Doppler ultrasound compared with electrocardiogram and pulse oximetry cardiac triggering: A pilot study

Accurate triggering of the cardiac cycle is mandatory for optimal image acquisition and thus diagnostic quality in cardiac magnetic resonance imaging. The purpose of this work was to evaluate Doppler ultrasound as an alternative trigger method in cardiac MRI.

Steady-state free precession (SSFP) 2D cine CMR was performed in 11 healthy subjects at 1.5T. Doppler ultrasound (DUS), electrocardiogram (ECG) and pulse oximetry (POX) were used for cardiac triggering. DUS peak detection was verified in comparison to ECG. Quantitative analysis of image quality of each gating method was determined by calculating endocardial border sharpness (EBS) and left ventricular (LV) function parameters and compared with ECG.

Mean difference between DUS and ECG in detected RR intervals was 0.04 ± 63 ms (r = 0.96). Trigger jitter was not different between ECG and DUS (P = 0.15) but significant different between ECG and POX (P = 0.01). EBS was similar between each method (3.1 ± 0.2 / 2.6 ± 0.2 / 2.9 ± 0.2 pixel). Mean differences in stroke volume were not significantly different with -1 ± 7 mL (ECG/DUS, P = 0.9) and 2 ± 10 mL (ECG/POX, P = 0.8).

Cine cardiac MRI using DUS was successfully demonstrated. DUS triggering is an alternative method for cardiac MRI and may be applied in a clinical setting.