Signa hdx

All subjects were scanned (eyes-open) by 3.0 Tesla scanners with different models, including Siemens TrioTim, GE Signa HDX, Philips, and Siemens Allegra. ADNI data were collected from 46 locations/sites, and B-SNIP data were collected from 6 sites. The imaging parameters of the two datasets are listed in Table 2.
The fMRI results underwent preprocessing through an SPM12 workflow that encompassed rigid body motion adjustment to rectify participant head movement, synchronization of slice timing, transformation to the standard MNI space utilizing the EPI template, resampling to isotropic voxels of (3mm)3, and smoothing via a Gaussian kernel (FWHM = 6mm). Quality assurance (QA) of the processed fMRI datasets involved eliminating images with low correlation to individual and/or group-level masks. Furthermore, fMRI data containing excessive head motion were removed to prevent possible erroneous variations in functional connectivity.

Acquisitions from multiple MR imaging scanners with different contrast agents were used to allow for a more robust and generalizable machine learning model. Scanners were 1.5 T and 3 T models produced by Siemens (Aera, Avanto, Espree, TrioTim, Skyra, Verio), General Electric (SIGNA HDx), and Philips (Achieva). Studies were performed with several contrast agents, including Gadavist (Bayer), Magnevist (Bayer), Eovist (Bayer), Multihance (Bracco Diagnostics), Prohance (Bracco Diagnostics), Optimark (Covidien), and Dotarem (Guerbet). Contrast agents were administered at a dose of 1–1.5 mmol/kg with an injection speed of 2–5 mL/s. The input for our model consisted of multi-parametric, gadolinium-enhanced T1-weighted gradient echo acquisitions including arterial phase (35 s post-injection), portal venous phase (70 s post-injection), and delayed phase (3–5 min post-injection) imaging. Repetition and echo times ranged from 2.5–5.5 ms and 1–3 ms, respectively. Pixel bandwidth ranged from 250 to 650 Hz, pixel spacing from 0.5 to 1.7 mm, slice thickness from 3 to 5 mm, number of slices from 43 to 125, and image matrices from 160 × 160 to 415 × 200.