3.0 t mri system

MR images were obtained using a Siemens 3.0 T MRI system (Siemens Verio, Erlangen, Germany), with a standard head coil. T1 and T2 images were taken with a self-spin echo sequence, and DTI images were taken with a planar echo sequence. The DTI scan consisted of 21 diffusion-weighted directions with a b-value of 1000 s/mm² and one volume without diffusion weighting (i.e., b0 image). The parameters of the DTI sequence were as follows: slice thickness = 3 mm, echo time = 86 ms, repetition time = 8300 ms, b = 1000 s/mm², field of view = 240 mm×240 mm, acquisition matrix = 128×128, and in-plane resolution = 2.2.×2.2 mm.
The DTI data were preprocessed by PANDA software [14] (link), following these steps: skull removal, correction of eddy-current distortion, and construction of FA maps. The FA maps generated for each patient were then transformed from individual space to a standard Montreal Neurological Institute (MNI) space via spatial normalization, and resliced with a voxel size of 2 mm×2 mm×2 mm. All FA maps were smoothed using an isotropic Gaussian filter with a full-width-at-half-maximum of 6 mm.

Magnetic resonance imaging data were collected using a 3.0 T MRI system (Siemens, Trio Tim, Erlangen, Germany) and a 12-channel phase-array head coil. Conventional brain axial fluid-attenuated inversion recovery (FLAIR) sequence was obtained to exclude visible brain abnormalities. The high-resolution 3D structural T1-weighted images were acquired by a three-dimensional (3D) magnetization- prepared rapid gradient-echo sequence (MPRAGE) in sagittal orientation. The imaging parameters were as follows: repetition time (TR) = 1800 ms, echo time (TE) = 2.13 ms, inversion time (TI) = 1100 ms, flip angle (FA) = 9°, field of view (FOV) = 256 mm × 256 mm, matrix size = 256 × 256, number of slices = 192, slice thickness = 1 mm, resulting an isotropic voxel size of 1 mm × 1 mm × 1 mm. Participants were instructed to stay awake, relax, and close their eyes during the resting-state data acquisition, then a gradient-echo-planar imaging (EPI) pulse sequence was used to collect the resting-state functional MRI (rs-fMRI) data, and the parameters were as follows: TR = 2000 ms, TE = 30 ms, slice thickness = 3 mm, inter-slice gap 1 mm, number of slices = 35, FOV = 220 mm × 220 mm, matrix size = 64 × 64, FA = 9°. The parameters resulted in an anisotropic voxel size of 3.4 mm × 3.4 mm × 3.0 mm. The total acquisition time of the resting-state fMRI scan was 6.08 min with 180 volumes.

MRIs of the lower extremities (pelvic girdle, bilateral thigh, and lower leg) were obtained using either a 1.5‐T or 3.0‐T MRI system (Siemens Healthcare, Frankfurt, Germany). MRIs were bilaterally obtained from three levels (proximal, mid, and distal) of the thigh muscles and two levels (proximal and distal) of the lower leg muscles. The axial T1‐weighted turbo spin‐echo images of the thigh and lower leg muscles were graded into a five‐point semiquantitative scale by the degree of fatty infiltration (Goutallier et al., 1994).

MRI data were collected at the Radiology Department of Zhongda Hospital using a 3.0 T MRI system (Siemens, Erlangen, Germany) with an 8-channel receiver array head coil. Structural images were acquired with a T1-weighted 3D spoiled gradient-echo sequence: sections = 176, repetition time (TR) = 1900 ms, echo time (TE) = 2.48 ms, slices = 176, section thickness = 1.0 mm, flip angle (FA) = 90°, FOV = 256 × 256 mm², acquisition matrix = 256 × 256. The fMRI data were obtained axially using a gradient-echo-planar (EPI) imaging sequence with the following parameters: 36 slices, TR/TE = 2000/25 ms, section thickness = 4.0 mm, FA = 90°, FOV = 240 × 240 mm², acquisition matrix = 64 × 64. The fMRI data were acquired over a period of 8 min and 6 s and images were acquired in an interleaved order. Subjects wore earplugs and earphones to attenuate scanner noise (approximately 32 dB) and a head cushion was used to reduce head motion. Subjects were instructed to keep their eyes closed, remain awake, lie quietly, and avoid specific thoughts.

The rs-fMRI data were collected on a Siemens 3.0 T MRI system with a 32-channel head coil (MAGNETOM Skyra, Siemens Medical Solutions, Erlangen, Germany), using a standard echo planar imaging (EPI) sequence. The foam padding and earplugs were used to minimize head motion and to muffle scanner noise. Participants were requested to relax, remain awake with their eyes closed, and avoid thinking during the MRI acquisition. Resting-state functional images were collected with a repetition time = 3.05 s, echo time = 22.5 ms, flip angle = 30°, 36 slices, thickness/gap = 4.0/1 mm, voxel size = 2.45 × 2.45 × 4 mm³, matrix size = 94 × 94, and field of view = 230 × 230 mm².

The clinical parameters including age at prostate biopsy, serum tPSA and fPSA values, PV, and reports of mpMRI examination were extracted from clinical records. The serum tPSA and fPSA were measured by immunofluorescence assay. PV was measured by mpMRI examination using the 3.0-T MRI system (SIEMENS, Germany). The protocol of mpMRI examination complied with the guidelines of the European Society of Urology Radiology, and included T2-weighted Imaging (T2WI), diffusion-weighted imaging (DWI), and dynamic contrast-enhanced imaging (DCE). The prostate mpMRI images were interpreted by two experienced radiologists with at least three years of prostate mpMRI experience. The mpMRI results were divided into three groups: “negative”, “equivocal”, and “suspicious” for the presence of PCa, according to the mpMRI reports. The “negative”, “equivocal”, and “suspicious” for MRI-PCa corresponded to the PI-RADS 1 or 2, PI-RADS 3, and PI-RADS 4 or 5 according to the latest Prostate Imaging Reporting and Data System version 2 (PI-RADS v2) guideline (16 (link)).