Susceptibility-weighted Imaging Sequences Research Articles

Role of Magnetic Resonance Imaging in Unconscious Patients due to Diffuse Axonal Injury and Its Prognostic Value

Aim To study the long-term prognostic value of early magnetic resonance imaging (MRI) in unconscious patients with traumatic brain injury with findings of NCCT of the brain suggestive of diffuse axonal injury (DAI). Background Studies addressing the correlation of MRI with the pattern and duration of loss of consciousness due to DAI are few. The utility of MRI in predicting the functional outcome has not been reported in the Indian population. Materials and Methods In patients with DAI, MRI sequences including T1, T2*GRE (gradient recall echo), fluid-attenuated inversion recovery (FLAIR), diffusion-weighted imaging (DWI), and susceptibility-weighted imaging (SWI) were obtained. Glasgow coma scale (GCS) and Glasgow outcome scale (GOS) scores were documented at admission, on discharge, and at 3 months. Results A total of 54 patients (53 males, 1 female) were included in the study. The mean age was 27 ± 11.7 years. The mean GCS score on admission and at follow-up were 9.14 ± 2.3 and 11.7 ± 2.3, respectively. The mean GOS score on discharge and at 3 months were 2.6 ± 0.8 and 3.18 ± 1.02, respectively. SWI sequence detected maximum number of lesions followed by GRE and DWI. Patients with lesions in brainstem and basal ganglia were found to have a less favorable outcome as assessed by GCS and GOS at 3 months. There was no correlation between the total lesion load and outcome at 3 months. Conclusion In patients with DAI, SWI was found to be the most sensitive MRI sequence detecting maximum number of lesions. Patients with lesions in the brainstem and basal ganglia appear to have longer duration of unconsciousness and poorer outcome at 3 months.

Susceptibility weighted imaging in acute cerebral ischemia: review of emerging technical concepts and clinical applications.

Susceptibility weighted imaging (SWI) is an essential magnetic resonance imaging sequence in the assessment of acute ischemic stroke. In this article, we discuss the physics principals and clinical application of conventional SWI and multi-echo SWI sequences. We review the research evidence and practical approach of SWI in acute ischemic stroke by focusing on the detection and characterization of thromboembolism in the cerebral circulation. In addition, we discuss the role of SWI in the assessment of neuroparenchyma by depiction of asymmetric hypointense cortical veins in the ischemic territory (surrogate tissue perfusion), detection of existing microbleeds before stroke treatment and monitoring for hemorrhagic transformation post-treatment. In conclusion, the SWI sequence complements other parameters in the stroke magnetic resonance imaging protocol and understanding of the research evidence is vital for practising stroke neurologists and neuroradiologists.

Using 'swallow-tail' sign and putaminal hypointensity as biomarkers to distinguish multiple system atrophy from idiopathic Parkinson's disease: A susceptibility-weighted imaging study.

To investigate the value of 'swallow-tail' sign and putaminal hypointensity on 3T susceptibility-weighted imaging (SWI) for distinguishing multiple system atrophy (MSA) from idiopathic Parkinson's disease (IPD). Three groups - 39 MSA patients, 18 IPD patients,and 31 healthy controls (HCs) - were administered a 3T SWI sequence to evaluate 'swallow-tail' sign and putaminal hypointensity using visual scales from 0 to 2 and 0 to 3 scores, respectively. The diagnostic accuracy of the two signs separately and combined was calculated using a receiver operating characteristic curve, with clinical diagnosis as the gold standard. The scores of 'swallow-tail' sign were lower in IPD than in MSA or in HCs, as well as for putaminal hypointensity in IPD or HCs than in MSA (p < 0.05). The sensitivity and specificity of 'swallow-tail' sign and putaminal hypointensity were 87.9% and 83.3%, and 35.9% and 100%, respectively, in the respective patient groups. The area under the curve of combined signs was increased from 0.85 ('swallow tail') or 0.68 (putaminal hypointensity) to 0.93. The combination of 'swallow-tail' sign and putaminal hypointensity can increase the accuracy of discriminating between MSA and IPD. • Differential diagnosis of MSA and IPD is still challenging in clinical practice. • Absence of 'swallow-tail' sign is a valuable biomarker for IPD on SWI. • Putaminal hypointensity is a valuable biomarker for MSA on SWI. • Combined 'swallow- tail' sign and putaminal hypointensity increase diagnostic accuracy.

