In vivo R1-enhancement mapping of canine myocardium using ceMRI with Gd(ABE-DTTA) in an acute ischemia-reperfusion model

Purpose To demonstrate the usefulness of normalized ΔR1 (ΔR1n) mapping in myocardial tissue following the administration of the contrast agent (CA) Gd(ABE‐DTTA). Materials and Methods Ischemia‐reperfusion experiments were carried out in 11 dogs. The method exploited the relatively long tissue lifetime of Gd(ABE‐DTTA), and thus no fast R1 measurement technique was needed. Myocardial perfusion was determined with colored microspheres (MP). Results With varying extent of ischemia, impaired wall motion (WM) and lower ΔR1n values were detected in the ischemic sectors, as opposed to the nonischemic sectors where normal WM and higher ΔR1n were observed. Based on the ΔR1n, data from the myocardial perfusion assay and the ΔR1n maps were compared in the ischemic sectors. A correlation analysis of these two parameters demonstrated a significant correlation (R = 0.694, P < 0.005), validating the ΔR1n‐mapping method for the quantitation of ischemia. Similarly, pairwise correlations were found for the MP, ΔR1n, and wall thickening (WT) values in the same areas. Based on the correlation between ΔR1n and MP, ΔR1n maps calculated with a pixel‐by‐pixel resolution can be converted to similarly high‐resolution myocardial perfusion maps. Conclusion These results suggest that the extent of the severity of ischemia can be quantitatively represented by ΔR1n maps obtained in the presence of our CA. J. Magn. Reson. Imaging 2006. © 2006 Wiley‐Liss, Inc.