Pet ct scanner

Fasting subjects underwent ¹⁸F-FDG PET/CT imaging on a PET/CT scanner (Philips, Best, the Netherlands) as previously described [22 (link)]. Imaging was initiated, 90 minutes post ¹⁸F-FDG infusion (250 MBq, 6.8 mCi), with a low-dose, noncontrast-enhanced CT scan for attenuation correction and anatomic co-registration, followed by PET imaging of the thoracic and splenic region.
Images were analyzed with dedicated software (OsiriX, Geneva, Switzerland; http://www.osirix-viewer.com). ¹⁸F-FDG uptake was assessed in the ascending aorta, bone marrow and spleen. In each artery five regions of interest (ROIs) were drawn. Maximum standardized uptake values (SUV_max) were averaged for each artery, and divided by the average venous background activity (SUV_mean) to obtain the target-to-background ratio (TBR_max). Three consecutive segments with the highest uptake were used to determine the most diseased segment (MDS) [22 (link)]. The SUV_max values in the bone marrow and spleen were determined as follows; bone marrow activity was calculated as the average SUV_max of all imaged vertebrae, and splenic SUV_max was obtained as an average of the SUV_max obtained in axial, sagittal, and coronal planes, as previously described [23 (link)].

Data collection of the primary outcome will be performed in duplicate, striving for an average PWV based on two good quality measurements during the concerning visits. Only three trained research team members will perform the PWV measurements and pre-specified quality criteria of the PWV assessment are summarized in Additional file 1. To prevent inter-assay variation laboratory measurements of T_50, CPPs, iPTH, cFGF-23, and Klotho will be measured centrally in one or limited batches. Since it is known freeze thaw cycles influence T_50-test and CPP measurement, samples will be frozen directly at − 80 °C and only thawed once for central measurement.
Radiologic assessment for the Kauppila index in the context of stratification is performed by the coordinating researcher, with prior established good interrater agreement (kappa of 0.89) in a test set that was scored by the trained researcher and an experienced radiologist. All PET-scans will be performed at the Philips Vereos PET CT-scanner of the Amsterdam UMC, location VUmc. Assessment of the nuclear images of ¹⁸F-NaF and ¹⁸F-FDG PET-scans will be performed by a trained researcher after finalization of all scans to reduce intra-rater reliability.

Imaging was performed at Sheba Medical Center. MRI on a 3T scanner (GE, Sigma HDxt, v16VO2) included high-resolution (1 mm³) 3-dimensional spoiled gradient recalled echo (SPGR) T1-weighted sequence and T2-weighted fluid attenuated inversion recovery (FLAIR) sequence^{26 (link)}. Amyloid-PET scans were performed on a Philips-Vereos PET/CT scanner in 3D acquisition mode with a low-dose CT scan for attenuation correction. Acquisition began 90 min post-injection 4–5 millicurie of [F18]Flutemetamol Vizamyl (GE Healthcare) and took 20 min.