A Simultaneous Non-contrast Angiography and intraPlaque hemorrhage (SNAP) MR imaging technique is proposed to detect both luminal stenosis and hemorrhage in atherosclerosis patients in a single scan. 13 patients with diagnosed carotid atherosclerotic plaque were recruited after informed consent. All scans were performed on a 3T MR imaging system with SNAP, 2D time-of-flight (TOF) and magnetization-prepared 3D rapid acquisition gradient echo (MP-RAGE) sequences. The SNAP sequence utilized a phase sensitive acquisition, and was designed to provide positive signals corresponding to intraplaque hemorrhage (IPH) and negative signals corresponding to lumen. SNAP images were compared to TOF images to evaluate lumen size measurements using linear mixed models and the intraclass correlation coefficient (ICC). IPH identification accuracy was evaluated by comparing to MP-RAGE images using Cohen’s Kappa. Diagnostic quality SNAP images were generated from all subjects. Quantitatively, the lumen size measurements by SNAP were strongly correlated (ICC=0.96, p<0.001) with those measured by TOF. For IPH detection, strong agreement (κ=0.82, p<0.001) was also identified between SNAP and MP-RAGE images. In conclusion, a Simultaneous Non-contrast Angiography and intraPlaque hemorrhage (SNAP) imaging technique was proposed and shows great promise for imaging both lumen size and carotid intraplaque hemorrhage with a single scan.

Purpose: To evaluate interscan reproducibility of both vessel morphology and tissue composition measurements of carotid atherosclerosis using a fast, optimized, 3T multicontrast protocol. Materials and Methods:A total of 20 patients with carotid stenosis >15% identified by duplex ultrasound were recruited for two independent 3T MRI (Philips) scans within one month. A multicontrast protocol including five MR sequences was applied: TOF, T1-/T2-/PD-weighted and magnetization-prepared rapid acquisition gradientecho (MP-RAGE). Carotid artery morphology (wall volume, lumen volume, total vessel volume, normalized wall index, and mean/maximum wall thickness) and plaque component size (lipid rich/necrotic core, calcification, and hemorrhage) were measured over two time points.Results: After exclusion of images with poor image quality, 257 matched locations from 18 subjects were available for analysis. For the quantitative carotid morphology measurements, coefficient of variation (CV) ranged from 2% to 15% and intraclass correlation coefficient (ICC) ranged from 0.87 to 0.99. Except for maximum wall thickness (ICC ¼ 0.87), all ICC were larger than 0.90. For the quantitative plaque composition measurements, the ICC of the volume and relative content of lipid rich/necrotic core and calcification were larger than 0.90 with CV ranging from 22% to 32%. Conclusion:The results from the multicontrast high-resolution 3T MR study show high reliability for carotid morphology and plaque component measurements. 3T MRI is a reliable tool for longitudinal clinical trials, with shorter scan time compared to 1.5T.

BackgroundMulti-contrast vessel wall cardiovascular magnetic resonance (CMR) has demonstrated its capability for atherosclerotic plaque morphology measurement and component characterization in different vasculatures. However, limited coverage and partial volume effect with conventional two-dimensional (2D) techniques might cause lesion underestimation. The aim of this work is to evaluate the performance in a) blood suppression and b) vessel wall delineation of three-dimensional (3D) multi-contrast joint intra- and extracranial vessel wall imaging at 3T.MethodsThree multi-contrast 3D black blood (BB) sequences with T1, T2 and heavy T1 weighting and a custom designed 36-channel neurovascular coil covering the entire intra- and extracranial vasculature have been used and investigated in this study. Two healthy subjects were recruited for sequence parameter optimization and twenty-five patients were consecutively scanned for image quality and blood suppression assessment. Qualitative image scores of vessel wall delineation as well as quantitative Signal-to-Noise Ratio (SNR) and Contrast-to-Noise Ratio (CNR) were evaluated at five typical locations ranging from common carotid arteries to middle cerebral arteries.ResultsThe 3D multi-contrast images acquired within 15mins allowed the vessel wall visualization with 0.8 mm isotropic spatial resolution covering intra- and extracranial segments. Quantitative wall and lumen SNR measurements for each sequence showed effective blood suppression at all selected locations (P < 0.0001). Although the wall-lumen CNR varied across measured locations, each sequence provided good or adequate image quality in both intra- and extracranial segments.ConclusionsThe proposed 3D multi-contrast vessel wall technique provides isotropic resolution and time efficient solution for joint intra- and extracranial vessel wall CMR.

