Objectives: Susceptibility-weighted (SW) magnetic resonance (MR) imaging is a sensitive test to detect intravenous deoxygenated blood. On SW images, dilated appearing draining veins in tissue with perfusion impairment occur due to an increase in intravenous deoxyhemoglobin levels, and could indicate poor perfusion areas in which there is an elevated oxygen extraction fraction. In this study, patients with possible chronic ischemia caused by internal carotid artery stenosis underwent carotid artery stenting (CAS). Changes in cortical vein diameters were evaluated before and after CAS using SW imaging.
Methods: Twenty-two patients with 25 lesions underwent 3 T SW imaging before and after CAS. The diameters of cortical veins were measured on SW images. Blood flow reduction and cerebrovascular reserve were examined before CAS using a single-photon emission computed tomography (SPECT) study, including an acetazolamide stress test.
Results: Two of six patients with both decreased blood flow and reduced cerebrovascular reserve on SPECT showed significantly increased cortical vein diameters on pre-CAS SW images (P<0.05). After CAS, these same two patients demonstrated a significant decrease in their cortical vein diameters (P<0.05).
Discussion: The present study demonstrates that dilated cortical veins as seen on SW imaging may reflect areas of altered oxygen extraction fraction due to chronic ischemia in patients with carotid artery stenosis, and that cortical venous dilatation is reversed after successful CAS. In the future, estimations of the cortical vein diameters on SW imaging may help to qualitatively evaluate areas of poor perfusion in chronic ischemia.