Abstract TP116: Perioperative Assessment of Cerebral Perfusion Territories Through Arterial Spin Labeling Magnetic Resonance Imaging in Carotid Stenosis

Abstract

Backgroud: Territorial arterial spin labeling (TASL) is a MRI technique that permits independent labeling of major individual feeding vessels and noninvasive visualization of their perfusion territories. Objective: The objectives of this study were to use TASL to assess perioperative changes in the perfusion territories of the internal carotid arteries (ICAs) in carotid stenosis patients and to investigate the usefulness of this technique. Methods: Thirty-two patients underwent TASL and SPECT before and after carotid endarterectomy (CEA) or carotid artery stenting (CAS). ICA perfusion volume was calculated using TASL images. ICA flow was measured during CEA, both before and after reconstruction, using electromagnetic flow meter. Results: In most cases, preoperative asymmetry ( Fig. A ) of ICA perfusion volume improved postoperatively ( Fig B ) (red, rt ICA; green, lt ICA; blue, VA-BA). We classified patients into the following two groups: (1) an elevated CBF group (CBF increase after surgery ≥50%, n=4) and (2) a stable CBF group (CBF increase after surgery <50%, n=28). ICA perfusion volume increased significantly after surgery in the stable CBF group (291.1±89.0cm 3 versus 396.4±40.9cm 3 , p<0.0001) but did not increase significantly in the elevated CBF group (246.4±103.2cm 3 versus 268.7±107.7cm 3 ) ( Fig. C ). However, ICA flow increased significantly after reconstruction in both the elevated CBF group (54.0±58.2ml/min → 177.7±25.4ml/min) and the stable CBF group (85.7±50.0ml/min → 171.8±56.1ml/min) (p<0.0001) ( Fig. D ). Conclusion: TASL clearly demonstrated that CEA and CAS elicited increases in the perfusion volumes of stenotic ICAs, which resulted in equalization of the perfusion volumes of the left and right ICA. In the elevated CBF group, however, ICA perfusion volume increased slightly, despite marked increase in ICA flow. These findings suggest that an imbalance between these parameters plays an important role in the pathophysiology of hyperperfusion.