Quantitative myocardial mapping using 3.0 T cardiac magnetic resonance imaging in dogs: adenosine stress-rest...

High-field cardiac magnetic resonance imaging (MRI) enables noninvasive assessment of myocardial tissue characteristics in anesthetized dogs; however, adenosine stress myocardial mapping at 3.0 T remains insufficiently characterized. This study evaluated stress-rest changes and level-dependent variation in quantitative myocardial mapping indices. Seven clinically asymptomatic dogs not receiving cardiac medications underwent 3.0 T cardiac MRI under general anesthesia in this prospective observational methodological study. Each dog completed two left ventricular myocardial mapping sessions (adenosine stress and rest) separated by ≥48 h. During stress, adenosine was infused at 140 μg/kg/min. T1 native, T1 post, T2, and extracellular volume fraction (ECV) were acquired at basal, mid, and apical short-axis levels. Stress-rest differences were tested with the Wilcoxon signed-rank test, and basal-mid-apical differences were assessed using generalized estimating equations (GEE) (p < 0.05). Under adenosine stress, global T1 native and T2 were 6.73 and 10.16% higher than at rest, whereas global T1 post and ECV did not change significantly. Level-wise analyses showed basal predominance for T1 native, a modest stress-only basal-mid difference for ECV, and lower basal T2 at rest. At 3.0 T, adenosine stress was associated with measurable increases in myocardial T1 native and T2 in anesthetized dogs, supporting further evaluation of protocol-specific, stress-associated mapping responses without relying solely on contrast-enhanced indices. Because mapping values varied across basal, mid, and apical levels, myocardial sampling level should be considered when interpreting or comparing canine stress-rest maps.