Lack of Correlation Between Pattern of Collateralization and Misery Perfusion in Patients With Carotid Occlusion

Abstract

Background and Purpose-Misery perfusion, identified by increased oxygen extraction fraction (OEF), predicts subsequent stroke in patients with carotid occlusion. The purpose of this investigation was to determine the relationship of angiographic findings to increased OEF in these patients. Methods-Forty-seven patients with carotid occlusion were studied with cerebral angiography and positron emission tomography (PET). The following angiographic data were collected blind to PET results: (1) pial collateralization, defined as retrograde filling of the MCA branches to the level of the insula; (2) presence of border zone shift; (3) presence of delayed venous phase; and (4) measurement of posterior communicating artery size. Patients were divided into 2 groups based on the PET measurement of normal or increased OEF. Results-Seventeen of 47 patients had increased OEF distal to the occluded carotid artery. No significant relationship between increased OEF and any angiographic finding was found. Pial collateralization was present in only 2 patients, both with increased OEF (Pϭ0.105). Border zone shift was equally distributed between the 2 groups (12 of 30 with normal OEF and 6 of 15 with increased OEF). Delayed venous phase was present in 4 patients, 3 of whom had increased OEF (Pϭ0.073). The relationship between the size of the posterior communicating artery and OEF was not significant by linear regression analysis (Pϭ0.242). Conclusions-With the possible but infrequent exceptions of delayed venous phase and pial collateralization, anatomic findings made on routine angiographic studies of patients with carotid occlusion do not correlate with increased OEF.

Effect of Collateral Blood Flow and Cerebral Vasomotor Reactivity on the Outcome of Carotid Artery Occlusion

“…This finding is in accordance with the results of a recent study that demonstrated the lack of correlation between pattern of collateralization, studied by cerebral angiography, and increased oxygen extraction fraction, measured by PET in patients with ICA occlusion. 37 In our study, as shown in Figure 3, the absence of any collateral pathways or the presence of all 3 collateral pathways were linked to a strongly impaired or normal cerebral VMR, respectively. These conditions were correlated with a high or low probability of a stroke, respectively.…”

Angiographically Defined Collateral Circulation and Risk of Stroke in Patients With Severe Carotid Artery Stenosis

“…12 Unexpectedly, angiographic demonstration of collaterals, or lack of collaterals, has not been shown to correlate with cerebral perfusion studies. 17 Blood supply to regions of the brain through the collateral circulation occurs with increasing severity of ICA stenosis and occlusion. To what extent collaterals modify the risk of stroke, independently of increasing stenoses, is unknown.…”

Ophthalmic Artery Flow and Cognitive Performance in Patients with Carotid Artery Stenosis

“…Cerebral hypo perfusion is one of main clinical manifestations in patients with severe CAS, and can be measured directly by various imaging techniques, such as CT perfusion [12,16,20], MR perfusion [14,21,22], single photon emission computed tomography [23], and positron emission tomography [24,25] imaging. In patients with mildly decreased cerebral perfusion pressure, the overall cerebral perfusion can be maintained by autoregulatory mechanisms; the cerebral blood volume (CBV), TTP and even oxygen extraction fraction (OEF) are gradually increased while the CBF remains unchanged or slightly decreased [26].…”

“…With regard to the influence of reversed OA flow on cerebral perfusion, some studies suggest that recruitment of secondary collaterals can protect the brain against further ischemic injury by augmenting blood supply [14,21,27], while others regard secondary collaterals as a marker of insufficient overall cerebral perfusion [4,13,24,28]. The presence of reversed OA flow is beneficial to regional CBF supply in patients with symptomatic unilateral carotid artery occlusion [14].…”