Modelling of the human thorax as a volume conductor -
Brief tutorial and some examples
Modelling group at TUT:
Jari Hyttinen (ECG applications, coordination)
Pasi Kauppinen (ICG application)
Päivi Laarne (EEG applications)
Ilmari Konkka> (EGG applications)
Hanna-Greta Puurtinen (ECG inverse problem)
Prof. Jaakko Malmivuo
Assoc. prof. Hannu Eskola
The models of the human body as a volume conductor are employed to learn
the relationship between the measured biopotentials and the sources generating
them. The simulations of the sources provide the forward solution.
The inverse solution of the sources are based on the measured potentials
and the forward solution obtained with the model. (see bioelectromagnetism)
We have developed tools for construction of patient tailored volume conductor
model of the human body (both head and thorax) from sectional images (CT,
MR). The tools include tissue
segmentation from the image data, model construction, field calculation
of the anatomy and the measured or calculated fields. The computational
model is based on the finite difference method providing easy formation
of accurate anatomical models.
One application of the tools has been the utilization of the Visible Human
Man data for the basis of the model.
From the cryosectional images of the VHM project 118 slices were selected.
These were converted to b/w 8 bit images for data storage and image processing.
All tissues visible in these selected slices were segmented and a very
accurate FDM model of the thorax was constructed.
Examples of visualized results:
Electric field generated in
the thorax generated by energization of the standard ECG lead I (this
is the lead field, e.g. sensitivity distribution of the lead I) (VHM model):
Effect of changing the tissue
conductivity's by 10% (cases: all inhomogeneities, intracardial blood masses)
Body surface potential maps
generated by simulated ischemic injury sources (model based on MR images):
Sensitivity distribution of
the impedance cardiography lead systems: original band electrode system
introduced by Kubizek and three spot electrode systems suggested in literature