Assessment of local pulse wave velocity distribution in mice using k-t BLAST PC-CMR with semi-automatic area segmentation

Abstract

BackgroundLocal aortic pulse wave velocity (PWV) is a measure for vascular stiffness and has a predictive value for cardiovascular events. Ultra high field CMR scanners allow the quantification of local PWV in mice, however these systems are yet unable to monitor the distribution of local elasticities.MethodsIn the present study we provide a new accelerated method to quantify local aortic PWV in mice with phase-contrast cardiovascular magnetic resonance imaging (PC-CMR) at 17.6 T. Based on a k-t BLAST (Broad-use Linear Acquisition Speed-up Technique) undersampling scheme, total measurement time could be reduced by a factor of 6. The fast data acquisition enables to quantify the local PWV at several locations along the aortic blood vessel based on the evaluation of local temporal changes in blood flow and vessel cross sectional area. To speed up post processing and to eliminate operator bias, we introduce a new semi-automatic segmentation algorithm to quantify cross-sectional areas of the aortic vessel. The new methods were applied in 10 eight-month-old mice (4 C57BL/6J-mice and 6 ApoE (−/−)-mice) at 12 adjacent locations along the abdominal aorta.ResultsAccelerated data acquisition and semi-automatic post-processing delivered reliable measures for the local PWV, similiar to those obtained with full data sampling and manual segmentation. No statistically significant differences of the mean values could be detected for the different measurement approaches. Mean PWV values were elevated for the ApoE (−/−)-group compared to the C57BL/6J-group (3.5 ± 0.7 m/s vs. 2.2 ± 0.4 m/s, p < 0.01). A more heterogeneous PWV-distribution in the ApoE (−/−)-animals could be observed compared to the C57BL/6J-mice, representing the local character of lesion development in atherosclerosis.ConclusionIn the present work, we showed that k-t BLAST PC-MRI enables the measurement of the local PWV distribution in the mouse aorta. The semi-automatic segmentation method based on PC-CMR data allowed rapid determination of local PWV. The findings of this study demonstrate the ability of the proposed methods to non-invasively quantify the spatial variations in local PWV along the aorta of ApoE (−/−)-mice as a relevant model of atherosclerosis.

Evaluation of Plaque Characteristics and Inflammation Using Magnetic Resonance Imaging

“…With a modified k-t BLAST (broad-use linear acquisition speed-up technique) method, the measurement time could be reduced to 1/8, allowing measurements of the PWV profile with the vessel morphology with a sampling density of 500 µm. With this technique, the measurement of the elasticity profile of the murine abdominal aorta could be realized for the first time, revealing a more heterogeneous distribution of PWV values in ApoE −/− mice and pointing out the local character of lesion development [ 120 ]. Conventional cartesian imaging techniques are prone to disturbances due to motion and flow and, therefore, require synchronization with ECG- and respiratory probes.…”

“…In the aortic arch, however, a complete profile is not obtainable due to the relatively high slice thickness and the curved geometry of the arch, especially in regions with high plaque susceptibility. Moreover, most of the flow velocity measurements are based on 2D-cine acquisition of single planes and the corresponding measurement of the velocity component perpendicular to it [ 68 , 89 , 119 , 120 , 121 ]. For a full determination of the flow dynamics in arteries, there is a need for 3D measurements with high temporal and spatial resolution, but in an adequate measurement time.…”

Journal of Cardiovascular Magnetic Resonance: 2017/2018 in review

“…Many technical advances are first implemented in the controlled environment of phantoms and ex-vivo/in-vivo animal models [35, 164–170].…”

The Progress of Advanced Ultrasonography in Assessing Aortic Stiffness and the Application Discrepancy between Humans and Rodents

“…Cardiovascular diseases remain one of the leading causes of morbidity and mortality, drawing numerous clinical and basic science studies. Various techniques have been clinically developed to detect the structural and functional alterations of cardiovascular systems, including non-invasive methods such as ultrasonography, magnetic resonance imaging, computed tomography, positron emission tomography, and single-photon emission computed tomography, and invasive procedures such as cardiac catheterization [ 1 , 2 , 3 , 4 ]. The applications of these new inventions have dramatically changed our knowledge and understanding of cardiovascular diseases and improved the evaluation of the latest treatments’ effects.…”