Computers in Imaging
Acquisition systems produce digital data that is converted to images and ultimately viewed by radiologists and surgeons. Present throughout this chain are computers, not just as convenient tools for storage, workflow and display, but also in the control of the scanning, the alignment of images, detection of different tissue types, calculation of quantitative measures, generation of new images such as maps of active regions in the brain and surgical guidance. Increasingly the hardware of scanners is under software control and we have the opportunity to produce algorithms that will intelligently enhance the image acquisition by responding in real time to patient data.
A key tool for generating new information is image registration, a field in which the UK has been very active in research. Registration algorithms compute the transformation needed to align, or warp, one image into another. With the ability to align images, comparisons between images taken on different days can reveal small changes in tissue size, for example the slow shrinkage of the brain over many years due to dementia. Finding the transformation from one image to another can be used to measure motion, for example a cine series of cardiac images can show abnormalities in heart wall motion due to tissue damaged by a heart attack. In another application of registration, images from different patients are aligned into one common space. A representative image or atlas can then be computed, against which new patients can be compared. Registration is used in the fusion of data from different scanners leading to enhanced understanding, for example, a PET image is sensitive to the uptake of glucose by tumours and an MRI image can show other anatomy in detail - combining the two provides a richer source of information to guide patient care.The UK is especially active in research into the workings and connectivity of the brain. Brain activity and thoughts cause changes in blood flow and oxygenation that show up as subtle differences in MRI scans. After computer processing involving registration, segmentation of relevant structures and statistical analysis, maps can be made revealing brain regions that are active during various tasks. These scans and processing are called functional MRI. Diffusion weighted MRI provides an image contrast that is sensitive to cellular architecture. Using this technique, we can now infer the directions of fibre bundles within the brain; for example, we can see how the spinal column is connected to the motor cortex.) In addition to enhancing our fundamental understanding, this research has the potential to guide brain surgery in order to avoid severing crucial nerve connections.
Imaging in clinical trialsDrug discovery and development can bring major advances in the treatment and management of disease. The costs from discovery to launch of a successful drug are estimated to be in the region of £1 billion when failures of other drugs are factored in. There is a big incentive to gauge the effectiveness of a trial drug early. In studies of dementia such as Alzheimer’s, disease progression can take decades and computing and imaging techniques are being developed to quantify small changes in brain volume early in a trial to predict outcome. This use of images to indicate underlying biology is termed “biomarkers” and can save time by halting trials early. The endpoint of a standard clinical trial may require waiting decades to observe complete disease progression, there is hope that imaging might act as a surrogate endpoint whereby a drug can be assessed more quickly thus saving money and enabling the drug to be made available sooner.
Thriving IndustryUniversity research groups have started to spin-out companies to market algorithms and services for medical imaging. The university origins and links of these companies benefit Postgraduates. Examples include Siemens Molecular Imaging (formerly Mirada) in Oxford, iMorphics in Manchester and IXICO in London. PhD and MSc projects are also sponsored by companies such as Vision RT who are experts in real time 3D surface imaging for radiotherapy applications, Kodak who are involved in the whole imaging chain, DePuy who develop surgical technology, the Wellcome Trust and the major medical equipment manufacturers such as Philips, Siemens and GE Healthcare. Many of the global pharmaceutical and healthcare companies have research sites in the UK. Notably, a new £76 million Clinical Imaging Centre is under construction as a joint venture between GlaxoSmithKline and Imperial College to use imaging in drug discovery and development.
In 2007, UCL plans to start an MSc dedicated to Medical Image Computing. The course can be taken full or part time and scholarships are available to some students.
The UK Engineering and Physical Sciences Research Council recognised the strength of medical imaging by funding a six-year project that now links Imperial College London, Kings College London, Manchester, Oxford and UCL. These groups, and others in the country, provide opportunities for obtaining a PhD in medical image computing. A bi-annual summer school brings together an international teaching faculty to provide lectures and workshops for Postgraduates studying in the UK and overseas.
Within the UK, university research in medical image computing is well-funded, industrial activity ranges from start-up companies to global pharmaceutical organisations and there is substantial investment by the government in the healthcare sector. This creates a healthy environment for Postgraduate study and research and in a subject that brings together computing, medicine, healthcare, biology, maths, engineering and physics for applications that benefit healthcare and well-being.
|David Atkinson is a lecturer in the Centre for Medical Image Computing at University College London. Since 1996 he has been researching novel algorithms to improve magnetic resonance images. He is currently preparing a new MSc in Medical Image Computing at UCL for launch in 2007.|