Paravision 7

MRI was performed on a 7 Tesla scanner (Bruker PharmaScan, Billerica, MA) operated by ParaVision 7 with a quadrature RF coil for signal transmission and reception. T2-weighted images were acquired at the axial direction using a TuborRARE sequence with the following parameters: TR/TE = 4200/48 ms, RARE factor = 8, Averaging = 4, Matrix size = 256 × 192, FOV = 20 × 20 mm², slice number = 21, slice thickness = 0.5 mm. T1-weighted MRI was performed using a MDEFT sequence with 4 segments, segment TR = 2600 ms, TE = 2.2 ms, TI = 950 ms, flip angle = 30°, Averaging = 3, Matrix = 256 × 256, FOV = 20 × 20 mm², slice number = 15, slice thickness = 0.5 mm. The T1- and T2-weighted MRI was followed by tail vein injection of gadolinium (MultiHance, Bracco Diagnostics) at 0.1 mmol/kg. After 15 min of gadolinium injection, the mouse was scanned using T1- and T2-weighted MRI again. Mice were anesthetized using 1.5% isoflurane carried by 1 L/min oxygen. The breathing rate and body temperature were monitored during scanning. The isoflurane was continuously adjusted to maintain the breathing rate between 40 and 80 bpm.
Region-of-interest (ROI) analysis in image J (imagej.nih.gov/ij/) was used to measure tumor volumes. The post-contrast T1-weighted images (T1post) were primarily used for the measurements with pre-contrast T1-weighted (T1pre) and T2-weighted images as references.

The FA and ADC were calculated using ParaVision 7 (PharmaScan 70/16 US; Bruker BioSpin, Ettlingen, Germany). The NODDI parameters, including the ICVF, ISO, and ODI, were calculated using MATLAB (MathWorks, Natick, MA, USA) [40 (link),41 (link)]. Analyses and calculations for APT imaging were performed using MATLAB (MathWorks) [40 (link),41 (link)]. The MTR asymmetry (MTR value) was calculated using the following equation: MTR_asym(%) = (S_[−αppm] − S_[+αppm])/S₀. The APT CEST signal was defined as an MTR asymmetry of +3.5 ppm. The MTR asymmetry is expressed as the mean ± standard deviation (SD). All the T₂WI signal intensity ratios and MTR, ADC, FA, ICVF, ODI, and ISO values were measured using ImageJ 1.53a (National Institutes of Health, Bethesda, MD, USA). The ROIs were placed around the entire tumor excluding hemorrhage and necrosis based on T₂WI and ADC maps (Figure 2). The tumor volume was defined as the total area of all the T₂WIs showing the tumor multiplied by the slice thickness of 1.0 mm. The T₂ signal intensity ratio was calculated as the ratio of the mean signal value of the tumor in the solid ROI to the mean signal value of the contralateral normal brain tissue in the dotted ROI (Figure 2).