Argus software

Left ventricular analysis images were analysed offline using Argus software (Siemens, Erlangen, Germany) by an experienced researcher (SZM). Segmentation involved tracing endocardial and epicardial contours on the short-axis left ventricle images at end-diastolic and end-systolic phases of the cardiac cycle. Papillary muscles were treated as part of the blood pool volume unless they were indistinguishable from the myocardial wall, and then they were assigned as left ventricle muscle. The left ventricular mass (LVM), stroke volume (LVSV), ejection fraction (LVEF), end-diastolic (LVEDV) and end-systolic volumes (LVESV) were determined using algorithm based on the Simpson rule. Results were normalised to body surface area using the DuBois formula [13 (link)]. Left ventricular mass volume ratio (LVMVR) was calculated as LVEDV/LVM. Left ventricular global function index (LVGFI) was calculated as LVGFI = (LVSV/LV global volume) × 100, where LV global volume was defined as the sum of the LV mean cavity volume [(LVEDV + LVESV)/2] and the myocardium volume [14 (link)]. The PSIR sequences of the left ventricle were inspected for evidence of late gadolinium enhancement (LGE) using an imaging workstation (Carestream, Rochester, NY, USA). 10 datasets were chosen at random and rescored by the same observer to derive intra-observer agreement.

LV indices were analysed by a single blinded observer as previously described^{9 (link)}. For T1 maps, LV contours were drawn onto colour-enhanced spatially co-registered maps. The anterior right ventricular insertion point was used as reference and T1 maps were segmented corresponding with the American Heart Association (AHA) 16-segment model^{26 (link)}. Segmental AHA regions were delineated by user-defined border delineation on Siemens Argus software. T1 times were measured in each segment. Care was taken to ensure adequate margins from tissue interfaces such as between the blood pool and myocardium. After removal of any segments affected by artefact, global T1 time was calculated as the mean of remaining segments. Septal T1 time was calculated by averaging remaining AHA anteroseptal, inferoseptal, and septal segments (i.e. segments 2, 3, 8, 9, 14). To determine GLS, strain rate and end-diastolic strain rate feature-tracking software (TomTec, Diogenes Image Arena, Munich, Germany) was used. On horizontal long-axis cine acquisition, the end-diastolic frame was identified for each image and endocardial borders were delineated. The delineated contour was then automatically propagated throughout the cardiac cycle and GLS, strain rate and early diastolic strain rate calculated²⁷ .

Left ventricular analysis images were analysed offline using Argus software (Siemens, Erlangen, Germany) by two experienced CMR researchers. The manual 3D digital segmentation involved tracing endocardial and epicardial contours on the short-axis left ventricle images at end-diastolic and end-systolic phases of the cardiac cycle. Papillary muscles were treated as part of the blood pool volume unless they were indistinguishable from the myocardial wall, and then they were assigned as left ventricle muscle. The left ventricular mass (LVM), stroke volume (SV), ejection fraction (EF), end-diastolic (EDV) and end-systolic volumes (ESV) were determined using an algorithm based on the Simpson rule [19 ]. Results were normalised to body surface area. Left ventricular hypertrophy was defined as an indexed LVM above the normal range for sex [19 ]. Late gadolinium enhanced images of the left ventricle were inspected for evidence of myocardial signal enhancement using a Carestream PACS workstation (Rochester, NY, USA). The location was recorded according to the AHA 17 segment model [20 ]. Delayed enhancement was defined as <50 % or >50 % wall thickness according to the maximum depth of delayed enhancement in any segment.