Achieva 3.0t

All 21 patients underwent CT scans (GE Light Speed 16 CT; Siemens Somatom Definition 64 CT) with the following parameters: 120KV, 240–320 mAs, pitch 1–1.5 mm, matrix 380*380. Nineteen patients had MRI scans (Philips Achieva 3.0 T; GE Excite HD 3.0 T), comprised of axial and sagittal T1-weighted imaging (T1WI) (TE 14–23.7 ms, TR 400–754 ms) and T2-weighted imaging (T2WI) (TE 76–138 ms, TR 3000–5100 ms), sagittal fat-suppressed T2WI (TE 80–127 ms, TR 3200–5100 ms), and axial, sagittal and coronal contrast-enhanced T1WI (TE4.6–23.4 ms, TR 189–750 ms). For all patients, contrast agent (Omniscan TM, GE Healthcare, Ireland; Magnevist, Schering, Berlin, Germany; gadopentetate dimeglumine, Consun, Guangzhou, China) was administered at a dose of 0.2 mmol/kg and a rate of 2.0–2.5 ml/s, using a power injector (Spectris Solarisl EP, Medrad, USA; TennesseeXD003, Ulrich Medical, Germany) through the antecubital vein, followed by a 20 ml sterile saline flush. Eight patients underwent 18F-FDG PET/CT examinations (Siemens, Germany), and semi-quantitative analysis was used to calculate the maximum standard uptake value (SUVmax) of tumors relative to the surrounding tissue.

All participants were scanned on the same MRI scanner (Philips Achieva; 3.0 T) and PET camera (Discovery RX VCT 64 PET-CT; General Electric Healthcare) at the Cyceron Center (Caen, France). High-resolution T1-weighted structural imaging were acquired to measure GM volume and an echo-planar imaging/spin echo diffusion weighted sequence (DKI) was performed to obtain white matter (WM) microstructural integrity measurements. Mean kurtosis parameter maps reflected WM microstructural integrity based on the number, density, orientation, and degree of organization of WM microstructures [39 (link)]. Myelin and axonal integrity was also estimated from the radial and axial parameters of DKI, respectively [40 (link)]. Fluorine 18-labeled (¹⁸F) florbetapir-PET scans were obtained with a 10-min acquisition beginning 50 min after the intravenous injection reflecting amyloid burden. ¹⁸F-fluorodeoxyglucose (FDG)-PET scans were acquired on a subset of participants (n = 92) to measure brain glucose metabolism. The detailed acquisition and preprocessing procedures [27 ] are available in Supplementary Material 1. The sample size for each imaging modality is reported in Supplementary Table 1.