Acute rejection (AR) remains a significant cause of morbidity and mortality in pediatric patients after heart transplant. Endomyocardial biopsy (EMB) of the right ventricular septum is the standard method for diagnosing AR. However, EMB is prone to additional risk and sampling error as AR is a heterogeneous process. Here we show that extracellular volume fraction (ECV) mapping of the left ventricle (LV) analyzed with standard descriptive statistics and specialized texture analysis may differentiate pediatric heart transplant recipients as having AR or not. This CMR diagnostic approach offers diagnostic advantages including greater sampling volume and minimal invasiveness.