Dual spin-echo magnetic resonance imaging may be used for calculation of transverse myocardial relaxation time from the signal intensity of the echoes considered. In this study, the ability of myocardial transverse relaxation time (T2) to quantitate myocardial edema of the right ventricle (RV) and left ventricle (LV) was tested. Dual spin-echo magnetic resonance images of the entire hearts were obtained and T2 of the RV and LV myocardium calculated from the signal intensities within multiple regions of interest distributed over the myocardium. Six hearts were intermittently perfused through an aortic cannula with three perfusates of decreasing osmolality. Biopsies were obtained for water content (WC) analysis both before and after imaging the hearts at baseline and post-perfusion. A seventh (control) heart was not perfused; instead dual spin-echo imaging was performed at the same time intervals as in the perfused hearts. Prior to any intervention, there was no significant difference between baseline RV (79.49 ± 2.10%) and LV (77.99 ± 2.44%, p = .2) myocardial water content; RV myocardial T2 (59.9 ± 5.8 msec) was slightly but not significantly longer than that of the LV (54.6 ± 5.7 msec, p = .1). After induction of edema, strong correlation was found between right ventricular myocardial water content measurements and right ventricular T2 (RV WC = 68.5 + 0.19 × RV T2; N = 27, R = 0.92, p < .0001, SEE = 1.56%). Similarly, strong correlation was found between left ventricular myocardial water content and T2 (LV WC = 62.1 + 0.29 × LV T2; N = 27, R = 0.92, p < .0001, SEE = 1.80%). However, slopes of these two regression lines were significantly different (p < .01). Thus, we conclude that myocardial T2 may be used to quantitate regional myocardial edema. Differences in the relationship between RV and LV myocardial water content and their effect on T2 may represent differences in the manner each tissue distributes edema fluid.
- Myocardial edema
- Transverse relaxation
ASJC Scopus subject areas
- Biomedical Engineering
- Radiology Nuclear Medicine and imaging