Black-blood Magnetic Resonance Research Articles

MR Imaging Measures of Intracranial Atherosclerosis in a Population-based Study.

Purpose To implement a magnetic resonance (MR) imaging protocol to measure intracranial atherosclerotic disease (ICAD) in a population-based multicenter study and report examination and reader reliability of these MR imaging measurements and descriptive statistics representative of the general population. Materials and Methods This prospective study was approved by the institutional review boards and compliant with HIPAA. Atherosclerosis Risk in Communities (ARIC) study participants (n = 1980) underwent brain MR imaging from 2011 to 2013 at four ARIC sites. Imaging included three-dimensional black-blood MR imaging and time-of-flight MR angiography. One hundred two participants returned for repeat MR imaging to estimate examination and reader variability. Plaque presence according to vessel segment was recorded. Quantitative measurements included lumen size and degree of stenosis, wall and/or plaque thickness, area and volume, and normalized wall index for each vessel segment. Reliability was assessed with percentage agreement, κ statistics, and intraclass correlation coefficients. Results Of the 1980 participants, 1755 (mean age, 77.6 years; 1026 women [59%]; 1234 white [70%]) completed examinations with adequate to excellent image quality. The weighted ICAD prevalence was 34.4% (637 of 1755 participants) and was higher in men than women (38.5% [302 of 729 participants] vs 31.7% [335 of 1026 participants], respectively; P = .012) and in African Americans compared with whites (41.1% [215 of 518 participants] vs 32.4% [422 of 1234 participants], respectively; P = .002). Percentage agreement of plaque identification per participant was 87.0% (interreader estimate), 89.2% (intrareader estimate), and 89.9% (examination estimate). Examination and reader reliability ranged from fair to good (κ, 0.50-0.78) for plaque presence and from good to excellent (intraclass correlation coefficient, 0.69-0.99) for quantitative vessel wall measurements. Conclusion Vessel wall MR imaging is a reliable tool for identifying and measuring ICAD and provided insight into ICAD distribution across a U.S. community-based population. (©) RSNA, 2016 Online supplemental material is available for this article.

Cervical carotid plaque evaluation using 3D T1-weighted black-blood magnetic resonance imaging: Comparison of turbo field-echo and turbo spin-echo sequences

PurposeTo compare the capability of three-dimensional (3D) T1-weighted turbo field-echo (TFE) black-blood (BB) magnetic resonance imaging (MRI) and turbo-spin echo (TSE) BB MRI for discerning carotid plaques and the difference of signal intensities of the plaques from that of adjacent muscle in patients with cervical carotid stenosis. MethodsCervical carotid stenosis was evaluated by 3.0-T MR in 43 patients (38 men and 5 women; age, 36–83 years; mean age, 70 years) during 8 months. The carotid BB MRI comprised 3D T1-weighted TSE BB (T1-TSEBB) and 3D T1-weighted TFE BB (T1-TFEBB) sequences. The delineation of the carotid plaque border was evaluated in comparison with digital subtraction angiography (DSA). The border between the plaque and vessel lumen was rated visually (4-point analysis) and quantitatively (contrast-to-noise ratio). The signal-intensity ratio (SIR) of the plaque to the adjacent muscle was also measured. Data of 3D T1-TSEBB and 3D T1-TFEBB were compared statistically using the Wilcoxon signed-rank test. ResultsVisual and quantitative analyses revealed that the border between the plaque and vessel lumen was better delineated on 3D T1-TSEBB MRI than on 3D T1-TFEBB MRI (p<0.01, respectively). SIR of the plaque-to-adjacent muscle was higher on 3D T1- TFEBB MRI than on 3D T1-TSEBB MRI (p<0.05). High signal plaques with a SIR of >1.5 were underestimated on 3D T1-TSEBB MRI. Conclusions3D T1-TSEBB MRI was superior to 3D T1-TFEBB MRI for delineating carotid plaques; however, high signal plaques were underestimated on 3D T1-TSEBB MRI.

Patterns and Implications of Intracranial Arterial Remodeling in Stroke Patients.

