Ge 1.5t signa scanner

Cardiac magnetic resonance studies were performed on a clinical GE 1.5T Signa scanner (General Electric, WI). The protocol included 2-dimensional balanced steady-state free-precession cine images, which were used to assess BAV fusion phenotype and aortic diameters (using the double-oblique cine cardiac magnetic resonance at late diastole) and a time-resolved 3-dimensional phase-contrast MRI acquisition (also known as 4D flow MRI) with retrospective ECG gating during free-breathing. Endovenous contrast was not given.
For 4D flow MRI, data were acquired using the VIPR (vastly undersampled isotropic projection) sequence, a radially undersampled acquisition with 5-point balanced velocity encoding.^{19 (link)} The acquisition volume included the entire thoracic aorta. Acquisitions were made with an 8-channel cardiac coil using the following parameters: velocity encoding 200 cm/s, field of view 400×400×400 mm, scan matrix 160×160×160 (voxel size 2.5×2.5×2.5 mm), flip angle 8°, repetition time 4.2 to 7.2 ms and echo time 2.2 to 3.6 ms. This data set was reconstructed according to the nominal temporal resolution of each patient and was (5×repetition time) 21 to 36 ms. Reconstructions were performed offline with corrections for background phase, eddy currents and trajectory errors.^{19 (link)}