Ingenuity tf pet mr

The acquisition of MRI scans has been extensively described previously [24 (link)]. During the period of 2005 to 2017, the following scanners have been used: Discovery MR750 and Signa HDXT (both GE Medical Systems, USA), Ingenuity TF PET/MR (Philips Medical Systems, The Netherlands), Titan (Toshiba Medical Systems, Japan), and Magnetom Impact and Sonata (Siemens Healthcare, Germany). The MRI protocol included 3D T1-weighted, T2-weighted, fluid-attenuated inversion recovery (FLAIR), gradient-echo T2*, and/or susceptibility-weighted imaging sequences. The scans were visually assessed by a neuroradiologist on three different image planes. Parietal atrophy was rated using the posterior cortical atrophy (PCA) scale [46 (link)], medial temporal atrophy using the medial temporal lobe atrophy (MTA) scale [47 (link)], and the extent of white matter hyperintensities according to the Fazekas scale [48 (link)]. MTA and PCA scores were scored separately for right and left and averaged thereafter. In addition, the scans were assessed for the existence of lacunes and microbleeds.

For n = 182 (72%), a visual rating of medial temporal lobe atrophy (MTA) according to the MTA-scale (range 0–4) [43 (link)] was performed. Right and left hemispheres were rated and subsequently averaged into one combined MTA score. MRI scans were acquired on 1.5 T MRI scanners (Sonata and Impact, Siemens, Germany; Signa HDXT, GE Healthcare, USA) or 3T MRI scanners (Discovery MR750 and Signa, GE Medical Systems, USA; Ingenuity TF PET/MR, Philips Medical Systems, the Netherlands; Titan, Toshiba Medical Systems, Japan).

All subjects underwent structural 3D–T1 weighted MRI on a 3.0 Tesla camera (Ingenuity TF PET/MR, Philips Medical Systems, Best, The Netherlands), including sagittal T1 weighted sequences. These T1 weighted MR images were co-registered to PET. MR images were segmented automatically into grey matter, white matter and CSF using SPM8 (Wellcome Trust Centre for Neuroimaging) incorporated in the PVElab software [19 (link)]. In addition, regions of interests (ROIs), as defined by the Hammers template [20 (link)], were delineated on the co-registered MRI scans. By projecting those ROIs onto the dynamic PET frames, regional time-activity curves (TACs) were generated.

Volunteers are recruited from oncologic patients undergoing routine clinical PET/CT scanning using a Philips GEMINI TF PET/CT or its Big Bore variant.³⁸ This procedure is immediately followed by PET/MR scanning using Philips Ingenuity TF PET/MR.³⁹, ⁴⁰ The low dose CT from the PET/CT and the 3T MR images from the PET/MR are used for the present study. Neither scan entails contrast injection. The CT acquisitions use a low‐dose, 120‐kV protocol and are reconstructed to a voxel spacing of 1.17 × 1.17 × 5.00 mm³. The MR acquisitions utilize a spin echo imaging pulse sequence to support mDixon reconstruction⁴¹: Repetition Time (TR) = 3.08 ms, Echo Time (TE) = 1.035 and 1.887 ms. Fat, water, in‐phase (IP), and opposed‐phase (OP) images with a voxel spacing 0.98 × 0.98 × 5.00 mm³ are reconstructed. Both CT and MR volumes use 512 × 512 × n matrices, where n depends on the subject size. Twenty‐five sets of whole‐body MR and CT data are acquired.
The subject recruitment, data collection, and management are in compliance with protocols reviewed and approved by the University Hospitals Cleveland Medical Center Institutional Review Board.

Before 2008, brain MRI was performed on 1.0 and 1.5T MRI systems (Siemens Magnetom Avanto, Vision, Impact and Sonata, GE Healthcare Signa HDXT). From 2008 on, MRI of the brain was performed on 3T MRI systems (MR750, GE Medical Systems, Ingenuity TF PET/MR, Philips Medical Systems; Titan, Toshiba Medical Systems). The standard dementia protocol with whole brain coverage included near-isotropic sagittal 3D T1-weighted images (including oblique coronal reconstructions), sagittal 3D T2-weighted fluid-attenuated inversion recovery (FLAIR) (including axial reconstructions), axial T2-weighted turbo spin-echo, and axial T2*-weighted gradient echo sequence or alternatively SWI sequences. MRI data was available for 432 (90%) individuals.
Bilateral hippocampal volume (HCV, mL) was estimated using FMRIBs Integrated Registration and Segmentation Tool (FIRST) [29 (link)]. Normalized brain volumes (NWBV, mL) were estimated with SIENAX (Structural Image Evaluation using Normalization of Atrophy Cross-sectional) using optimized settings [30 (link)]. Additionally, visual rating of MRI was performed according to semi-quantitative visual rating scales for medial temporal lobe atrophy (MTA, 0–4) and global cortical atrophy (GCA, 0–3) [31 (link), 32 (link)].

We performed a subgroup analysis in the subgroup of amyloid-positive patients only. We used amyloid-PET and CSF Aβ42 to determine whether a patient was amyloid-positive or amyloid-negative. Patients were categorized in the amyloid-positive group if they had a positive amyloid-PET scan and/or CSF Aβ42<1000 pg/ml. Amyloid-PET scans were performed using 3-Tesla Philips Ingenuity TF PET/MR, Philips Ingenuity TF PET/CT, and Philips Gemini TF PET/CT scanners. PET scans were visually rated as positive or negative by a trained nuclear medical physician. The amyloid PET procedure using ¹⁸F-florbetaben, ¹⁸F-Florbetapir, ¹⁸F-flutemetamol, or ¹¹C-Pittsburgh compound B (PiB) has been described in detail elsewhere [40 (link)].