Table 5.

Comparison of the practicalities to apply echocardiography and CMR in mice for the assessment of cardiac function and fibrosis

	Echocardiography	CMR
Imaging resolution	• Specialized small animal echocardiography systems have very high temporal resolution, and adequate spatial resolution for most study requirements. Excellent for assessing cardiac function but inferior for assessing cardiac fibrosis in comparison to CMR.	• Specialized small animal CMR systems have lower temporal resolution, and exceptional spatial resolution, with additional capabilities including advanced tissue characterization, e.g., fibrosis.
Cost	• Lower	• Higher
Availability	• In small animal research, echocardiography is a relatively high-throughput, widely accessible, safe, and noninvasive imaging technique.	• CMR imaging is a relatively low-throughput, noninvasive imaging technique, becoming available to a growing number of well-resourced laboratories.
Training and expertise	• Acquisition and analysis of small animal echocardiography is practical, achievable, and relatively high throughput, with standardized training available to maintain essential rigor and reproducibility.	• Acquisition of CMR imaging, particularly with less well-characterized techniques, requires specialized expertise. Similarly, CMR analysis requires at least moderate understanding of MR physics, generally requiring multidisciplinary teams (biologists/physiologists and physicists/radiologists).
Time	• Due to its low cost and rapid acquisition time, echocardiography is suitable for imaging of all mice within each cohort of a given study (∼15–50 scans/day), depending on the parameters required.	• Due to its longer setup/scan duration, it is typically only suitable for scanning small study cohorts (∼4–10 scans/day), depending on the parameters/protocols/sequences required. Sample size calculations should be performed for the parameter of interest (104).

CMR, cardiac magnetic resonance; MR, magnetic resonance.