Brain injury scanning – the controversy

Neuroimaging has been critical in the diagnosis of brain injuries for the purposes of personal injury claims for many years. Expert neuroradiologists and neurologists have relied both upon the results of initial CT (computer tomography) scans and conventional MRI (magnetic resonance imaging) scans immediately post-accident and beyond. The use of these scans is not controversial and is often used together with other evidence including accident circumstances, claimant’s reporting of symptoms, medical history, neuropsychological testing, knowledge of any psychiatric injury and Glasgow Coma Score, to assess the severity of a brain injury.

Explaining the different scanning techniques 

A CT brain scan is a diagnostic imaging procedure that uses x-rays to create detailed cross-sectional images of the brain. CT scans are readily available at most A&E departments, quick to use, relatively cheap and help to triage the claimant when they first appear at hospital. Traditional MRI scans use strong magnetic field and radio waves to create detailed images of the brain and brainstem. They are less readily available and require specialist equipment. An MRI scan is not available in every hospital, takes longer and is not suitable for some patients depending on their medical history.  A 3T MRI brain scan generally offers a better image quality and is quicker than a 1.5T MRI brain scan. However, 3T MRI scans are a higher cost to the NHS so are not available everywhere, but certainly it is accepted that the 3T scans are more sensitive.

DTI (diffuse tensor imaging) scanning is an improved version of conventional MRI where the signals are solely generated from the movement of water molecules as they move along the brain’s neural pathways. A DTI brain scan is non-invasive and takes between 1-2 hours. They are not routinely used within the NHS for the diagnosis and treatment of brain injuries. DTI scanning has been around since the 1990s and in recent years they have been used in personal injury claims by neuroradiologists and neurologists predominantly instructed by claimants in mild or subtle brain injury claims. Claimants will argue the microscopic changes to the brain prove a traumatic brain injury, where the traditional scans have not detected a change and as such explain on-going neuropsychological symptoms. In some cases, DTI scanning has been used as a stand-alone biomarker for advancing the argument that the claimant has suffered a traumatic brain injury in an accident and is the only objective evidence available.

Understanding the current state of DTI technology and its limitations is key to evaluating the usefulness of the DTI scan results in personal injury claims and the need to challenge the reliance on such scans. The use of DTI scanning in personal injury claims remains extremely controversial. The scan is very sensitive and will identify all microscopic changes to the brain since birth. Every person’s brain will look different on a DTI scanner regardless of whether they have been involved in an accident. Imaging will be different based on factors including age, sex, whether they are dominant in their right or left hand and medical history. A 30-year-old woman’s brain will look remarkably different to a 50-year-old man’s brain. Microscopic changes to the brain are normal. Whilst the DTI scan may correctly identify microscopic changes to the brain, the scan crucially cannot establish when those microscopic changes occurred and whether it can be linked to sustaining brain damage.  

There have been very few clinical studies and data is extremely limited. It is quite clear that there has not been enough research to say with any degree of certainty that any microscopic changes on a particular claimant’s brain are accident related or not. The scan results should not be relied upon by the court to establish a traumatic brain injury on the balance of probabilities in the absence of other objective evidence. It is critical that defendants robustly object to the use of DTI scanners if mooted in a personal injury claim and that if produced, obtain their own objective analysis of the DTI scan results from an expert neuroradiologist and neurologist. It is crucial that the DTI scan evidence is analysed against other available evidence including Glasgow Coma Score, details of the accident circumstances, medical history, medical records, claimant’s self-reporting, neuropsychological test results and other factors including whether there has been a psychiatric injury that could account for the on-going symptoms. Thus, at best, the results of the DTI scan, are one small piece in a large jigsaw of evidence. What is clear is that the DTI scan results certainly should not be produced as evidence alone of any brain injury as a result of an accident.