Estimation of the EEG power spectrum using MRI T2 relaxation time in traumatic brain injury

Thatcher, R.W.; Biver, C.; Gomez, J.F.; North, D.; Curtin, R.; Walker, R.A.; Salazar, A.

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Volume 112, Issue 9 , Pages 1729-1745, September 2001

Estimation of the EEG power spectrum using MRI T₂ relaxation time in traumatic brain injury

R.W. Thatcher
- Bay Pines Veterans Administration Medical Center, Research and Development Service – 151, Bldg 23, Room 117, Bay Pines, FL 33744, USA
- University of South Florida College of Medicine, Departments of Neurology and Radiology, Tampa, FL, USA
- Defense and Veterans Head Injury Program, 6825 Georgia Ave., Washington, DC 20307, USA
- Corresponding author. Fax: +1-727-391-0890
C. Biver
- Bay Pines Veterans Administration Medical Center, Research and Development Service – 151, Bldg 23, Room 117, Bay Pines, FL 33744, USA
- Defense and Veterans Head Injury Program, 6825 Georgia Ave., Washington, DC 20307, USA
J.F. Gomez
- Bay Pines Veterans Administration Medical Center, Research and Development Service – 151, Bldg 23, Room 117, Bay Pines, FL 33744, USA
- Defense and Veterans Head Injury Program, 6825 Georgia Ave., Washington, DC 20307, USA
D. North
- Bay Pines Veterans Administration Medical Center, Research and Development Service – 151, Bldg 23, Room 117, Bay Pines, FL 33744, USA
- Defense and Veterans Head Injury Program, 6825 Georgia Ave., Washington, DC 20307, USA
R. Curtin
- Bay Pines Veterans Administration Medical Center, Research and Development Service – 151, Bldg 23, Room 117, Bay Pines, FL 33744, USA
- Defense and Veterans Head Injury Program, 6825 Georgia Ave., Washington, DC 20307, USA
R.A. Walker
- Bay Pines Veterans Administration Medical Center, Research and Development Service – 151, Bldg 23, Room 117, Bay Pines, FL 33744, USA
A. Salazar
- Defense and Veterans Head Injury Program, 6825 Georgia Ave., Washington, DC 20307, USA

Accepted 24 May 2001.

Abstract

Objectives: To study the relationship between magnetic resonance imaging (MRI) T₂ relaxation time and the power spectrum of the electroencephalogram (EEG) in long-term follow up of traumatic brain injury.

Methods: Nineteen channel quantitative electroencephalograms or qEEG, tests of cognitive function and quantitative MRI T₂ relaxation times (qMRI) were measured in 18 mild to severe closed head injured outpatients 2 months to 4.6 years after injury and 11 normal controls. MRI T₂ and the Laplacian of T₂ were then correlated with the power spectrum of the scalp electrical potentials and current source densities of the qEEG.

Results: qEEG and qMRI T₂ were related by a frequency tuning with maxima in the alpha (8–12Hz) and the lower EEG frequencies (0.5–5Hz), which varied as a function of spatial location. The Laplacian of T₂ acted like a spatial–temporal ‘lens’ by increasing the spatial–temporal resolution of correlation between 3-dimensional T₂ and the ear referenced alert but resting spontaneous qEEG.

Conclusions: The severity of traumatic brain injury can be modeled by a linear transfer function that relates the molecular qMRI to qEEG resonant frequencies.

Keywords: Traumatic brain injury, Magnetic resonance imaging T₂ relaxation time, Entropy, qEEG