3D-TOF MRA序列筛查脑微出血在脑梗死出血性转化中的预警价值

目的：探讨三维时间飞跃法磁共振血管成像(Three dimensional time-of-flight magnetic resonance angiography, 3D-TOF MRA)原始图像评估脑梗死患者脑微出血(Cerebral microbleeds, CMBs)病灶的可行性，进一步探讨3D-TOF序列在预测脑梗死出血性转化中的应用价值。方法：选取192例脑梗死患者为研究对象，分别进行磁敏感加权成像(Susceptibility weighted imaging, SWI)和3D-TOF序列扫描，评估SWI及3D-TOF MRA原始轴位图像显示CMBs的优劣。观察脑梗死出血性转化在CT、T1WI、DWI、SWI及3D-TOF MRA序列原始图像中的影像学表现及CMBs的分布和信号特点，明确基于3D-TOF序列CMBs病灶数量分级与出血性转化的关系，探讨3D-TOF序列在预测脑梗死出血性转化中的应用价值。结果: 因影像学资料显示不清排除12例，实际纳入180例脑梗死患者，SWI共发现微出血病灶264个，CMBs数目分级：28例为轻度，8例为中度，4例为重度。3D-TOF MRA序列原始图像发现微出血病灶188个，其中24例为轻度，4例为中度，4例为重度。两种序列对微出血病灶的检出率比较差异有统计学意义(皮质和皮质下、丘脑、小脑，p < 0.05)；两者对基底节和脑干的微出血病灶检出率差异无统计学意义(p < 0.05)。180例患者中，24例发生出血性转化(13.3%)，T1WI、DWI、SWI及3D-TOF MRA序列检测出血性转化的敏感度分别为25.0%、62.5%、100%及83.3%。CMBs病灶数量与出血性转化的发生率呈正相关。结论：在缺乏SWI序列的情况下，3D-TOF MRA原始图像可有效显示CMBs病灶，可作为预测脑梗死发生出血性转化的有效手段之一。 Objective: To investigate the feasibility of the original image of the three-dimensional time of flight MR angiography (Three dimensional time-of-flight magnetic resonance angiography, 3D- TOF MRA) assessing cerebral microbleeds (CMBs) in the patients with cerebral infarction, and further investigate the application value of 3D-TOF sequence in predicting hemorrhagic transformation from cerebral infarction. Methods: 192 cases of patients with cerebral infarction were enrolled into this study, and susceptibility weighted imaging (SWI) and 3D-TOF sequence scanning were performed to assess the ability of SWI and original axial images of 3D-TOF MRA showing CMBs. We investigated the imaging signal distribution of hemorrhagic transformation with cerebral infarction in the original image of CT, T1WI, DWI, SWI and 3D-TOF MRA sequences and the characteristics of CMBs to clarify the relationship between the number grade of lesions and hemorrhagic transformation a clear sequence of CMBs based on 3D-TOF sequence, and explored the application value of 3D-TOF predicting hemorrhagic transformation with cerebral infarction. Results: 12 cases were excluded for the unclear imaging data. SWI found 264 lesions of CMBs among 180 cases with cerebral infarction. Classification of CMBs: 28 cases of mild, 8 cases of moderate, and 4 cases of severe. The original sequences of 3D-TOF MRA found 188 lesions of CMBs including 24 cases of mild, four cases of moderate, and four cases of severe. There was statistically significant difference in the CMBs lesions detection rate between these two sequences (cortical vs. subcortical, thalamus, cerebellum, p < 0.05). There was no significant difference in CMBs lesions detection rate in the basal ganglia and brainstem between them (p < 0.05). Among 180 patients, there were a total of 24 cases of hemorrhagic transformation (13.3%). The detection sensitivities of hemorrhagic transformation of T1WI, DWI, SWI and 3D-TOF MRA sequence were 25.0%, 62.5%, 100% and 83.3%. CMBs lesions number was positively correlated with the incidence of hemorrhagic transformation. Conclusion: In the absence of SWI sequence, the original image of 3D-TOF MRA sequence can effectively display CMBs lesions, which can be used as an effective means of predicting hemorrhagic transformation of cerebral infarction.

Susceptibility weighted imaging - a problem-solving tool in differentiation of cerebellopontine angle schwannomas and meningiomas.

