3t and 1.5t mri scanners

Images were obtained on Siemens 3T and 1.5T MRI scanners with standard head/neck coils. The standard clinical MRI/MRA protocol for these patients included brain MRI (axial DWI, axial T2-weighted, axial FLAIR and sagittal T1-weighted images), brain MRA (3D axial TOF) and neck MRA (2D axial TOF, coronal precontrast T1-weighted, coronal postcontrast arterial and venous phase images). Coronal postcontrast MRA neck images were obtained from the aortic arch through the circle of Willis. Total scan time was approximately 45 minutes, of which the MPRAGE sequence required approximately 5 minutes. In cases when renal insufficiency precluded intravenous contrast (GFR < 30 ml/min/1.73m²), postcontrast MRA images were replaced with 3D noncontrast TOF with 1 mm slice thickness combined with duplex ultrasound.

Images were obtained on Siemens 3T and 1.5T MRI scanners with standard head/neck coils. The MRI/MRA dissection protocol for these patients included axial brain diffusion weighted imaging (DWI), brain MRA (3D axial time-of-flight, TOF), neck MRA (2D axial TOF, coronal precontrast T1-weighted, coronal postcontrast arterial phase, and venous phase images) and included both MPRAGE and T1FS. Coronal postcontrast MRA neck images were obtained from the aortic arch through the circle of Willis. Total scan time was approximately 45 minutes. In patients with renal failure (GFR <30ml/min/1.73m², 38/227 or 16.7% of patients), 3D-TOF was used with 1mm slice thickness.