Airport security-style technology could help doctors decide on stroke treatment

A new computer program could help doctors predict which patients might suffer potentially fatal side-effects from a key stroke treatment.

The program, which assesses brain scans using pattern recognition software similar to that used in airport security and passport control, has been developed by researchers at Imperial College London. Results of a pilot study funded by the Wellcome Trust, which used the software are published in the journal Neuroimage Clinical.

Stroke affects over 15 million people each year worldwide. Ischemic strokes are the most common and these occur when small clots interrupt the blood supply to the brain. The most effective treatment is called intravenous thrombolysis, which injects a chemical into the blood vessels to break up or ‘bust’ the clots, allowing blood to flow again.

However, because intravenous thombolysis effectively thins the blood, it can cause harmful side effects in about six per cent of patients, who suffer bleeding within the skull. This often worsens the disability and can cause death.

Clinicians attempt to identify patients most at risk of bleeding on the basis of several signs assessed from brain scans. However, these signs can often be very subtle and human judgements about their presence and severity tend to lack accuracy and reliability.

In the new study, researchers trained a computer program to recognise patterns in the brain scans that represent signs such as brain-thinning or diffuse small-vessel narrowing, in order to predict the likelihood of bleeding. They then pitted the automated pattern recognition software against radiologists’ ratings of the scans. The computer program predicted the occurrence of bleeding with 74 per cent accuracy compared to 63 per cent for the standard prognostic approach.

Dr Paul Bentley from the Department of Medicine, lead author of the study, said: “For each patient that doctors see, they have to weigh up whether the benefits of a treatment will outweigh the risks of side effects. Intravenous thrombolysis carries the risk of very severe side effects for a small proportion of patients, so having the best possible information on which to base our decisions is vital. Our new study is a pilot but it suggests that ultimately doctors might be able to use our pattern recognition software, alongside existing methods, in order to make more accurate assessments about who is most at risk and treat them accordingly. We are now planning to carry out a much larger study to more fully assess its potential.”

The research team conducted a retrospective analysis of computerized tomography (CT) scans from 116 patients. These are scans that use x-rays to produce ‘virtual slices’ of the brain. All the patients had suffered ischemic strokes and undergone intravenous thrombolysis in Charing Cross Hospital. In the sample the researchers included scans from 16 patients who had subsequently developed serious bleeding within the brain.

Without knowing the outcomes of the treatment, three independent experts examined the scans and used standard prognostic tools to predict whether patients would develop bleeding after treatment.

In parallel the computer program directly assessed and classified the patterns of the brain scans to produce its own predictions.

Researchers evaluated the performance of both approaches by comparing their predictions of bleeding with the actual experiences of the patients.

Using a statistical test the research showed the computer program predicted the occurrence of bleeding with 74 per cent accuracy compared to 63 per cent for the standard prognostic approach. 

The researchers also gave the computer a series of ‘identity parades’ by asking the software to choose which patient out of ten scans went on to suffer bleeding. The computer correctly identified the patient 56 per cent of the time while the standard approach was correct 31 per cent of the time.

The researchers are keen to explore whether their software could also be used to identify stroke patients who might be helped by intravenous thrombolysis who are not currently offered this treatment. At present only about 20 per cent of patients with strokes are treated using intravenous thrombolysis, as doctors usually exclude those with particularly severe strokes or patients who have suffered the stroke more than four and half hours before arriving at hospital. The researchers believe that their software has the potential to help doctors to identify which of those patients are at low risk of suffering side effects and hence might benefit from treatment.

Beating the clock for sufferers of ischemic stroke

A ground-breaking computer technology raises hope for people struck by ischemic stroke (缺乏血性中風), which is a very common kind of stroke accounting for over 80 per cent of overall stroke cases. Developed by research experts at The Hong Kong Polytechnic University (PolyU), this novel application that expertly analyses brain scans could save lives by helping doctors determine if a patient has the life-threatening condition.

The CAD stroke technology is capable of detecting signs of stroke from computed tomography (CT) scans. A CT scan uses X-rays to take pictures of the brain in slices. When blood flow to the brain is blocked, an area of the brain turns softer or decreases in density due to insufficient blood flow, pointing to an ischemic stroke.

As demonstrated by Dr Fuk-hay Tang from the Department of Health Technology and Informatics at PolyU, CT scans are fed into the CAD stroke computer, which will make sophisticated calculations and comparisons to locate areas suspected of insufficient blood flow. In 10 minutes, scans with highlighted areas of abnormality will come out for doctors’ review. Early changes including loss of insular ribbon, loss of sulcus and dense MCA signs can be identified, helping doctors determine if blood clots are present.

Ischemic stroke occurs when an artery to the brain is blocked, cutting off oxygen and essential nutrients being sent to the brain, and brain cells will die in just a few minutes. Clot-busting drugs are effective in minimising brain damage but they should be administered within 3 hours from the onset. Immediate diagnosis and treatment are therefore absolutely essential.

In that sense, a diagnostic tool that can expedite the process will be greatly helpful in saving lives. As Dr Tang shared with us, “The clock is ticking for stroke patients. Medications taken in three hours from the onset of stroke are deemed most effective. Chances of recovery decrease with every minute passing by. It usually takes half an hour for the ambulance to arrive at the hospital, at best. Then, another 45 minutes to 1 hour are needed for CT or MRI scans after the patient has been checked and dispatched for the test, which means some waiting and time will slip by. Afterwards, the brain scan will take another 10 to 15 minutes. If our tool can help doctors arrive at a diagnosis in 10 minutes, the shorter response time will make meeting the target more achievable.”

“It might come in handy for physicians with less experience in stroke,” added Dr Tang, “and patient care can be maintained in hospitals where human and other vital resources are already stretched to the limit.”

The life-saving application can also detect subtle and minute changes in the brain that would escape the eye of even an experienced specialist, slashing the chances of missed diagnosis. False-positive and false-negative cases, and other less serious conditions that mimic a stroke can also be ruled out, allowing a fully-informed decision to be made.

Furthermore, equipped with the built-in artificial intelligence feature, the CAD stroke technology would learn by experience. With every scan passing through, along with feedback from stroke specialists, the application will improve on its accuracy over time.

“It is important to identify stroke patients and help them get the urgent treatment they need,” said Dr Tang. “Prompt and accurate diagnosis is in the forefront of our minds when designing the medical application. Healthcare professionals should focus on what they do best and let us take care of the rest.”