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Application of susceptibility weighted imaging in the diagnosis of hemorrhagic transformation of acute massive cerebral infarction and assessment of collateral circulation re-formation

Hai-Yan Yan, Hong-Yan Xi, Hong-Mei Wang, Feng-Chun Zhang, Duan-Hua Cao

Objective: Application of Susceptibility Weighted Imaging (SWI) in diagnosis of Hemorrhagic Transformation (HT) of acute Massive Cerebral Infarction (MCI) and assessment of collateral circulation re-formation.

Methods: 50 patients with MCI in internal carotid artery system were included. Magnetic Resonance Imaging (MRI) scans of T1WI (T1 Weighted Image), T2WI (T2 Weighted Image), DWI (Diffusion Weighted Image), MRA (Magnetic Resonance Angiography) and SWI sequences were performed on patients. WI and routine MR (Magnetic Resonance) sequence images obtained before and after treatment were statistically analyzed to detect HT of MCI and reveal differences in collateral circulation re-formation in ischemic regions before and after treatment.

Results: (1) HT was detected in 18 patients (36%) in SWI scans including 14 cases (28%) of HI (Hemorrhagic Infarction) and four cases (8%) of PH (parenchymal hemorrhage). 11 cases (22%) of hemorrhagic transformation was detected in routine MR sequence scans, in which seven cases (14%) were HI and four cases (8%) were PH. The difference between groups was statistically significant (P<0.05). In SWI scans, 106 post-infarction hemorrhagic lesions were detected, with 100% detection rate. In routine MR sequence scans, only 26 hemorrhagic lesions were detected, with a detection rate of 32.51%. Mainly micro hemorrhagic lesions were missing. Difference between groups was statistically significant (P<0.05); (2) SWI sequence images provide a good display of microvessels in cerebral infarct region. Microvessels in patients in acute phase were found to reduce or disappear, while microvessels surrounding infarct area in patients in recovery phase were found to increase; occurrence rate was 66%. MRA scans were able to find 82% of responsible blood vessels of cerebral infarction.

Conclusion: SWI sequence scans are more sensitive than routine MRI sequence scans in revealing HT of acute MCI. MRA combined with SWI can effectively detect responsible blood vessels of cerebral infarction and monitor collateral circulation re-formation in infarct area.