Biograph 40 pet ct

Structural MR (Biograph mMR) and [¹⁸F]florbetapir and [¹⁸F]flortaucipir PET neuroimaging (Biograph 40 PET/CT; Siemens Medical Solutions; Erlanger, Germany) were performed as previously described (Day et al. , 2017 (link), Day et al. , 2018 (link)). Briefly, T1-weighted images were acquired using magnetization-prepared rapid-acquisition gradient echo sequences, before cortical and subcortical parcellation was completed using FreeSurfer 5.3 (http://freesurfer.net), yielding 46 unique brain regions, corresponding to the Desikan atlas. PET imaging was performed following injection of 7.4–11.3 mCi of [¹⁸F]florbetapir or 6.8–10.9 mCi of [¹⁸F]flortaucipir, and data from the 50- to 70- minute and 80- to 100-minute post-injection windows converted to SUVRs, respectively, using the cerebellar cortex as a reference. Regional values were partial volume corrected using a geometric transfer matrix approach (Su et al. , 2015 (link), Su et al. , 2013 (link)). For visualization, voxel-wise PET were aligned to the patient’s T1 images.

One day prior to the PET study, patients were instructed to abstain from caffeinated or xanthine-containing foods and beta-blockers. On the day of the PET study, subjects were placed supine and a computed tomography (CT) scan was collected for localization and estimation of attenuation. All subjects underwent a 10 minute dynamic PET collected on a Biograph 40 PET/CT (Siemens Medical Solutions, Erlangen, Germany) immediately following a 370 MBq bolus of [N-13]-ammonia. Approximately, 1 hour later, an additional 10 minute dynamic stress study was collected by first intravenously administering adenosine (140 μg/kg/min) for 3 minutes prior to the administration of [N-13]-ammonia. Adenosine infusion was terminated at 6 minutes total duration. PET list mode data were divided into 21 frames (12 × 10 sec, 6 × 30 sec, 2 × 60 sec, 1 × 180 sec) and reconstructed with a 3-dimensional ordered-subset expectation maximization algorithm (4 iterations, 8 subsets) including all data corrections to a 168 × 168 × 111 matrix with 1.85 × 1.85 x. 3mm voxels. A post-reconstruction filter of 5 mm full-width-at-half-maximum was applied to all frames.