‐CT and 31P‐MRS

The effects of sodium bicarbonate on cerebral blood flow (CBF) and intracellular pH were studied in five normal volunteers. CBF and intracellular pH were measured by stable xenon computed tomography and phosphorus‐31 magnetic resonance spectroscopy (31P‐MRS) respectively. Each patient received 7% sodium bicarbonate (3.5 ml/kg body weight) infused intravenously for 15 minutes. Before and after this injection, CBF, intracellular pH and physiological parameters were measured. CBF and PaCO2 were significantly increased. On the other hand, hematocrit and intracellular pH were decreased. These result suggests that three factors are thought to contribute to increase CBF during administration of sodium bicarbonate in humans: 1) arterial dilatation in response to carbon dioxide 2) an decrease of hematocrit 3) intracellular acidosis.

Regression of rnoyamoya vessels and hemodynamic changes after successful revascularization in childhood movarnova disease

Successful revascularization improves ischemic symptoms in the pediatric patients with moyamoya disease. However, it is not clear whether the revascularization prevents future intracranial hemorrhage from the residual moyamoya vessels. The purpose of this study is to investigate perioperative morphological and hemodynamic changes in the moyamoya vessels. Four pediatric patients (age < 15 years old) with bilateral moyamoya disease were selected for this study. To quantify the number of moyamoya vessels, T1‐weighted transverse images at the level of the basal ganglia and the thalamus were selected and characteristic flow voids in the lentiform nucleus were counted. Resting CBF and cerebrovascular reserve capacity (CRC) were measured pre‐ and 1 year after surgery using Xenon‐CT CBF method with acetazolamide test. The ratio of deep CBF/kortical CBF was calculated as an index of hemodynamic stress distribution. The one‐year follow‐up studies showed that 1) the number of moyamoya vessels decreased on the operative side, but did not change on the nonoperative sides in all cases; 2) the ratio of deep CBFkortical CBF decreased on the operative sides, but did not change in the non‐operative sides; and 3) the CRC increased on both sides. This observation suggests the possibility that revascularization surgery may be effective for preventing the future risk of intracranial hemorrhage.

Surgery for Expansion of Spinal Tuberculoma during Antituberculous Chemotherapy: A Case Report

We report a case of intramedullary spinal tuberculoma in a girl aged 2 years and 6 months. At the age of 18 months, the patient was hospitalized for 2 months with tuberculous meningitis. Tuberculomas then appeared in the thoracic spinal cord, and the patient developed paraparesis despite continuation of chemotherapy. Spinal magnetic resonance imaging demonstrated multiple ring-enhanced lesions in the cord on the T1-weighted image; on the T2-weighted image, the lesions had a bright core surrounded by a hypointense rim. Laminectomy and partial excision were performed, and the paraparesis improved. In addition to antituberculous chemotherapy and dexamethasone, surgical decompression was needed to treat the expansion of the spinal tuberculoma.

Effect of local administration of basic fibroblast growth factor against neuronal damage caused by transient intracerebral mass lesion in rats

There has been controversy regarding the best treatment for acute intracerebral hemorrhage. Early surgical evacuation alone seems to provide only limited amelioration of this condition, and additional therapeutic strategies should be investigated to obtain a better outcome. To test the feasibility of post-evacuation treatment, basic fibroblast growth factor (b-FGF) was administered into the evacuated cavity and its effect was evaluated in terms of the pathological changes around the lesion. A transient (10 min) intracerebral mass lesion was created by inflation of a microballoon in the caudate nucleus in rats. Basic-FGF (500 or 1000 ng) was injected into the evacuated cavity after deflation and removal of the balloon, and then histological changes were evaluated in the CA1 subfield of the hippocampus and cavity wall. The results demonstrate a protective effect against the neuronal damage in CA1 pyramidal cells and an increase of angiogenesis in the evacuated cavity wall after b-FGF administration. These observations suggest that local administration of b-FGF after evacuation may prevent secondary neuronal damage in the area surrounding an acute mass lesion and facilitate more rapid repair of the damaged brain.

Reproducibility of cerebral blood flow assessment using a quantitative SPECT reconstruction program and split-dose 123I-iodoamphetamine in institutions with different γ-cameras and collimators.

Single photon emission computed tomography (SPECT) is used widely in clinical studies. However, the technique requires image reconstruction and the methods for correcting scattered radiation and absorption are not standardized among SPECT procedures. Therefore, quantitation of cerebral blood flow (CBF) may not be constant across SPECT models. The quantitative SPECT (QSPECT) software package has been developed for standardization of CBF. Using the QSPECT/dual-table autoradiographic (DTARG) method, CBF and cerebral vascular reactivity (CVR) at rest and after acetazolamide challenge can be evaluated using 123I-iodoamphetamine in a single SPECT session. In this study, we examined the reproducibility of quantitative regional CBF and CVR in QSPECT/DTARG using different SPECT models at two facilities. The subjects were nine patients with chronic cerebral ischemic disease who underwent QSPECT/DTARG at both facilities with use of different γ-cameras and collimators. There were significant correlations for CBF at rest and after acetazolamide challenge measured at the two facilities. The consistency of the CBFs of the patients measured at the two facilities were good in all cases. Our results show that CBF measured by QSPECT/DTARG in the same patients is reproducible in different SPECT models. This indicates that standardized evaluation of CBF can be performed in large multicenter studies.

