A comparison of methods for determining the partition coefficient of gadolinium in the myocardium using T1 mapping
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ORAL PRESENTATION
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A comparison of methods for determining the partition coefficient of gadolinium in the myocardium using T1 mapping Rajesh Janardhanan*, Ronny S Jiji, Jeremy Brooks, Frederick H Epstein, Christopher M Kramer, Michael Salerno From 2011 SCMR/Euro CMR Joint Scientific Sessions Nice, France. 3-6 February 2011 Introduction Late gadolinium enhancement can evaluate focal, but not diffuse myocardial fibrosis. T1-mapping techniques can quantify fibrosis by calculating the partition coefficient (l) of gadolinium (Gd). One method (CI) calculates l at equilibrium following a continuous infusion of Gd, while the other, early post-contrast method (EPC), determines l from multiple post-contrast time points after Gd injection. The Modified Look-Locker Inversion Recovery (MOLLI) technique accurately performs T1 mapping, but may be limited in practice due to the long breathhold required. A shortened-MOLLI technique (Sh-MOLLI) has been described, which only allows a single heart beat for magnetization recovery. Objectives To (i) compare T1 values determined with reduced breathhold MOLLI schemes to the standard MOLLI technique, and (ii) to directly compare l determined by the CI and EPC methods.
Methods T1 mapping was performed in 10 healthy volunteers (age 34±11) on a Siemens 1.5T Avanto using 3 MOLLI schemes: (i) Standard MOLLI (ii) 3-5 MOLLI (11 heart beats, 2 inversions, 3 recovery beats, 8 images), (iii) 2-24 MOLLI (12 heart beats, 3 inversions, 2 recovery beats, 8 images). Sequence Parameters included: TE/TR/FA 1.1 ms/2.5ms/35°, FOV= 340 x 260, resolution 1.8mm x 1.8mm, thickness 8mm. T1 was determined pre-contrast and every 5 minutes following injection of 0.1mmol/kg Gd-DTPA. At 15 minutes a continuous infusion of 0.001 mmol/kg Gd was administered until equilibrium was achieved. l was determined using the CI and EPC methods. T1 maps were calculated and manually segmented using an in-house MATLAB program. Results The standard MOLLI and the 3-5 MOLLI sequences provided comparable T1 values for myocardium and blood both pre- and post-contrast, whereas the 2-2-4
Table 1 Mean T1 values and partition co-efficients observed Mean Values
Standard MOLLI
3-5 MOLLI
2-2-4 MOLLI
P-value
T1 of blood pre-contrast (msec)
1478±86
1480±100
1390±91
0.06
T1 of myocardium pre-contrast (msec)
972±27
953±38
919±84
0.11
T1 of blood post-contrast (msec)
488±36
487±43
484±44
0.97
T1 of myocardium post-contrast (msec) Partition Co-efficients (CI-based method)
601±37 0.47±0.04
597±37 0.45±0.05
600±30 0.45±0.03
0.96 0.39
Partition Co-efficients (EPC-based method)
0.49±0.05
0.47±0.05
0.45±0.04
0.20
University of Virginia, Charlottesville, VA, USA © 2011 Janardhanan et al; licensee BioMed Central Ltd. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Janardhanan et al. Journal
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