Histologic validation of stress cardiac magnetic resonance T1-mapping techniques for detection of coronary microvascular dysfunction in rabbits.

BACKGROUND

To investigate the diagnostic performance of stress cardiac magnetic resonance (CMR) T1-mapping for the detection of coronary microvascular dysfunction (CMD) by correlating microvascular density (MVD) and collagen volume fraction (CVF) with T1 response to adenosine triphosphate (ATP) stress (stress ΔT1) in rabbits.

METHODS

Twenty-four New Zealand white rabbits were randomly divided into the CMD group induced by microembolization spheres (n = 10), sham-operated group (n = 5), and control group (n = 9). All rabbits underwent 3.0 T CMR, both rest and ATP stress T1-maps were obtained, and first-pass perfusion imaging was performed. Stress ΔT1 and myocardial perfusion reserve index (MPRI) were calculated. For the histologic study, each rabbit was sacrificed after CMR scanning. Left ventricular myocardial tissue was stained with Hematoxylin-eosin (H&E), Masson, and CD31, from which MVD and CVF were extracted. Pearson correlation analyses were performed to determine the strength of the association between the stress ΔT1 and both MVD and CVF.

RESULTS

The stress ΔT1 values (CMD, 2.53 ± 0.37% vs. control, 6.00 ± 0.64% vs. Sham, 6.07 ± 0.97%, p < 0.001) and MPRI (CMD, 1.45 ± 0.13 vs. control, 1.94 ± 0.23, vs. sham, 1.89 ± 0.15, p < 0.001) were both lower in CMD rabbits compared with sham-operated and control rabbits. Further, the stress ΔT1 showed a high correlation with CVF (r = -0.806, p < 0.001) and MVD (r = 0.920, p < 0.001).

CONCLUSIONS

Stress T1 response strongly correlates with pathological MVD and CVF, indicating that stress CMR T1 mapping can accurately detect microvascular dysfunction.