Susceptibility Vessel Sign for the Detection of Hyperacute MCA Occlusion: Evaluation with Susceptibility-weighted MR Imaging

PURPOSE: Susceptibility vessel sign (SVS) on gradient echo image, which is caused by MR signal loss due to arterial thrombosis, has been reported in acute middle cerebral artery (MCA) infarction. However, the reported sensitivity and diagnostic accuracy of SVS have been variable. Susceptibility-weighted imaging (SWI) is a newly developed MR sequence. Recent studies have found that SWI may be useful in the field of cerebrovascular diseases, especially for detecting the presence of prominent veins, microbleeds and the SVS. The purpose of this study was to evaluate the diagnostic values of SWI for the detection of hyperacute MCA occlusion. MATERIALS AND METHODS: Sixty-nine patients (37 males, 32 females; 46-89 years old [mean, 69.1]) with acute stroke involving the MCA territory underwent MR imaging within 6 hours after the symptom onset. MR examination included T2, FLAIR (fluid-attenuated inversion recovery), DWI, SWI, PWI (perfusion-weighted imaging), contrast-enhanced MR angiography (MRA) and contrast-enhanced T1. Of these patients, 28 patients also underwent digital subtraction angiography (DSA) within 2 hours after MR examination. Presence or absence of SVS on SWI was assessed without knowledge of clinical, DSA and other MR imaging findings. RESULTS: On MRA or DSA, 34 patients (49.3%) showed MCA occlusion. Of these patients, SVS was detected in 30 (88.2%) on SWI. The sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy of SWI were 88.2%, 97.1%, 96.8%, 89.5% and 92.8%, respectively. CONCLUSION: SWI was sensitive, specific and accurate for the detection of hyperacute MCA occlusion.

Associated Brain Parenchymal Abnormalities in Developmental Venous Anomalies: Evaluation with Susceptibility-weighted MR Imaging

PURPOSE: The purpose of this study was to evaluate the associated brain parenchymal abnormalities of developmental venous anomalies (DVA) with susceptibility-weighted image (SWI). MATERIALS AND METHODS: Between January 2012 and June 2013, 2356 patients underwent brain MR examinations with contrast enhancement. We retrospectively reviewed their MR examinations and data were collected as per the following criteria: incidence, locations, and associated parenchymal signal abnormalities of DVAs on T2-weighted image, fluid-attenuated inversion recovery (FLAIR), and SWI. Contrast enhanced T1-weighted image was used to diagnose DVA. RESULTS: Of the 2356 patients examined, 57 DVAs were detected in 57 patients (2.4%); 47 (82.4%) were in either lobe of the supratentorial brain, 9 (15.7%) were in the cerebellum, and 1 (1.7%) was in the pons. Of the 57 DVAs identified, 20 (35.1%) had associated parenchymal abnormalities in the drainage area. Among the 20 DVAs which had associated parenchymal abnormalities, 13 showed hemorrhagic foci on SWI, and 7 demonstrated only increased parenchymal signal abnormalities on T2-weighted and FLAIR images. In 5 of the 13 patients (38.5%) who had hemorrhagic foci, the hemorrhagic lesions were demonstrated only on SWI. CONCLUSION: The overall incidence of DVAs was 2.4%. Parenchymal abnormalities were associated with DVAs in 35.1% of the cases. On SWI, hemorrhage was detected in 22.8% of DVAs. Thus, we conclude that SWI might give a potential for understanding of the pathophysiology of parenchymal abnormalities in DVAs.

Diagnosis of metastases encephaloma by using susceptibility weighted imaging and contrast-enhanced T1-weighted imaging of MR before and after radiotherapy / 实用放射学杂志

Objective To evaluate the value of susceptibility-weighted imaging (SWI)sequence in the diagnosis of metastatic en-cephaloma pre and after radiotherapy by comparing the appearance of the SWI and contrast-enhanced T1-weighted imaging(T1 WI). Methods Thirty-eight lung cancer patients with brain metastases underwent SWI and contrast-enhanced T1-weighted imaging re-spectively before and 2-3 months after radiotherapy.Evaluated the two methods by score(the score ranged from 0-3,0 represen-ted no showing,1 represented not showing clearly,2 represented could judging,3 represented showing obviously).Results Before radiotherapy,SWI detected 1 61 lesions of metastases and could obviously show tumor vascular in brain metastases (mean score 2.73±0.05).Contrast-enhanced T1 WI detected 1 61 lesions(mean score 1.93±0.04 ).SWI showed significantly higher score than enhanced T1 WI(P <0.05)through paired sample t test.After radiotherapy,SWI found 98 lesions (mean score 1.47±0.1 1 )and en-hanced T1 WI found 140 lesions (mean score 1.80±0.07),enhanced T1 WI had significantly higher score than SWI(P <0.05).Con-clusion SWI is superior to contrast-enhanced T1 WI to show the metastases before radiotherapy and can show tumor vascular in brain metastases obviously.SWI is inferior to enhanced T1 WI after radiotherapy.It has some value and may provide a new method for evaluating effects of radiotherapy.