Background and purpose Vestibular schwannomas and meningiomas of the cerebellopontine angle can be differentiated by the presence of foci of blooming on susceptibility weighted imaging. Materials and methods In this retrospective study, magnetic resonance imaging with susceptibility weighted imaging sequence in addition to other routine sequences was done in 73 patients. All the cases were studied for the presence of foci of blooming within the tumor on susceptibility weighted imaging. Histopathological examination confirmed the diagnosis in all cases. Results There were 59 patients in the vestibular schwannoma group and 14 in the meningioma group. Susceptibility weighted imaging showed presence of blooming (due to microhemorrhages) in all the cases of cerebellopontine angle schwannomas. In the meningioma group, 13 cases showed no blooming within the lesion; one case showed blooming which was confirmed to be due to calcification on computed tomography study. For the detection of foci of blooming and predicting histopathologic diagnosis of schwannoma pre-operatively, susceptibility weighted imaging showed a sensitivity of 100%, specificity of 92%, positive predictive value of 98.3%, and negative predictive value of 100%. The Fisher exact test showed a statistically significant difference in the differentiation of vestibular schwannoma from meningioma on the basis of detection of blooming on susceptibility weighted imaging ( p < 0.0001). Conclusion Susceptibility weighted imaging is a problem-solving tool in making accurate pre-operative differentiation of vestibular schwannoma from meningioma.

Contribution of susceptibility weighted imaging sequence of MRI to diagnosis of parkinsons disease

Contribution of susceptibility weighted imaging sequence of MRI to diagnosis of parkinsons disease

Contribution of susceptibility weighted imaging sequence of MRI to diagnosis of parkinsons disease

Contribution of susceptibility weighted imaging sequence of MRI to diagnosis of parkinsons disease

Suseptibilite ağırlıklı manyetik rezonans görüntüleme sekansının abdominal duvar endometriozisi tanısına katkısı

Objective: Abdominal wall endometriosis is a rare subtype of extra-pelvic endometriosis; and the patients present with a painful abdominal mass that is particularly aggravated by menstruation. Ultrasound and MRI are the recommended diagnostic tools for the evaluation of the mass lesions. Biopsy is performed when calcifications in the granulation tissue cannot be differentiated from chronic blood products. Susceptibility weighted imaging (SWI) is a relatively new MR technique where the image contrast is mainly based on magnetic susceptibility differences. SWI has higher sensitivity to blood products compared to conventional MRI sequences. Although it has been mostly used in neuroimaging studies, recent studies have shown that it provides additional diagnostic information abdominal imaging. In this article, we aim to demonstrate the diagnostic utility of SWI for lesions of abdominal wall endometriosis. Case: A 29-year-old woman with a history of Caesarean-section delivery five years ago presented with a cyclic pain and slowly growing abdominal mass located superior to the Caesarean incision scar on the left side of the midline. A heterogeneous hypoechoic solid mass was detected ultrasonographically underneath the fascia of rectus muscle. On MRI, a solid heterogeneous enhancing lesion located anterior to the rectus muscle was seen in which blood products and calcifications could not be differentiated by their signal intensities. On SWI sequence, signal voids within the lesion on magnitude images were hyperintense on phase images and this excluded calcifications endorsing endometriosis as diagnosis. Conclusion: SWI imaging with its high sensitivity to blood products, contributes to the diagnosis of abdominal wall endometriosis by depicting different phases of hemorrhage during menstruation and non-menstruating days. Another advantage of SWI is the ability to differentiate between blood products and calcification which provides additional value to improve diagnostic ability of pelvic MRI.

Accuracy of SWI sequences compared to T2*-weighted gradient echo sequences in the detection of cerebral cavernous malformations in the familial form.

