Kai Nassenstein, Presenter: Nothing to Disclose

Frank Breuckmann, Abstract Co-Author: Nothing to Disclose

Stefan Maderwald, Abstract Co-Author: Nothing to Disclose

Oliver Bruder, Abstract Co-Author: Nothing to Disclose

Joerg Barkhausen MD, Abstract Co-Author: Nothing to Disclose

Thomas W. Schlosser MD, Abstract Co-Author: Nothing to Disclose

According to the Lake Louise criteria an increased global myocardial early gadolinium enhancement ratio between myocardium and skeletal muscle (EGEr) is an important criterion for diagnosis of acute myocarditis (AM). So far, EGEr has been measured inconsistently at various points in time after contrast injection. Due to the fact the pharmacokinetics of low-molecular Gd-based contrast agents is complex, time-related changes in EGEr after contrast injection are highly likely. Since the knowledge of time-related changes of EGEr may improve diagnostic accuracy of CMR, our study aimed to estimate the time course of EGEr after contrast injection in patients as well as in healthy volunteers.

An ECG triggered inversion recovery SSFP sequence with incrementally increasing inversion times (TE 1.2 ms, TR 2.4 ms, FA 50°, increasing inversion times in steps of 27.5 ms) was acquired repetitively over 15 minutes after injection of 0.2 Gd-DTPA per kg body weight in a 4 chamber view in 15 patients with acute myocarditis and in 20 healthy volunteers. From these measurements, the T1-relaxation times and the longitudinal relaxation rates (R1) of myocardium and skeletal musculature were calculated for each point in time after contrast injection. Based on the linear relationship between R1 and tissue Gd-concentration, the time course of EGEr was calculated for patients with AM and healthy volunteers.

EGEr decreased over time in form of a negative power function with asymptotic approximation to the value of 1 in patients with AM and in healthy controls. EGEr of patients with AM tended to be higher than in controls (maximum difference one minute after injection), although no statistically relevant differences between the two groups were found.

Our study demonstrates for the first time, that EGEr rapidly changes after contrast injection, which must be carefully considered when using EGEr as a diagnostic tool. Moreover in our study, measurement of EGEr does not allow a differentiation between patients with AM and healthy volunteers. The trend for a higher EGEr in the patients is largest one minute after contrast injection.

EGEr is an equivocal parameter for diagnosis of AM since it rapidly changes after contrast injection and it did not allow a reliable differentiation between patients with AM and healthy controls.

Nassenstein, K, Breuckmann, F, Maderwald, S, Bruder, O, Barkhausen, J, Schlosser, T, Cardiac MRI: Estimation of Changes in the Global Myocardial Gd-enhancement Ratio between Myocardium and Skeletal Muscle over Time after Contrast Injection in Patients with Acute Myocarditis and Healthy Volunteers.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11004185.html