Magnetom prisma 3.0 t mri scanner

All MRI examinations were performed on a MAGNETOM Prisma 3.0 T MRI scanner (Siemens Healthcare, Erlangen, Germany) with an 18-channel body coil. Before the MR scanning, each subject fasted for 4 h, and a 40-ml enema (Glycerol Enema, Shanghai, China) was rectally administered 1–2 h to achieve better contrast between the tumor and the rectal lumen for detecting small lesions (19 (link)). All examinations followed a standard procedure in our hospital. First, a sagittal T2-weighted turbo spin-echo sequence without fat saturation was obtained for the selection of both oblique axial and coronal images, which were orthogonal and parallel to the long axis of the tumor, respectively. Two DWI sequences, one with b-values of 0 and 1,000 s/mm² (aDWI_b1,000) and another with b-values of 0 and 700 s/mm² were performed in the oblique axial plane by using a single-shot echo-planar imaging sequence with comparable parameters (Table 1). The diffusion gradients were set along three orthogonal directions. A dynamic field correction is applied inline to correct eddy current-induced geometric distortion for all diffusion-weighted images.

To determine the biodistribution of SMID nanoparticles by fluorescence imaging in vivo, tumor bearing BALB/c mice were intravenously injected with free ICG or SMID nanoparticles (equivalent ICG concentration: 3 mg·kg^-1). At 2, 6, 12, 24 and 48 h after injection, infrared fluorescence images of mice were acquired using a fluorescence imaging system (λ_ex = 780 nm, λ_em = 830 nm, Fusion FX7 Spectra, VILBER, France). At 24 h post-injection, mice were sacrificed to harvest the major organs and tumors for ex vivo imaging to determine the biodistribution of SMID nanoparticles semi-quantitatively using the same luminescence imaging system. MRI was carried out using Siemens MAGNETOM Prisma 3.0 T MRI scanner (Erlangen, Germany) with gradient strength up to 80 mT/m (TR = 800 ms, TE = 12 ms). T₁-weighted MR signal intensity of each sample was measured from the MR images in the region of interest (ROI). The relaxation rate r₁ (1/T₁) was then calculated from T₁ values under different Mn²⁺ concentrations. For MRI in vivo, T₁-weighted MR images of tumors were taken at 1, 2, 6, 12, 24 h after intravenous injection of SMID nanoparticles (equivalent ICG concentration: 2 mg·kg^-1).

Both fMRI studies were conducted at the Center for Medical Imaging and Visualization (CMIV), Linköping University. Neuroimaging data were acquired with a Siemens Magnetom Prisma 3.0 T MRI scanner, using a twenty-channel head coil. High-resolution T1-weighted structural scans were acquired for each subject (208 slices, 0.9 mm³ slice thickness, TR =2300 ms, TE =2.36 ms, flip = 8°). Three BOLD-sensitive T2*-weighted ascending Echo Planar Imaging (EPI) pulse sequence runs were performed for each participant during whole-brain functional scans (48 slices, 3.0 mm³ slice thickness, TR =1340 ms, TE =30 ms, flip = 69°).