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ISI values and interhemispheric differences in patients with ischemic cerebrovascular disease; correlations with
Insights
Xenon 133 inhalation studies reveal that high asymmetry in hemispheric blood flow (ISI ratio) indicates poor collateral capacity in patients with carotid artery disease, even with mild symptoms. This highlights the importance of assessing collateral function in cerebrovascular disease.
Area of Science:
- Neurology
- Vascular Medicine
- Radiology
Background:
- Ischemic cerebrovascular disease often involves stenosis or occlusion of major arteries.
- Collateral capacity is crucial for maintaining brain perfusion in affected areas.
- Assessing collateral function aids in understanding disease severity and prognosis.
Purpose of the Study:
- To investigate collateral capacity in patients with ischemic cerebrovascular disease using Xenon 133 inhalation.
- To correlate hemispheric asymmetry index (ISI) ratios with arterial stenosis or occlusion.
- To evaluate the clinical significance of collateral insufficiency.
Main Methods:
- Xenon 133 inhalation cerebral blood flow (CBF) studies were performed on 100 patients.
- Patients had ischemic cerebrovascular disease in the carotid artery territory.
- Asymmetry of hemispheric ISI values was quantified as a ratio.
Main Results:
- High ISI ratios (indicating greater asymmetry) were observed in patients with internal carotid or middle cerebral artery occlusion.
- Elevated ISI ratios correlated with more severe clinical symptoms.
- An elevated ISI ratio suggested collateral supply insufficiency, even in clinically stable patients.
Conclusions:
- High hemispheric blood flow asymmetry, measured by ISI ratio, reflects compromised collateral capacity in cerebrovascular disease.
- This ratio is particularly indicative of insufficiency in cases of major artery occlusion.
- Individual ISI values may be less reliable due to age-related variations.
Abstract:
Xenon 133 inhalation CBF studies of one hundred patients with ischemic cerebrovascular disease in the territory of the carotid artery were compared in an attempt to gain more insight into the collateral capacity, especially in those with a stenosis or occlusion of one of the major arteries. Asymmetry of the ISI values for the two hemispheres was expressed as a ratio. High ratios (greater ISI asymmetries) were found for patients with an occlusion of the internal carotid or middle cerebral artery, especially--but not exclusively--those with the more severe clinical symptoms. It also appeared that even when the patient is in a good clinical condition, an elevated ratio reflects insufficiency of the collateral supply to the affected side. The ISI values for individual patients seem to be less useful, partly due to the variable age dependency of this flow parameter.