Preliminary studies suggest that intracranial arteries are capable of accommodating plaque formation by remodeling. We sought to study the ability and extent of intracranial arteries to remodel using 3-dimensional high-resolution black blood magnetic resonance imaging and investigate its relation to ischemic events. Forty-two patients with cerebrovascular ischemic events underwent 3-dimensional time-of-flight magnetic resonance angiography and contrast-enhanced black blood magnetic resonance imaging examinations at 3 T for intracranial atherosclerotic disease. Each plaque was classified by location (eg, posterior versus anterior circulation) and its likelihood to have caused a stroke identified on magnetic resonance imaging (culprit, indeterminate, or nonculprit). Lumen area, outer wall area, and wall area were measured at the lesion and reference sites. Plaque burden was calculated as wall area divided by outer wall area. The arterial remodeling ratio (RR) was calculated as outer wall area at the lesion site divided by outer wall area at the reference site after adjusting for vessel tapering. Arterial remodeling was categorized as positive if RR>1.05, intermediate if 0.95≤RR≤1.05, and negative if RR<0.95. One hundred and thirty-seven plaques were identified in 42 patients (37% [50] posterior and 63% [87] anterior). Compared with anterior circulation plaques, posterior circulation plaques had a larger plaque burden (77.7±15.7 versus 69.0±14.0; P=0.008), higher RR (1.14±0.38 versus 0.95±0.32; P=0.002), and more often exhibited positive remodeling (54.0% versus29.9%; P=0.011). Positive remodeling was marginally associated with downstream stroke presence when adjusted for plaque burden (odds ratio 1.34, 95% confidence interval: 0.99-1.81). Intracranial arteries remodel in response to plaque formation, and posterior circulation arteries have a greater capacity for positive remodeling and, consequently, may more likely elude angiographic detection. Arterial remodeling may provide insight into stroke risk.

Advantage in Bright-blood and Black-blood Magnetic Resonance Imaging with High-resolution for Analysis of Carotid Atherosclerotic Plaques.

Background:About 50% of the cerebral ischemia events are induced by intracranial and extracranial atherosclerosis. This study aimed to evaluate the feasibility and accuracy for displaying atherosclerotic plaques in carotid arteries and analyzing their ingredients by using high-resolution new magnetic resonance imaging (MRI) techniques.Methods:Totally, 49 patients suspected of extracranial carotid artery stenosis were subjected to cranial MRI scan and magnetic resonance angiography (MRA) examination on carotid arteries, and high-resolution bright-blood and black-blood MRI analysis was carried out within 1 week. Digital subtraction angiography (DSA) examination was carried out for 16 patients within 1 month.Results:Totally, 103 plaques were detected in the 49 patients, which were characterized by localized or diffusive thickening of the vessel wall, with the intrusion of crescent-shaped abnormal signal into lumens. Fibrous cap was displayed as isointensity in T1-weighted image (T1WI) and hyperintensities in proton density weighted image (PDWI) and T2-weighted image (T2WI), lipid core was displayed as isointensity or slight hyperintensities in T1WI, isointensity, hyperintensities or hypointensity in PDWI, and hypointensity in T2WI. Calcification in plaques was detected in 11 patients. Eight patients were detected with irregular plaque surface or ulcerative plaques, which were characterized by irregular intravascular space surface in the black-blood sequences, black hypointensity band was not detected in three-dimensional time-of-flight, or the hypointensity band was not continuous, and intrusion of hyperintensities into plaques can be detected. Bright-blood and black-blood techniques were highly correlated with the diagnosis of contrast-enhanced MRA in angiostenosis degree, Rs = 0.97, P < 0.001. In comparison to DSA, the sensitivity, specificity, and accuracy of MRI diagnosis of stenosis for ≥50% were 88.9%, 100%, and 97.9%, respectively.Conclusions:High-resolution bright-blood and black-blood sequential MRI analysis can accurately analyze ingredients in atherosclerotic plaques. Determined by DSA, MRI diagnosis of stenosis can correctly evaluate the serious degree of arteriostenosis.

