Three-Dimensional Carotid Plaque MR Imaging

High-resolution magnetic resonance vessel wall imaging provides new insights into Moyamoya disease

Moyamoya disease (MMD) is a rare condition that affects the blood vessels of the central nervous system. This cerebrovascular disease is characterized by progressive narrowing and blockage of the internal carotid, middle cerebral, and anterior cerebral arteries, which results in the formation of a compensatory fragile vascular network. Currently, digital subtraction angiography (DSA) is considered the gold standard in diagnosing MMD. However, this diagnostic technique is invasive and may not be suitable for all patients. Hence, non-invasive imaging methods such as computed tomography angiography (CTA) and magnetic resonance angiography (MRA) are often used. However, these methods may have less reliable diagnostic results. Therefore, High-Resolution Magnetic Resonance Vessel Wall Imaging (HR-VWI) has emerged as the most accurate method for observing and analyzing arterial wall structure. It enhances the resolution of arterial walls and enables quantitative and qualitative analysis of plaque, facilitating the identification of atherosclerotic lesions, vascular entrapment, myofibrillar dysplasia, moyamoya vasculopathy, and other related conditions. Consequently, HR-VWI provides a new and more reliable evaluation criterion for diagnosing vascular lesions in patients with Moyamoya disease.

Segmentation of carotid artery vessel wall and diagnosis of carotid atherosclerosis on black blood magnetic resonance imaging with multi-task learning

BACKGROUND

Atherosclerotic cardiovascular disease is the leading cause of death worldwide. Early detection of carotid atherosclerosis can prevent the progression of cardiovascular disease. Many (semi-) automatic methods have been designed for the segmentation of carotid vessel wall and the diagnosis of carotid atherosclerosis (i.e., the lumen segmentation, the outer wall segmentation, and the carotid atherosclerosis diagnosis) on black blood magnetic resonance imaging (BB-MRI). However, most of these methods ignore the intrinsic correlation among different tasks on BB-MRI, leading to limited performance.

PURPOSE

Thus, we model the intrinsic correlation among the lumen segmentation, the outer wall segmentation, and the carotid atherosclerosis diagnosis tasks on BB-MRI by using the multi-task learning technique and propose a gated multi-task network (GMT-Net) to perform three related tasks in a neural network (i.e., carotid artery lumen segmentation, outer wall segmentation, and carotid atherosclerosis diagnosis).

METHODS

In the proposed method, the GMT-Net is composed of three modules, including the sharing module, the segmentation module, and the diagnosis module, which interact with each other to achieve better learning performance. At the same time, two new adaptive layers, namely, the gated exchange layer and the gated fusion layer, are presented to exchange and merge branch features.

RESULTS

The proposed method is applied to the CAREII dataset (i.e., 1057 scans) for the lumen segmentation, the outer wall segmentation, and the carotid atherosclerosis diagnosis. The proposed method can achieve promising segmentation performances (0.9677 Dice for the lumen and 0.9669 Dice for the outer wall) and better diagnosis accuracy of carotid atherosclerosis (0.9516 AUC and 0.9024 Accuracy) in the "CAREII test" dataset (i.e., 106 scans). The results show that the proposed method has statistically significant accuracy and efficiency.

CONCLUSIONS

Even without the intervention of reviewers required for the previous works, the proposed method automatically segments the lumen and outer wall together and diagnoses carotid atherosclerosis with high performance. The proposed method can be used in clinical trials to help radiologists get rid of tedious reading tasks, such as screening review to separate normal carotid arteries from atherosclerotic arteries and to outline vessel wall contours.

Fabrication of Customizable Intraplaque Hemorrhage Phantoms for Magnetic Resonance Imaging

PURPOSE

Magnetic resonance (MR) imaging detection of methemoglobin, a molecular marker of intraplaque hemorrhage (IPH), in atherosclerotic plaque is a promising method of assessing stroke risk. However, the multicenter imaging studies required to further validate this technique necessitate the development of IPH phantoms to standardize images acquired across different scanners. This study developed a set of phantoms that modeled methemoglobin-laden IPH for use in MR image standardization.

