Magnetom sonata

Intracranial atherosclerotic plaque was analyzed using MR [17 (link)]. We used time-of-flight MRA to assess the intracranial vasculature of our patients. All imaging was performed using a 1.5 Tesla system (Magnetom Sonata, Siemens, Erlangen).

Acquired MR sequences included MPRAGE, FLAIR, T1-weighted, T2-weigthed, diffusion weighted images (DWI), with apparent diffusion coefficient (ADC) map reconstruction, and perfusion weighted images (PWI) with dynamic susceptibility contrast (DSC) technique. MRI examinations were acquired on a 1.5 T (Magnetom Sonata, Siemens, Erlangen, Germany) and a 3 T scanner (Discovery MR750w; GE Medical Systems, Waukesha, WI, USA). Patients underwent the following protocol: axial T1-weighted spin echo, axial T2-weighted fast spin echo, axial FLAIR; DWI acquired with three levels of diffusion sensitization (b-values 0, 500 and 1000); DSC acquired during contrast injection (DOTAREM.; dose 0.1 mmol/kg, injection rate 4 mL/s), followed by a 20-mL saline flush, based on T2*-weighted gradient-echo echo-planar; MPRAGE after administration of contrast. Perfusion parametric maps were obtained through a dedicated software package OleaSphere software version 3.0 (Olea Medical, La Ciotat, France). A rCBV map was generated by using an established tracer kinetic model applied to the first-pass data [20 (link)]. As previously described [21 (link)], the dynamic curves were mathematically corrected to reduce contrast agent leakage effects.

The structural images of participants in cohort A were obtained from the ADNI database. Detailed information regarding the acquisition protocol is publicly available on the LONI website. The structural MRI data of participants from cohort B were acquired using a 3.0 T MRI scanner (Magnetom Sonata; Siemens Healthineers AG, Erlangen, Germany) or an integrated simultaneous 3.0 T time‐of‐flight PET/MR (SIGNA; GE Healthcare, Chicago, IL). The structural MRI images (Siemens scanner) were obtained with a magnetisation‐prepared rapid gradient echo sequence: repetition time (TR) = 1900 ms, echo time (TE) = 2.2 ms, and number of slices = 176. The parameters for the structural images (GE scanner) were as follows: FOV = 256 × 256 mm², matrix = 256 × 256, slice thickness = 1 mm, gap = 0, number of slices = 192, TR = 6.9 ms, TE = 2.98 ms, inversion time (TI) = 450 ms, flip angle = 12°, and voxel size = 1 × 1 × 1 mm³.

Images were acquired with 1.5 Tesla scanners (Magnetom^® Symphony, Magnetom^® Avanto, and Magnetom^® Sonata, all manufactured by Siemens Healthcare, Erlangen, Germany) or 3 Tesla scanners (Ingenia^®, Philips Medical Systems, Best, The Netherlands; Magnetom^® Skyra and Magnetom^® Vida, Siemens Healthineers AG, Erlangen, Germany). Since some MRI studies were acquired in external clinics, the scanners could not be traced for all included patients. Employed imaging protocols included non-enhanced axial T1-weighted (T1w NE) spin echo with flow compensation and non-contrast axial-fluid-attenuated inversion recovery (FLAIR). After weight-adjusted injection of a gadolinium-based contrast agent (0.1 mmol/kg), contrast-enhanced axial T1-weighted spin echo sequences with flow compensation or three-dimensional T1w gradient echo sequences were acquired (T1w CE).