Joint segmentation of lumen and outer wall from femoral artery MR images: Towards 3D imaging measurements of peripheral arterial disease

Three-dimensional (3D) measurements of peripheral arterial disease (PAD) plaque burden extracted from fast black-blood magnetic resonance (MR) images have shown to be more predictive of clinical outcomes than PAD stenosis measurements. To this end, accurate segmentation of the femoral artery lumen and outer wall is required for generating volumetric measurements of PAD plaque burden. Here, we propose a semi-automated algorithm to jointly segment the femoral artery lumen and outer wall surfaces from 3D black-blood MR images, which are reoriented and reconstructed along the medial axis of the femoral artery to obtain improved spatial coherence between slices of the long, thin femoral artery and to reduce computation time. The developed segmentation algorithm enforces two priors in a global optimization manner: the spatial consistency between the adjacent 2D slices and the anatomical region order between the femoral artery lumen and outer wall surfaces. The formulated combinatorial optimization problem for segmentation is solved globally and exactly by means of convex relaxation using a coupled continuous max-flow (CCMF) model, which is a dual formulation to the convex relaxed optimization problem. In addition, the CCMF model directly derives an efficient duality-based algorithm based on the modern multiplier augmented optimization scheme, which has been implemented on a GPU for fast computation. The computed segmentations from the developed algorithm were compared to manual delineations from experts using 20 black-blood MR images. The developed algorithm yielded both high accuracy (Dice similarity coefficients ≥ 87% for both the lumen and outer wall surfaces) and high reproducibility (intra-class correlation coefficient of 0.95 for generating vessel wall area), while outperforming the state-of-the-art method in terms of computational time by a factor of ≈ 20.

Clinical value of black-blood high-resolution magnetic resonance imaging for intracranial atherosclerotic plaques.

The present study evaluated the value of black-blood high-resolution magnetic resonance imaging (HRMRI) for the visualization of intracranial atherosclerosis (ICAS) plaques. A total of 110 patients with cerebral artery or vertebrobasilar stenosis, vessel occlusion or a significantly weakened signal in black-blood magnetic resonance angiography (MRA; three-dimensional time-of-flight) were examined. Black-blood MRA was used to observe whether plaques were present in the abnormal vascular walls. Among the 110 patients with cerebral infarction, 16 cases presented with no significant abnormality of the lumen and walls, while plaques were observed in 94 cases. The plaques were categorized according to their signal characteristics, which resulted in the identification of four cases of type I and II plaques, 15 cases of type III, 26 cases of type IV and V, 23 cases of type VI, 11 cases of type VII, 14 cases of type VIII and one case of a mixed plaque. In summary, 3.0 T black-blood HRMRI was demonstrated to objectively exhibit characteristics of various types of ICAS plaques. Therefore, this imaging technique may be applied as a key method for the clinical non-invasive determination of ICAS plaques.

Fast segmentation of the femoral arteries from 3D MR images: A tool for rapid assessment of peripheral arterial disease.

The peripheral arterial disease is a powerful indicator of coexistent generalized atherosclerosis. As plaques in femoral arteries are diffused and can span a length of 30 cm, a large coverage of the arteries is required to assess the full extent of atherosclerosis. Recent development of 3D black-blood magnetic resonance imaging sequences has allowed fast acquisition of images with an extended longitudinal coverage. Vessel wall volume quantification requires the segmentation of the lumen and outer wall boundaries, and conventional manual planimetry would be too time-consuming to be feasible for analyzing images with such a large coverage. To address this challenge in image analysis, this work introduces an efficient 3D algorithm to segment the lumen and outer wall boundaries for plaque and vessel wall quantification in the femoral artery. To generate the initial lumen surface, a user identified the location of the lumen centers manually on a set of transverse images with a user-specified interslice distance (ISD). A number of geometric operators were introduced to automatically adjust the initial lumen surface based on pixel intensity and gradient along the boundary and at the center of each transverse slice. The adjusted surface was optimized by a 3D deformable model driven by the local stiffness force and external force based on image gradient. The optimized lumen surface was expanded to obtain the initial outer wall surface, which was subsequently optimized by the 3D deformable model. The algorithm was executed with and without adjustment of the initial lumen surface and for three different selections of ISD: 10, 20, and 30 mm. The segmentation accuracy was improved in a statistically significant way with the introduction of initial lumen surface adjustment, but was insensitive to the ISD setting. When compared with the manual segmentation, the settings with adjustment have, on average, mean absolute differences (MADs) of 0.28 and 0.36 mm, respectively, for lumen and outer wall segmentations, which are significantly lower than those obtained when the adjustment operators were not applied (MAD = 0.43 and 0.59 mm for lumen and outer wall segmentations). The algorithm took about 1% of the time required for manual segmentation to complete segmenting the whole 3D femoral artery. The proposed semiautomatic algorithm generated accurate lumen and outer wall boundaries from 3D black-blood MR images with few user interactions, thereby allowing rapid and streamlined assessment of plaque burden in the femoral arteries.

