In vivo MR-angiography for the assessment of aortic aneurysms in an experimental mouse model on a clinical MRI scanner: Comparison with high-frequency ultrasound and histology

Abstract

BackgroundMR-angiography currently represents one of the clinical reference-standards for the assessment of aortic-dimensions. For experimental research in mice, dedicated preclinical high-field MRI scanners are used in most studies. This type of MRI scanner is not available in most institutions. The aim of this study was to evaluate the potential of MR-angiography performed on a clinical MR scanner for the assessment of aortic aneurysms in an experimental mouse model, compared to a preclinical high-resolution ultrasound imaging system and histopathology.MethodsAll in vivo MR imaging was performed with a clinical 3T MRI system (Philips Achieva) equipped with a clinical gradient system in combination with a single-loop surface-coil (47 mm). All MR sequences were based on clinically used sequences. For ultrasound, a dedicated preclinical high-resolution system (30 MHz linear transducer, Vevo770, VisualSonics) was used. All imaging was performed with an ApoE knockout mouse-model for aortic aneurysms. Histopathology was performed as reference-standard at all stages of aneurysm development.ResultsMR-angiography on a clinical 3T system enabled the clear visualization of the aortic lumen and aneurysmal dilation at different stages of aneurysm development. A close correlation (R2 = 0.98; p < 0.001) with histological area measurements was found. Additionally, a good agreement between MR and ultrasound area measurements in systole (R2 = 0.91; p < 0.001) and diastole (R2 = 0.94; p < 0.001) were measured. Regarding interobserver reproducibility, MRI measurements yielded a smaller 95% confidence interval and a closer interreader correlation compared to ultrasound measurements (-0.37–0.46; R2 = 0.97 vs. -0.78–0.88; R2 = 0.87).ConclusionThis study demonstrates that MR-angiography, performed on a clinical 3T MR scanner, enables the reliable detection and quantification of the aortic dilatation at different stages of aneurysm development in an experimental mouse model.

Comparative Analysis of Micro-Computed Tomography and 3D Micro-Ultrasound for Measurement of the Mouse Aorta

“…Due to the high degree of agreement among observers and methodologies, these approaches are well-suited for multi-observer and longitudinal research. Previous studies have demonstrated a high correlation between the USS three-dimensional lumen volume (3DLV) measurement of the murine aorta and more accurate modalities like CT and MRI, as well as histological examination of aortic aneurysms [ 16 , 27 , 28 ]. This is consistent with our findings, which showed a correlation between USS and μCT for the aortic volume measurements.…”

High-Frequency Three-Dimensional Lumen Volume Ultrasound Is a Sensitive Method to Detect Early Aneurysmal Change in Elastase-Induced Murine Abdominal Aortic Aneurysm

“… 11 Furthermore, 3DLV measurement of murine aorta has been demonstrated to highly correlate with more sensitive modalities, such as computer tomography and magnetic resonance imaging, as well as histological assessment of aneurysmal aorta. 8 12 13 Despite these observations, 2D USS assessment of murine aorta remains the dominant strategy. 9 10 The results of our study may help preclinical researcher interpret and compare the results between studies utilizing the two differing measurement techniques.…”