Effects of global signal regression and subtraction methods on resting-state functional connectivity using arterial spin labeling data

Silva, João Paulo Santos; Mônaco, Luciana da Mata; Paschoal, André Monteiro; Oliveira, Ícaro A.F.; Leoni, Renata Ferranti

doi:10.1016/j.mri.2018.05.006

Cited by 5 publications

(4 citation statements)

References 37 publications

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“…We report extensive functional connectivity changes in lower limb amputees without pain during two tactile stimulations: residual limb stimulation and remaining foot stimulation, as compared to controls. Sensorimotor brain connectivity was investigated using the region of interest (ROI-to-ROI) connectivity method 20,21 . A priori ROIs were: primary motor cortex (M1); premotor cortex/supplementary motor area (M2); primary somatosensory cortex (S1); and secondary somatosensory cortex (S2).…”

Section: Resultsmentioning

confidence: 99%

Lower limb amputees undergo long-distance plasticity in sensorimotor functional connectivity

Rodrigues

Simões

Melo

et al. 2019

Sci Rep

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Amputation in adults is associated with an extensive remapping of cortical topography in primary and secondary sensorimotor areas. Here, we used tactile residual limb stimulation and 3T functional magnetic resonance imaging in humans to investigate functional connectivity changes in the sensorimotor network of patients with long-term lower limb traumatic amputations with phantom sensation, but without pain. We found a pronounced reduction of inter-hemispheric functional connectivity between homologous sensorimotor cortical regions in amputees, including the primary (S1) and secondary (S2) somatosensory areas, and primary (M1) and secondary (M2) motor areas. We additionally observed an intra-hemispheric increased functional connectivity between primary and secondary somatosensory regions, and between the primary and premotor areas, contralateral to amputation. These functional connectivity changes in specialized small-scale sensory-motor networks improve our understanding of the functional impact of lower limb amputation in the brain. Our findings in a selective group of patients with phantom limb sensations, but without pain suggest that disinhibition of neural inputs following traumatic limb amputation disrupts sensorimotor topology, unbalancing functional brain network organization. These findings step up the description of brain plasticity related with phantom sensations by showing that pain is not critical for sensorimotor network changes after peripheral injury.

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Section: Resultsmentioning

confidence: 99%

Lower limb amputees undergo long-distance plasticity in sensorimotor functional connectivity

Rodrigues

Simões

Melo

et al. 2019

Sci Rep

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“…Perfusion maps were generated by the subtraction of control and label images. For basal CBF analysis, we used the sync subtraction, while for functional analysis we performed a running pairwise subtraction to increase the number of perfusion images [23]. Quantification was based on the General Kinetic Model [8] using the following parameters: blood longitudinal relaxation time (T1 b ) = 1650 ms; labeling efficiency = 0.85; blood/tissue water partition coefficient (GM/WM) = 0.98/0.84 g/mL; tissue T1 (GM/WM) = 1020/770 ms calculated using a Look-Locker sequence [24].…”

Section: Cbf Quantificationmentioning

confidence: 99%

Dual-Echo Arterial Spin Labeling for Brain Perfusion Quantification and Functional Analysis

