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Neuro rehab technology

Smartphones could detect stroke catalyst



According to to new research, smartphones could help to discover a risk factor of stroke through video recordings. 

The way this catalyst can be discovered is through motion analysis of the recorded video.

By analysing the motion of the video, the researchers were able to detect narrowed arteries in the neck, which are a risk factor of stroke.

Stenosis, which is the narrowing of arteries is caused by a build up of fatty deposits (plaque.)

Narrowed arteries in the carotid artery, which are in the neck, can lead to an ischemic stroke, which occurs when a vessel that supplies blood to the brain is obstructed by a clot.

It is estimated that 87 per cent of strokes are ischemic strokes.

Lead study author Hsien-Li Kao says: “Between 2% and 5% of strokes each year occur in people with no symptoms, so better and earlier detection of stroke risk is needed.

“This was an exciting ‘eureka’ moment for us.

“Existing diagnostic methods – ultrasound, CT and MRI – require screening with specialised medical imaging equipment and personnel. 

“Analysis of video recorded on a smartphone is non-invasive and easy to perform, so it may provide an opportunity to increase screening. 

“Though more research and development are needed, the recordings and motion analysis may be able to be implemented remotely, or a downloadable app may even be feasible.”

Arteries in the neck are just below the surface of the skin, any changes in velocity and pattern of blood flow through them are reflected in the motion of the overlying skin.

However, these differences are too subtle to be discovered by the naked eye.

The study used motion magnification and pixel analysis to detect the minute changes in pulse characteristics on the skin’s surface, captured in a smartphone video recording.

The study sample involved 202 Taiwanese adults, with the average age of 68-years-old, who received care at a single Taiwanese hospital.

79 per cent of the study sample were male.

Amongst the partaking individuals, 54 per cent had significant carotid artery stenosis, thus meaning they had at least 50 per cent blockage that had previously been discovered by ultrasound.

46 per cent did not have significant stenosis.

All study participants had standard Doppler ultrasound testing to confirm narrowing in their arteries and to gauge and validate the estimates from the video motion analysis.

The recordings were taken with participants lying on their back, with their heads tilted back in a custom made box, that minimised outside movement.

An Apple iPhone 6 was mounted to the box in order to capture a 30 second recording of the individuals neck.

The researchers believed by using an older model of iPhone, that would be more common to the average smartphone user.

The research team discovered that the video motion analysis algorithm had a 87 per cent accuracy rate of detection stenosis in the group of individuals in their study sample that were known to have carotid artery stenosis.

Kao says: “More research is needed to determine whether video recorded on smartphones is a promising approach to help expedite and increase stroke screening.

“Carotid artery stenosis is silent until a stroke happens. 

“With this method, clinicians may be able to record a video of the patient’s neck with a smartphone, upload the videos for analysis and receive a report within five minutes. 

“The early detection of carotid artery stenosis may improve patient outcomes.”

However, there were several limitations to the study, including the small number of participants in the study, all of whom were considered high risk for a cardiovascular event. 

Neck lengths and neck angles also were not analysed, which could of affected the results of the video analysis. 

According to Kao, skin colour was not likely to hinder applications to a broader population since a standard lighting method was used.