24 channel spine matrix coil

MRI studies of the lumbar spines of all participants were performed on a clinical 3 Tesla (T) MRI scanner (Magnetom Prisma, Siemens Healthineers, Erlangen, Germany) with a 32-channel body and a 24-channel spine matrix coil (Siemens Healthineers, Erlangen, Germany) in the supine position.
In line with earlier studies, the MRI exams comprised both morphologic and compositional sequences. The morphologic sequences included T1-weighted (T1w), T2-weighted (T2w), and short-tau-inversion-recovery (STIR) sequences in the sagittal orientation and a T2w sequence in the transversal orientation. Compositional imaging included CEST and Water Saturation Shift Referencing (WASSR) sequences to compensate for magnetic field inhomogeneities in the sagittal orientation. Detailed sequence parameters are presented in Table 2.

All participants underwent MR imaging of their lumbar spine on a whole-body clinical 3.0T MRI system (Magnetom Prisma, Siemens Healthineers, Erlangen, Germany). Patients were examined in the supine position and imaged with a 32-channel body and a 24-channel spine matrix coil (both Siemens Healthineers). The imaging protocol consisted of a clinical routine protocol, i.e., T1- (T1w) and T2-weighted (T2w) sequences and a short tau inversion recovery (STIR) sequence, and compositional sequences using gagCEST and water saturation shift referencing (WASSR) imaging. All sequences were acquired in the sagittal orientation. Detailed sequence parameters are given in Table 2.

A short stack of cine images was obtained using a 24-channel spine matrix coil, 6-channel body array coil (both Siemens), and steady-state free precession sequences, as described previously.^{32 (link)} In brief, all images were ECG-gated and taken during end-expiratory breath-hold. Typical steady-state free precession sequence measures were: slice thickness, 8 mm; gap, 2 mm; retrospective gating, 1.5 ms; repetition time (TR), 46 ms; flip angle 50º; field of view, 400 mm; and matrix size, 256 in frequency encode direction. When necessary, prospective gating was used in atrial fibrillation. Images were analyzed with manually drawn LV endocardial and epicardial contours in cvi42 (Circle Cardiovascular Imaging), as described previously.^{33 (link)} The validation of CMR-derived pressure–volume loops from CMR and blood pressure is described separately in the Expanded Methods in the Supplemental Material.