Aquillion one

Magnetic resonance imaging was performed as part of the patient's clinical care on a 1.5 Tesla scanner (Siemens Healthineers) at the Edinburgh Heart Center. Sequences were acquired according to the clinical indication, but included localisers, axial HASTE images, and standard breath-held and electrocardiogram-gated CINE sequences. Delayed enhancement images (gradient echo inversion recovery sequences) were performed 10 min after injection of gadolinium contrast agent (0.2 mmol/kg).
Patients underwent cardiac CT imaging using a 320 multidetector scanner (Aquillion One, Canon Medical Systems) at Edinburgh Imaging, University of Edinburgh. Participants with a heart rate of greater than 60 beats/min received intravenous beta blockade prior to CT imaging. Sublingual glyceryl trinitrate was administered prior to CT imaging, unless contraindicated. Electrocardiogram-gated CT was performed 4 min after injection of 100 ml of iodinated contrast (Iomeron 400). Patients underwent CT using four tube voltages in rapid succession (80, 100, 120, and 135 kV). Only the 80 and 100 kV images were used in this study. Tube current was automatically set based on scout image attenuation. Mean radiation dose of 80 kV images was 1.6 ± 0.4 millisievert (mSv) and 100 kV images was 2.6 ± 1.2 mSv (conversion factor 0.028 mSv/mGy.cm).

All the patients in the internal training and validation cohorts were scanned using a 320-row CT (Aquillion ONE, Canon medical systems, Tokyo, Japan). Prospective gated CCT was obtained just before CCTA, at 75% of R-R interval, with a tube current of 50–250 mA (depending on body mass index), and voltage of 120 KVp. The slice thickness was 3.0 mm. Images of the external test cohort were obtained with a same voltage and slice thickness; however, the other detailed conditions are not disclosed.

CT acquisition was acquired using a 320-slice scanner (Aquillion One, Canon Medical Systems Corporation, Tochigi, Japan), with a CT angiography protocol (thickness 0.5 mm; 100 kV; rotation time 0.5 s; mA R 388). To provide realistic contrast enhancement for the vascular structures, the phantom was submerged in a mixture of water and Iodixanol (Visipaque, GE Healthcare, Chicago, IL, USA), a water soluble, isosmolar, non-ionic, iodinated radiographic contrast agent.