Signa hdxt

MRI images were acquired with a 3.0 Tesla scanner (primary cohort: Signa HDxt or Discovery MR750; validation cohort: Signa HDxt, both from GE, Waukesha, WI, USA). Detailed MRI parameters are provided in supplemental Appendix S1. Dynamic contrast-enhanced scans were collected in the arterial phase (AP), portal venous phase (PVP), and equilibration phase (EP) at 14-20 s, 45-60 s, and 150-180 s, respectively, after injecting 0.1 mmol/kg Gd-DTPA.

Abdominal and pelvic MRI examinations were conducted using the 3.0 Tesla whole-body MRI system in institution A (Signa HDxt, GE Medical Systems, Milwaukee, Wisconsin). All patients underwent MRI using a body phased-array coil that ranged from the top of the diaphragm to the inferior pubic symphysis, which was completed in two batches. Imaging sequences were as follows: axial T1-DEI (flip angle/time of repetition [TR], 80°/265 ms); slice thickness, 5 mm; gap, 1 mm; field of view, 40 cm; and NEX, 0.5. DWI was performed in the axial planes with a b value of 800 s/mm² using spin-echo echo-planar imaging (SE-EPI; TR/time of echo [TE], 5500 ms/63.9 ms). In institution B, all patients also underwent abdominal and pelvic MRI examinations using the 1.5 Tesla MRI system (Signa HDxt, GE Medical Systems), and the imaging parameters were as follows: axial T1-DEI (flip angle/TR, 80°/200 ms); slice thickness, 5 mm; gap, 1 mm; field of view, 40 cm; and NEX, 0.75. DWI used SE-EPI (TR/TE, 4000 ms/74.8 ms), with a b value of 800 s/mm².

All MR images were acquired using a 1.5-T MRI system (GE Signa HDxt) with a 12-channel head coil. The following parameters were used for T1w imaging: 3D-IR-SPGR, sagittal plane, TR, 7 ms; TE, 3 ms; flip angle, 15°; FOV, 240 mm × 240 mm; matrix, 256 × 256; voxel size, 0.86 mm × 0.86 mm × 1.5 mm; number of slices, 248; and number of excitations, 1. For T2w imaging, the following were used: 2D-TSE; TR, 4000 ms; TE, 100 ms; FOV, 220 mm × 220 mm; matrix, 320 × 256; voxel size, 0.43 mm × 0.43 mm × 6 mm; number of slices, 23; interslice gap, 6 mm; and number of excitations, 1.

For in vitro cell tracking by MRI, a clinical 1.5 T MRI scanner (General Electric, Signa HDXt, GE Healthcare, Chicago, USA) was used. The T2-weighted MR imaging parameters were slice thickness of 3 mm, repetition time of 460 ms, echo time of 24 ms, magnetic field strength of 1.5, flip angle of 25, matrix size of 512 × 512, and field of view of 220.01 mm. The SPIONs had a small crystal size. Therefore, the orientation of their lattice did not hinder their magnetic moments. The contrast agent significantly shortened the T2 relaxation time and this in turn led to the creation of a hypointense contrast on the spin-echo sequences. The SPIONs resulted in a larger hypointense contrast on the T2 gradient echo images. Hypointense areas of signal voids highlighted the existence of iron oxide-labeled cells.

All subjects underwent multisequence imaging protocol on a 1.5-T MRI scanner (MAGNETOM ESSENZA, Siemens Healthineers, Germany and Signa HDxt, GE Healthcare, USA). For each patient, two sequences were collected in our study: (1) T1-weighted spin-echo (T1W) image: repetition time/echo time (TR/TE) = 1800/22 ms; matrix size = 512 × 512; field of view (FOV) = 240 × 240 mm²; slice thickness = 3 mm; gap = 1.5 mm; (2) T2 fluid attenuated inversion recovery (T2 FLAIR) image: TR/TE = 8000/120 ms; matrix size = 512 × 512; field of view (FOV) = 240 × 240 mm²; slice thickness = 3 mm; gap = 1.5 mm.

All mpMRI scans were performed using a 3-T scanner (Signa HDxt, GE Healthcare, Milwaukee, WI, USA) with an eight-channel high resolution cardiac array coil. No endorectal coil was used. The scanning protocol was performed as described previously [26 (link)]. In brief, the protocol included T2-weighted imaging to provide anatomical information and diffusion-weighted imaging with b values of 0–1000 s/mm², apparent diffusion coefficient map, and dynamic contrast-enhanced imaging as functional imaging modalities (Supplementary Table S1). All mpMRI scans were interpreted by a radiologist (W.C.L.) with more than 10 years of experience in reading prostate mpMRI. Each suspicious lesion was scored in accordance with the Prostate Imaging-Reporting and Data System v2.1 [8 (link)]. Before biopsy, one urologist (P.F.H.) reviewed the mpMRI and identified suspicious lesions with a PI-RADS score ≥ 3 as the target lesions. The index lesion was defined as the target lesion with the highest PI-RADS score. If there were two or more target lesions with the same PI-RADS score, the index lesion was defined as the largest one. T2-weighted imaging was used for contouring the prostate and target lesions, and then a 3-D model of the prostate and target lesions was built using a BioJet (D&K Technologies GmbH, Barum, Germany) or bkFusion (BK Medical, Herlev, Denmark) system.