Comparison of MOLLI and ShMOLLI Regarding T1 Reactivity, and the Relationship of T1 Reactivity with Conventional Signs of Response During Adenosine Stress Perfusion CMR.

Background: Cardiac Magnetic Resonance (CMR) has proven to be a valuable imaging modality used both to diagnose and to differentiate coronary heart diseases (CHD) from other cardiomyopathies. One of the most important techniques of CMR in assessment of CHD is Adenosine Stress Myocardial First Pass Perfusion Imaging. During this imaging method to make an accurate evaluation, there should be an adequate response to the drug adenosine. The conventional signs of drug response are not always observed, and are often subjective. The methods based on splenic perfusion might possess limitations too. Therefore T1 mapping presents as a novel, quantitative and reliable method. There are several studies analyzing this newly discovered property of different T1 mapping sequences, however most of them are enrolling only one of the techniques. Aims: We aimed to compare MOLLI and ShMOLLI sequences in terms of T1 reactivity (DeltaT1), and to determine the relationship between DeltaT1 and conventional stress adequacy assessment methods in Adenosine Stress Perfusion CMR. Study Design: This is a cross-sectional study and STARD reporting guidelines were used. Methods: 34 consecutive patients, who were referred for adenosine stress perfusion CMR because of the suspicion of myocardial ischaemia, were prospectively enrolled. 4 patients were disqualified, and 30 patients were included in the final analysis. Mid-ventricular short axis slices of T1 maps using both MOLLI and ShMOLLI were acquired at rest and during peak adenosine stress before gadolinium administration. Then they were divided into 6 segments according to the American Heart Association 17 segments model, and separate measurements were made from each segment. Mean rest and mean stress T1 values of remote, ischaemic, infarcted myocardiums were calculated individually per subject. During adenosine administration patients' heart rates (HR) and blood pressures (BP) are measured and recorded every one minute. Adenosine stress perfusion images were examined for the presence of splenic switch-off. Results: There was significant difference between rest and stress T1 values of remote myocardium in both MOLLI and ShMOLLI (p<0.001). In both MOLLI and ShMOLLI there was no significant correlation between DeltaT1 and HR response (MOLLI p=0.30, ShMOLLI p=0.10), BP response (MOLLI p=0.062, ShMOLLI p=0. 0.078), splenic perfusion (MOLLI p=0.35, ShMOLLI p=0.053). There was no statistically significant difference between MOLLI and ShMOLLI regarding DeltaT1 of remote (p=0.330), ischaemic (p=0.068), and infarcted (p=0.116) myocardiums. Conclusion: In summary, we found that DeltaT1 is independent of the other stress response signs. MOLLI and ShMOLLI do not differ in terms of DeltaT1.