Paschoal

Paiva

Leoni

2019

Concepts in Magnetic Resonance Part A

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Arterial Spin Labeling (ASL) is a noninvasive MRI-based method to measure cerebral blood flow (CBF). Recently, the study of ASL as a functional tool has emerged once CBF fluctuation comes from capillaries in brain tissue, giving a more spatially specific response when compared to the standard functional MRI method, based on the blood oxygenation level-dependent (BOLD) contrast. Although the BOLD effect could be desirable to study brain function, if one aims to quantify CBF, such effect is considered contamination that can be more attenuated if short TE value is used in the image acquisition. An approach that provides both CBF and function information in a simultaneous acquisition is the use of a dual-echo ASL (DE-ASL) readout. Our purpose was to evaluate the information provided by DE-ASL regarding CBF quantification and functional connectivity with a motor task. Pseudocontinuous ASL of twenty healthy subjects (age: 32.4 ± 10.2 years, 13 male) was acquired at a 3T scanner. We analyzed the influence of TE on CBF values and brain connectivity provided by CBF and concurrent BOLD (cc-BOLD) time series. Brain networks were obtained by the general linear model and independent component analysis. Connectivity matrices were generated using a bivariate correlation (Fisher Z values). No effect of the sequence readout, but significant effect of the TE value, was observed on gray matter CBF values. Motor networks with reduced extension and more connections with important regions for brain integration were observed for CBF data acquired with short TE, proving its higher spatial specificity. Therefore, it was possible to use a dual-echo readout provided by a standard commercial ASL pulse sequence to obtain reliable quantitative CBF values and functional information simultaneously.

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“…Perfusion maps were generated by subtracting unlabeled and label images acquired with the short TE (= 9 ms). Quantification was performed using the sinc subtraction for regional CBF mapping, while a running pairwise subtraction was performed for functional analysis to increase the number of perfusion-weighted images in the time series [45]. Quantification was based on the General Kinetic Model [29] using the following parameters: blood longitudinal relaxation time (T1b) = 1650 ms; labeling efficiency = 0.85; blood/tissue water partition coefficient (gray matter/white matter) = 0.98/0.84 g ml −1 ; tissue T1 (gray matter-/white matter) = 1020/770 ms [46].…”

Section: Cbf Quantificationmentioning

confidence: 99%

Semantic verbal fluency brain network: delineating a physiological basis for the functional hubs using dual-echo ASL and graph theory approach

Paschoal¹,

Silva²,

Rondinoni³

et al. 2021

J. Neural Eng.

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Objective. Semantic verbal fluency (SFV) is a cognitive process that engages and modulates specific brain areas related to language comprehension and production, decision making, response inhibition, and memory retrieval. The impairment of the brain network responsible for these functions is related to various neurological conditions, and different strategies have been proposed to assess SVF-related deficits in such diseases. In the present study, the concomitant changes of brain perfusion and functional connectivity were investigated during the resting state and SVF task performance. Approach. Arterial spin labeling (ASL), a perfusion-based magnetic resonance imaging (MRI) method, was used with a pseudocontinuous labeling approach and dual-echo readout in 28 healthy right-handed Brazilian Portuguese speakers. The acquisition was performed in a resting state condition and during the performance of a SVF task. Main results. During task performance, a significant increase in cerebral blood flow (CBF) was observed in language-related regions of the frontal lobe, including Brodmann's areas 6, 9, 45, and 47, associated with semantic processing, word retrieval, and speech motor programming. Such regions, along with the posterior cingulate, showed a crucial role in the SVF functional network, assessed by seed-to-voxel and graph analysis. Our approach successfully overcame the generalization problem regarding functional MRI (fMRI) graph analysis with cognitive, task-based paradigms. Moreover, the CBF maps enabled the functional assessment of orbital frontal and temporal regions commonly affected by magnetic susceptibility artifacts in conventional T2 * -weighted fMRI approaches. Significance. Our results demonstrated the capability of ASL to evaluate perfusion alterations and functional patterns simultaneously regarding the SVF network providing a quantitative physiological basis to functional hubs in this network, which may support future clinical studies.

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Effects of global signal regression and subtraction methods on resting-state functional connectivity using arterial spin labeling data

Cited by 5 publications

References 37 publications

Lower limb amputees undergo long-distance plasticity in sensorimotor functional connectivity

Lower limb amputees undergo long-distance plasticity in sensorimotor functional connectivity

Dual-Echo Arterial Spin Labeling for Brain Perfusion Quantification and Functional Analysis

Semantic verbal fluency brain network: delineating a physiological basis for the functional hubs using dual-echo ASL and graph theory approach

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