9 T1-mapping is superior to T2-mapping in detecting acute myocardial oedema with a larger effect size: a head-to-head comparison

<h3>Introduction</h3> Detection of acute myocardial oedema is essential, given its role in many cardiovascular disease processes. T1- and T2-mapping can be used to detect myocardial oedema, but it is unclear whether T1-mapping is required for the detection of oedema. Patients with Takotsubo syndrome (TTS) were used as a model for acute myocardial oedema to assess relative diagnostic performance of T1- and T2-mapping. <h3>Materials and Methods</h3> 37 patients (17 with acute TTS syndrome and 20 healthy volunteers) were prospectively recruited and underwent CMR at 3 Tesla. Segmental analysis of matched cines/T1/T2 maps was performed. Receiver operating characteristic (ROC) curves were constructed to determine the ability of T1- and T2-mapping to distinguish between normal myocardium (in healthy controls) and oedematous myocardium (abnormal wall motion in patients with TTS). Effect sizes for T1- and T2-mapping were determined using results from this study and also from data from other studies that used T1- and T2-mapping in acute TTS. <h3>Results</h3> T1- and T2-values were raised in TTS patients compared to controls (T1 mean values TTS 1344ms v controls 1180ms; T2 mean values TTS 48.5ms v 41.6ms). T1-values correlated significantly better to regional wall motion abnormalities (RWMAs) than T2-values (T1 rho=0.787 p&lt;0.0001; T2 rho=0.725 p&lt;0.0001; p=0.0122). T1-mapping was superior to T2-mapping in detection of acute myocardial oedema (T1 area-under-the-curve [AUC] 0.964; T2 AUC 0.923; p&lt;0.0001). There was a greater effect size seen for T1- than T2-mapping at higher field strengths (3 Tesla studies effect size T1 = 2.6 v T2 = 1.9 and T1 = 1.3 v T2 = 0.7) with similar effect sizes for T1- and T2-mapping at 1.5 Tesla (1.5 Tesla studies effect size T1 = 1.6 v T2 = 1.6; T1 = 2.5 v T2 = 2.4; T1 = 4.1 v T2 = 3.9). <h3>Discussion</h3> This is the first study to perform a head-to-head comparison of T1- and T2-mapping using whole heart coverage to investigate the comparative ability of T1- and T2-mapping to detect acute myocardial oedema (using acute Takotsubo syndrome as a model). <h3>Conclusion</h3> T1-mapping is superior to T2-mapping in the detection of acute myocardial oedema, especially at higher field strengths (3 Tesla). T1-mapping may detect more subtle abnormalities than T2-mapping, such as subclinical or more chronic oedema and inflammation. <h3>Acknowledgements</h3> KET acknowledges support from the National Institute for Health Research (NIHR) Research Capacity Fund (RCF21/009) and the British Heart Foundation (BHF) Clinical Research Training Fellowship (FS/CRT/21/24268). LSC is supported by a NIHR Academic Clinical Fellowship. VMF acknowledges support from the BHF (CH/16/1/32013). SN, SKP and VMF acknowledge support from the Oxford BHF Centre of Research Excellence (RE/18/3/34214), and the NIHR Oxford Biomedical Research Centre at Oxford University Hospitals NHS Foundation Trust.