Achieva dstream

Cranial MRI was acquired in supine position on a 3-Tesla scanner (Achieva dStream or Ingenia; Philips Healthcare, Best, The Netherlands) using a 32-channel head coil. Both scanning for MRI_1 and MRI_2 was performed with the identical imaging protocol. The standardized protocol for brain tumors at our institution includes, amongst further dedicated sequences, a three-dimensional (3D) FLAIR sequence that covers the whole head with the following parameters: repetition time/echo time = 4800/274 ms, inversion time = 1650 ms, echo train length = 170, number of phase encoding steps = 250, flip angle = 90°, acquisition matrix = 0/250/250/0, voxel size = 1 × 1 × 1 mm³, parallel imaging using Compressed SENSE, acquisition duration ~4 min.

All MRI studies were performed at our department on a 1,5T system (Achieva DStream, Philips Medical Systems) equipped with a dedicated double breast coil (Breast Sense Coil). Patients were in the prone position. Standard sequences were acquired: a T2-weighted Turbo Spin Echo (TSE) sequence was performed in the axial plane (FOV 270 × 331 mm², TR 4100 ms, TE 120 ms, matrix 300 × 301, slice thickness 2.2 mm, gap 0.5 mm, and time of acquisition = 3′36′′). DWI was performed using a single-shot echo-planar image (EPI) sequence on the axial plane with the following parameters: FOV 280 × 336 mm², TR/TE 7585/81 ms, matrix 156 × 132, slice thickness 3 mm, gap = 1 mm, and acquisition time 2′54′′. Sensitizing diffusion gradients were applied along the x-, y-, and z-axes with b value of 0 and 900 s/mm2.
A precontrast axial 3D T1-weighted Dixon Fast Field Echo (FFE) sequence (FOV 330 × 330 mm², TR 12 ms, TE1 2.1 ms, TE2 4.0 ms, matrix 400 × 394, slice thickness 2.2 mm, gap = 0 mm, and time of acquisition = 1′30′′). Then, 0.1 mmol/kg of gadobutrol (Gadovist, Bayer) was injected intravenously (v = 2 ml/s), followed by 20 ml of saline, and 10 s later the T1-weighted sequence was repeated 5 times with the same parameters used in the precontrast acquisition. Following the acquisition, the axial precontrast T1-weighted sequence was subtracted from the axial postcontrast images.

FMRI scanning took place on a 3T Philips Achieva dStream using a 32-channel head coil. A high resolution individual T1-weighted structural image was first collected in 192 sagittal slices with a voxel size of 1 mm3. Then, 290 whole-brain functional images were measured for each experimental run. An echo planar imaging (EPI) sequence parallel to the anterior-posterior commissure in axial planes was utilized. The sequence acquired 35 slices in ascending order with a spatial resolution of 3 mm³ (TR = 2 s, TE = 30 ms, FOV = 240 × 240, flip angle = 90).
Preprocessing and statistical analyses of the functional images was realized with the Statistical Parametric Mapping software (SPM12, Wellcome Trust Center for Neuroimaging, London) running on Matlab Version 2021b (the Mathworks Inc, MA). Preprocessing with SPM encompassed realignment to the first image in the respective run and co-registration of all images to the individual mean. Functional images were then spatially normalized to the anatomical T1 template provided by SPM (normalized voxel size of 2 mm3) and smoothed with a 6 mm FWHM istotropic Gaussian kernel. A highpass filter was applied at a cutoff of 1/128 Hz to remove low-frequency drifts.