Clinical Application Of Susceptibility Weighted Imaging In Diagnosing Arterial Thrombosis In Ischemic Stroke

Purpose: To evaluate the clinical application value of susceptibility-weightedimaging in diagnosis of arterial thrombosis in ischemic stroke.Materials and methods:190cases of the ischemic stroke patients were collected inthe study according to the inclusion criteria. All patients underwent MRI and CTexaminations. The MRI protocol included T1WI、T2WI、FLAIR、DWI、3D-TOFMRA and SWI. Presence or absence of the susceptibility vessel sign (SWI),hyper-intense vessel sign (FLAIR) and hyper-dense arterial sign (CT) compared with3D TOF-MRA reference were assessed in consensus by three observers. Three vesselsigns were respectively compared to corresponding arterial thrombosis of3D TOFMRA, and the Kappa value was calculated. The patients of arterial occlusion on3DTOF MRA were classified into two groups according to the susceptibility vessel sign.Differences in age, sex, time to onset of symptoms, vascular risk factors, admissionNational Institute of Heath Stroke Scale（NIHSS）score, and lesion volume on DWIbetween two groups were evaluated. The short-term outcome was measured byNIHSS score after two weeks, and the patients of arterial occlusion on3D TOF MRAwere divided into good(NIHSS score≥7) and bad prognosis(NIHSS score＜7) groups.We performed a binary logistic regression including the following variables:susceptibility vessel sign, admission NIHSS score, heart disease and lesion volume onDWI to determine any independent predictors of short-term prognosis.Result:1.108cerebral arteries thrombosis were demonstrated in all190patients on3DTOF MRA. The sensitivity of the susceptibility vessel sign, hyper-intense vessel signand hyper-dense arterial sign to detect thrombosis were82.41%(89/108)、60.19%(65/108)、19.44%(21/108), respectively. There was good consistency betweensusceptibility vessel sign on SWI and arterial thrombosis on3D TOF MRA (Kappa value=0.855). However，FLAIR(k=0.436), CT(k=0.162) had the poor consistencycompared with3D TOF MRA, respectively.2.5patients were excluded because of severe hemorrhage on SWI. The follow-upSWI and MRA results of other24patients with susceptibility vessel sign wereclassified four types:(1)15cases had the recanalization of vessel on MRA, and theSVS was disappeared.(2)4cases still had the occlusion or partial recanalization ofvessel on MRA, but the size of SVS was reduced or the signal was moreheterogeneous than the former results.(3)1cases still had the occlusion of vessel onMRA, but the size of SVS was enlarged.(4) The follow-up MRA and SWIperformances of4cases were the same with the former MRI.2cases of them had thecalcified thrombus confirmed by SWI and CT.3. The admission NIHSS score for the positive SVS group was significantly higherthan scores for the negative SVS group (9±10versus5±5，P<0.05). The infarctionlesion volume on DWI for the positive SVS group was also significantly higher thanvolume for the negative SVS group (11.46±18.92cm2versus3.02±13.38cm2, P<0.05).4. The binary logistic regression analysis showed that only admission NIHSS scorewas an independent predictor of short-term outcome(OR1.352,95%CI1.186-1.541,P＜0.001), but the susceptibility sign was not(OR0.667,95%CI0.151-2.951,P=0.594).5. The positive SVS rate of cardio-embolic stroke patients (18/21,85.71%) wasslightly higher than rate of other stroke subtypes (71/87,81.61%), but no significantdifferences between two groups (P=0.759).Conclusion:1.’Susceptibility vessel sign’ on SWI is more sensitive in detecting the arterialthrombosis as compared to ’hyper-dense artery sign’ on CT and ’hyper-intensevessel sign’ on FLAIR images.2. SWI is able to demonstrate the evolution and outcome of thrombosis, which canbe used to predict the therapeutic effect of ischemic stroke.3. Although susceptibility vessel sign patients showed a serious neurologicalsymptom, it is not an independent predictor of short-term prognosis andcardio-embolic stroke.