Varicella-Zoster Virus Vasculopathy: A Case Report Demonstrating Vasculitis using Black-Blood MRI.

Infections are rare but important causes of stroke. Among these, varicella zoster virus has been known to cause ischemic stroke. During an attack of herpes zoster ophthalmicus, it has been hypothesized that the virus replicates in the trigeminal ganglion and travels via the trigeminal nerve centrally to cause cerebral vasculopathy. Here we present a case of a 69 year-old Caucasian immunocompromised woman who suffered recurrent ischemic infarcts within the same vascular distribution following an episode of zoster ophthalmicus three months prior. An imaging technique termed black-blood magnetic resonance imaging was utilized to aid in the diagnosis of cerebral vasculitis. The case is used to provide a literature review of the pathogenesis, diagnosis, and treatment of cerebral varicella zoster vasculopathy. In situations where an isolated unilateral cerebral vasculopathy is identified, neurologists are urged to consider varicella zoster as a treatable etiologic agent, as untreated vasculopathy can lead to further strokes.

Predictors of change in carotid atherosclerotic plaque inflammation and burden as measured by 18-FDG-PET and MRI, respectively, in the dal-PLAQUE study

Baseline predictors of response to treatment of patients with coronary heart disease (CHD) with respect to vascular inflammation and atherosclerotic plaque burden are poorly understood. From post hoc analysis of the dal-PLAQUE study (NCT00655473), 18F-fluorodeoxyglucose-positron emission tomography (18-FDG-PET) imaging and carotid black blood magnetic resonance imaging (MRI) were used to track changes in these vascular parameters. Baseline demographics, imaging, and biomarkers were collected/measured in 130 patients with CHD or CHD risk-equivalents, and imaging follow-up at 6 months (PET) and 24 months (MRI) was performed. Using stepwise linear regression, predictors of change in carotid plaque inflammation by PET [target-to-background ratio (TBR), n = 92] and plaque burden by MRI [wall area (WA) and total vessel area (TVA), n = 89] were determined. Variables with p < 0.05 in multivariable models were considered independently significant. Interleukin-6, systolic blood pressure and standard deviation of wall thickness (WT) at baseline were independently positively associated with 18-FDG uptake (mean of maximum [MeanMax] TBR change over 6 months). Mean of mean TBR, phospholipase A2, apolipoprotein A-I, and high-sensitivity C-reactive protein at baseline were independently negatively associated with MeanMax TBR change over 6 months. Mean WT and plasminogen activator inhibitor-1 (PAI-1) activity at baseline, and age, were independently associated with change in WA over 24 months. For TVA changes; mean WA and PAI-1 activity at baseline, age, and female gender were independent predictors. These findings may help determine patients most suitable for clinical trials employing plaque inflammation or burden changes as endpoints.

