Abstract

Background Coronary microvascular dysfunction (CMD) is a major contributor to cardiovascular complications in diabetes. Although noninvasive techniques such as arterial spin labeling cardiac MRI (ASL-MRI) and transthoracic echocardiography (TTE) are available, their comparative performance for CMD remains unclear. Purpose To compare ASL-MRI and TTE for CMD assessment in type 1 and type 2 (T1DM, T2DM) mouse models and relate functional indices to histological microvascular and myocardial remodeling, including early-stage T2DM (8w-T2DM). Study Type Prospective. Animal Model Forty 8-week-old male C57BL/6J mice allocated to five groups: control, T1DM, and T2DM ( n = 10 per group, imaged 16 weeks postinduction), and early-stage T2DM (8w-T2DM) and age-matched controls ( n = 5 per group, imaged 8 weeks post-induction). Field Strength/Sequence Segmented FLASH cine, steady-pulsed labeling ASL, and inversion-recovery segmented FLASH (T1 mapping) sequences at 9.4 T. Assessment Rest/stress myocardial blood flow (MBF) and myocardial perfusion reserve (MPR) were derived from ASL data using a model-based approach incorporating native T1 (from segmented FLASH data). Coronary flow velocity (CFV) and reserve (CFVR) were measured by TTE at rest (1.5% isoflurane) and stress (2.5% isoflurane). Histology included assessment of hematoxylin–eosin (myocyte area), Masson (collagen), and IB4 (capillary density). Statistical Tests Group comparisons used t -tests, Mann–Whitney U tests, and one-/two-way ANOVA with Bonferroni correction; correlations were assessed with Pearson or Spearman coefficients ( r ). p < 0.05 was considered significant. Results 38 animals completed MR and TTE imaging. At 16 weeks, stress diastolic MBF was significantly lower in T1DM (14.67 ± 1.62 mL/g/min) and T2DM (13.42 ± 2.44 mL/g/min) vs. controls (22.19 ± 0.25 mL/g/min), with significantly reduced MPR in T2DM (1.53 ± 0.17 vs. 2.27 ± 0.15). TTE showed significantly reduced CFVR only in T2DM (2.16 ± 0.24 vs. 2.75 ± 0.