Fast, whole-heart, free-breathing 3D T2 mapping at 3T with application to myocardial edema imaging
Journal of Cardiovascular Magnetic Resonance volume 17, Article number: Q125 (2015)
Cardiac MRI (CMR) T2 mapping is a proven method for myocardial edema detection. However, the current approach requires multiple breath-holds and can take nearly 10-15 minutes to complete. Faster acquisitions could potentially improve patient comfort and cost-effectiveness of CMR exams. the objecttive of this study is to develop and test a free-breathing, three-dimensional, cardiac MR approach which can yield fast, accurate, T2 maps of the whole left ventricle at 3T.
We developed an ECG-triggered, free-breathing, T2-prepared, three-dimensional gradient-echo acquisitions with different echo times (0, 24, 55 ms) with near perfect navigator efficiency on a clinical 3T system. The proposed approach was tested and validated in ex-vivo porcine hearts, healthy volunteers and canines with reperfused acute myocardial infarction (rAMI). On the basis of the navigator signals, images were corrected for respiratory motion and were fit to a mono-exponential function to derive T2 maps of the whole left-ventricular myocardium.
Ex-vivo myocardial T2 values of the proposed approach (3D FB MoCo) were not different from standard 2D approaches (all p<0.05): 48.7±0.9 ms (3D FB MoCo) vs. 48.2±0.6 ms (2D spin echo) and 47.5±0.8 ms (2D T2-prepared bSSFP (T2-prep bSSFP)). In healthy volunteers, compared to 3D FB MoCo and 2D BH, myocardial T2 maps, 3D FB Non-MoCo T2 myocardial maps showed longer T2 values (p<0.05), larger coefficient-of-variations (COV) in T2 (p<0.05), and lower image quality (p<0.05). Conversely, the mean and COV in myocardial T2 and image quality of 2D BH and 3D FB MoCo T2 were not different (p=0.99, p=0.74, p=0.14, respectively). In canines with rAMI, edema volumes measured from 2D BH and 3D FB MoCo T2 maps were closely correlated (both R2 = 0.97 and p<0.05). In Bland-Altman analysis, mean T2 of edematous and remote zones and edema volumes were within the limits of agreement (bias in T2 = 0.4 ms and edema volume = 0.9%).
The proposed free-breathing, three-dimensional T2 mapping approach at 3T enabled whole-heart acquisitions within 5 minutes with an accuracy in T2 not different from that of the state-of-the-art breath-held T2 mapping approach.
This work was supported in part by National Heart, Lung, and Blood Institute HL091989 (R.D.).The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Heart, Lung, And Blood Institute or the National Institutes of Health.
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Yang, HJ., Pang, J., Sharif, B. et al. Fast, whole-heart, free-breathing 3D T2 mapping at 3T with application to myocardial edema imaging. J Cardiovasc Magn Reson 17 (Suppl 1), Q125 (2015). https://doi.org/10.1186/1532-429X-17-S1-Q125