Gen Takeshita

NORMAL PERFUSION PRESSURE BREAKTHROUGH SYNDROME IN GIANT ARTERIOVENOUS MALFORMATIONS

The treatment of large, high-flow cerebral arteriovenous malformations is one of the most difficult operations which neurosurgeons encounter because of the complex surgery and the post-operative effects on the brain. We have evaluated 10 patients with large, high-flow AVMs who underwent surgical resection. Patients were investigated with contrast-enhanced computed tomography and magnetic resonance imaging, 1231-IMP single photon emission computed tomography (SPECT) studies of cerebral flow and cerebral vasodilatory function, intraoperative Laser Doppler flowmetry (4 or 10 patients), and conventional angiography. The volume of the arteriovenous malformation nidi ranged from 32.8 to 210.5 cc. SPECT imaging performed on the first post-operative day showed marked hyperperfusion in the brain tissue surrounding the resected nidus, and these regions were normal on images on the 7th post-operative day. Laser Doppler flowmetry showed sudden, and marked increase in CBF immediately following placement of temporary clips on the main feeding artery. Angiograms done on 7-14 days following surgery showed a stagnating artery, fragile vessel, and a prolonged circulation time. Our results indicate that pre- and post-operative SPECT study, especially a dynamic SPECT study done on the first post-operative day, was the most useful examination for ascertaining the post-operative normal perfusion pressure breakthrough.

Development and early trials of real-time CT fluoroscopy

A CT fluoroscopy system that permits real-time monitoring of CT images was developed. In phantom studies the images were displayed at a rate of 6 per s, with a delay time of 0.67 s. Early clinical trials in aspiration of intracranial haematoma and brain tumour biopsy indicated that CT fluoroscopy is useful for CT-guided intervention on the central nervous system.

The detectability of intracranial aneurysms using helical CT compared with conventional cerebral angiography

Helical CT (HCT) was applied to the diagnosis of cerebral aneurysms. The diagnostic accuracy of HCT, including the detectability of aneurysms, was compared with that of conventional cerebral angiography in 62 aneurysms of 43 patients. The scanning parameters were 135 kV, 260 mA and 1 mm slice thickness. The couch top was moved at 1 to 1.2 mm/s during the scanning of 30 s. In a prospective study, the detection rates using HCT and angiography were 91.9% and 93.5%. Retrospectively, the detection rates with HCT and with angiography were 95.4% and 98.4%. HCT was also effective in illustrating the detailed contours of aneurysms and calcifications and thrombosed parts of aneurysms. Three-dimensional CT (3D-CT) images were helpful in diagnosing complicated vascular anomalies. Our results indicate that HCT was an effective diagnostic modality to supplement cerebral angiography.

Quantitative measurement of regional cerebral blood flow with I-123 IMP SPECT: A correction of the microsphere model by global extraction between artery and internal jugular vein

Quantitative measurements of regional cerebral blood flow with N-isopropyl-(Iodine 123)p-iodoamphetamine (I-123 IMP) as a microsphere model were performed in forty cases. The regional cerebral blood flow values obtained with I-123 IMP were slightly underestimated compared with those of Xe-133 inhalation methods (y=0.90x–2.1, r=0.85, p< 0.01). After correction by global extraction (87 %) between the artery and internal jugular vein, which was measured in four patients by means of a catheter technique, the underestimation of the values obtained with I-123 IMP was improved (y=1.0x–2.4, r=0.85, p< 0.01). Several problems in the accurate quantitative measurement of regional cerebral blood flow with I-123 IMP are discussed.

Correlation of clinical features and high-dose steroid therapy in spinal multiple sclerosis with MRI

MRI is useful for detecting spinal lesions in multiple sclerosis (MS). We have performed MRI in 14 patients (26 attacks) with clinically definite MS and investigated correlations between neurological and MRI findings and their changes before and after high-dose steroid “pulse therapy”. The spinal level at which the lesion was suspected on the basis of neurological examinations was located as high-intensity areas on T2-weighted images. The lesions on Gd-DTPA enhanced T1-weighted images correlated better with clinically suspected lesions. Since the Gd-DTPA enhancing area disappeared after treatment in most cases, the enhancing lesions were useful for our understanding of the activity and the reaction to therapy in MS.

Clinical utility of synthesised brain surface imaging: Surface anatomy scanning and MR angiography

An MRI technique permitting direct, noninvasive display of brain surface structures (surface anatomy scanning, SAS) was developed using T2-weighted images. In this study, synthesised SAS, which combines contrast-enhanced MR angiography and SAS, was used to 50 cases, and the detection rate of lesions and preoperative simulation was evaluated. Synthesised SAS enabled detection of more lesions (94%) than SAS alone (52%). Synthesised SAS has the following advantages: noninvasive visualisation of the brain surface structures (sulci, lesions and veins) and skin markers for surgical planning; practical data acquisition and postprocessing times; preoperative assessment of the suitability for a craniotomy; and minimisation of surgical damage to normal brain tissues and veins.