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SARAH HILGENBERG gave the 鈥渋nformed consent鈥� paperwork only a cursory read before she volunteered for a brain-imaging study in September 2002. She had just started as a medical student at Stanford University in California and was keen to help her new friend Matt, who needed a few more volunteers to have an MRI scan for his PhD on memory. She gave little thought to the warning that 鈥渙n occasion the investigator may notice a finding in a MRI scan that seems abnormal鈥�.

The first clue that something was wrong came when Matt asked her some odd questions. Was she having headaches? Any problems with her eyesight? A few hours later, an agitated Matt called her at home. 鈥淲e found something on your scan,鈥� he said. Hilgenberg was rushed in for tests, which revealed a knot of blood vessels called an arteriovenous malformation. It was a potential time bomb, putting her at risk of a brain haemorrhage. She was quickly scheduled for surgery.

Thankfully, the operation was successful, and today Hilgenberg is a paediatrics resident at the University of Washington in Seattle. Still, she wonders if the incident could have been better handled. 鈥淩eceiving the news over the phone was hard,鈥� she says. After consulting with a neurologist, Matt decided to bring Hilgenberg into the emergency room. But was a worried phone call the best approach? And what would he have done if the results had been more ambiguous?

Now there is a road map to help scientists and research volunteers negotiate this ethical minefield. In the latest (vol 36, p 219), a panel of bioethicists, lawyers and scientists suggest ways to manage such situations. Their recommendations include a guide on how to decide whether an 鈥渋ncidental finding鈥�, such as a brain abnormality, is serious enough to tell the volunteer about (see Table). They stress the importance of developing a plan to assess incidental findings and communicate them to volunteers, and the need to make this plan clear during the informed consent process 鈥� in which volunteers are made aware of the purpose of the study and any risks, and sign a form to that effect.

鈥淭his is the first major consensus statement on how to handle incidental findings,鈥� says , a specialist in health law at the University of Minnesota in Minneapolis, who led the panel.

It is a difficult issue to tackle. Research projects are not generally set up to diagnose disease, yet brain researchers are increasingly carrying out MRI scans as part of their studies 鈥� and they frequently discover abnormalities with medical implications (see 鈥淚ll-prepared to communicate bad news鈥�). Similar issues are likely to emerge in genetics research, where studies are now accumulating vast quantities of information from across each volunteer鈥檚 entire genome (see 鈥淓ditorial: Dilemmas posed by chance research results鈥�).

It would be straightforward if every case were like Hilgenberg鈥檚, with a clear and positive outcome. But they are often more complicated 鈥� as one anonymous neuroscientist revealed in 2005 in a letter to Nature (vol 434, p 17). Like Hilgenberg, he volunteered for an MRI study giving little thought to the consequences. The scan revealed a golf-ball-sized tumour, creating a huge dilemma.

The neuroscientist was told the tumour could be removed by surgery, but that there was a risk he would lose the ability to speak. At the time, his wife was expecting her first child, and the couple were applying for insurance to support the family should one of them lose their job though injury or disease. After some deliberation, he reported the scan results, and as a result lost the insurance policy. The neuroscientist was left facing an operation that might force him to leave his job, yet lacking loss-of-job insurance. 鈥淚 should have thought about the consequences of volunteering more thoroughly,鈥� he concluded.

Such cases are especially troubling, because doctors do not always know whether it is better to operate on a tumour identified on an MRI scan before any symptoms appear, or to wait and only plan surgery if the tumour starts causing problems.

Sometimes, abnormalities that show up in research MRI scans seem benign, but the volunteer is monitored, just to be on the safe side, which takes a financial and psychological toll. , a neuropsychiatrist at the Columbia College of Physicians and Surgeons in New York, had this experience with one of his research volunteers. More than six years later, she still has occasional MRI scans. 鈥淪he鈥檚 got to live with this worry of not knowing, and the cost and the hassle,鈥� Peterson says. 鈥淗ealth insurance often doesn鈥檛 cover it in full.鈥�

What鈥檚 more, many researchers are not trained to make clinical diagnoses, and work with information that is not optimised for the task. Research MRI scans, for instance, usually lack the definition needed for proper diagnosis. This is usually explained in the informed consent form, but volunteers do not always take this message on board. In 2006, and her colleagues at Stanford University surveyed more than 100 volunteers in MRI studies and found that 54 per cent of them expected the scans to detect abnormalities if they existed (Journal of Magnetic Resonance Imaging, vol 23, p 205).

Some MRI researchers ask neuroradiologists to review research scans that seem suspicious. And at the National Institutes of Health in Bethesda, Maryland, all MRI research volunteers are routinely given a clinical-grade scan. But this bumps up costs. Clinical scans cost around $1500, compared to about $500 for a research scan. And Illes, now at the University of British Columbia in Vancouver, Canada, argues that clinical scans are not appropriate for many labs because they blur the line between research and medicine, effectively expecting scientists to have the same duty of care as doctors.

Given these complex ethical issues, Wolf accepts that her team鈥檚 recommendations will not be the final word. According to Illes, who helped write the guidelines, the priority for now should be to improve the informed consent process, so that volunteers clearly understand that research projects cannot be expected to deliver clinical diagnoses.

With the current ambiguity, some lawyers see an opportunity to pursue researchers for damages. 鈥淚 maintain that MRI is a medical procedure,鈥� says , an attorney who handles bioethics cases at Sherman, Silverstein, Kohl, Rose & Podolsky in Pennsauken, New Jersey. 鈥淭he poor, uneducated mother of a child is going to see someone in a white coat and they will expect care that is rendered conforming to standards of using that machine.鈥�

Milstein argues that researchers who do brain imaging and fail to spot health problems in their volunteers could face substantial liability. He also raises the hypothetical case of a child who is found to have a brain tumour on a research scan but whose family cannot afford the operation needed to remove it. 鈥淭here is a moral and an ethical obligation to care for that child,鈥� claims Milstein, who says he would be prepared to sue the researchers to make them pay.

鈥淲hat do you do with a child found to have a brain tumour on a research scan whose family cannot afford treatment?鈥�

The Human Brain 鈥� With one hundred billion nerve cells, the complexity is mind-boggling. Learn more in our cutting edge special report.