Premium
P2‐464: BIOLOGICAL CORRELATES OF WHITE MATTER CHANGES IN AUTOSOMAL DOMINANT ALZHEIMER'S DISEASE
Author(s) -
Strain Jeremy F.,
Smith Robert X.,
Wang Qing,
Fagan Anne M.,
Gordon Brian A.,
Hassenstab Jason,
Xiong Chengjie,
McDade Eric,
Morris John C.,
Benzinger Tammie L.S.,
Bateman Randall J.,
Ances Beau M.
Publication year - 2018
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.2018.06.1157
Subject(s) - cingulum (brain) , white matter , diffusion mri , fractional anisotropy , dementia , clinical dementia rating , disease , pathology , medicine , psychology , neuroscience , magnetic resonance imaging , radiology
Background: Reference tissue is used in some methods such as simplified reference tissue methods, reference Logan plot, and pseudo-equilibrium method. Although true equilibrium is never achieved, pseudo-equilibrium method is the simplest method in the world, which does not require arterial blood sampling or PET scanner-occupying dynamic scan. Its index, SUVR has been widely used as a substitute for distribution volume ratio (DVR). Reference tissue is required to have the same K1/k2 as the target region and not to have the specific binds to amyloid. Cerebellar cortex fulfils almost the requirement and it has been used as a reference region. However, some studies with Florbetapir use white matter as a reference region and show the advantage in longitudinal study over cerebellar reference region. Apparantly, white matter does not fulfil the requirement of the reference tissue. What makes the advantage of white matter reference region? Decrease in K1 caused by CBF change has been shown to affect SUVR. One study with Florbetaben showed cerebellar reference region is the best for longitudinal studies. What is the difference?–acquisition time? To discover the source of the advantage of white matter reference region, we have executed simulations. Methods: Simulation was executed with Python. We changed the various parameters including K1, input functions, and noise in the time-activity curves. We tested the stability of SUVRs in the various conditions. Results: CVs in the conditions of K1 changes, input function variety showed the superiority of cerebellar reference region. High accumulation in the white matter reduced CVs. However, the slight difference by the high accumulation in white matter could not overcome the inferiority by K1 changes and input function changes. Nine times larger noise in time-activity curve in the cerebellum than white matter could make white matter reference region superior to cerebellum. Conclusions:White matter reference makes SUVR stabilize if the noise is 9 times smaller than cerebellum. Cerebellar regions are susceptible to noise due to their small size, low signal level, and proximity to the axial periphery of the PET scanner bore. Second acquisition with cerebellum in the central may be useful for longitudinal study.