Quantitative evaluation of atlas-based high-density diffuse optical tomography for imaging of the human visual cortex

Abstract

Image recovery in diffuse optical tomography (DOT) of the human brain often relies on accurate models of light propagation within the head. In the absence of subject specific models for image reconstruction, the use of atlas based models are showing strong promise. Although there exists some understanding in the use of some limited rigid model registrations in DOT, there has been a lack of a detailed analysis between errors in geometrical accuracy, light propagation in tissue and subsequent errors in dynamic imaging of recovered focal activations in the brain. In this work 11 different rigid registration algorithms, across 24 simulated subjects, are evaluated for DOT studies in the visual cortex. Although there exists a strong correlation (R 2 = 0.97) between geometrical surface error and internal light propagation errors, the overall variation is minimal when analysing recovered focal activations in the visual cortex. While a subject specific mesh gives the best results with a 1.2 mm average location error, no single algorithm provides errors greater than 4.5 mm. This work demonstrates that the use of rigid algorithms for atlas based imaging is a promising route when subject specific models are not available.

Automated voxel classification used with atlas-guided diffuse optical tomography for assessment of functional brain networks in young and older adults

“…[1][2][3][4][5][6][7][8]46 GTA is a network analysis tool that has been commonly used in functional neuroimaging to study brain connectivity and networks. [13][14][15]18,19 To date, however, atlas-DOT and GTA have not been used jointly to extract or derive large-scale brain connectivity and networks from the NIRS measurements because of computational challenges posed by atlas-DOT.…”

“…However, we suggest further examining and confirming the noise effect using other approaches. Future studies could use a computational method such as independent component analysis 27,61 or an experimental approach such as short-distance measurement regression 2,4,7,8,46,57 to minimize global signal or noise effects.…”

“…5,6 A significant improvement of accuracy in image reconstruction and source localization has been achieved with atlas-DOT. 7 More recently, atlas-DOT has been utilized together with the general linear model analysis, which further extended its feasibility of measuring hemodynamic changes in complex brain tasks. Several groups have reported consistent and accurate results of brain hemodynamic changes under visual stimulation, 7 speech, 8 and risk decision-making.…”

“…7 More recently, atlas-DOT has been utilized together with the general linear model analysis, which further extended its feasibility of measuring hemodynamic changes in complex brain tasks. Several groups have reported consistent and accurate results of brain hemodynamic changes under visual stimulation, 7 speech, 8 and risk decision-making. 5 It is well known that the human brain is naturally organized into groups of networks, with anatomical brain regions involved in either individualized processing or integration with other brain regions, to accomplish different functions.…”

Evaluation of rigid registration methods for whole head imaging in diffuse optical tomography

“…This gives rise to 11 registration methods consisting of basic-4-landmark, EEG 19 nP2P, EEG 19 P2P, EEG ICP, EEG 40 nP2P, EEG 40 P2P, EEG 40 ICP, full-head-landmark nP2P, full-headlandmark P2P, full-head-landmark ICP, and line-fitting registration methods, further details of which are covered in depth elsewhere. 41 Additionally, a spherical coordinate landmark system has also been used which defines a spherical coordinate system based on three fiducial points (the nasion and the left and right temple points) and extracts arbitrary points from the subject scalp as landmarks based on the spherical coordinates. This approach may be considered practically easier to apply than those outlined above.…”