3.0t discovery mr 750

All MR scans were performed using a 3.0T Discovery MR750 (GE Healthcare, Milwaukee, WI, USA). T1-weighted images were collected for the purpose of placing the region-of-interest (ROI). T1 images were obtained by sagittal 3-D fast spoiled gradient-echo (FSPGR) sequences. The following parameters were used for the T1-weighted images: repetition time, 6.4 ms; echo time, 2.6 ms; inversion time, 420 ms; flip angle, 15°; field-of-view, 240 × 240 mm; matrix, 256 × 256; slices, 178; slice thickness, 1.4 mm; overlap, 0.7 mm; and scan time, 214 s. Transaxial fluid attenuation inversion (FLAIR) imaging was also conducted for screening purposes. No intracranial abnormal structures were identified in any of the participants.

MRI scans were acquired on a GE 3.0 T Discovery MR750 (General Electric, Milwaukee, USA) with a 32-channel head coil at the Amsterdam UMC location VUmc. We acquired diffusion-weighted images with a multi-shell single-spin echo echo-planar imaging sequence (TR = 7350 ms, TE = 81 ms, 2.5 × 2.5 mm² in-plane resolution with 56 slices of 2.5 mm; no gap) with 73 interleaved directions (25 b = 1000 s/mm², 24 b = 2000s/mm², and 24 b = 3000 s/mm²) and 7 non-diffusion-weighted volumes (b = 0 s/mm²). We additionally acquired a 3D T1-weighted structural magnetization-prepared rapid acquisition gradient-echo (MPRAGE) with scan parameters according to the ADNI-3 protocol [17 (link)]: TR = 6.9 ms, TI = 900 ms, TE = 3.0 ms, matrix size 256 × 256, 1 mm³ isotropic voxels. Patients followed the same protocol at both time points.

Magnetic resonance [] images were acquired using a 3.0 T Discovery MR750 (General Electric, Madison, WI, USA) scanner available through the Umeå Center for Functional Brain Imaging (UFBI). The scanner was equipped with a 32-channel head coil. The stimulus presentation software E-prime (Psychology Software Tools, Sharpsburg, PA, USA) was used for paradigm handling and viewed through a tilted mirror attached to the head coil. fMRI images were acquired with a gradient echo planar imaging sequence [37 transaxial slices; thickness, 3.4 mm; gap; 0.5 mm, repetition time (TR), 2000 ms; echo time (TE), 30 ms; flip angle, 80°; field of view, 25 × 25 cm; 200 volumes; duration, 07:00 min]. High-resolution T1-weighted structural images were collected with a 3D fast spoiled gradient echo sequence (176 transaxial slices; thickness, 1 mm; TR, 8.2 ms; TE, 3.2 ms; flip angle, 12°; field of view, 25 × 25 cm; duration, 08:11 min). A field map was acquired prior to the fMRI images and used for controlling for magnetic field (B0) inhomogeneities [46 transaxial slices; thickness; 4 mm; gap; 0 mm; repetition time (TR), 800 ms; flip angle, 10°; field of view, 25.6 × 25.6 cm; duration, 01:05 min]. All sequences were acquired in the A/P (anterior-to-posterior) frequency-encoding direction.

MR images were obtained with a 3.0-T DISCOVERY MR750 (GE Healthcare, UK). T1rho-weighted MR images (512 × 512 pixels, 88 slices) were used to segment the meniscus. Using a three-dimensional MR image, two sagittal slices were extracted: one including the longest diameter of the lateral meniscus and the other including the longest diameter of the medial meniscus. Figure 1 shows the segmentation procedure [8 (link)]. First, the sagittal slice was selected as shown in Fig. 1a. The binarization process was then performed to isolate the meniscus from the surrounding tissue. The mode method was used for this purpose [9 ]. This method automatically identifies a valley between two peaks in the histogram and uses it as a threshold for binarization. Figure 1b represents the binarization result of the original image shown in Fig. 1a. Finally, by manual segmentation, the meniscal region was determined from the binary image as shown in Fig. 1c.Fig. 1

Meniscal segmentation procedure. a Schematic illustration of slice selection. b Binarization of the image in a with a proper threshold. c Manually segmented meniscus