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 equipmentAn 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.

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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

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Impedance tomography of the brain has been studied

for about four years, particularly in the past two. The

results have been promising.

Sizeable marketsSiltanen expects a helmet for use in ambulances to be

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sales are considerable. Finland alone has about 1,000

ambulances, the United States about 48,000.

Moreover, certain groups of sports people, such as

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stant tests that a helmet allows.

Complex mathematicsSiltanen says that, although similar projects have been

carried out elsewhere, the mathematics has not been

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“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

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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

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More information

Samuli SiltanenprofessorUniversity of HelsinkiVDPXOL�VLOWDQHQ#KHOVLQNL�í+358 40 594 3560

Kimmo Uutelaprincipal engineerGE Healthcare Finland Oykimmo.uutela@ge.com+358 10 394 3353