MR Imaging of Individual Perfusion Reorganization Using Superselective Pseudocontinuous Arterial Spin-Labeling in Patients with Complex Extracranial Steno-Occlusive Disease

Correlation between pCASL- (global labeling) and DSC-PWI–identified infarct lesion volumes.

Illustration of individual perfusion patterns in 2 different patients with similar chronic high-grade (>70%) right bifurcation ICA stenosis. The red arrows indicate the stenosis in patient 1 (a) and patient 2 (A). Both patients had patent AcomAs and bilateral PcomAs. Nonselective labeling in b and B shows no significant perfusion deficits. These patients did not have any infarct lesions. Labeling was performed for the right ICA, left ICA, and right VA in both patients (the left VA was hypoplastic in both cases). In patient 1 (upper row), the stenotic right ICA (c) continues to provide perfusion to the right cerebral hemisphere; The left ICA (d) and right VA (e) do not collateralize. In patient 2 (bottom row), right ICA perfusion is diminished (C) and supplies only the MCA territory; the anterior and posterior territories are perfused by recruitment of the left ICA (D) and right VA (E). These cases illustrate situations in which the individual perfusion pattern is not predictable: Even though extracranial stenoses and circle of Willis anatomies are similar, the perfusion patterns are different.

A 78-year-old male patient with extracranial left ICA occlusion and an extracranial high-grade right ICA stenosis (red arrow) and a left VA stenosis in the V1 segment (white arrow, A). The AcomA and both PcomAs are patent. A perfusion deficit (white dotted line) is seen in the left corona radiata in both the DSC-PWI (B) and the nonselective pCASL map (C). Selective labeling was performed for the left common carotid artery (D), right ICA (E), right VA (F and G), and left VA (H). The intracranial perfusion signal is missing on labeling of the left common carotid artery (D) as a proof of left ICA occlusion. Right ICA labeling (E) shows perfusion of the left anterior cerebral artery and MCA territory. Right VA labeling (F and G) shows recruitment of the posterior circulation for the perfusion of the left MCA territory. The new watershed region with a perfusion deficit and chronic infarcts is seen between the posterior circulation and the right ICA (E and G). A subacute infarct lesion in the left occipital lobe is localized within the perfusion territory of the left VA (H) and can be categorized as a territorial infarct.