Table 6.

Pros and Cons of using CMR for assessing myocardial fibrosis in mice

Pros	Cons
• Noninvasive: CMR is a noninvasive imaging technique. It doesn’t require complex surgical procedures or tissue sampling, and therefore, is not a terminal procedure.	• Indirect measure of fibrosis: CMR provides an indirect measure of cardiac fibrosis, and not all methods/sequences have been validated against cardiac biopsy samples with direct measures of collagen fibers. Depending on the imaging methods and mouse models used, this may lead to an over or under representation of cardiac fibrosis. CMR results should be validated with histological analysis incorporating stains for collagen including Masson's trichrome or Picrosirius red. Molecular assessment of collagen gene and protein abundance by qPCR or Western blotting can also be used as a complementary approach.
• Longitudinal Studies: Since CMR is noninvasive, it allows for longitudinal studies, enabling researchers to monitor changes in fibrosis over time within the same animal. This is critical for understanding disease progression with or without interventions or treatments.	• Cost and Infrastructure: CMR is a relatively expensive imaging modality, and it requires specialized equipment and facilities. This can be a limiting factor for some research groups.
• Multiparameter Imaging: Multiple imaging sequences or modalities can be used to obtain comprehensive data on cardiac structure and function, in addition to cardiac fibrosis in the same mice.	• Limitations detecting diffuse fibrosis: CMR techniques require further optimization to accurately and reproducibly detect diffuse fibrosis in mice. This limits the ability to detect subtle changes in diffuse fibrosis with interventions or treatments.

CMR, cardiac magnetic resonance; qPCR, quantitative polymerase chain reaction.