Detecting misery perfusion in unilateral steno-occlusive disease of the internal carotid artery or middle cerebral artery by MR imaging

Abstract

Background and purpose: Elevated OEF is a surrogate for misery perfusion. Our aim was to detect misery perfusion in patients with unilateral steno-occlusive disease of the ICA or MCA by using T2*-based MR imaging and to determine the relationship between brain ischemia and OEF.

Materials and methods: Twenty-three patients with unilateral steno-occlusive disease of the ICA or MCA and 8 healthy volunteers were included in this study. Hemodynamic information was obtained in all subjects by MR imaging. Three regions of interest were placed in the anterior, middle, and posterior parts of the brain bilaterally to measure the OEF and CBF values. The OEFs of the regions of interest in the hemispheres ipsilateral and contralateral to the vascular lesions were compared. Brain regions with OEF greater than that in controls were determined as misery perfusion in patients. The association of vascular lesions, rCBF, and the presence of territory infarction with elevated OEF was investigated.

Results: There was a statistically significant difference in OEF between the ipsilateral and contralateral hemispheres in the patients (t = 3.632, P = .001). Fourteen regions of interest with misery perfusion were determined in the ipsilateral hemispheres, while 3 regions with elevated OEFs were found in the contralateral hemispheres. In the ipsilateral hemispheres, decreased rCBF was associated with elevated OEF (r = -0.451, P < .001). Patients with territory infarction had more regions of interest with misery perfusion than patients without territory infarction (χ(2) = 3.889, P = .049).

Conclusions: By using the MR imaging technique, misery perfusion demonstrated as elevated OEF was detected in patients with severe atherosclerotic ICA or MCA disease. Identification of misery perfusion with MR imaging may be helpful in the evaluation of brain ischemia.

Fig 1.

Representative region-of-interest placement for OEF measurement in the study, shown on the OEF map from a patient. Each region of interest was placed in the anterior, middle, and posterior parts of bilateral hemispheres, which correspond to the territory of the ACA, MCA, and borderzone of the MCA and posterior cerebral artery, respectively. CBF was measured in the same way.

Fig 2.

OEF of anterior, middle, and posterior regions of interest in the ipsilateral and contralateral hemispheres. Compared with the contralateral hemisphere, OEF was increased in the hemisphere ipsilateral to the vascular lesion.

Fig 3.

Correlation between rCBF and OEF in the regions of interest of the hemisphere ipsilateral to the vascular lesion. The more the rCBF decreased, the more the OEF increased. The solid line is a reference reflecting the correlation coefficiency between rCBF and OEF. The dashed line in the graph represents the upper limit of the normal OEF. There are 14 regions of interest with elevated OEF in the ipsilateral hemispheres.

Fig 4.

A patient with territory infarction 2 weeks earlier due to left ICA severe stenosis. DSA and MRA show severe stenosis of the left ICA and no visualization of the bilateral ACAs and left MCA. T2-weighted MR image shows a left frontal infarction (top right). Severe reduction of CBF is noted in the anterior and middle parts of the left hemisphere (bottom left), which shows a markedly elevated OEF (bottom right).

Fig 5.

A patient with severe MCA stenosis on MRA (top left). FLAIR image shows small ischemic foci in the right semiovale center (top right). Although severe CBF reduction is detected in the right MCA territory on the CBF map (bottom left), OEF is only slightly increased (0.350) in the corresponding region (bottom right).