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Cerebral blood flow in acute and chronic ischemic stroke using xenon-133 inhalation tomography
Insights
Serial measurements of cerebral blood flow (CBF) in ischemic stroke patients revealed persistent low-flow areas, even months after the acute phase. Reduced vasoreactivity was observed in infarct and peri-infarct tissues, suggesting potential for diaschisis.
Area of Science:
- Neurology
- Radiology
- Medical Imaging
Background:
- Ischemic cerebrovascular disease requires accurate assessment of cerebral blood flow (CBF) and vascular reactivity.
- Serial CBF measurements using xenon-133 inhalation and SPECT provide insights into acute and chronic stroke pathophysiology.
Observation:
- In patients with severe strokes, acute CBF studies revealed low-flow areas larger than CT-defined infarcts.
- Cerebral vasoconstrictor and vasodilator capacity tests showed preserved but reduced reactivity in infarct and peri-infarct zones.
- Transient CBF increases were noted in some patients, potentially due to embolic occlusion lysis or internal carotid artery occlusion.
Findings:
- Persistent large areas of reduced CBF were observed in severe stroke patients at 2 and 6 months.
- Vasoreactivity remained reduced in infarct and peri-infarct tissues at 6-month follow-up.
- Patients with smaller lesions showed slight, persistent CBF reduction without altered vasoreactivity.
Implications:
- The findings suggest intrahemispheric uncrossed diaschisis as a likely explanation for superjacent low-flow areas.
- Understanding persistent CBF changes and reduced vasoreactivity is crucial for managing ischemic stroke patients.
- Serial CBF monitoring and reactivity testing can offer valuable prognostic information in cerebrovascular disease.
Abstract:
Serial measurements of cerebral blood flow (CBF) were performed in 12 patients with acute symptoms of ischemic cerebrovascular disease. CBF was measured by xenon-133 inhalation and single photon emission computer tomography. Six patients had severe strokes and large infarcts on the CT scan. They showed in the acute phase (Days 1-3) very large low-flow areas, larger than the hypodense areas seen on the CT scan. The cerebral vasoconstrictor and vasodilator capacity was tested in the acute phase following aminophylline and acetazolamide, respectively. A preserved but reduced reactivity was seen at both tests in all 6 cases in the infarct and the peri-infarct areas. On Days 5-25, 4 of the patients had transitory increases (59-108%) of CBF, probably corresponding to lysis of an intracerebral embolic occlusion. The other 2 patients showed on Days 7-15 only a moderate CBF increase (appr. 20%), both had occlusion of the relevant internal carotid artery. In all 6 patients, CBF studies at 2 and 6 months resembled the acute phase, showing large areas with reduced flow. At the 6 months follow-up, the vasodilatory stress test was repeated, and all but one showed a preserved but reduced vasoreactivity in the infarct and peri-infarct tissue. Of the remaining 6 patients, one had a pontine infarct and one had no lesions on the CT scan, both having normal angiograms and CBF maps. Four patients had small deep or subcortical CT lesions, and showed a slight, but persistent CBF reduction of about 6-8% in the parietal region on the affected side. No changes in the flow pattern were seen at the vasoreactive studies. A likely explanation for the finding of superjacent low-flow areas is an intrahemispheric uncrossed diaschisis. This interpretation is discussed in relation to the peri-infarct low-flow area seen in the 6 cases with large infarcts.