The purpose of this study was to assess the accuracy of susceptibility-weighted imaging (SWI), compared with T2*-weighted gradient echo (GRE) imaging in assessing cerebral cavernous malformations. We retrospectively evaluated 21 patients with a familial form of cavernous malformation. Magnetic resonance (MR) protocol included non-enhanced and contrast-enhanced fast-spin echo (FSE) T1-weighted sequences, FSE T2-weighted sequences, fluid-attenuated inversion-recovery (FLAIR), GRE T2*-weighted and SWI sequences. Images were reviewed in consensus by two expert neuroradiologists to assess the location, number, size and conspicuity of the lesions on T2*-weighted GRE and SWI sequences. Statistical differences in the number, size and conspicuity of the lesions seen on the SWI images and the T2*-weighted GRE images were assessed with the nonparametric Wilcoxon signed rank test. The number of cavernous malformations was significantly higher (p < .001) on the SWI images (n = 152) than on T2*-weighted GRE images (n = 56). Lesion size was significantly higher (p < .001) on SWI images (mean: 0.4 cm, SD ± 0.55) than on T2*-weighted GRE sequences (mean: 0.2 cm, SD ± 0.51) and the differences were statistically significant (p < .001). Lesion conspicuity was significant higher (p < .001) on SWI than on T2*-weighted GRE images. In one patient who underwent a 2-month follow-up for the onset of neurologic symptoms related to cerebral hemorrhage, a cerebral hematoma was identified at the site of a cerebral cavernous malformation that was demonstrated only on the SWI images in the previous MR examination. The SWI sequence, being more sensitive to substances which distort the local magnetic field than the GRE T2*W sequence, showed a higher sensitivity in identifying cerebral cavernous malformations. Thus, routine clinical neuroimaging protocol should contain SWI sequences to evaluate patients with (or suspected) cerebral cavernous malformations.

Calcification in Globus Pallidus and Putamen of Multiple Sclerosis Patients Versus Healthy Subjects Using Quantitative Susceptibility Mapping.

BackgroundCalcification has been well reported in basal ganglia and it grows rapidly in globus pallidus (GP) followed by putamen (PUT) and caudate nucleus because of their high metabolic rate and displays high susceptibility effects. Therefore, the current study focused on magnetic susceptibility effect of calcium content in normal and diseased tissue due to metabolic changes.ObjectivesTo evaluate calcium content in GP and PUT structures of multiple sclerosis (MS) patients versus healthy subjects using quantitative susceptibility mapping.Patients and MethodsWe compared 10 MS patients with mean age of 48.3 years (standard deviation [SD]=11.89) with 10 healthy subjects with mean age of 39.6 years (SD=11.52). Scanning of subjects was performed with high resolution (0.5×0.5×2 mm3) using susceptibility weighted imaging sequence on 3 Tesla (Trio-Siemens, Erlangen, Germany). Data was processed in homemade SPIN software to produce susceptibility mapping. Threshold was set in healthy subjects to detect calcium content in PUT and GP structures.ResultsMagnetic susceptibility(x) of calcium content was assessed by number of pixels induced by GP and PUT in MS patients as well as healthy subjects. Two sample t-test was used to assess the difference between susceptibilities of GP and PUT of MS patients (P = 0.06, P > 0.05). Susceptibilities of GP and PUT also showed P = 0.3 in healthy subjects. One way analysis of variance was used to assess the difference of susceptibilities in four variables of both populations. Insignificant results (P = 0.7, P > 0.05) were found among four variables. There was no statistically significant difference between magnetic susceptibilities of both populations.ConclusionStatistical analysis of susceptibilities of MS patients versus healthy subjects found no excess deposition of calcium content in deep gray matter of MS patients. Calcification may not be considered as a biomarker of prognosis in MS.

Susceptibility-Weighted Imaging of Glioma: Update on Current Imaging Status and Future Directions.

Susceptibility-weighted imaging (SWI) provides invaluable insight into glioma pathophysiology and internal tumoral architecture. The physical contribution of intratumoral susceptibility signal (ITSS) may correspond to intralesional hemorrhage, calcification, or tumoral neovascularity. In this review, we present emerging evidence of ITSS for assessment of intratumoral calcification, grading of glioma, and factors influencing the pattern of ITSS in glioblastoma. SWI phase imaging assists in identification of intratumoral calcification that aids in narrowing the differential diagnosis. Development of intratumoral calcification posttreatment of glioma serves as an imaging marker of positive therapy response. Grading of tumors with ITSS using information attributed to microhemorrhage and neovascularity in SWI correlates with MR perfusion parameters and histologic grading of glioma and enriches preoperative prognosis. Quantitative susceptibility mapping may provide a means to discriminate subtle calcifications and hemorrhage in tumor imaging. Recent data suggest ITSS patterns in glioblastoma vary depending on tumoral volume and sublocation and correlate with degree of intratumoral necrosis and neovascularity. Increasingly, there is a recognized role of obtaining contrast-enhanced SWI (CE-SWI) for assessment of tumoral margin in high-grade glioma. Significant higher concentration of gadolinium accumulates at the border of the tumoral invasion zone as seen on the SWI sequence; this results from contrast-induced phase shift that clearly delineates the tumor margin. Lastly, absence of ITSS may aid in differentiation between high-grade glioma and primary CNS lymphoma, which typically shows absence of ITSS. We conclude that SWI and CE-SWI are indispensable tools for diagnosis, preoperative grading, posttherapy surveillance, and assessment of glioma.