OBJECTIVE-The objective of our study was to compare the diagnostic performance of coronary MR angiography (MRA) and 64-MDCT angiography (MDCTA) for the detection of significant stenosis (≥ 50%) in patients with high calcium scores. MATERIALS AND METHODS-Eighteenpatients (12 men, six women; mean age, 56 y; age range, 38-77 y) who had at least one calcified plaque with a calcium score of > 100 underwent coronary MRA and conventional coronary angiography (CAG) within 2 weeks of MDCTA. Coronary MRA image quality of the calcified segments was assessed by two observers in consensus on a 4-point scale (1 = not visible, 2 = poor, 3 = good, 4 = excellent) using a 10-segment model from the modified American Heart Association classification. Three experienced radiologists, unaware of the results of conventional CAG, independently assessed for the presence of significant stenosis on MDCTA images and the corresponding MRA images. Receiver operating characteristic (ROC) curves were calculated for each reader using conventional CAG as the gold standard.RESULTS-Thirty-three calcified plaques with a calcium score of > 100 were detected on MDCTA in the 18 patients. The coronary segments with nodal calcification (n = 17) showed a higher mean image quality score than the segments with diffuse calcification (n = 16) (3.47 ± 0.62 vs 2.94 ± 0.77, respectively; p < 0.05). Of the 33 coronary segments with calcification, 12 significant stenoses were identified on conventional CAG. The sensitivity, specificity, and area under the ROC curve (AUC) for MRA and MDCTA, respectively, were as follows: reader 1, 75%, 81%, 0.82 versus 75%, 48%, 0.68; reader 2, 83%, 71%, 0.82 versus 67%, 52%, 0.63; and reader 3, © American Roentgen Ray Society Address correspondence to J. C. Carr.. Thirty-two eligible patients were recruited for the coronary MRA section of the study within 1-3 days after MDCTA examination. Twenty-seven patients (19 men and eight women; mean age, 58 y; age range, 38-79 y) successfully completed the MRA study. MRA studies could not be completed because of failed respiratory gating in three patients and failed ECG gating in two patients. Eighteen of the 27 patients subsequently underwent conventional CAG 3-10 days (mean, 6 days) after the MRA study. NIH Public AccessThere were no clinical events or medication changes recorded between examinations.Patients who had a heart rate of > 70 beats per minute (bpm) at rest received an oral β-blocker (25-50 mg) or IV metoprolol (5 mg) to decrease their heart rate before both the MDCTA and MRA examinations. The difference in heart rate between the MDCTA and MRA studies was < 5 bpm. Sublingual or IV nitroglycerine (5 mg) was used in both coronary MDCTA and MRA to achieve maximal coronary vasodilation in all patients. Coronary MDCTACoronary MDCTA was performed and calcium scores were obtained using a 64-MDCT scanner (Somatom Sensation Cardiac 64, Siemens Medical Solutions). An initial unenhanced ECG-gated scan was obtained for coronary calcium scoring (collimation, 24 × 0.6 mm; pitch, 0.2;...

Surface calcification and multiple calcifications in carotid atherosclerotic plaques are independently associated with the presence of IPH, suggesting that both quantity and location of calcification may play important roles in the occurrence of IPH. These findings may provide novel insights for understanding mechanisms of IPH.