Figure 6.

Longitudinal evaluation of progressive changes from infarcted myocardium to large LM (arrows) by in vivo, ex vivo cMRI and histological study. Serial images of the midcardiac slice by T1WI (A1-D1), T2WI (A2-D2), DE-MRI (A3-D3) and Cine-MRI (A4-D4 and A5-D5) were taken at 48 hours (A1-A5), 2 weeks (B1-B5), 2 months (C1-C5) and 9 months (D1-D5), respectively. Acute (48 hours) MI (A1-A5): The infarct appeared isointense on T1WI (A1); hyperintense including papillary muscle on T2WI (A2); hyperenhanced on DE-cMRI (A3); and isointense but hypokinetic on Cine-MRI (A4, A5). Early (2 weeks) chronic MI (B1-B5): The infarct remained isointense on T1WI (B1); hyperintense but smaller on T2WI (B2); hyperenhanced transmural on DE-MRI, thinner than before (B3); and dyskinesia of the lateral wall on Cine-MRI (B4, B5). Chronic (2 months) MI (C1-C5): slightly hypointense on T1WI (C1); almost isointense with irregular, boundary on T2WI (C2); moderately enhanced on DE-MRI (C3); partially signal lost on the fat suppression Cine-MRI, suggesting the initiation of LM (C4, C5). Healed (9 months) MI (D1-D5): hyperintense with clear boundary on T1WI (D1); moderately hyperintense on T2WI (D2); lack of contrast enhancement on DE-MRI (D3); and signal void on cine-MRI with fat suppression (D4, D5). Postmortem T1WI and T2WI MRI with fat suppression (E1, E2): drastic signal losses corresponded to the high signal on in vivo T1WI and T2WI (D1, D2), suggesting large LM. Macroscopies (F1: fresh section; F2: 15 min after TTC staining; F3: 24 hours after TTC staining) corresponded well with MR images. Fat extensively occupied TTC-negative region. Histology (G1-G4): MTC stained photograph (G1) and photomicrograph (G2) (magnification, ×100) and H&E stained photograph (G3) and photomicrograph (G4) (magnification, ×100) demonstrated clearly LM, with high densities of the adipose cells surrounded by few fibers and macrophages. Dashed square indicates where microscopy was focused.