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[IC‐P‐005]: CONCORDANCE BETWEEN CEREBROSPINAL FLUID AMYLOID‐β AND [ 18 F]FLORBETABEN PET IN AN UNSELECTED COHORT OF MEMORY CLINIC PATIENTS
Author(s) -
Wilde Arno,
Flier Wiesje M.,
Bouwman Femke H.,
Ossenkoppele Rik,
Pelkmans Wiesje,
Groot Colin,
Zwan Marissa D.,
Yaqub Maqsood M.,
Teunissen Charlotte E.,
Stephens Andrew,
Lammertsma Adriaan A.,
Berckel Bart N.M.,
Scheltens Philip
Publication year - 2017
Publication title -
alzheimer's and dementia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.713
H-Index - 118
eISSN - 1552-5279
pISSN - 1552-5260
DOI - 10.1016/j.jalz.2017.06.2277
Subject(s) - concordance , cerebrospinal fluid , medicine , positron emission tomography , memory clinic , cohort , cognitive impairment , nuclear medicine , pathology , disease
not be sensitive to the initial signs of amyloid deposition. Cutpoints are also highly dependent on many analytical issues including: region of interest (ROI), reference region, partial volume correction, and the statistical criteria for choosing the cutpoint. In the absence of CT scanning, quantifying amyloid load with combined PET/MR scanners requires novel techniques for attenuation correction. We examined these aspects in a large UK sample of individuals born in the same week in 1946, all scanned on the same PET/MR scanner. Methods: PET and MR data were acquired on 250 participants enrolled in Insight 1946, a sub-study of the MRC National Survey of Health and Development (NSHD). Scanning was performed on a Siemens Biograph PET-MR scanner using 18F-florbetapir. PET images were reconstructed from 50 to 60 minutes post-injection using two different attenuation correction techniques: an ultrashort echo time (UTE) and a pseudo CT (pCT) method. Volumetric T1MR data were parcellated into ROIs and co-registered to PET to compute standard uptake value ratios (SUVR) against four commonly used reference regions, with and without partial volume correction. Cutpoints for amyloid positivity were created by fitting Gaussian mixture models (with 1 to 3 clusters) and using the 99 percentile of the Gaussian representing the amyloid negative population. Results:240 participants with suitable T1 and amyloid PET data were included in the analysis. The mixture modelling for cortical ROIs typically resulted in 2 clusters, confirming the expected bimodal distribution of amyloid deposition. Across the different reference regions, the rate of amyloid positive individuals was consistently 15 – 18% without PVC correction and 19-23% with PVC correction (Table). Precuneus and posterior cingulate SUVRs classified slightly more participants as amyloid positive, while those based on occipital lobe were much lower (Figure). Subcortical ROIs provided inconsistent evidence of bimodal distributions. Conclusions: Quantification of SUVR based measures of amyloid load using data acquired on PET/MR produces consistent rates of amyloid positivity across a variety of analysis options.