title: Accelerated vs. unaccelerated serial MRI based TBM-SyN measurements for clinical trials in Alzheimer's disease.
abstract: OBJECTIVE
  Our primary objective was to compare the performance of unaccelerated vs. accelerated structural MRI for measuring disease progression using serial scans in Alzheimer's disease (AD).
  
  
  METHODS
  We identified cognitively normal (CN), early mild cognitive impairment (EMCI), late mild cognitive impairment (LMCI) and AD subjects from all available Alzheimer's Disease Neuroimaging Initiative (ADNI) subjects with usable pairs of accelerated and unaccelerated scans. There were a total of 696 subjects with baseline and 3 month scans, 628 subjects with baseline and 6 month scans and 464 subjects with baseline and 12 month scans available. We employed the Symmetric Diffeomorphic Image Normalization method (SyN) for normalization of the serial scans to obtain tensor based morphometry (TBM) maps which indicate the structural changes between pairs of scans. We computed a TBM-SyN summary score of annualized structural changes over 31 regions of interest (ROIs) that are characteristically affected in AD. TBM-SyN scores were computed using accelerated and unaccelerated scan pairs and compared in terms of agreement, group-wise discrimination, and sample size estimates for a hypothetical therapeutic trial.
  
  
  RESULTS
  We observed a number of systematic differences between TBM-SyN scores computed from accelerated and unaccelerated pairs of scans. TBM-SyN scores computed from accelerated scans tended to have overall higher estimated values than those from unaccelerated scans. However, the performance of accelerated scans was comparable to unaccelerated scans in terms of discrimination between clinical groups and sample sizes required in each clinical group for a therapeutic trial. We also found that the quality of both accelerated vs. unaccelerated scans were similar.
  
  
  CONCLUSIONS
  Accelerated scanning protocols reduce scan time considerably. Their group-wise discrimination and sample size estimates were comparable to those obtained with unaccelerated scans. The two protocols did not produce interchangeable TBM-SyN estimates, so it is arguably important to use either accelerated pairs of scans or unaccelerated pairs of scans throughout the study duration.
authors: Departments of Radiology, MN, USA. Electronic address: vemuri.prashanthi@mayo.edu.
authors: Prashanthi
authors: P
authors: Vemuri
authors: Departments of Radiology, MN, USA; Information Technology, MN, USA.
authors: Matthew L
authors: ML
authors: Senjem
authors: Departments of Radiology, MN, USA; Information Technology, MN, USA.
authors: Jeffrey L
authors: JL
authors: Gunter
authors: Health Sciences Research, MN, USA.
authors: Emily S
authors: ES
authors: Lundt
authors: Health Sciences Research, MN, USA.
authors: Nirubol
authors: N
authors: Tosakulwong
authors: Health Sciences Research, MN, USA.
authors: Stephen D
authors: SD
authors: Weigand
authors: Departments of Radiology, MN, USA.
authors: Bret J
authors: BJ
authors: Borowski
authors: Departments of Radiology, MN, USA.
authors: Matt A
authors: MA
authors: Bernstein
authors: Departments of Radiology, MN, USA.
authors: Samantha M
authors: SM
authors: Zuk
authors: Departments of Radiology, MN, USA.
authors: Val J
authors: VJ
authors: Lowe
authors: Neurology Mayo Clinic Rochester, MN, USA.
authors: David S
authors: DS
authors: Knopman
authors: Neurology Mayo Clinic Rochester, MN, USA.
authors: Ronald C
authors: RC
authors: Petersen
authors: Dementia Research Center, UCL Institute of Neurology, London, UK.
authors: Nick C
authors: NC
authors: Fox
authors: Imaging genetics Center, Institute for Neuroimaging and Informatics, Department of Neurology, University of Southern California, Los Angeles, CA, USA; Department of Psychiatry, University of Southern California, Los Angeles, CA, USA; Department of Radiology, University of Southern California, Los Angeles, CA, USA; Department of Pediatrics, University of Southern California, Los Angeles, CA, USA; Department of Engineering, University of Southern California, Los Angeles, CA, USA; Department of Opthalmology , University of Southern California, Los Angeles, CA, USA.
authors: Paul M
authors: PM
authors: Thompson
authors: University of California at San Francisco, Department of Veterans Affairs Medical Center, San Francisco, CA, USA; Center for Imaging of Neurodegenerative Diseases, Department of Veterans Affairs Medical Center, San Francisco, CA, USA.
authors: Michael W
authors: MW
authors: Weiner
authors: Departments of Radiology, MN, USA.
authors: Clifford R
authors: CR
authors: Jack
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D000544:Alzheimer Disease / Q000473:pathology* / Q000523:psychology; D001185:Artificial Intelligence; D001931:Brain Mapping / Q000379:methods; D060825:Cognitive Dysfunction / Q000473:pathology / Q000523:psychology; D066264:Datasets as Topic; D056324:Diffusion Tensor Imaging / Q000379:methods*; D018450:Disease Progression; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D059906:Neuroimaging; D011786:Quality Control