Susceptibility-Weighted MR Imaging for the Detection of Developmental Venous Anomaly: Comparison with T2 and FLAIR Imaging

PURPOSE: We evaluated the diagnostic value of susceptibility-weighted imaging (SWI) for the detection of developmental venous anomaly (DVA). MATERIALS AND METHODS: Retrospective review of 1068 brain MR examinations found 28 DVAs in 28 patients (2.6%) on contrast-enhanced T1-weighted images. SWI, T2, and FLAIR images of 28 patients with DVA and 28 sex- and age-matched control patients without DVA were analyzed by blinded readers on each type of sequences. All images were independently reviewed by two radiologists who were blinded to other MR imaging finding. In cases of discrepancy, two reviewers reached a consensus later. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of each MR sequence for the detection of DVA were determined. Statistical analysis was performed by using the Mcnemar test. The significance level was p < 0.05. RESULTS: The sensitivity, specificity, PPV, and NPV of SWI for the detection of DVA were 85.7%, 92.9%, 92.3%, and 86.7%, respectively. T2 and FLAIR images showed sensitivity of 35.7% and 35.7%, specificity of 92.9% and 96.4%, PPV of 83.3% and 90.9%, and NPV of 59.1% and 60.0%, respectively. On SWI, the sensitivity and NPV for the detection of DVAs were significantly higher than those of T2 and FLAIR images (p < 0.05). CONCLUSION: SWI was sensitive and specific for the detection of DVA.

Diagnostic value of magnetic susceptibility weighted imaging in diffuse axonal injury / 中华放射学杂志

Objective To study the diagnostic value of susceptibility weighted imaging (SWI) in diffuse axonal injury (DAI) and investigate the relationship between SWI and clinical prognosis. MethodsTwenty patients (15 males and 5 females) with DAI were included in this study. Routine sequences (T1WI, T2WI and FLAIR) and SWI were performed on a 3.0 T MRI scanner. There were 8 cases whose Glasgow score scale (GCS) ranged from 3.0 to 5.0, 4 cases from 6.0 to 8.0 and 8 from 9.0 to 12.0. The interval time between injury and examination were from 3 hours to 20 days. The number and volume of lesions observed on SWI and routine sequence were compared using Mann-Whitney U-test and paired t-test. Pearson correlation was used to analyze the relationship between the number and volume of all lesions and GCS. Results The lesions showed punctate, beaded, patchy and cord-like hypointense signal with various size on SWI (lesion diameter <2.0 cm). Distribution of lesions was multifocal with clear boundary. Routine MRI scan found a total of 78 lesions, while SWI sequence detected 424 lesions. The number of the lesions found on SWI was more than that on conventional MRI (U=-15.447,P＜0.01). The total volume of the lesions measured on routine MRI and SWI were 19 340 mm3 and 38 042 mm3, respectively. The total volume measured on SWI was more than that on routine MR (t=5.870,P＜0.01). The number and volume of all lesions were negatively correlated with GCS (r=-0.802, -0.767, P＜0.01). Conclusion SWI sequence could find more bleeding lesions than the routine MRI sequences. The number and the volume of the lesions were closely related to GCS. SWI showed high value in the diagnosis and prediction of the prognosis of DAI.

Clinical application MR susceptibility weighted imaging(SWI) in brain diseases / 重庆医科大学学报

Objective:To study the clinical value of susceptibility weighted imaging(SWI)in brain diseases.Methods:37 cases with blood vessel pathological change of brain diseases were collected and analyzed,including 8 example of angioma cavernosum,10 cerebral infarction,15 brain tumor,2 venous malformation and 2 venous sinus thrombus.Conventional T1WI,T2WI,DWI,the SWI and enhanced T1WI,MRA images were performed to compare the superiority of the SWI images to the others in demonstrating the small hemorrhagic focuses,the small vein,hemosiderin,calcification and other paramagnetic materials.Results:SWI could distinguish the hemorrhage from the blood vessel and discover the smaller hemorrhagic focuses of the angioma cavernosum.It could discover more tiny veins adjacent to the dilated draining vein.SWI could detect small hemorrhages in acute cerebral infarction and small draining veins in brain tumor.And draining veins in deep part and expanded rete venosum in the surfaces of brains could be obviously demonstrated when sinus venosus thrombus occurred.Conclusion:SWI is a new pulse sequence that can demonstrate the abnormal low current capacity blood vessels,the structure of small vein,the tiny hemorrhages as well as ferrugination and calcium deposition sensitively.So it can be applied in the diagnosis and antidiastole of the central nervous system diseases as an important supplement to the MRI conventional sequences.