MR angiography of the head/neck vascular system in mice on a clinical mri system

Background. Magnetic resonance angiography (MRA) represents a clinical reference standard for the in vivo assessment of the vasculature. In this study, the potential of non-contrast-enhanced and contrast-enhanced angiography of the head/neck vasculature in mice on a clinical MR imaging system was tested. Methods. All in vivo magnetic resonance imaging was performed with a 3T clinical system (Siemens). Non-contrast-enhanced (time-of-flight, TOF) and contrast-enhanced angiography (gadofosveset-Trisodium, GdT) were performed in C57BL/6J mouse strain. Lumen-To-muscle ratios (LMRs) and area measurements were assessed. Histology was performed as reference standard of all relevant vascular structures. Results. A close correlation between TOF (R² = 0.79; p<0.05) and contrast-enhanced (GdT) angiography (R² = 0.92; p<0.05) with histological area measurements was found. LMRs were comparable between both sequences. Regarding interobserver reproducibility, contrast-enhanced (GdT) angiography yielded a smaller 95% confidence interval and a closer interreader correlation compared to non-contrast-enhanced (TOF) measurements (-0.73-0.89; R² = 0.81 vs.-0.55-0.56; R² = 0.94). Conclusion. This study demonstrates that non-contrast-enhanced and contrast-enhanced angiographies of the head/neck vasculature of small animals can reliably performed on a clinical 3T MR scanner. Contrast-enhanced angiography enables the visualization of vascular structures with higher intravascular contrast and higher reproducibility.