Susceptibility–Diffusion Mismatch in Hyperacute Stroke: Correlation with Perfusion–Diffusion Mismatch and Clinical Outcome

A prominent vein (PV) on susceptibility-weighted imaging (SWI) was recently proposed to be a marker of the penumbra. We aimed to compare the utility of SWI and perfusion-weighted imaging (PWI) sequences for the evaluation of the penumbra in hyperacute middle cerebral artery (MCA) stroke, and to determine whether SWI-DWI mismatch is a neuroimaging marker of clinical outcome. A total of 149 consecutive patients with MCA stroke were prospectively enrolled. Magnetic resonance imaging (MRI) was performed within 6 hours of the onset of stroke. The ASPECTS values on diffusion-weighted imaging (DWI), PWI (delayed mean transit time), and SWI (visualization of PVs) were calculated by 2 independent raters. Correlation between PWI-ASPECTS and SWI-ASPECTS was calculated with the Pearson coefficient. Reliability of the PV rating system was calculated by an intraclass correlation coefficient (ICC). Favorable outcome was defined as a modified Rankin Scale score of 0-2 at 3 months for the 88 patients who received thrombolytic therapy. The ASPECTS-SWI and ASPECTS-PWI scores showed a good correlation (Pearson coefficient of .69, P <.001). The reproducibility between the findings of the junior and the senior radiologists was excellent with an ICC of .89 (confidence interval of 95% (IC95): .85-.92, P <.001). However, neither SWI-DWI mismatch nor PWI-SWI mismatch was associated with clinical outcome. SWI and PWI were complementary but not commutable for the assessment of the penumbra. Susceptibility-diffusion mismatch was not found in this study to have predictive value for stroke outcome.

The value of susceptibility weighted imaging in evaluating ischemia-reperfusion injury of the rabbit kidney

Objective To explore the value of susceptibility weighted imaging (SWI) in the quantitative analysis of ischemia- reperfusion injury (IRI) of the rabbit kidneys. Methods Thirty New Zealand white rabbits were randomly assigned to IRI group (n=24, operation with clamping) and Sham group (n=6, operation without clamping). Left renal ischemia-reperfusion was performed by occlusion (calmping) of the left renal arterial for 60 minutes, followed by reperfusion. All the rabbits underwent MRI including T2WI and SWI before and 0.5 h, 12 h, 24 h and 48 h after the establishments of models. Three rabbits in IRI group were randomly sacrificed 0.5 h, 12 h, and 24 h after the establishment of model. The rest of the rabbits in IRI group and 6 rabbits in sham group were sacrificed for pathological examination 48 h after the establishment of model All specimen were cut into slices and stained with hematoxylin-eosin (HE). Region of interest (ROI) was manually created by outlining the inner medulla, inner stripe of outer medulla, outer stripe of outer medulla, and cortex, then relative signal-to-noise ratio of the kidney (rSNR) to muscle in SWI sequence was recorded. and compared with histopathologic features. One- way ANOVA was performed to compare difference of rSNR to muscle in respective location at 5 time-points between Sham group and IRI group, and the differences between groups were tested using repetitive measure analysis of variance, repetitive measure analysis of variance was performed to compare difference of rSNR to muscle in respective location at respective time- points between Sham group and IRI group. Results rSNR value in the inner medulla 0.5 h, 12 h, 24 h and 48 h after the establishments of models were 0.28±0.04, 0.98±0.14, 0.69±0.07, 0.57±0.06, 0.43±0.03, respectively (F=69.82,P<0.01), the inner stripe of outer medulla at the five timepoints 0.08±0.03, 0.57±0.05, 0.32±0.07, 0.16±0.02, 0.04±0.01, respectively (F=16.59,P<0.01), the outer stripe of outer medulla were 0.31±0.04, 0.86±0.09, 0.65±0.07, 0.55±0.06 0.43±0.04 (F=67.52,P<0.01), respectively,the cortex 0.05±0.01, 0.80±0.04, 0.68±0.07, 0.47±0.07, 0.36±0.08, respectively (F=118.96, P< 0.01). The difference of the rSNR was statistically significant in the inner medulla, inner stripe of outer medulla, outer stripe of outer medulla, and cortex at the five different time-points. The differences between two groups were significant (F=206.29, 14.25, 42.8, 39.12,P all<0.05). The pathological findings in Sham group included normalglomerular structure l, clear cavity of tubular, no interstitial hyperemia and edema. The pathological findings in IRI group demonstated, at 0.5 h after IRI, Bowman's capsule cavity expansion, glomerular shrinkage, swelling of renal tubular epithelial cells, vacuoles degeneration, the tube cavity expansion, interstitial edema and congestion ecta became slender, andat 12 h after IR, Bowman's capsule expansion became more obvious, foam degeneration of renal tubular epithelial cells, apoptosis, partial loss of the brush border of the proximal convoluted tubule, formation of protein cast, and a small amount of inflammatory cells appeared in the renal interstitium, swelling of endothelial cells of the vasa recta, congestion of small vessels, and at 24 and 48 h after IRI, more serious injury of renal tubular in the outer stripe of outer medulla , massive necrosis of renal tubular epithelial cells, apoptosis, parts of the renal tubular had the contour lines, and renal tubular outline, increment in inflammatory cells, red cell and protein cast. Conclusion rSNR of SWI in the inner medulla, inner stripe of outer medulla, outer stripe of outer medulla, and cortex of the kidney varies with the degree of IRI over time, and is consistent with corresponding pathological feature, suggesting SWI is useful imaging tool to detect early damage of renal IRI quantitatively. Key words: Reperfusion injury; Magnetic resonance imaging; Pathology

