Introduction: Susceptibility vessel sign (SVS) on T2*-weighted imaging (T2*WI) is associated with a high proportion of RBCs. Susceptibility weighted imaging (SWI) is more sensitive to visualize SVS than T2*WI, resulting both RBC- and platelet-rich thrombi detectable. Clot composition and burden impact the success of recanalization therapy, but how SVS influences the likelihood of recanalization is still debated.
Hypothesis: We assessed the hypothesis that increased conspicuity of SWI-SVS reflects high proportion of RBCs and subsequent recanalization by endovascular treatment.
Methods: From total of 143 ischemic stroke patients who was performed endovascular treatment between February 2010 and June 2015, the authors collected eligible cases with the following inclusion criteria; (1) SWI performed before endovascular treatment (N=123); (2) intracranial portion of ICA, MCA, and ACA occlusion (N=93). We excluded 4 cases with SWI of poor quality and analyzed 89 cases. Clinical information including stroke subtype, use of rt-PA, and time from puncture to recanalization was analyzed. All MR images and angiographies were analyzed for the presence, location, diameter, length, and volume (diameter*length) of SWI-SVS, and TICI grade.
Results: Female was 47.2% (n=42) and mean age was 68.4±13.2. SWI-SVS was identified in 77.5% (n=69) of patients. SWI-SVS was more commonly associated with cardioembolism (CE; 49 of 57, 86.0%) than with other stroke subtypes (20 of 32, 62.5%; P=0.011). SVS length (11.20±7.96 vs. 6.90±7.03 mm; P=0.013) and diameter (4.72±2.53 vs. 2.48±2.21 mm; P<0.001) were longer in CE group than the other. SVS diameter was longer in recanalization group (TICI≥2b) than in non-recanalization group (4.21±2.63 vs. 2.82±2.42 mm; P=0.040). Multivariate analysis showed that SVS diameter and volume were independent predictors of CE and recanalization, respectively (OR, 1.67 and 1.02; 95% CI, 1.15-2.41 and 1.00-1.04; P=0.007 and 0.005).
Conclusions: Diameter and volume of SWI-SVS can predict cardioembolic stroke and recanalization, respectively. It may be useful for choosing the optimal treatment based on clot composition.