PROCEDURES

A time-stable material mimicking the MR properties of methemoglobin in IPH was created by doping agarose hydrogel with gadolinium and sodium alginate. This material was used to create a phantom that consisted of 9 cylindrical IPH sites (with sizes from 1 to 8 mm). Anatomical replicas of IPH-positive atherosclerosis were also created using 3D printed molds. These plaque replicas also modeled other common plaque components including a lipid core and atheroma cap. T1 mapping and a magnetization-prepared rapid acquisition gradient echo (MPRAGE) carotid imaging protocol were used to assess phantom realism and long-term stability.

RESULTS

Cylindrical phantom IPH sites possessed a T1 time of 335 ± 51 ms and exhibited little change in size or MPRAGE signal intensity over 31 days; the mean (SD) magnitude of changes in size and signal were 6.4 % (2.7 %) and 7.3 % (6.7 %), respectively. IPH sites incorporated into complex anatomical plaque phantoms exhibited contrast comparable to clinical images.

CONCLUSIONS

The cylindrical IPH phantom accurately modeled the short T1 time characteristic of methemoglobin-laden IPH, with the IPH sites exhibiting little variation in imaging properties over 31 days. Furthermore, MPRAGE images of the anatomical atherosclerosis replicas closely matched those of clinical plaques. In combination, these phantoms will allow for IPH imaging protocol standardization and thus facilitate future multicenter IPH imaging.

Comparison of carotid atherosclerotic plaque characteristics between symptomatic patients with transient ischemic attack and stroke using high-resolution magnetic resonance imaging

Background

This study aimed to compare the characteristics of carotid plaques between patients with transient ischemic attack (TIA) and ischemic stroke using magnetic resonance (MR) imaging.

Methods

Patients with a recent ischemic stroke or TIA who exhibited atherosclerotic plaques of carotid arteries in the symptomatic sides determined by MR vessel wall imaging were recruited. The plaque morphology and compositions including intraplaque hemorrhage (IPH), lipid-rich necrotic-core (LRNC) and calcification were compared between TIA and stroke patients. Logistic regression was performed to relate the plaque characteristics to the types of ischemic events.

Results

A total of 270 patients with TIA or ischemic stroke were recruited. Stroke patients had a significantly higher prevalence of diabetes (42.2% vs. 28.2%, p = 0.021), greater mean wall area (35.1 ± 10.1 mm² vs. 32.0 ± 7.7 mm², p = 0.004), mean wall thickness (1.3 ± 0.2 mm vs. 1.2 ± 0.2 mm, p = 0.001), maximum normalized wall index (NWI)(63.9% ± 6.0% vs. 62.2% ± 5.9%, p = 0.023) and %volume of LRNC (9.7% ± 8.2% vs. 7.4% ± 7.9%, p = 0.025) in the carotid arteries compared to those with TIA. After adjustment for clinical factors, above characteristics of carotid arteries were significantly associated with the type of ischemic events. After further adjustment for maximum NWI, this association remained statistically significant (OR, 1.41; CI, 1.01–1.96; p = 0.041).

Conclusions

Ischemic stroke patients had larger plaque burden and greater proportion of LRNC in carotid plaques compared to those with TIA. This study suggests that ischemic stroke patients had more vulnerable plaques compared to those with TIA.

Dark blood cardiovascular magnetic resonance of the heart, great vessels, and lungs using electrocardiographic-gated three-dimensional unbalanced steady-state free precession

BACKGROUND

Recently, we reported a novel neuroimaging technique, unbalanced T1 Relaxation-Enhanced Steady-State (uT1RESS), which uses a tailored 3D unbalanced steady-state free precession (3D uSSFP) acquisition to suppress the blood pool signal while minimizing bulk motion sensitivity. In the present work, we hypothesized that 3D uSSFP might also be useful for dark blood imaging of the chest. To test the feasibility of this approach, we performed a pilot study in healthy subjects and patients undergoing cardiovascular magnetic resonance (CMR).

