A helmet of electrodes can help to distinguish between a cerebral infarction and a cerebral haemorrhage. Rapid diagnosis, even in the ambulance, has a strong impact on the patient’s prognosis. The sooner that treatment is initiated to dissolve a blockage, the better the results.

1. Electrode helmet for rapid stroke diagnosis
shows promising results
A stroke can be the result of a clot in a blood vessel
supplying the brain or bleeding in the brain tissue
itself. The only proven form of acute treatment for a
clot is to dissolve it. The effectiveness of thromboly-
sis is greatest immediately after the clot forms, but
gradually declines over the next four and half hours.
However, thrombolysis can be life-threatening for
patients with a cerebral haemorrhage and so it can-
not be administered before an infarction has been
diagnosed. So far the only way of distinguishing be-
tween a haemorrhage and an infarction is by magnetic
computer-assisted tomography, which can be carried
out in major hospitals only.
Part of ambulance equipment
An electrode helmet, intended for quick stroke di-
agnosis in an ambulance, has been studied in the
SalWe Mind and Body programme. The University of
Helsinki, Colorado State University and the Techni-
cal University of Denmark participated in the pro-
ject alongside GE Healthcare Finland, the industrial
partner.
“The helmet uses an imaging technology called elec-
trical impedance tomography. An alternating current
of the right frequency is applied to the cranium via
electrodes embedded in the helmet and the returning
signal is measured,” says Samuli Siltanen, Professor of
SalWe - the Enabler of Joint Research in Health and Wellbeing
A helmet of electrodes, studied in the SalWe Mind and Body programme, can help to distinguish between
a cerebral infarction and a cerebral haemorrhage. Rapid diagnosis, even in the ambulance, has a strong impact
on the patient’s prognosis. The sooner that treatment is initiated to dissolve a blockage, the better the results.

2. Industrial Mathematics at the University of Helsinki,
who has been the project leader.
“From the brain conductivity readings, a three-dimen-
sional image can be mathematically constructed of
the brain tissue, in which a haemorrhage looks very
Impedance tomography of the brain has been studied
for about four years, particularly in the past two. The
results have been promising.
Sizeable markets
Siltanen expects a helmet for use in ambulances to be
sales are considerable. Finland alone has about 1,000
ambulances, the United States about 48,000.
Moreover, certain groups of sports people, such as
-
stant tests that a helmet allows.
Complex mathematics
Siltanen says that, although similar projects have been
carried out elsewhere, the mathematics has not been
“To derive a three-dimensional image is very complex.”
It is an inverse problem, where the outcome is known
but the precise causes are not. Mathematics is needed
to determine the causes, in this case biological proper-
ties that cannot be directly measured.
“It is harmless and cheap to probe the human body
with electricity and record conductivity in different
parts, but information is not easily extracted from the
x-rays, for example, travel only in straight lines.”
Solutions to this non-linear inverse problem have been
developed by professors Jennifer Mueller of Colorado,
Kim Knudsen of Denmark and Siltanen. “The challenge
has been to derive a big picture from small data.”
Although great advances have been made, more work
is needed to develop algorithms to build a picture
of the cranium from the information yielded from a
limited number of electrodes.
Tangible support from SalWe
“Finance from SalWe was of vital importance. This
technology would certainly not have advanced so well
without it,” says Samuli Siltanen.
“SalWe offered a concrete way of combining the in-
house work of GE Healthcare with the methods of my
research team.”
SalWe - the Enabler of Joint Research in Health and Wellbeing
06/2014
More information
Samuli Siltanen
professor
University of Helsinki
+358 40 594 3560
Kimmo Uutela
principal engineer
GE Healthcare Finland Oy
kimmo.uutela@ge.com
+358 10 394 3353