J Korean Soc Radiol.  2011 Jan;64(1):1-9. 10.3348/jksr.2011.64.1.1.

The Susceptibility Vessel Sign of the Middle Cerebral Artery on the T2*-Weighted Gradient Echo Imaging: Semi-quantification to Predict the Response to Multimodal Intra-Arterial Thrombolysis

• Youn SW
• Jung C
• Choi BS
• Kim JH
• Kwon OK
• Han MK
• Bae HJ
• Kwon BJ
• Han MH

• KMID: 1443575
• DOI: http://doi.org/10.3348/jksr.2011.64.1.1

Abstract

PURPOSE
We wanted to determine whether or not the "susceptibility asymmetry index" (SAI) of acute stroke on the T2*-weighted image is related with successful recanalization using multimodal intra-arterial thrombolysis (IAT).
MATERIALS AND METHODS
The 81 patients who underwent multimodal IAT for middle cerebral artery (MCA) territory acute stroke were included in this retrospective study. The multimodal IAT included intra-arterial urokinase infusion, clot disruption by a microwire, microcatheter and balloon manipulation, and balloon angioplasty and/or stenting for the flow-limiting stenosis. The diameter of the susceptibility vessel sign was measured on the T2*-weighted gradient echo imaging (GRE), and the diameter of the contralateral normal MCA at the corresponding level was measured on magnetic resonance angiography (MRA); the ratio between these two diameters was defined as the susceptibility asymmetry index. The relation between the TICI (Thrombolysis In Cerebral Infarction) score of 2-3 after multimodal IAT and the SAI was assessed. The receiver operating characteristic (ROC) curve analysis was performed on the SAI to predict a TICI score of 2-3 after multimodal IAT.
RESULTS
The mean SAI of 81 patients was 1.66 +/- 0.66. Seventy nine percent of the patients had a TICI of 2-3 after multimodal IAT. According to the ROC curve analysis, an SAI less than 1.3 was optimal for predicting the presence of stenotic lesion after recanalization (area under the curve: 0.821, sensitivity: 88.2%, specificity: 69.8%, p=0.0001), and the SAI < or = 1.61 (area under the curve: 0.652, sensitivity: 60.9%, specificity: 70.6%, p=0.0226) could predict a TICI score of 2-3. The TICI score of 2-3 after multimodal IAT was achieved in 88.6% of the cases with a SAI < or = 1.61 and in 67.6% of the cases with a SAI >1.61 (p=0.028).
CONCLUSION
The lower SAI on T2*-GRE could predict stenotic lesion and successful recanalization after performing IAT.

MeSH Terms

Angioplasty, Balloon
Constriction, Pathologic
Glycosaminoglycans
Humans
Magnetic Resonance Angiography
Magnetic Resonance Imaging
Middle Cerebral Artery
Retrospective Studies
ROC Curve
Stents
Stroke
Thrombolytic Therapy
Urokinase-Type Plasminogen Activator
Glycosaminoglycans
Urokinase-Type Plasminogen Activator

Figure

• 

  Fig. 1 Inclusion of the patients who underwent intra-arterial thrombolysis (IAT) for acute middle cerebral artery (MCA) stroke from January 2005 to January 2007. DWI = diffusion-weighted imaging, T2* GRE = T2*-weighted gradient echo imaging, MRA = magnetic resonance angiography, MCA = middle cerebral artery, ICAT = internal carotid artery terminal, p-MCAs = proximal middle cerebral artery, d-MCAs = distal middle cerebral artery, M2 = M2 segment of the MCA, DSA = digital subtraction angiography, IV-IA = intravenousintra-arterial thrombolysis

• 

  Fig. 2 The definition of the susceptibility asymmetry index (SAI). The diameter of the susceptibility vessel sign on the T2*-GRE (A; white double arrow) and that on the contralateral normal middle cerebral artery at the level corresponding to the MRA (B; black double arrow) is measured. SAI = A / B . The patient was the 70-year-old male with acute left MCA occlusion and atrial fibrillation. The SAI was measured as 2.92. After mechanical disruption with wire and balloon, the occluded MCA was not recanalized.

• 

  Fig. 3 The receiver operating characteristic (ROC) curve analysis between the susceptibility asymmetry index (SAI) and the presence of stenotic lesion (A), and between the SAI and successful recanalization (B). A. The SAI≤1.3 is optimal for predicting the presence of stenotic lesion (asterisk: area under the curve= 0.821, sensitivity: 88.2%, specificity: 69.8%, p=0.0001). B. Successful recanalization is optimally predicted by a SAI≤1.61 (sharp the area under the curve= 0.652, sensitivity: 60.94%, specificity: 70.59%, p=0.0226).

• 

  Fig. 4 A 60-year-old male with acute left MCA occlusion. The SAI was measure as 1.07 (= a/b in A and B). After balloon angioplasty, a TICI score of 3 was achieved with residual stenosis (arrow C).

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