MR vessel-encoded arterial spin labeling with the placement of metallic items to visualize the territorial blood flow after extracranial-intracranial bypass surgery: a proof-of-concept study.

Abstract

Depiction of bypass blood flow in patients who received extracranial-intracranial (EC-IC) bypass surgery is important for patient care. To develop a vessel-encoded arterial spin labeling (VE-ASL) method using surgical staples as a magnetic resonance (MR)-conditional product in patients who received EC-IC bypass surgery. Pseudo-continuous labeling was used for VE-ASL acquisition with a 3-T MR unit. First, an experimental study was conducted to determine the appropriate number of surgical staples to obtain a spatially sufficient saturation effect. Thereafter, four healthy normal volunteers underwent a VE-ASL study to confirm the sufficiency of the saturation effect to the right or left common carotid artery. Finally, VE-ASL scanning was performed in seven patients after EC-IC bypass surgery to confirm the ability of VE-ASL to visualize the territorial bypass perfusion. All qualitative evaluation was performed by two neuroradiologists using a 3-point grading system (2 = good, 1 = moderate, 0 = poor). A quantity of 200 staples was found to be appropriate for VE-ASL scanning. In healthy volunteers, one neuroradiologist rated the images of all four cases as good, while the other rated three cases as good and one case as moderate. For the seven patients after EC-IC bypass surgery, one neuroradiologist rated all seven cases as good, and the other rated six cases as good and one case as moderate. VE-ASL using surgical staples might be useful for the evaluation of territorial bypass perfusion in patients after EC-IC bypass surgery.