3.0 t mri scanner

The magnetic resonance imaging (MRI) of knee joints was obtained with a 3.0-T MRI Scanner (United Imaging, China). The high-resolution MRI images were obtained in the sagittal plane. The images of the maximum cross-section of defect area were selected to assess the repaired cartilage. The repaired tissue was assessed referring to the International Cartilage Repair Society (ICRS) Whole-Organ MRI Score (WORMS) of the knee in OA. The scoring was finished by three different observers.

All the subjects underwent a 3.0 T MRI scanner (United Imaging Healthcare, Shanghai) with a 32-channel head coil. The imaging sequences and parameters were as follows: three-dimensional (3D) time-of-flight (TOF) MR angiography: repetition time (TR)/echo time (TE) of 18.6/3.4 ms, field of view (FOV) of 27.2 cm × 22 cm, flip angle of 16, slice thickness of 0.35, and 336 slices; diffuse-weighted imaging (DWI): repetition time (TR)/echo time (TE) of 4,930/99.20 ms, field of view (FOV) of 27.2 cm × 22 cm, flip angle of 90, slice thickness of 5, and 20 slices; precontrast and postcontrast T1-weighted (T1W): repetition time (TR) /echo time (TE) of 750/22.4 ms, field of view (FOV) of 27.2 cm × 22 cm, flip angle of 65, slice thickness 0.66, and 220 slices. Postcontrast images were acquired after intravenous injection of a contrast agent (Gadobenate Dimeglumine Injection; BRACCO, China; 0.2 mg/kg body weight).

MR imaging was conducted on a 3.0 T MRI scanner (United Imaging, China) with the following sequence: $\text{TR}=600$ ms and $\text{TE}=12.6$ ms. For in vitro MRI experiment, MMSNs with varied Mn concentrations (0, 0.02, 0.04, 0.06, 0.1, and 0.2 mM) were dispersed in SBF (1 mL) at diverse pH values (7.4 or 5.5) and GSH concentrations (0 or 10 mM). In vivo T₁-weighted MR imaging signals were acquired before and 1, 4, and 6 h after intravenous injection of GR@MMSNs-P (1.5 mg kg^-1 Mn) on 4T1 tumor-bearing mice.