Do Left- and Right-Handed People Have Similar Iron Deposition in the Basal Ganglia?

This study aimed to investigate whether right-, left-, or mixed-handed people differ in terms of iron deposition using susceptibility weighted imaging in healthy subjects. A total of 87 people (right-handed, 51 subjects; left-handed, 19 subjects; mixed-handed, 17 subjects) aged 20 to 40 years participated. All underwent magnetic resonance examination, including conventional and susceptibility weighted imaging sequences. Phase images were used to quantify iron deposition in the head of the caudate nucleus and lenticular nucleus. The radian angle value was calculated and compared between the 3 (right-, left-, or mixed-handed) groups. There was no significant difference in the radian angle values between left-, right-, or mixed-handed people for either the right or left side of the caudate nucleus head. However, the amount of iron deposition in the left lenticular nucleus was significantly higher for right-handed than for the left-handed subjects (P < 0.001) and significantly higher for mixed-handed than for left-handed subjects (P = 0.006). In addition, the amount of iron deposition in the right lenticular nucleus was significantly lower for left-handed than for right-handed subjects (P < 0.001). The results revealed no significant differences in iron deposition in the head of the caudate nucleus. However, there was a significant difference in iron deposition in the lenticular nucleus between left- and right-handed subjects and between left- and mixed-handed subjects.

A fully flow-compensated multiecho susceptibility-weighted imaging sequence: The effects of acceleration and background field on flow compensation.

To present a fully flow-compensated multiecho gradient echo sequence that can be used for MR angiography (MRA), susceptibility weighted imaging (SWI), and quantitative susceptibility mapping (QSM) and to study the effects of flow acceleration and background field gradients on flow compensation. The quality of flow compensation was evaluated using the data from eight volunteers. The effects of flow acceleration were studied by changing the polarities of the readout gradients in two consecutive scans. The background field was used to estimate the phase errors of flow compensation in the presence of field inhomogeneities. SWI and QSM data were generated with confounding arterial phase removed. T2 * maps were obtained from the multiecho data to estimate T2 * of arterial blood. Reasonable flow compensation was achieved. Nevertheless, background field gradients and acceleration-induced phase errors were found to be as large as π/2 and π/3, respectively, both in agreement with theory. T2 * was measured as 82 ± 4 ms and 74 ± 9 ms for arteries inside and outside the brain, respectively, at 3T. High-quality MRA, SWI, and QSM data can be obtained simultaneously. Masking out the arteries to remove the phase due to flow acceleration and background field gradients improves the quality of both SWI and QSM data. Magn Reson Med 76:478-489, 2016. © 2015 Wiley Periodicals, Inc.

