sup 23^Na chemical shift imaging and Gd enhancement of myocardial edema

• Published in: The international journal of cardiovascular imaging 2013-02, Vol.29 (2), p.343
• Main Authors: Aguor, Eissa N, E, van de Kolk, Cees W, A, Arslan, Fatih, Nederhoff, Marcel G, J, Doevendans, Pieter A, F, M, Pasterkamp, Gerard, Strijkers, Gustav J, van Echteld, Cees J
• Format: Article
• Language: English
• ISSN: 1569-5794; 1573-0743
• DOI: 10.1007/s10554-012-0093-6

Myocardial edema can arise in several disease states. MRI contrast agent can accumulate in edematous tissue, which complicates differential diagnosis with contrast-enhanced (CE)-MRI and might lead to overestimation of infarct size. Sodium Chemical Shift Imaging (^sup 23^Na-CSI) may provide an alternative for edema imaging. We have developed a non-infarct, isolated rat heart model with two levels of edema, which was studied with ^sup 23^Na-CSI and CE-MRI. In edematous, but viable tissue the extracellular sodium (Na^sub e^^sup +^) signal is hypothesized to increase, but not the intracellular sodium (Na^sub i^^sup +^) signal. Isolated hearts were perfused at 60 (n = 6) and 140 mmHg (n = 5). Dimethyl methylphosphonate (DMMP) and phenylphosphonate (PPA) were used to follow edema formation by ^sup 31^P-MR Spectroscopy. In separate groups, Thulium(III)1,4,7,10 tetraazacyclododecane-N,N',N'',N'''-tetra(methylenephosphonate) (TmDOTP^sup 5-^) and Gadovist were used for ^sup 23^Na-CSI (n = 8) and CE-MRI (n = 6), respectively. PPA normalized signal intensity (SI) was higher at 140 versus 60 mmHg, with a ratio of 1.27 ± 0.12 (p < 0.05). The (DMMP-PPA)/dry weight ratio, as a marker of intracellular volume, remained unchanged. The mid-heart cross sectional area (CSA) of the left ventricle (LV) was significantly increased at 140 mmHg. In addition, at 140 mmHg, the LV Na^sub e^^sup +^ SI increased with a 140 mmHg/60 mmHg ratio of 1.24 ± 0.18 (p < 0.05). Na^sub i^^sup +^ SI remained essentially unchanged. With CE-MRI, a subendocardially enhanced CSA was identified, increasing from 0.20 ± 0.02 cm^sup 2^ at 60 mmHg to 0.31 ± 0.02 cm^sup 2^ at 140 mmHg (p < 0.05). Edema shows up in both CE-MRI and Na^sub e^^sup +^. High perfusion pressure causes more edema subendocardially than subepicardially. ^sup 23^Na-CSI is an attractive alternative for imaging of edema and is a promising tool to discriminate between edema, acute and chronic MI.[PUBLICATION ABSTRACT]