Vascular Remodeling and Plaque Vulnerability in a Rabbit Model of Atherosclerosis: Comparison of Delayed-Enhancement MR Imaging with an Elastin-specific Contrast Agent and Unenhanced Black-Blood MR Imaging

To compare delayed-enhancement (DE) magnetic resonance (MR) imaging with an elastin-specific contrast agent and unenhanced black-blood (BB) MR imaging with regard to vessel wall delineation and assessment of vascular remodeling and to test the prospective value for predicting plaque disruption in a rabbit model of atherosclerosis. All procedures were approved by the animal ethics committee. Atherosclerosis was induced in 14 New Zealand White rabbits by means of a 1% cholesterol diet and endothelial denudation. Plaque disruption was triggered with Russell's viper venom and histamine. Animals with atherosclerosis were imaged before triggering to identify plaques and vascular remodeling and after triggering to identify thrombus. Plaques were classified as nondisrupted (stable) or disrupted (vulnerable). Control rabbits fed a regular diet were imaged twice. Unenhanced T1-weighted BB MR imaging, DE MR imaging with an elastin-specific contrast agent, and T1 mapping were used to assess vascular remodeling and calculate the plaque area and vessel wall relaxation rate (R1 = 1/T1). Elastin was quantified by using elastica-van Gieson stain. Group comparisons were analyzed with the Mann-Whitney or paired t test. Agreement between methods was performed with Bland-Altman analysis. Unenhanced T1-weighted BB MR imaging and DE MR imaging showed that, compared with nondisrupted plaques, disrupted plaques had larger plaque area (T1-weighted BB MR imaging: 5.1 mm(2) vs 5.7 mm(2); DE MR imaging: 6.0 mm(2) vs 7.9 mm(2); P < .001) and vessel area (T1-weighted BB MR imaging: 11.8 mm(2) vs 14.3 mm(2); DE MR imaging: 10.8 mm(2) vs 13.9 mm(2); P < .001) and underwent positive remodeling. Assessment of positive remodeling with DE MR imaging enabled better prediction of plaque disruption compared to that with unenhanced T1-weighted BB imaging (sensitivity: 83.7% vs 58.1%). DE MR imaging showed a stronger agreement with histologic findings, whereas the vessel area was overestimated with unenhanced T1-weighted BB imaging. Compared with unenhanced T1-weighted BB MR imaging, DE MR imaging with an elastin-specific contrast agent enables more accurate assessment of vascular remodeling in the prediction of vulnerable plaque.

Intracranial Plaque Enhancement in Patients with Cerebrovascular Events on High-Spatial-Resolution MR Images

To characterize intracranial plaque inflammation in vivo by using three-dimensional (3D) high-spatial-resolution contrast material-enhanced black-blood (BB) magnetic resonance (MR) imaging and to investigate the relationship between intracranial plaque inflammation and cerebrovascular ischemic events. The study was approved by the institutional review board and was HIPAA compliant. Twenty-seven patients (19 men; mean age, 56.8 years ± 12.4 [standard deviation]) with cerebrovascular ischemic events (acute stroke, n = 20; subacute stroke, n = 2; chronic stroke, n = 3; transient ischemic attack, n = 2) underwent 3D time-of-flight MR angiography and contrast-enhanced BB 3-T MR imaging for intracranial atherosclerotic disease. Each identified plaque was classified as either culprit (the only or most stenotic lesion upstream from a stroke), probably culprit (not the most stenotic lesion upstream from a stroke), or nonculprit (not within the vascular territory of a stroke). Plaque contrast enhancement was categorized on BB MR images (grade 0, enhancement less than or equal to that of normal arterial walls seen elsewhere; grade 1, enhancement greater than grade 0 but less than that of the pituitary infundibulum; grade 2, enhancement greater than or equal to that of the pituitary infundibulum), and degree of contrast enhancement was calculated. Associations of the likelihood of being a culprit lesion with both plaque contrast enhancement and plaque thickness were estimated with ordinal logistic regression. Seventy-eight plaques were identified in 20 patients with acute stroke (21 [27%] culprit, 12 [15%] probably culprit, and 45 [58%] nonculprit plaques). In these patients, grade 2 contrast enhancement was associated with culprit plaques (odds ratio 34.6; 95% confidence interval: 4.5, 266.5 compared with grade 0) when adjusted for plaque thickness. Grade 0 was observed in only nonculprit plaques. Culprit plaques had a higher degree of contrast enhancement than did nonculprit plaques (25.9% ± 13.4 vs 13.6% ± 12.3, P = .003). Contrast enhancement of intracranial atherosclerotic plaque is associated with its likelihood to have caused a recent ischemic event and may serve as a marker of its stability, thereby providing important insight into stroke risk.