P99. Predictors of new cerebral microbleeds in patients with antiplatelet drug therapy

Background Cerebral microbleeds (CMBs) are an MRI marker of vascular damage in the brain and are associated with an increased risk for ischemic and especially hemorrhagic stroke. CMBs are known to be more prevalent in patients who take antiplatelet drug therapy, which is commonly used for secondary prevention in patients with ischemic stroke. The aim of the present study was to evaluate the usefulness of susceptibility weighted imaging (SWI) to identify patients at high risk for the development of new CMBs under antiplatelet drug therapy. Methods We examined 58 patients with a first ischemic stroke or transitory ischemic attack (TIA) in whom a secondary prevention with an antiplatelet drug therapy was initiated. In the first week after the onset of stroke a 3T MRI including a susceptibility weighted imaging (SWI) sequence was performed. 40 patients were available for follow-up MRI after 6 months. The association of baseline CMBs with presence and number of new CMBs at follow-up was investigated using stepwise logistic regression and Spearman’s correlation coefficient. Also, the association of cardiovascular risk factors and stroke etiology with the presence and number of CMBs at baseline and follow-up was analysed using the same statistical methods. Results When including only the patients with CMBs at baseline, there was a significant association between the number of CMBs at baseline and the number of new CMBs. This association was not present when including all patients. At follow-up the presence and number of CMBs was significantly associated with hyperlipidemia. At this stage there was a significant correlation between the number of CMBs and atherothrombotic stroke. The number of new CMBs was significantly associated with the cardiovascular risk factors male sex and age >70 years. It also correlated significantly with atherothrombotic stroke. Conclusions Risk factors associated with the presence of or number of new CMBs when taking antiplatelet therapy included several known cardiovascular risk factors like hyperlipidemia, male sex and age >70 years. Also, atherothrombotic stroke was significantly associated with the presence or number of new CMBs. The number of CMBs in the SWI sequence was only associated to the number of new CMBs when patients without CMBs were excluded. It might therefore only be helpful in patients who already show CMBs before taking antiplatelet drug therapy.

The diagnostic efficacy of quantitative liver MR imaging with diffusion-weighted, SWI, and hepato-specific contrast-enhanced sequences in staging liver fibrosis--a multiparametric approach.

To assess the diagnostic efficacy of multiparametric MRI using quantitative measurements of the apparent diffusion coefficient (ADC) of the liver parenchyma on diffusion-weighted imaging (DWI), signal intensity (SI) on susceptibility-weighted imaging (SWI), and gadoxetic acid-enhanced T1-weighted imaging during the hepatobiliary phase for the staging of liver fibrosis. Seventy-seven patients underwent a 3T MRI examination, including DWI/SWI sequences and gadoxetic acid-enhanced T1-weighted MRI. Liver fibrosis according to liver biopsy was staged using the Metavir fibrosis score: F0 (n = 21, 27.3%); F1 (n = 7, 9.1%); F2 (n = 8, 10.4%); F3 (n = 12, 15.6%); and F4 (n = 29, 37.7%). SI of the liver was defined using region-of-interest measurements to calculate the ADC values, the relative enhancement (RE) in the hepatobiliary phase, and the liver-to-muscle ratio (LMR) measurements for SWI. The values of RE, LMR, and ADC measurements were statistically significantly different among the five fibrosis stages (p < 0.004). Combining the three parameters in a multiparametric approach, the AUC for detecting F1 stage or greater (≥ F1) was 94%, for F2 or greater (≥F2) was 95%, for F3 or greater (≥F3) was 90%, and for stage F4 was 93%. Multiparametric MRI is an efficient non-invasive diagnostic tool for the staging of liver fibrosis. • Multiparametric MRI has high accuracy in predicting moderate or greater liver fibrosis. • Relative enhancement post- gadoxetic acid is an independent predictor of liver fibrosis. • Liver SWI signal intensity and ADC values enhance the diagnostic ability.

Characterization of multiple sclerosis plaques using susceptibility-weighted imaging at 1.5 T: can perivenular localization improve specificity of imaging criteria?

