Comparison of Susceptibility Weighted Imaging and TOF-Angiography for the Detection of Thrombi in Acute Stroke

Abstract

Background and PurposeTime-of-flight (TOF) angiography detects embolic occlusion of arteries in patients with acute ischemic stroke due to the absence of blood flow in the occluded vessel. In contrast, susceptibility weighted imaging (SWI) directly enables intravascular clot visualization due to hypointense susceptibility vessel signs (SVS) in the occluded vessel. The aim of this study was to compare the diagnostic accuracy of both methods to determine vessel occlusion in patients with acute stroke.Methods94 patients were included who presented with clinical symptoms for acute stroke and displayed a delay on the time-to-peak perfusion map in the territory of the anterior (ACA), middle (M1, M1/M2, M2/M3) or posterior (PCA) cerebral artery. The frequency of SVS on SWI and vessel occlusion or stenosis on TOF-angiography was compared using the McNemar-Test.Results87 of 94 patients displayed a clearly definable SVS on SWI. In 72 patients the SVS was associated with occlusion or stenosis on TOF-angiography. Fifteen patients exclusively displayed SVS on SWI (14 M2/M3, 1 M1), whereas no patient revealed exclusively occlusion or stenosis on TOF-angiography. Sensitivity for detection of embolic occlusion within major vessel segments (M1, M1/M2, ACA, and PCA) did not show any significant difference between both techniques (97% for SWI versus 96% for TOF-angiography) while the sensitivity for detection of embolic occlusion within M2/M3 was significantly different (84% for SWI versus 39% for TOF-angiography, p<0.00012).ConclusionsSWI and TOF-angiography provide similar sensitivity for central thrombi while SWI is superior for the detection of peripheral thrombi in small arterial vessel segments.

Susceptibility Vessel Sign for the Detection of Hyperacute MCA Occlusion: Evaluation with Susceptibility-weighted MR Imaging

“…Among 34 patients with MCA occlusion, SVS was demonstrated in 30 on SWI. Our results were similar to those of recent studies, in which SWI showed high sensitivity (75-93%) and specificity (90%) for the detection of the major intracranial arterial occlusion in acute stroke patients (19)(20)(21).…”

Is Unexplained Early Neurological Deterioration After Intravenous Thrombolysis Associated With Thrombus Extension?

“…Mean age was 69±15 years, median National Institutes of Health Stroke Scale was 16 (interquartile range, [12][13][14][15][16][17][18][19][20], and proximal occlusion (internal carotid artery or M1) was present in 83% of patients. Unexplained END occurred in 22 patients.…”

“…Furthermore, SVS extension or regression might reflect structural or metabolic changes within the thrombus over time rather than true thrombus evolution, 15,16 which may explain why 10 patients had complete regression of SVS on follow-up MRI, despite persistent occlusion on MRA. Although some MR sequences, such as susceptibility-weighted imaging, are more sensitive than T2* for thrombus detection, 10,17,18 they are more timeconsuming and particularly their use in the hyperacute stroke setting is questionable. Lastly, the purposely devised assessment of SVS extension relied on qualitative, although expertbased, visual image analysis.…”

Cortical vessel sign on susceptibility weighted imaging reveals clinically relevant hypoperfusion in internal carotid artery stenosis

“…It has been used for the detection of cerebral microbleeds or intracranial hemorrhage for many years [8]. Recently, changes in cortical and deep medullary vessels were described in [9][10][11][12][13][14][15][16]. Signs for hypoperfusion have been described in T2*-weighted imaging before, but due to the calculation of the SWI maps explained above, the findings are more prominent and therefore easier to examine on SWI [17].…”