• Gang Li, Bo Xiang, Guangping Dai, Anthony Shaw, Hongyu Liu, Baofeng Yang, Mike Jackson, Roxanne Deslauriers, and Ganghong Tian.
• Institute for Biodiagnostics, National Research Council, Winnipeg, Canada.
• J Magn Reson Imaging. 2005 Jun 1; 21 (6): 744-51.

PurposeTo determine whether tissue edema changes gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA)-enhanced T1 relaxation times of the viable myocardium.Materials And MethodsA total of 16 isolated pig hearts were divided into four groups (N=4/group) and perfused in a Langendorff apparatus. Gd-DTPA was injected into the aortic perfusion line. Tissue edema was then induced by two hours of simultaneous arterial/venous perfusion (SAVP). Myocardial water content and T1 relaxation times were monitored throughout SAVP. The volumes of the extracellular and intracellular compartments were assessed using 31P MRS-detectable markers, phenylphosphonic acid (PPA) and dimethyl methylphosphonate (DMMP).ResultsTissue water content in both viable and infarcted myocardium increased significantly during two-hour SAVP. However, Gd-DTPA-enhanced T1 relaxation times of the viable myocardium remained relatively unchanged. Infarcted myocardium, on the other hand, exhibited significant T1 shortening during SAVP. Furthermore, SAVP resulted in significant expansions of both extracellular and intracellular compartments, but the ratio of the volumes of the two compartments remained relatively constant.ConclusionTissue edema in the viable myocardium does not increase the relative distribution volume of the contrast agent. As a result, edema does not change Gd-DTPA-enhanced T1 relaxation times of the viable myocardium.

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