Signa architect

All examinations were performed on a 3T MR imaging system (Signa Architect, GE Healthcare, Milwaukee, WI, USA) with a 48-channel head coil. 4D flow MRI was performed with non-contrast technique. MRI sequences included intracranial time of flight MRA and 4D flow MRI. Imaging parameters for 4D flow MRI were the following: FOV = 200 × 200 mm², TR/TE = 5.5/2.9 ms, VENC = 80–100 cm/s, flip angle = 8°, bandwidth = 50 kHz, matrix = 200 × 200, number of slabs = 80, spatial resolution for the composite image = 0.5 × 0.5 × 1 cm³. Retrospective cardiac gating with electrocardiogram was acquired for 4D flow MRI. The 20 time-frames per heartbeat resulted in a temporal resolution that varied from 42 to 56 ms depending on the patient’s heart rate. Consequently, total acquisition times were between 10 and 12 min.

MR images were obtained using a commercial 3T scanner (Signa Architect, GE Healthcare, Milwaukee, WI, USA). ZTE imaging is performed as part of routine chest MRI protocol at our institution (Gyeongsang University Changwon Hospital, Changwon, Korea). Two sets of ZTE lung MR imaging were obtained using 16-channel CAA (ZTE-CAA) and 30-channel AIR coils (ZTE-AIR), respectively, combined with a 40-channel posterior array coil. The order of the two ZTE scanning was random for each patient.
Scans were performed during quiet breathing. Signals of respiratory bellows wrapped around the patient’s upper abdomen were used as surrogates of respiratory motion. Data were prospectively acquired when the position of the diaphragm was within an acceptance window during approximately one-third of the end-expiration phase. Coronal images with isotropic resolution of 1.5 mm were obtained. Original coronal image data were reformatted into axial images. ZTE scan parameters in both scans were as follows: repetition time, 393~503 ms; echo time (ΔT), 16 μs; flip angle, 2°; No. of spokes per segment, 256; field of view, 384 × 384 mm²; receiver bandwidth, ±31.25 kHz; respiration trigger window, 30% of respiratory cycle; and mean scan time, 137 s (127–148 s).

Dynamic contrast-enhanced breast MRI examinations were performed with a 3.0-T or 1.5-T system (SIGNA Architect, GE Healthcare, Milwaukee, USA or Avanto, Siemens, Germany) and a dedicated 16-channel or 4-channel SENSE breast coil, with the patient in the prone position. Firstly, unenhanced T2-weighted propeller short T1 inversion recovery (STIR) or turbo inversion recovery magnitude (TIRM) axial images and T1-weighted spin echo axial images were obtained, and then 0.1 mmol/kg gadoteridol (15 mL ProHance; Bracco imaging, Singen, Germany) was administrated via intravenous injection. Dynamic contrast-enhanced examinations included one pre-contrast and four post-contrast bilateral axial image acquisitions using a fat-suppressed T1-weighted 3D fast field echo sequence (TR/TE;7.0/1.7 300 × 280 matrixes, field of view; 360 × 360 mm, slice thickness; 2 mm, no gap for 3.0-T, TR/TE; 4.8/2.4, 384 × 338 matrixes, field of view; 380 × 380 mm, slice thickness; 1 mm, no gap for 1.5-T). Four post-contrast image series were obtained at 90, 180, 270, 360 s after contrast administration. In all studies, dynamic subtraction (i.e., post-contrast images minus precontrast images) and 3D maximum intensity projection images were generated. The approximate total time per examination was 30 min.

Fourier transform infrared (FTIR) spectra were delineated on a Perkin-Elmer spectrophotometer in the region of 4000–400 cm⁻¹ with a powder sample on a KBr plate. X-ray diffraction (XRD) patterns were collected on a Dandong Fangyuan DX-1000 diffractometer (Haoyuan Instrument, China) with a Cu Kα radiation source (λ = 1.5418 Å) in the 2θ range 20–80^°. Thermogravimetric analysis of all samples was performed on NETZSCH TG209F1 Thermogravimetric Analyzer (NETZSCH Scientific Instruments Trading Ltd, Germany). Elemental analyses were performed by energy-dispersive spectrometer (EDS) on INCAPentaFETx3 (Oxford Instruments, UK). The size distribution and morphology of all samples were investigated by TEM (Tecnai G2 F20 S-TWIN, FEI), for which 10 µl of the samples were dried on a copper grid. The hydration diameter and zeta potential of all samples were tested by DLS on a Malvern Nanosizer (Zetasizer Nano ZS, UK). Iron and gadolinium concentration of all samples were evaluated by elemental analysis using an atomic absorption spectroscopy (AA800, Perkin-Elmer, USA). T₁ and T₂ relaxivities were recorded and calculated on a 1.5 T (μMR 588, United Imaging Healthcare, PRC) and 3.0 T clinical MRI scanner (Signa Architect, GE Medical systems, USA) at room temperature.

All patients underwent MR examinations with 3.0-Tesla (T) scanners (MAGENTOM Skyra, Siemens Healthcare Sector, Germany; SIGNA Architect, GE Medical System, America; Ingenia Elition X, Philips, the Netherlands). Patients underwent some special bowel preparations before the MRI examination, including consuming liquid food on the day before the examination, and were administered a routine cleansing enema to ensure that the rectum was clear and empty 3 to 4 h before the examination. The main MR serial name was fast spin-echo no fat suppression T2-weighted imaging (FSE-T2WI). The parameters were set up as follows: repetition/echo time (TR/TE), 6890/100 ms; slice thickness, 3 mm; field of view (FOV), 220 × 220 mm; echo train length, 25; number of averages, 3; pacing between slices, 3.9 mm; flip angle, 150°; voxel size, 0.7 mm × 0.7 mm × 4.0 mm.

Resting-state fMRI data acquisition was performed on a 3.0 T MRI scanner (SIGNA Architect, GE Healthcare, USA) equipped with a 48-channel head coil. The gradient echo echo-planar imaging (EPI) pulse sequence was used to acquire BOLD functional images with the following parameters: repetition time (TR) = 2000 ms, echo time (TE) = 30 ms, flip angle (FA) = 90°, 34 slices with interleaved acquisition, no gap, slice thickness = 5 mm, field of view (FOV) = 220 mm × 220 mm, acquisition matrix = 64 × 64, and a total of 240 volumes. During the scan, these subjects were instructed to stay awake and focus on the fixation point to significantly increase the likelihood of the subjects remaining stably awake (Tagliazucchi and Laufs, 2014 (link)) and remain as still as possible while their head was properly restrained to minimize involuntary movement effects (Peng et al., 2021 (link)).

MRI images were acquired using a 3.0 T MRI scanner (SIGNA Architect; GE Healthcare, Milwaukee, WI, USA) for all subjects (n = 43). Single-shot, spin-echo, echo-planar imaging (EPI) was performed. Axial diffusion-weighted images were acquired with the following parameters: echo time (TE) = 75 ms, repetition time (TR) = 6,000 ms, matrix size = 128 × 128, field of view (FOV) = 260 × 260 mm², slice thickness = 3 mm, and number of slices = 50. Diffusion sensitization gradient was applied with 25 non-collinear gradient directions and a b value of 1,000 s/mm², in addition to one non-diffusion-weighted scan. The children who could not keep still for the scanning were sedated with either pentobarbital, thiopental, pentazocine, levomepromazine, risperidone, triclofos, diazepam, midazolam, or a combination of the afore mentioned sedatives.