High-Resolution Contrast-Enhanced MRI of Atherosclerosis With Digital Cardiac and Respiratory Gating in Mice

Atherosclerosis initially develops predominantly at the aortic root and carotid origin, where effective visualization in mice requires efficient cardiac and respiratory gating. The present study sought to first compare the high-resolution MRI gating performance of two digital gating strategies using: 1) separate cardiac and respiratory signals (double-sensor); and 2) a single-sensor cardiorespiratory signal (ECG demodulation), and sec-ond, to apply an optimized processing technique to dynamic contrast-enhanced (CE) carotid origin vessel-wall imaging in mice. High-resolution MR mouse heart and aortic arch images were acquired by ECG signal detection, digital signal process-ing, and gating signal generation modeled using Simulink (MathWorks, USA). Double-sensor gating used a respiratory sensor while single-sensor gating used breathing-modulated ECG to generate a demodulated respiratory signal. Pre- and postcontrast T1-weighted images were acquired to evaluate vessel-wall enhancement with a gadolinium blood-pool agent (P792; Guerbet, France) at the carotid origin in vivo in ApoE–/– and C57BL/6 mice, using the optimized cardiorespiratory gat-ing processing technique. Both strategies provided images with improved spatial resolution, less artifacts, and 100 % correct transistor-to-transistor logic (TTL) signals. Image quality al-lowed vessel-wall enhancement measurement in all the ApoE–/– mice, with maximal (32%) enhancement 27 min postinjection. The study demonstrated the efficiency of both cardiorespira-tory gating strategies for dynamic contrast-enhanced vessel