MAIN BODY

The study was approved by the hospital institutional review board. Thirty-one adult subjects were imaged at 1.5 T, including 5 healthy adult subjects and 26 patients (44 to 86 years, 10 female) undergoing a clinically indicated CMR. Breath-holding was used in 29 subjects and navigator gating in 2 subjects. For breath-hold acquisitions, the 3D uSSFP pulse sequence used a high sampling bandwidth, asymmetric readout, and single-shot along the phase-encoding direction, while 3 shots were acquired for navigator-gated scans. To minimize signal dephasing from bulk motion, electrocardiographic (ECG) gating was used to synchronize the data acquisition to the diastolic phase of the cardiac cycle. To further reduce motion sensitivity, the moment of the dephasing gradient was set to one-fifth of the moment of the readout gradient. Image quality using 3D uSSFP was good-to-excellent in all subjects. The blood pool signal in the thoracic aorta was uniformly suppressed with sharp delineation of the aortic wall including two cases of ascending aortic aneurysm and two cases of aortic dissection. Compared with variable flip angle 3D turbo spin-echo, 3D uSSFP showed improved aortic wall sharpness. It was also more efficient, permitting the acquisition of 24 slices in each breath-hold versus 16 slices with 3D turbo spin-echo and a single slice with dual inversion 2D turbo spin-echo. In addition, lung and mediastinal lesions appeared highly conspicuous compared with the low blood pool signals within the heart and blood vessels. In two subjects, navigator-gated 3D uSSFP provided excellent delineation of cardiac morphology in double oblique multiplanar reformations.

CONCLUSION

In this pilot study, we have demonstrated the feasibility of using ECG-gated 3D uSSFP for dark blood imaging of the heart, great vessels, and lungs. Further study will be required to fully optimize the technique and to assess clinical utility.

Intraplaque CTA characteristics as predictors of symptomatology: a semiautomated volumetric analysis

BACKGROUND

Prior studies comparing CT characteristics of carotid plaques to symptomatology have relied on gross morphologic imaging features. This study sought to determine if volumetric measurements of carotid plaque components are associated with ipsilateral neurologic symptoms.

MATERIALS AND METHODS

CTA images of consecutive patients that underwent a carotid endarterectomy were reviewed with a semiautomated software package. Intraplaque volumes of intraplaque hemorrhage (IPH), lipid-rich necrotic core (LRNC), and matrix were computed, as was the degree of arterial stenosis. Statistics were analyzed on a per cerebral hemisphere basis, and dichotomized into symptomatic and asymptomatic. Clinical and radiological endpoints included transient ischemic attack (TIA), ischemic stroke diagnosed on imaging studies, ophthalmologically diagnosed central or branch retinal artery occlusion (RAO), or amaurosis fugax.

RESULTS

One hundred sixty-eight carotid plaques were reviewed. The average age is 70.8 years (SD = 8.8); 32/87 (36.8%) were female. Sixty-seven of eighty-seven (77.0%) patients were symptomatic. Sixty-six of one hundred sixty-eight (39.3%) plaques were ipsilateral to the patient's symptoms, while 102/168 (60.7%) were ipsilateral to an asymptomatic hemisphere. Greater intraplaque volumes of IPH (p = 0.03), LRNC (p = 0.008), and matrix (p = 0.0008) were associated with symptoms, as was greater proportion of LRNC in regard to plaque volume (p = 0.04). All but proportion of LRNC remained statistically significant after adjustment for plaque size. More severe luminal stenosis was also associated with ipsilateral neurologic symptoms, both when calculated by smallest diameter or by area (p < 0.0001 for both).

