006 Role of T1 mapping as a complementary tool to T2* for non-invasive cardiac iron overload assessment

Background Iron overload-related heart failure is the principal cause of death in transfused Thalassemia Major1–2 and other iron overload patients. Linking cardiac siderosis measured by T2* to therapy improves outcome in Thalassemia Major. Aim of our study is to compare T1 mapping (Modified Lock Locker Inversion recovery, MOLLI) to dark (DB) and bright (BB) blood T2*3–4 in cardiac iron overload and to support the hypothesis that T1 mapping has higher sensibility to T2* for small amount of iron, which would make it a complementary tool to T2* in borderline iron overload patients.5–6 Methods In a prospectively large single centre study of 138 Thalassemia Major patients and 32 healthy controls, we compared MOLLI to DB and BB T2* acquired on an Avanto 1.5T scanner (Siemens Healthcare, Erlangen, Germany). Linear regression analysis was used to assess the association between DBT2* and either BBT2* and MOLLI, and the determination coefficient was computed in a log-log scale with moving windows to detect the point where this association decreases. Results The relationship between T2* (here DB) and MOLLI is described by a log-log linear regression, which can be split in three different slopes: 1) T2* low, <20ms: r2=0.92; 2) T2*=20–28 ms: r2=0.80; 3) T2*>28 ms, no relationship. All subjects with T2*<20 ms had low T1; of those with T2*>20 ms, 38% had low T1. Conclusions These data support the former proposal that T1 detects missed iron 1 in 3 subjects with normal T2* and that T1 mapping is a complementary tool for non-invasive assessment of cardiac iron. The clinical significance of a low T1, normal T2* should be further investigated. A trend toward LV end diastolic volume increase was observed in the patients with low T1 and normal T2* at 24 months, but the sample was too small to be analysed (n=9). References. Modell B, Khan M, Darlison M, Westwood MA, Ingram D, Pennell DJ. Improved survival of thalassaemia major in the UK and relation to T2* cardiovascular magnetic resonance. J Cardiovasc Magn Reson2008;10:42.. Carpenter JP, Pennell DJ. On T2* Magnetic Resonance and Cardiac Iron. Circulation2011;14:1519–28.. Wood JC, Otto-Duessel M, Aguilar M, et al. Cardiac Iron Determines Cardiac T2*, T2, and T1 in the Gerbil Model of Iron Cardiomyopathy. Circulation2005;112(4):535–543.. Carpenter JP, He T, Kirk P, et al. Calibration of myocardial T2 and T1 against iron concentration. J Cardiovasc Magn Reson2014;16:62.. Alam MH, Auger D, Smith GC, et al. T1 at 1.5T and 3T compared with conventional T2* at 1.5T for cardiac siderosis. J Cardiovasc Magn Reson. 2015;17:102.. Messroghli DR, Radjenovic A, Kozerke S, Higgins DM, Sivananthan MU, Ridgway JP. Modified Look-Locker inversion recovery (MOLLI) for high-resolution T1 mapping of the heart. Magn Reson Med2004;52(1):141–6.. Alam MH, Auger D, Smith GC, et al. T1 at 1.5T and 3T compared with conventional T2* at 1.5T for cardiac siderosis. J Cardiovasc Magn Reson2015;17(24):102. Figure. No caption available.