Lindsey A. Crowe

Applications of phase-contrast flow and velocity imaging in cardiovascular MRI

A review of cardiovascular clinical and research applications of MRI phase-contrast velocity imaging, also known as velocity mapping or flow imaging. Phase-contrast basic principles, advantages, limitations, common pitfalls and artefacts are described. It can measure many different aspects of the complicated blood flow in the heart and vessels: volume flow (cardiac output, shunt, valve regurgitation), peak blood velocity (for stenosis), patterns and timings of velocity waveforms and flow distributions within heart chambers (abnormal ventricular function) and vessels (pulse-wave velocity, vessel wall disease). The review includes phase-contrast applications in cardiac function, heart valves, congenital heart diseases, major blood vessels, coronary arteries and myocardial wall velocity.

Volume-selective 3D turbo spin echo imaging for vascular wall imaging and distensibility measurement

To use a volume‐selective 3D turbo spin echo (TSE) technique to image the carotid artery wall and measure distensibility.

Image-based carotid flow reconstruction: a comparison between MRI and ultrasound.

Atherosclerosis is a major cause of morbidity and mortality. Its apparent link with wall shear stress (WSS) has led to considerable interest in the in vivo estimation of WSS. Determining WSS by combining medical images with computational fluid dynamics (CFD) simulations can be performed both with magnetic resonance imaging (MRI) and three-dimensional ultrasound (3DUS). This study compares predicted 3D flow patterns based on black blood MRI and 3DUS. Velocity fields in the carotid arteries of nine subjects have been reconstructed, and the haemodynamic wall parameters WSS, oscillatory shear index (OSI), WSS gradients (WSSG) and angle gradients (WSSAG) were compared between the two imaging techniques. There was a good qualitative agreement between results derived from MRI and 3DUS (average correlation strength above 0.60). The root mean square error between haemodynamic wall parameters was comparable to the range of the expected variability of each imaging technique (WSS: 0.411 N m(-2); OSI: 0.048; temporal WSSG: 150 N s(-1) m(-2); spatial WSSG: 2.29 N m(-3); WSSAG: 87.6 rad m(-1)). In conclusion, MRI and 3DUS are capable of providing haemodynamic parameters when combined with CFD, and the predictions are in most cases qualitatively and quantitatively similar. The relatively high cost of MRI and continuing improvement in ultrasound favour US to MRI for future haemodynamic studies of superficial arteries.

Interstudy reproducibility of three-dimensional volume-selective fast spin echo magnetic resonance for quantifying carotid artery wall volume.

To assess the interstudy reproducibility of a three‐dimensional volume‐selective, fast spin echo (FSE) magnetic resonance technique for the assessment of carotid artery wall volume, which is a marker for total carotid plaque volume.

Carotid geometry reconstruction: a comparison between MRI and ultrasound

Image-based Computational Fluid Dynamics (CFD) has become a popular tool for the prediction of in vivo flow profiles and hemodynamic wall parameters. Currently, Magnetic Resonance Imaging (MRI) is most widely used for in vivo geometry acquisition. For superficial arteries such as the carotids and the femoral artery, three-dimensional (3-D) extravascular ultrasound (3-DUS) could be a cost-effective alternative to MRI. In this study, nine healthy subjects were scanned both with MRI and 3-DUS. The reconstructed carotid artery geometries for each subject were compared by evaluating cross-sectional areas, centerlines, and carotid nonplanarity. Lumen areas agreed very well between the two different acquisition techniques, whereas centerlines and nonplanarity parameters showed measurable disagreement, possibly due to the different neck and head positions adopted for 3-DUS versus MRI. With the current level of agreement achieved, 3-DUS has the potential to become an inexpensive and fast alternative to MRI for image-based CFD modeling of superficial arteries.

Comparison between three‐dimensional volume‐selective turbo spin‐echo imaging and two‐dimensional ultrasound for assessing carotid artery structure and function

To compare a volume‐selective three‐dimensional turbo spin echo (TSE) technique with ultrasound (US) for assessing carotid artery wall structure and function.

3D volume-selective turbo spin echo for carotid artery wall imaging with navigator detection of swallowing.

To improve 3D volume‐selective turbo spin echo (TSE) carotid artery wall imaging by incorporating navigators to reduce artifacts caused by swallowing.

Elimination of residual blood flow-related signal in 3D volume-selective TSE arterial wall imaging using velocity-sensitive phase reconstruction†

To improve 3D volume‐selective turbo spin–echo (TSE) arterial wall imaging by introducing velocity phase sensitivity to the sequence.

Effect of rosiglitazone on progression of atherosclerosis: insights using 3D carotid cardiovascular magnetic resonance.

BackgroundThere is recent evidence suggesting that rosiglitazone increases death from cardiovascular causes. We investigated the direct effect of this drug on atheroma using 3D carotid cardiovascular magnetic resonance.ResultsA randomized, placebo-controlled, double-blind study was performed to evaluate the effect of rosiglitazone treatment on carotid atherosclerosis in subjects with type 2 diabetes and coexisting vascular disease or hypertension. The primary endpoint of the study was the change from baseline to 52 weeks of carotid arterial wall volume, reflecting plaque burden, as measured by carotid cardiovascular magnetic resonance. Rosiglitazone or placebo was allocated to 28 and 29 patients respectively. Patients were managed to have equivalent glycemic control over the study period, but in fact the rosiglitazone group lowered their HbA1c by 0.88% relative to placebo (P < 0.001). Most patients received a statin or fibrate as lipid control medication (rosiglitazone 78%, controls 83%). Data are presented as mean ± SD. At baseline, the carotid arterial wall volume in the placebo group was 1146 ± 550 mm3 and in the rosiglitazone group was 1354 ± 532 mm3. After 52 weeks, the respective volumes were 1134 ± 523 mm3 and 1348 ± 531 mm3. These changes (-12.1 mm3 and -5.7 mm3 in the placebo and rosiglitazone groups, respectively) were not statistically significant between groups (P = 0.57).ConclusionTreatment with rosiglitazone over 1 year had no effect on progression of carotid atheroma in patients with type 2 diabetes mellitus compared to placebo.

Evaluation of carotid artery wall volume measurement using novel semiautomated analysis software

To evaluate semiautomated analysis software for measuring the total carotid arterial wall volume (TWV) as a measure of atheroma burden.