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Phys Med Biol. 2009 Oct 21;54(20):6201-16. doi: 10.1088/0031-9155/54/20/011. Epub 2009 Oct 1.

Optimal parameters for near infrared fluorescence imaging of amyloid plaques in Alzheimer's disease mouse models.

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  • 1The Harvard-MIT Division of Health Sciences and Technology, 77 Mass Ave., E25-519, Cambridge, MA 02139, USA.

Abstract

Amyloid-beta plaques are an Alzheimer's disease biomarker which present unique challenges for near-infrared fluorescence tomography because of size (<50 microm diameter) and distribution. We used high-resolution simulations of fluorescence in a digital Alzheimer's disease mouse model to investigate the optimal fluorophore and imaging parameters for near-infrared fluorescence tomography of amyloid plaques. Fluorescence was simulated for amyloid-targeted probes with emission at 630 and 800 nm, plaque-to-background ratios from 1-1000, amyloid burden from 0-10%, and for transmission and reflection measurement geometries. Fluorophores with high plaque-to-background contrast ratios and 800 nm emission performed significantly better than current amyloid imaging probes. We tested idealized fluorophores in transmission and full-angle tomographic measurement schemes (900 source-detector pairs), with and without anatomical priors. Transmission reconstructions demonstrated strong linear correlation with increasing amyloid burden, but underestimated fluorescence yield and suffered from localization artifacts. Full-angle measurements did not improve upon the transmission reconstruction qualitatively or in semi-quantitative measures of accuracy; anatomical and initial-value priors did improve reconstruction localization and accuracy for both transmission and full-angle schemes. Region-based reconstructions, in which the unknowns were reduced to a few distinct anatomical regions, produced highly accurate yield estimates for cortex, hippocampus and brain regions, even with a reduced number of measurements (144 source-detector pairs).

PMID:
19794239
[PubMed - indexed for MEDLINE]
PMCID:
PMC3290001
Free PMC Article
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