CONCLUSION

Higher volumes of intraplaque IPH, LRNC, matrix, and degree of arterial stenosis are associated with ipsilateral neurologic symptoms. Greater intraplaque proportions of LRNC are also associated with ipsilateral ischemic manifestations, suggesting that larger relative composition of lipids may be particularly predictive of symptomatology.

Detection of Advanced Lesions of Atherosclerosis in Carotid Arteries Using 3-Dimensional Motion-Sensitized Driven-Equilibrium Prepared Rapid Gradient Echo (3D-MERGE) Magnetic Resonance Imaging as a Screening Tool

BACKGROUND AND PURPOSE

Two-dimensional high-resolution multicontrast magnetic resonance imaging (2D-MC MRI) is currently the most reliable and reproducible noninvasive carotid vessel wall imaging technique. However, the long scan time required for 2D-MC MRI restricts its practical clinical application. Alternatively, 3-dimensional motion-sensitized driven-equilibrium prepared rapid gradient echo (3D-MERGE) vessel wall MRI can provide high isotropic resolution with extensive coverage in two minutes. In this study, we sought to prove that 3D-MERGE alone can serve as a screening tool to identify advanced carotid lesions.

METHODS

Two hundred twenty-seven subjects suspected of recent ischemic stroke or transient ischemic attack were imaged using 2D-MC MRI with an imaging time of 30 minutes, then with 3D-MERGE with an imaging time of 2 minutes, on 3T-MRI scanners. Two experienced reviewers interpreted plaque components using 2D-MC MRI as the reference standard and categorized plaques using a modified American Heart Association lesion classification for MRI. Plaques of American Heart Association type IV and above were classified as advanced. Arteries of American Heart Association types I to II and III were categorized as normal or with early lesions, respectively. One radiologist independently reviewed only 3D-MERGE and labeled the plaques as advanced if they had a wall thickness of >2 mm with high or low signal intensity compared with the adjacent sternocleidomastoid muscle. Sensitivity, specificity, and accuracy for 3D-MERGE were calculated.

RESULTS

Four hundred forty-nine arteries from 227 participants (mean age 61.2 years old, 64% male) were included in the analysis. Sensitivity, specificity, and accuracy for identification of advanced lesions on 3D-MERGE were 95.0% (95% CI, 91.8-97.2), 86.9% (95% CI, 81.4-92.0), 93.8% (95% CI, 91.1-95.8), respectively.

CONCLUSIONS

3D-MERGE can accurately identify advanced carotid atherosclerotic plaques in patients suspected of stroke or transient ischemic attack. It has a more extensive coverage and higher sensitivity and specificity for advanced plaque detection with a much shorter acquisition time than 2D-MC MRI.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT02017756.

High-Resolution Magnetic Resonance Vessel Wall Imaging for the Evaluation of Intracranial Vascular Pathology

Intracranial vessel wall imaging (IVWI) is an advanced MR imaging technique that allows for direct visualization of the walls of intracranial blood vessels and detection of subtle pathologic vessel wall changes before they become apparent on conventional luminal imaging. When performed correctly, IVWI can increase diagnostic confidence, aid in the differentiation of intracranial vasculopathies, and assist in patient risk stratification and prognostication. This review covers the essential technical underpinnings of IVWI and presents emerging clinical research highlighting its utility for the evaluation of multiple intracranial vascular pathologies.

Cervical Carotid Plaque MRI : Review of Atherosclerosis Imaging Features and their Histologic Underpinnings

Magnetic resonance (MR) imaging is considered the gold standard for non-invasive evaluation of carotid artery plaque morphology and composition. A number of studies have demonstrated the clinical utility of MR plaque imaging in the risk stratification of carotid atherosclerotic disease, determination of stroke etiology, and identification of surgical and endovascular candidates for carotid revascularization procedures. The MR plaque imaging also provides researchers and clinicians with valuable insights into the pathogenesis, natural history and composition of carotid atherosclerotic disease. Nevertheless, the field of MR plaque imaging is complex, and requires a thorough knowledge of the histologic basis for how various plaque features appear on imaging. This article details the pathogenesis and histology of atherosclerosis, reviews the expected appearance of different plaque components, and describes how MR imaging features may be related to symptomatology or predict future ischemic events.

