Accuracy of MRI T2*-weighted sequences (GRE-EPI) compared to CTA for detection of anterior circulation large vessel thrombus

Abstract

Purpose: Rapid detection of vessel occlusion is pivotal to the management of patients with acute stroke. Magnetic resonance (MR) T2*-weighted (W) sequence has proven its capability to detect intravascular thrombi, but its diagnostic value compared to computed tomography angiography (CTA) is not well established. We aimed to determine the diagnostic performance of fast 1.5-T MR T2*W sequences compared to CTA for the detection of intra-arterial thrombi in patients with acute stroke.

Methods: About 71 consecutive patients with known middle cerebral artery (MCA) territory stroke were identified. Patients with CTA and MR imaging within 12 h of symptom onset were included in the study. Two investigators reviewed the DWI and T2*W sequences for the presence of infarction and susceptibility vessel sign (SVS). A comparison to the corresponding internal carotid artery (ICA) and M1 and M2 segments of the MCA findings on CTA was made.

Results: Of the 51 patients included in our study, CTA thrombi were identified 84% patients (43/51). Of these, 77% (33/43) presented a corresponding SVS on T2*W. A total of 29 CTA thrombi were identified in the M1 segment, and of these, 22 patients had a corresponding SVS. Of the patients without M1 thrombus on CTA, no M1-SVS was detected on T2*W sequences. We found an accuracy of 92%, sensitivity of 85%, specificity of 100%, PPV 100%, and NPV of 86% for M1 occlusion. The Kappa coefficient was 0.79.

Conclusion: Fast T2*W sequences demonstrated very good diagnostic performance and inter-reader agreement for detecting SVS in the M1 segment in patients with acute ischemic stroke.

Keywords: Accuracy; Acute stroke; Magnetic resonance imaging; Middle cerebral artery; Sensitivity; Susceptibility vessel sign; Thrombus.