Dynamic late gadolinium enhancement simply quantified using myocardium to lumen signal ratio: Normal range of ratio and diffuse abnormal enhancement of cardiac amyloidosis

Purpose: To detect abnormal myocardial tissue in patients with diffuse myocardial disease, we propose a simple technique of late gadolinium enhancement (LGE) using routine myocardial imaging modalities. Materials and Methods: We retrospectively reviewed LGE images from 51 patients with normal myocardium and 10 patients with pathologically proven cardiac amyloidosis (CA). We obtained sequential LGE images from patients at 2, 5, 10, and 20 minutes after injection of Gd-DTPA (0.15 mmol/kg) with a fixed inversion time of 300 msec. We evaluated the signal intensity ratio of the myocardium to the left ventricular lumen (M/L) in one long and two short axial sections within 463 and 120 segments of normal myocardium and CA, respectively. Visually unenhanced and enhanced regions of myocardium were evaluated in each segment of patients with CA. Results: Among normal myocardium, M/L (means ± standard deviation; SD) was stable with time (2, 5, 10, and 20 min: 0.34 ± 0.03, 0.31 ± 0.05, 0.34 ± 0.07, and 0.42 ± 0.11, respectively). The calculated M/L of unenhanced (0.60 ± 0.20, 0.68 ± 0.19, 0.76 ± 0.20, and 1.09 ± 0.25, respectively) and enhanced myocardium (0.77 ± 0.27, 0.99 ± 0.29, 1.20 ± 0.40, and 1.45 ± 0.54, respectively) in patients with CA was significantly greater than that seen for the normal myocardium at each time and increased over time. Conclusion: In patients with CA, diffuse myocardial abnormalities can be demonstrated using M/L, and this technique may be useful for the characterization of other myocardial diseases.