Automated Artery Localization and Vessel Wall Segmentation using Tracklet Refinement and Polar Conversion

Quantitative analysis of blood vessel wall structures is important to study atherosclerotic diseases and assess cardiovascular event risks. To achieve this, accurate identification of vessel luminal and outer wall contours is needed. Computer-assisted tools exist, but manual preprocessing steps, such as region of interest identification and/or boundary initialization, are still needed. In addition, prior knowledge of the ring shape of vessel walls has not been fully explored in designing segmentation methods. In this work, a fully automated artery localization and vessel wall segmentation system is proposed. A tracklet refinement algorithm was adapted to robustly identify the artery of interest from a neural network-based artery centerline identification architecture. Image patches were extracted from the centerlines and converted in a polar coordinate system for vessel wall segmentation. The segmentation method used 3D polar information and overcame problems such as contour discontinuity, complex vessel geometry, and interference from neighboring vessels. Verified by a large (>32000 images) carotid artery dataset collected from multiple sites, the proposed system was shown to better automatically segment the vessel wall than traditional vessel wall segmentation methods or standard convolutional neural network approaches. In addition, a segmentation uncertainty score was estimated to effectively identify slices likely to have errors and prompt manual confirmation of the segmentation. This robust vessel wall segmentation system has applications in different vascular beds and will facilitate vessel wall feature extraction and cardiovascular risk assessment.

SCMR Position Paper (2020) on clinical indications for cardiovascular magnetic resonance

The Society for Cardiovascular Magnetic Resonance (SCMR) last published its comprehensive expert panel report of clinical indications for CMR in 2004. This new Consensus Panel report brings those indications up to date for 2020 and includes the very substantial increase in scanning techniques, clinical applicability and adoption of CMR worldwide. We have used a nearly identical grading system for indications as in 2004 to ensure comparability with the previous report but have added the presence of randomized controlled trials as evidence for level 1 indications. In addition to the text, tables of the consensus indication levels are included for rapid assimilation and illustrative figures of some key techniques are provided.

Magnetic resonance imaging of carotid plaques: current status and clinical perspectives

Rupture of a vulnerable carotid plaque is one of the leading causes of stroke. Carotid magnetic resonance imaging (MRI) is able to visualize all the main hallmarks of plaque vulnerability. Various MRI sequences have been developed in the last two decades to quantify carotid plaque burden and composition. Often, a combination of multiple sequences is used. These MRI techniques have been extensively validated with histological analysis of carotid endarterectomy specimens. High agreement between the MRI and histological measures of plaque burden, intraplaque hemorrhage (IPH), lipid-rich necrotic core (LRNC), fibrous cap (FC) status, inflammation and neovascularization has been demonstrated. Novel MRI sequences allow to generate three-dimensional isotropic images with a large longitudinal coverage. Other new sequences can acquire multiple contrasts using a single sequence leading to a tremendous reduction in scan time. IPH can be easily identified as a hyperintense signal in the bulk of the plaque on strongly T₁-weighted images, such as magnetization-prepared rapid acquisition gradient echo images, acquired within a few minutes with a standard neurovascular coil. Carotid MRI can also be used to evaluate treatment effects. Several meta-analyses have demonstrated a strong predictive value of IPH, LRNC, thinning or rupture of the FC for ischemic cerebrovascular events. Recently, in a large meta-analysis based on individual patient data of asymptomatic and symptomatic individuals with carotid artery stenosis, it was shown that IPH on MRI is an independent risk predictor for stroke, stronger than any known clinical risk parameter. Expert recommendations on carotid plaque MRI protocols have recently been described in a white paper. The present review provides an overview of the current status and applications of carotid plaque MR imaging and its future potential in daily clinical practice.

