Cerebral functional-morphological match or mismatch in cerebrovascular disease: a comparison of flow-volume SPET, CT findings and Doppler sonography.

Cerebral ischaemia (thromboembolic, haemodynamic) is usually classified according to morphological criteria, but intracerebral rheological aspects often remain underestimated, even though prognosis may depend on areas of reduced perfusion or perfusion reserve around a morphological defect. The aim of this study was to investigate regional haemodynamics in patients with cerebrovascular ischaemia by comparing the size of morphological defects (MD) and perfusion deficits (PD). Ninety patients with cerebrovascular disease were investigated and the size of morphological defects on computed tomography (CT) was compared to the size of perfusion deficits or the extent of exhausted cerebral perfusion reserve (CPR) on a combined flow-volume single photon emission tomographic (SPET) study. Carotid arteries were examined by Doppler ultrasonography. Defect/deficit size ratios of MD, PD and CPR were classified as: (1) CT/SPET mismatch: A (no MD or PD, reduced CPR), B (PD > MD); or (2) CT/SPET match: C (PD = MD). A CT/SPET mismatch was found in 79% of patients with a haemodynamic pattern and in 67% of transient ischaemic attack/reversible ischaemic neurological deficit patients who showed no MD. A mismatch was also found in 21% of patients with thromboembolic infarction. A match was found in 79% of the thromboembolic and in 16% of the haemodynamic infarctions. High grade (> 80%) stenosis of the internal carotid arteries was found in 81% of the mismatch cases, but in only 57% of the match cases. In conclusion, haemodynamic infarctions show a predominance of functional/morphological mismatch, a match being predominant in thromboembolic infarctions. Doppler failed to indicate disturbed intracerebral perfusion in nearly one-fifth of haemodynamically compromised patients. In addition to CT and Doppler, flow-volume SPET enables an assessment of intracerebral haemodynamics which might be relevant for prognosis and therapy.