Exclusion criteria

Upon initial review of these patients’ images, it was determined that those who had blockages in the ICA were not amenable to clot length measurement on mCTA or DSA, since the lack of blood flow through the ICA abolishes the normal pressure gradient of the vessel causing its collapse on imaging. The collapse of the vessel gives the appearance of a pseudo-clot extending the length of the ICA. This eliminated six of the 37 patients from the study. Furthermore, patients with clots distal to the M1 segment of the MCA did not have adequate collateral flow in order to measure clot length; these nine patients were also not amenable to measurement. Although they had proximal MCA clots, two cases completely lacked collateral circulation on mCTA, and were therefore also eliminated. This left us with 20 qualifying cases of patients with proximal MCA occlusions and adequate collateral circulation. Of those, three patients were eliminated for poor image quality. After completing the file review, 17 patients were eligible for our study.