Evaluation of chronic carotid artery occlusion by non-contrast 3D-MERGE MR vessel wall imaging: comparison with 3D-TOF-MRA, contrast-enhanced MRA, and DSA

OBJECTIVES

To analyze the accuracy of a non-contrast MR vessel wall imaging technique, three-dimensional motion-sensitized driven equilibrium prepared rapid gradient echo (3D-MERGE) for diagnosing chronic carotid artery occlusion (CCAO) characteristics compared with 3D time-of-flight (TOF) MRA, and contrast-enhanced MRA (CE-MRA), using digital subtraction angiography (DSA) as a reference standard.

METHODS

Subjects diagnosed with possible CCAO by ultrasound were retrospectively analyzed. Patients underwent 3.0-T MR imaging with 3D-MERGE, 3D-TOF-MRA, and CE-MRA followed by DSA within 1 week. Diagnostic accuracy of occlusion, occlusion site, and proximal stump condition were assessed independently on 3 MRI sequences and DSA. Agreement of the above indicators was evaluated in reference to DSA.

RESULTS

One hundred twenty-four patients with 129 suspected CCAO (5 with bilateral occlusions) met the inclusion criteria for our study. 3D-MERGE demonstrated a sensitivity, specificity, and accuracy of 97.0%, 86.7%, and 94.6%, respectively, with excellent agreement (Cohen's κ = 0.85; 95% CI, 0.71, 0.94) for diagnosing CCAO in reference to DSA. 3D-MERGE was superior in diagnosing CCAO compared with 3D-TOF-MRA (Cohen's κ = 0.61; 95% CI, 0.42, 0.77) and similar to CE-MRA (Cohen's κ = 0.93; 95% CI, 0.86, 1.00). 3D-MERGE also had excellent agreement compared with DSA for assessing occlusion sites (Cohen's κ = 0.85; 95% CI, 0.71, 0.97) and stump condition (Cohen's κ = 0.83; 95% CI, 0.71, 0.94). Moreover, 3D-MERGE provided additional information regarding the occluded segment, such as distal lumen collapse and vessel wall lesion components.

CONCLUSION

3D-MERGE can reliably assess chronic carotid occlusive characteristics and has the ability to identify other vessel wall features of the occluded segment. This non-contrast MR vessel wall imaging technique is promising for assessment of CCAO.

KEY POINTS

• Excellent agreement was found between 3D-MERGE and DSA for assessing chronic carotid artery occlusion, occlusion site, and proximal stump condition. • 3D-MERGE was shown to be a more accurate and efficient tool than 3D-TOF-MRA to detect the characteristics of the occluded segment. • 3D-MERGE provides not only luminal images for characterizing the proximal characteristics of occlusion but also vessel wall images for assessing the distal lumen and morphology of occlusion segment, which might help clinicians to optimize the treatment strategy for patients with chronic carotid artery occlusion.

Segment-specific progression of carotid artery atherosclerosis: a magnetic resonance vessel wall imaging study

PURPOSE

This study aimed to investigate the segment-specific progression of atherosclerotic carotid plaques using serial multi-contrast magnetic resonance (MR) imaging.

METHODS

Symptomatic patients with carotid 30-70% stenosis were recruited and underwent carotid MR vessel wall imaging at baseline and follow-up time point (≥ 6 months after baseline). The location of plaques was determined according to the maximum wall thickness located above or below carotid bifurcation. The baseline and changing characteristics of carotid plaques were compared between plaques above and below carotid bifurcation, and the risk factors for segment-specific plaque progression were analyzed with logistic regression.