Atherosclerosis imaging using 3D black blood TSE SPACEvs2D TSE

To compare 3D Black Blood turbo spin echo (TSE) sampling perfection with application-optimized contrast using different flip angle evolution (SPACE) vs 2D TSE in evaluating atherosclerotic plaques in multiple vascular territories. The carotid, aortic, and femoral arterial walls of 16 patients at risk for cardiovascular or atherosclerotic disease were studied using both 3D black blood magnetic resonance imaging SPACE and conventional 2D multi-contrast TSE sequences using a consolidated imaging approach in the same imaging session. Qualitative and quantitative analyses were performed on the images. Agreement of morphometric measurements between the two imaging sequences was assessed using a two-sample t-test, calculation of the intra-class correlation coefficient and by the method of linear regression and Bland-Altman analyses. No statistically significant qualitative differences were found between the 3D SPACE and 2D TSE techniques for images of the carotids and aorta. For images of the femoral arteries, however, there were statistically significant differences in all four qualitative scores between the two techniques. Using the current approach, 3D SPACE is suboptimal for femoral imaging. However, this may be due to coils not being optimized for femoral imaging. Quantitatively, in our study, higher mean total vessel area measurements for the 3D SPACE technique across all three vascular beds were observed. No significant differences in lumen area for both the right and left carotids were observed between the two techniques. Overall, a significant-correlation existed between measures obtained between the two approaches. Qualitative and quantitative measurements between 3D SPACE and 2D TSE techniques are comparable. 3D-SPACE may be a feasible approach in the evaluation of cardiovascular patients.

Effects of respiratory motion on coronary wall MR imaging: a quantitative study of older adults

The aim of the present study is to assess the effects of respiratory motion on the image quality of two-dimensional (2D), free-breathing, black-blood coronary wall magnetic resonance (MR) imaging. This study was compliance with the HIPPA. With the approval of the institution review board, 230 asymptomatic participants, including 164 male patients (72.9 ± 4.4 years) and 66 female patients (72.4 ± 5.1 years), were recruited. Written informed consent was obtained. A 2D navigator (NAV)-gated, black-blood coronary wall MR imaging sequence was run on the left main artery, the left anterior descending artery and the right coronary artery. The drift of the location of the NAV and scan efficiency were compared between good (scored 2 or 3) and poor images (scored 1). Age, body weight, body weight index, heart rate, length of the rest period of cardiac motion, diaphragm excursion and breathing frequency were compared using a t test between the "successful" (having 2 or 3 good images) and "unsuccessful" cases (having 1 or 0 good images). A logistic regression model was applied to identify the contributors to good image quality. The drift of the NAV location and the scan efficiency were higher in the 411 good images compared with the 279 poor images. Minimal drift of the NAV location and low body weight were identified as independent predictors of good images after using a logistic regression model to adjust for multiple physiological and technical factors. The stability of respiratory motion significantly influences the image quality of 2D, free-breathing, black-blood coronary wall MR imaging.

可動性プラークに対するBlack Blood CINEの最適化

For examining carotid plaque, black blood (BB) magnetic resonance (MR) imaging can diagnose plaque components based on MR signals. Dynamic images for evaluating the mobility of carotid plaque may also be useful as an adjunct to the diagnosis of carotid plaque. The aim of this study was to find optimal parameters for dynamic images using the black blood technique (BB CINE). All experiments were acquired using electrocardiographically (ECG)-gated T1 turbo field echo (T1 TFE) combined with the regional saturation technique (REST) and improved motion-sensitized driven equilibrium (iMSDE) at 1.5 tesla (T). The following parameters were investigated. (1) Four fat suppression techniques: spectral presaturation with IR (SPIR), the principle of selective excitation technique (PROSET) with a binomial excitation of 1-1 (PROSET1-1), PROSET1-2-1 and PROSET1-3-3-1; (2) TFE factors 1 and 2; and (3) flow velocity encoding (venc) of 1, 3, 5, 10 and 15 cm/s for iMSDE. The results showed the optimal parameters for BB CINE to be PROSET1-2-1, TFE factor 2, and flow venc of 3-5 cm/s for iMSDE.

