R2* Map by IDEAL IQ for Acute Cerebral Infarction: Compared with Susceptibility Vessel Sign on T2*-Weighted Imaging

BACKGROUND To evaluate the detectability of arterial acute thrombus on R2* map by iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) IQ compared with T2*-weighted imaging (T2*WI). METHODS Twenty-six patients with acute cerebral infarction who underwent R2* map and T2*WI were reviewed. We performed visual assessment of each sequence regarding the visibility of susceptibility effect reflecting acute thrombus and quantitative evaluation of the thrombus on R2* map. RESULTS Both R2* map and T2*WI showed susceptibility effect reflecting acute thrombi at the occluded site of magnetic resonance angiography (MRA) in 9 patients. R2* map revealed positive while T2*WI showed equivocal findings in 3 patients due to the surrounding vessel signal intensity. Acute thrombus at distal internal carotid artery (ICA) on R2* map was more clearly detected than that on T2*WI without any apparent susceptibility artifact from the skull base in 4 patients. Most of cardiogenic embolic infarction (CEI) and artery-to-artery embolic infarction (A-to-A) demonstrated positive and most of atherothrombotic infarction (ATI) revealed negative findings on R2* map, although quantitative R2* values of thrombi did not show significant differences between CEI (136.6 /msec) and A-to-A (189.9 /msec) (P = 0.332). CONCLUSION The detectability of acute thrombus on R2* map is comparable to that on T2*WI. Regarding thrombus at distal ICA, its detectability on R2* map is superior to that on T2*WI. R2* map provide additional information to distinguish between embolic and atherothrombotic infarctions.