RESULTS

Ninety-six carotid plaques from 73 patients (mean age 66.5 ± 11.4 years old) were eligible for statistical analysis. Compared with plaques located below carotid bifurcation, those above bifurcation had significantly greater stenosis at baseline (57.2 ± 13.0% vs. 50.4 ± 13.5%, p = 0.016, adjusted p = 0.005) and greater progression rate of carotid wall volume (35.2 ± 68.8 mm³/year vs. 4.2 ± 65.0 mm³/year, p = 0.026, adjusted p = 0.005) before and after adjusting for all clinical risk factors and baseline stenosis and wall volume of carotid arteries. Logistic regression showed that the related risk factors were age, hypertension, and smoke for the progression of plaques located above the bifurcation and age for plaques below the bifurcation, respectively.

CONCLUSION

Plaques located above the bifurcation of carotid arteries had greater annual progression and correlated with more cardiovascular risk factors compared with those located below the bifurcation.

Age-Specific Sex Differences in Magnetic Resonance Imaging-Depicted Carotid Intraplaque Hemorrhage

BACKGROUND AND PURPOSE

Stroke rates are higher in men compared with women in the fourth through seventh decades of life, and higher rates may result from differences in carotid intraplaque hemorrhage (IPH), an unstable atherosclerotic plaque component. We report age-specific sex differences in the presence of magnetic resonance imaging-depicted carotid IPH.

METHODS

Patients (n=1115) underwent magnetic resonance imaging for carotid IPH between 2005 and 2014. Low-grade carotid stenosis patients (n=906) without prior endarterectomy were eligible for this cross-sectional study.

RESULTS

Of the 906 patients included (mean age±SD in years, 66.98±15.15), 63 (6.95%) had carotid IPH. In men and women, carotid IPH was present in 11.43% (48 of 420) and 3.09% (15 of 486), respectively (P<0.0001). Multivariable logistic regression analysis confirmed greater odds of carotid IPH in men for all ages: 45 to 54 (odds ratio=45.45; 95% confidence interval, 3.43-500), 55 to 64 years (odds ratio=21.74; 95% confidence interval, 3.21-142.86), 65 to 74 years (odds ratio=10.42; 95% confidence interval, 2.91-37.04), and ≥75 years (odds ratio=5.00; 95% confidence interval, 2.31-10.75). Male sex modified the effect of age on the presence of carotid IPH (β=0.074; SE=0.036; P=0.0411).

CONCLUSIONS

Men have greater age-specific odds of magnetic resonance imaging-depicted carotid IPH compared with women. With increasing age post-menopause, the odds of carotid IPH in women becomes closer to that of men. Delayed onset of carotid IPH in women, an unstable plaque component, may partly explain differential stroke rates between sexes, and further studies are warranted.

Interchangeable neck shape-specific coils for a clinically realizable anterior neck phased array system

PURPOSE

To demonstrate the interchangeable neck shape-specific (NSS) coil concept that supplements standard commercial spine and head/neck coils to provide simultaneous high-resolution (hi-res) head/neck imaging with high signal-to-noise ratio (SNR).

METHODS

Two NSS coils were constructed on formers designed to fit two different neck shapes. A 7-channel (7ch) ladder array was constructed on a medium neck former, and a 9-channel (9ch) ladder array was constructed on large neck former. Both coils were interchangeable with the same preamp housing.

RESULTS

The 7ch and 9ch coils demonstrate SNR gains of approximately 4 times and 3 times over the Siemens 20-channel head/neck coil in the carotid arteries of our volunteers, respectively. Coupling between the Siemens 32-channel spine coil, Siemens 20-channel head/neck coil, and the NSS coils was negligible, allowing for simultaneous hi-res head/neck imaging with high SNR.

CONCLUSIONS

This study demonstrates that supplementing existing commercial spine and head/neck coils with an NSS coil allows uniform simultaneous hi-res imaging with high SNR in the anterior neck, while maintaining SNR of the commercial coil in the head and posterior neck. Magn Reson Med 78:2460-2468, 2017. © 2017 International Society for Magnetic Resonance in Medicine.