TY - JOUR
T1 - Detection of brain oedema using magnetic induction tomography
T2 - A feasibility study of the likely sensitivity and detectability
AU - Merwa, Robert
AU - Hollaus, Karl
AU - Oszkar, Biro
AU - Scharfetter, Hermann
N1 - Copyright:
Copyright 2008 Elsevier B.V., All rights reserved.
PY - 2004/2
Y1 - 2004/2
N2 - The detection and continuous monitoring of brain oedema is of particular interest in clinical applications because existing methods (invasive measurement of the intracranial pressure) may cause considerable distress for the patients. A new non-invasive method for continuous monitoring of an oedema promises the use of multi-frequency magnetic induction tomography (MIT). MIT is an imaging method for reconstructing the changes of the conductivity Δκ in a target object. The sensitivity of a single MIT-channel to a spherical oedematous region was analysed with a realistic model of the human brain. The model considers the cerebrospinal fluid around the brain, the grey matter, the white matter, the ventricle system and an oedema (spherical perturbation). Sensitivity maps were generated for different sizes and positions of the oedema when using a coaxial coil system. The maps show minimum sensitivity along the coil axis, and increasing values when moving the perturbation towards the brain surface. Parallel to the coil axis, however, the sensitivity does not vary significantly. When assuming a standard deviation of 10-7 for the relative voltage change due to the system's noise, a centrally placed oedema with a conductivity contrast of 2 with respect to the background and a radius of 20 mm can be detected at 100 kHz. At higher frequencies the sensitivity increases considerably, thus suggesting the capability of multifrequency MIT to detect cerebral oedema.
AB - The detection and continuous monitoring of brain oedema is of particular interest in clinical applications because existing methods (invasive measurement of the intracranial pressure) may cause considerable distress for the patients. A new non-invasive method for continuous monitoring of an oedema promises the use of multi-frequency magnetic induction tomography (MIT). MIT is an imaging method for reconstructing the changes of the conductivity Δκ in a target object. The sensitivity of a single MIT-channel to a spherical oedematous region was analysed with a realistic model of the human brain. The model considers the cerebrospinal fluid around the brain, the grey matter, the white matter, the ventricle system and an oedema (spherical perturbation). Sensitivity maps were generated for different sizes and positions of the oedema when using a coaxial coil system. The maps show minimum sensitivity along the coil axis, and increasing values when moving the perturbation towards the brain surface. Parallel to the coil axis, however, the sensitivity does not vary significantly. When assuming a standard deviation of 10-7 for the relative voltage change due to the system's noise, a centrally placed oedema with a conductivity contrast of 2 with respect to the background and a radius of 20 mm can be detected at 100 kHz. At higher frequencies the sensitivity increases considerably, thus suggesting the capability of multifrequency MIT to detect cerebral oedema.
KW - Eddy currents
KW - Finite elements
KW - Human brain
KW - Magnetic induction tomography
KW - Oedema
KW - Sensitivity distribution
KW - Magnetics/instrumentation
KW - Brain Edema/diagnosis
KW - Humans
KW - Feasibility Studies
KW - Models, Biological
KW - Computer Simulation
KW - Sensitivity and Specificity
KW - Tomography/methods
UR - http://www.scopus.com/inward/record.url?scp=1342332813&partnerID=8YFLogxK
U2 - 10.1088/0967-3334/25/1/038
DO - 10.1088/0967-3334/25/1/038
M3 - Article
C2 - 15005328
SN - 0967-3334
VL - 25
SP - 347
EP - 354
JO - Physiological Measurement
JF - Physiological Measurement
IS - 1
ER -