In HD research, imaging is useful in two ways: Firstly, it can help understand what goes wrong in the brain when somebody develops symptoms of HD. This knowledge can help foresee for example cognitive or motor problems before they become apparent in clinical examinations. Secondly, imaging has been shown to be a useful biomarker to measure progression of HD. Such biomarkers are critical in the preparation of clinical trials. For HD, a predictive genetic test can be used to confirm the presence of the HD gene mutation before any clinical signs of disease onset. Imaging studies have shown that a degenerative process takes place in the brain during the pre-symptomatic phase. Therefore, any treatment is likely to be most beneficial during this phase. Imaging is helpful to evaluate the efficacy of such treatments, as it can show a slowing of degeneration when clinical markers are absent.
The Imaging Working Group aims to explore the usefulness of imaging techniques, specifically MRI (magnetic resonance imaging) and PET (positron emission tomography), as non-invasive tools to track progression of the disease in symptomatic and pre-symptomatic HD gene carriers. It acts as a platform to facilitate research by providing technical expertise and analysis methods. Furthermore, a centralised collection of imaging data from several centres allows more meaningful comparative studies.
Currently, the Imaging Working Group is developing a multi-centre study using diffusion-weighted imaging. This technique targets the white matter, which contains connections between different parts of the brain. Preliminary findings from a single-centre study have shown that the white matter is particularly affected in HD.
HD gene carriers and controls are eligible to participate in the local and EHDN-wide imaging studies. If you are interested, please contact the working group lead facilitator or your local HD imaging centre. Study participants are examined at the local imaging sites, where imaging data is acquired using a brain MRI scanner. This machine employs a strong magnetic field but does not emit any harmful radiation. Because of the magnetic field, it is important that you do not have any metal pieces in or on your body. People who have a pacemaker are therefore excluded from imaging studies. The frequency of the visits varies greatly. Most local projects include a single visit to the local centre, whereas EHDN-wide projects usually require annual follow-up visits. Data collected from all local studies will be handled according to regulations from the local ethics committee. Any data shared between imaging centres is coded anonymously.
Imaging Working Group has approximately 30 members (June 2008), with a
high number of affiliated members from the PREDICT-HD Group. The ideal
member should have a strong interest in imaging. Imaging and/or
clinical expertise are desired but not a prerequisite. The working
group meets once or twice a year.