Gray blood magnetic resonance for carotid wall imaging and visualization of deep‐seated and superficial vascular calcifications

White blood and black blood magnetic resonance imaging methods are often used for lumenography and visualization of the arterial wall, respectively. However, the use of white blood imaging invariably obscures arterial wall boundaries, and thus, impedes precise measurement of arterial wall area. Conversely, black blood imaging imposes strict limits on sequence timing to suppress the arterial lumen, and by itself, precludes separation of superficial calcification from the hypointense arterial lumen. In this work, a three-dimensional arterial wall imaging methodology providing gray blood image contrast is described that remedies the above limitations. When applied to the carotid arteries, the described gray blood imaging method is found to clearly depict the inner and outer arterial wall boundaries as well as superficial and deep-seated vascular calcifications. A tailored phase-encoding schedule is also presented that enables concurrent gray and black blood, or "dual contrast," imaging of the arterial wall with no increase in the acquisition time. Taken together, presented data demonstrate that gray and dual blood contrast magnetic resonance imaging provide an efficient means for viewing and characterizing the composition of atherosclerotic plaques.

Cardiac MR Imaging of Nonischemic Cardiomyopathies: Imaging Protocols and Spectra of Appearances

Recent technologic advances in cardiac magnetic resonance (MR) imaging have resulted in images with high spatial and temporal resolution and excellent myocardial tissue characterization. Cardiac MR is a valuable imaging technique for detection and assessment of the morphology and functional characteristics of the nonischemic cardiomyopathy. It has gained acceptance as a standalone imaging modality that can provide further information beyond the capabilities of traditional modalities such as echocardiography and angiography. Black-blood fast spin-echo MR images allow morphologic assessment of the heart with high spatial resolution, while T2-weighted MR images can depict acute myocardial edema. Contrast material-enhanced images can depict and be used to quantify myocardial edema, infiltration, and fibrosis. This review presents recommended cardiac MR protocols for and the spectrum of imaging appearances of the nonischemic cardiomyopathies.

Abstract 2971: Atheromatous Plaques of the Middle Cerebral Artery in the Lateral Lenticulostriate Artery Territory Infarction

OBJECTIVES: We evaluated the utility of black-blood double inversion recovery magnetic resonance imaging (BBDIR-MRI) for depiction of the intracranial branch atheromatous disease caused by occlusion at the vessel orifices of lager-caliber penetrating arteries. METHODS: BBDIR-MRI was performed on 15 consecutive patients with acute cerebral infarcts in the territories of lateral lenticulostriate arteries, which were classified into small artery occlusion by TOAST criteria. Abnormal wall thickening of the horizontal part (M1) of the middle cerebral artery was considered as the atheromatous plaque causing the occlusion of the vessel orifices. The clinical characteristics including the prevalence of various vascular risk factors, the final size of infarcts and the rate of disease progression were compared between two groups with and without the atheromatous plaque. RESULTS: By BBDIR-MRI, the atheromatous plaques were detected in 8 patiennts (53%), while Time of flight (TOF)-MRA revealed the irregular stenosis in one patient. All of them had the eccentric wall thickening with iso-signal intensity on T1- and T2-weighted images of BBDIR-MRI. The large infarcts exceeding 1.5 cm in diameter tended to be more often in patients with the atheromatous plaque (100%) than those without it (57%). However, there were no significant differences of clinical characteristics between the two groups with and without the atheromatous plaque. CONCLUSIONS: BBDIR-MRI could reveal the atheromatous plaque at M1 portion of the middle cerebral artery more easily than TOF-MRA. It might be useful to distinguish the intracranial branch atheromatous diseases from the other types of infarcts in the territories of lateral lenticulostriate arteries.

