1.5 t mr system

The mpMR images were obtained from April 2019 to February 2020 by a 1.5 T MR system (Siemens Medical Solutions, Germany) consisting of T2W, DW-MRI, and DCE-MRI. The MR imaging parameters are summarized in Table 2 [30 (link)].Table 2

MRI parameters

Sequence	TR/TE (ms)	Slice thickness (mm)	Matrix size	FOV (mm)	Voxel size (mm)
T2W-axial	7920/93	3	320 × 320	200	0.62 × 0.62 × 3
T2W-coronal	7570/101	3	256 × 256	200	0.78 × 0.78 × 3
T2W-sagittal	7680/101	3	256 × 256	200	0.78 × 0.78 × 3
DW-MRI	4600/72	3	112 × 112	199	1.78 × 1.78 × 3
DCE-MRI	4.5/1.69	3	192 × 192	259	1.35 × 1.35 × 3

TR/TE: Repetition time/echo time; FOV: field of view

For DW-MRI, three different b-values were used. An ADC map was automatically calculated. using the following formula: $${\text{SI}}_{\text{i}}={\text{SI}}_0\times {\text{e}}^{(-\text{bi}\times \text{ADC})}$$ where SI_i is the signal intensity measured on the ith b-value image, bi the corresponding b-value (being: 50, 800, 1200 s/mm²), and SI₀ a variable estimating the exact signal intensity for b = 0 s/mm². The DCE-MRI was performed by administrating 15 mL of gadolinium at a rate of 2 mL/s as an intravenous bolus injection. It should be noted that the Ktrans maps were generated by fitting a Tofts model for each voxel and all the patients using an individual-based arterial input function (AIF). The Fire Voxel version 324B software package (New York University, USA) was used to display and analyze the DCE-MRI and ADC images.