1328790 - Usefulness of Motion Correction T1mapping under free breathing in cardiac MRI

Myocardial T1 mapping has allowed direct myocardial signal quantification and has shown potential for better characterization of myocardial tissue composition. Modified Look-Locker Inversion-recovery (MOLLI) sequence provides high resolution T1 map of myocardium with breath hold (BH) However, long breath holds often limit clinical application in patients due to motion artifact and heart rate variability. Recently, a novel motion correction technique (MOCO), which is non-rigid registration algorithm based on estimating motion-free synthetic images presenting similar contrast to original data, has been developed. MOLLI with this robust MOCO has a potential to enable the precise T1 map reconstruction, even in under free breathing (FB). In this study, we evaluated the feasibility of FB MOCO T1map, compared to conventional BH MOCO T1map.




Methods:

Nineteen healthy normal volunteers (45.02±15.6 years, man: woman = 12:7) underwent cardiac MRI at 3T clinical machine  (MAGNETOM Vida, Siemens AG Healthcare Sector). MOLLI method 5beats-(3beats)-3beats were performed at short-axial slice in basal, mid-ventricular and apical levels with breath hold (BH) and free breathing (FB), in repeated three times. The T1 map was reconstructed using MOCO and was divided into AHA 16-segment model using dedicated workstation (Circle cardiovascular Imaging Inc, cvi42) programmed based on deep learning. Correlations and differences in T1 values between BH and FB were evaluated.



Results:

All segments of T1 map showed good image quality without artifact, in not only BH but FB with MOCO. There were no significant differences in the global T1 obtained using BH and FB (1218.3±33.6 msec and 1225.8±38.1 msec, P=0.52)  and the good correlation between BH and FB methods were shown (r=0.92). The Bland-Altman analysis showed that the mean difference in the GCS between the BH and FB methods was -7.5 msec with limits of agreement between -35.9 and 20.8 msec. In all segments but antero-lateral wall, the Bland-Altman plot showed a good agreement between both methods, with good reproducibility, especially in the septal segments. Whereas, in basal and mid-anterolateral wall, T1 values obtained using FB method were significantly higher (p=0.02 and p=0.01) compared with those of BH method and relatively large differences were observed with mean difference of -86.5 msec (basal) and -91.3 msec (mid).

Conclusion:

The free breathing T1 map with MOCO permit the accurate and reproducible T1 measurement in similar to conventional breath hold method, except for a few segments of anterolateral wall.