The relationship between plaque imaging characterization and treatment modality selection

It is commonly accepted that knowledge of the degree of luminal stenosis alone is insufficient to predict a plaque’s vulnerability. Recently, several imaging techniques, such as high-resolution black-blood magnetic resonance imaging, positron emission tomography/computed tomography, ultrasound, intravascular ultrasound and computed tomography angiography, have emerged that are able to depict the arterial lumen and the vessel wall. This article will describe the potential of these imaging techniques for the identification of vulnerable plaques and will focus on the current evidence that describe the relationship between plaque imaging characterization and treatment modality selection in the coronary and carotid arteries.

Plaque Vulnerability in Internal Carotid Arteries with Positive Remodeling

Background: This study aimed to evaluate the efficacy of assessing positive remodeling for predicting future stroke events in the internal carotid artery. We therefore assessed narrowing of the carotid artery lumen using multidetector-row computer tomography (MDCT) angiography and carotid plaque characteristics using black-blood (BB) magnetic resonance (MR). Methods: We retrospectively selected 17 symptomatic and 11 asymptomatic lesions with luminal narrowing >50%. We compared remodeling parameters of luminal stenosis (remodeling ratio, RR/remodeling index, RI) using MDCT and MR intensities of atherosclerotic plaque contents using the BB technique (relative signal intensity, rSI). We also confirmed the validity of the relationship between MR intensity and atherosclerotic plaque contents by histology. The levels of biological markers related to vessel atherosclerosis were measured. Results: Plaque lesions with positive remodeling in carotid arteries were associated with a significantly higher prevalence of stroke compared with plaques with negative remodeling (p < 0.05). Radiologic and histologic analyses determined that plaques with positive remodeling had higher signal intensities (with respect to their lipid-rich content or to hemorrhage) compared with negative remodeling (correlation coefficients: RI and rSI, r = 0.41, p < 0.05; RR and rSI, r = 0.50, p < 0.05). Levels of biological markers, including high-sensitivity C-reactive protein, hemoglobin A1C, total cholesterol, low-density lipoprotein cholesterol and high-density lipoprotein cholesterol, were not useful for predicting stroke events. Conclusions: The results of this study suggest that the combined analysis of RR, RI and rSI could potentially help to predict future stroke events.

Embolic complications after carotid artery stenting or carotid endarterectomy are associated with tissue characteristics of carotid plaques evaluated by magnetic resonance imaging

BackgroundUnstable carotid plaques are associated with an increased incidence of embolic complications after carotid artery stenting (CAS) or carotid endarterectomy (CEA). The aim of this study was to elucidate the relationship between the tissue components of carotid plaques and the incidence of new ipsilateral silent ischemic lesions (NISIL) after CAS or CEA. MethodsWe performed CAS in 56 patients and CEA in 25 patients. We also performed quantitative analyses of carotid plaque characteristics before treatment using T1 weighted black-blood magnetic resonance imaging (BB-MRI). The signal intensity ratio (SIR) was defined as the ratio of signal intensity evaluated by BB-MRI in carotid plaques to that of sternocleidomastoid muscle. According to criteria that we and other investigators previously reported, an SIR≥1.25 was defined as “high”. NISIL were evaluated by diffusion-weighted imaging of MRI before and after CAS or CEA. ResultsIn the high SIR group, the incidence of NISIL was significantly greater after CAS than after CEA (61% vs 13%, respectively, p=0.006), whereas there were no significant difference in NISIL after the two procedures when the SIR was <1.25 (21% vs 0%). In multivariate regression analysis, the independent predictors of NISIL were CAS (p=0.002), symptomatic stenosis (p=0.036) and the SIR (p=0.049). ConclusionsNoninvasive quantitative tissue characterization of carotid plaques using BB-MRI is useful to determine the indication for CAS.