Hemodynamics of hypertensive putaminal hemorrhage evaluated by Xenon‐enhanced computed tomography and acetazolamide test

Cerebral blood flow (CBF) is usually decreased in patients with hypertensive putaminal hemorrhage (HPH). However, there are few reports concerning cerebrovascular reserve capacity (CRC) in these cases. This study evaluated cerebral hemodynamics in patients with HPH by measuring CBF and CRC. CBF and CRC were measured by stable xenon enhanced computed tomography (Xe‐CT) in 11 patients with HPH (HPH group) and 11 patients with essential hypertension without intracerebral hematoma (non‐HPH group). CBFs of the hemisphere and thalamus in the HPH group were lower than those in the non‐HPH group. And the CBF of the hemisphere was increased transiently after the surgical evacuation of the hematoma. Thereafter, it fell gradually. The CRCs were also lower in acute stage of the HPH group. The CRC recovered during the chronic stage. Hemodynamics in patients with HPH can be modulated by surgical removal of hematoma. However, some adjunct therapies are necessary to prevent delayed neuronal inactivity. Stable Xe‐CT with acetazolamide test is useful to evaluate hemodynamics in the HPH patients.

Modulation of cerebral hemodynamics by surgical revascularization in patients with moyamoya disease

The purpose of this study was to evaluate hemodynamic compromise in the patients with moyamoya discase and surgical modulation of the hemodynamics using stable xenon enhanced computed tomographic CBF measurement with the acetazolamide challenge. The study group consisted of 15 preoperative cases and 17 postoperative cases. In the preoperative group, regional resting cerebral blood flow (rCBF) and regional cerebrovascular reserve capacity (rCRC) were reduced. The reduction was more prominent in the anterior circulation than in the posterior circulation. In the postoperative group, rCBF and rCRC were still low in the anterior circulation. Revascularization increased the resting CBF but did not change the CRC. Postoperative CBF did not increase in adults but increased in children. These findings suggest that the misery perfusion state may be present only in the childs brain. Measurement of CBF and CRC is useful to evaluate the hemodynamics of moyamoya disease.

Effect of angiotensin converting enzyme inhibitor on chronic ischemic patients

Most of patients with cerebrovascular diseases are associated with hyper‐tension. Hypertension induces progressive atheromatous changes in cerebral arteries, and often causes steno‐occlusive lesions of cerebral arteries. Angiotensin converting enzyme (ACE) inhibitor cilazapril is one of the antihypertensive drugs. It was reported that cilazapril improved resting cerebral blood flow (CBF) and cerebrovascular reserve capacity (CRC) in experimental studies. In this clinical study, the authors investigated whether long‐term treatment with cilazapril could improve CBF and CRC in patients with steno‐occlusive lesions of the major cerebral arterial trunk, measured by stable xenon computerized tomography (Xe‐CT) with acetazolamide challenge. On the other hand, CBF and CRC in the calcium blocker‐treated patients were measured in the same way. CBF did not change after long‐term treatment with both cilazapril and calcium blocker. In the cilazapril‐treated group, CRC was increased significantly (p < 0.05). However, CRC did not change in the calcium blocker‐treated group. It was recognized that long‐term treatment with cilazapril did not decrease CBF and improved CRC in patients with occlusive lesions of the major cerebral arterial trunk.

Surgical modulation of the natural course of collateral circulation in chronic ischemic patients

The purpose of this study was to evaluate hemodynamic compromise in terms of baseline CBF and CRC in patients with chronic cerebral occlusive lesions and its modulation by a superficial temporal artery to middle cerebral artery (STA‐MCA) anastomosis. The study subjects were 10 healthy volunteers and 49 chronic ischemic patients with stenosis or occlusion of the internal carotid artery (ICA) or middle cerebral artery (MCA) The hemodynamics were measured using stable xenon enhanced computed tomographic CBF measurement with the acetazolamide challenge. The compromised hemodynamics in patients with chronic steno‐occlusive lesions did not improve during their natural course after two months. STAMCA bypass modulated hemodynamic compromise in the ischemic patients. We recommend STAMCA bypass for patients with reduced CRC, regardless of whether baseline CBF is reduced or normal. Hemodynamic classification using a combination of baseline CBF values and CRC values is useful for evaluating cerebral hemodynamics and for choosing the best treatment for cerebral ischemia with occlusive lesions.

Coronal flow mapping with Xe/Helical CT

Transverse section is utilized for ordinary flow mapping in Xe/CT. Transverse flow map is adequate to see horizontal flow distribution, but not so convenient to know vertical flow distribution. To know vertical flow distribution, the shuttle method with multiple transverse flow maps is used in general (1). But this method does not give us a direct visual image of vertical flow distribution. Then a new method of coronal flow mapping was developed with a helical CT scanner to visualize a direct image of vertical flow distribution. This method of coronal flow mapping needs a speedy CT scanner such as a helical CT scanner. This study is an examination of our method of coronal flow mapping on anatomical resolution, validity of flow values and flow distribution patterns in clinical cases.