The purpose of this study was to determine if magnetic resonance (MR) susceptibility-weighted imaging (SWI) can increase the conspicuity of corticomedullary veins within the white matter lesions of multiple sclerosis (MS) and, thus, aid in distinguishing plaques from leukoaraiosis. We retrospectively reviewed MR examinations in 21 patients with a clinical diagnosis of MS and 18 patients with a clinical diagnosis of dementia. Examinations included fluid-attenuated inversion recovery (FLAIR) and SWI sequences obtained in the axial plane. Lesions greater than 5 mm in diameter on the axial FLAIR sequence were identified as periventricular or subcortical. Three neuroradiologists evaluated SWI images, compared with FLAIR, for a centrally located signal void in each lesion that was scored as present, absent, or indeterminate. In patients with MS, central veins were present in both periventricular lesions (75%, P < 0.001) and subcortical lesions (52%, P < 0.005). In patients with dementia, central veins were seen much less frequently in subcortical lesions (14%, P < 0.001); their association with periventricular lesions was not significant. Central veins were detected in MS lesions with a significantly greater frequency than that in patients with dementia. Susceptibility-weighted imaging increases the conspicuity of corticomedullary veins and may improve the specificity of MR findings in MS.

Abstract W MP119: Sensitivity and Reliability of MRI SWI Compared With GRE Sequences for Detecting Microbleeds in a Community Population

Background: MRI susceptibility-weighted imaging (SWI) provides better contrast and is typically done at higher spatial resolution than MRI T2*-weighted gradient-recalled echo (GRE), increasing the sensitivity for cerebral microbleed (CMB) detection. However, few studies have implemented SWI and GRE in the same scan session, and there is uncertainty regarding whether findings on SWI are comparable to findings on GRE. We compared the sensitivity and reliability of SWI vs. GRE sequences for detecting CMBs in a community population. Methods: Using a standardized case report form, two radiologists independently identified CMBs on SWI and GRE in 247 participants age 40 to 75 in the community-based Prospective Urban Rural (PURE) MIND substudy. MRI was performed on the same GE 3T MRI scanner using typical clinical sequence parameters. SWI and GRE were read &gt;2 weeks apart. After the independent readings, the two raters met to determine CMB presence by consensus. Results: Mean age was 58.0±7.6 years, 65% were women, 23% had hypertension and 8.6% had diabetes. By consensus, CMBs were seen in 30 participants (12.2%) on SWI but in only 13 (5.2%) on GRE (p&lt;0.001). Inter-rater reliability was moderately good on SWI (kappa 0.52, 95% CI 0.34-0.71) and GRE (kappa 0.51, 95% CI 0.30-0.73). A pattern of lobar CMBs, with or without cerebellar CMBs but without other non-lobar CMBs, was seen in 8/13 (62%) with GRE CMBs and 19/30 with SWI CMBs (63%). Increased age and diabetes were associated with CMBs on both SWI and GRE. Conclusions: More than twice as many CMBs were detected on MRI SWI compared to GRE, with the same inter-rater reliability. SWI may be the preferred sequence for detecting CMBs, given its greater sensitivity. However, CMB distribution patterns and risk factors were similar regardless of sequence type, suggesting that the findings of studies using either sequence are comparable.

Magnetic Resonance Imaging Findings in Cerebral Venous Thrombosis due to Behcet's Disease and the Importance of Susceptibility-Weighted Imaging: Case Report

Cerebral venous thrombosis (CVT) is an uncommon disorder that can lead to an unfavorable prognosis and even be fatal in some cases. CVT is seen mainly in females, especially those between the ages of 20 and 35 years. The disorder has many etiologic factors. This report presents the case of a 34-year-old male patient with Behcet’s disease admitted with complaints of headache and vomiting. The major venous vascular structures that were visible in cranial magnetic resonance imaging (MRI) and MR venography were found to be filled with thrombosis. The patient’s susceptibilityweighted imaging (SWI) revealed marked hypointensities consistent with thrombosis in the transverse sinus, sigmoid sinus, and in the venous vascular structures of the posterior fossa. Thus, it was found that cerebral venous thrombosis due to Behcet disease could clearly be determined by the SWI sequence; in addition, thrombosis by the venous vascularity in veins of the posterior fossa were more visible than via the other MR sequences. The conclusion was made that SWI can promptly demonstrate cerebral venous thrombosis, contribute to the diagnosis, and provide useful additional information.