Putting patients in the picture

The ability to look inside the human body revolutionised medical science over 100 years ago. However, standard imaging techniques like X-ray and MR (magnetic resonance) imaging don’t always give us the true picture.

Historically, the biggest problem has been comparing images taken at different times to see how symptoms are changing. Despite efforts to immobilise patients it has remained almost impossible to be certain whether tiny changes between images are due to actual physical changes or to the patient being in a slightly different position when the image is taken.

This could be set to change thanks to a computer-based image processing technique undergoing trials at Hammersmith hospital in London.

The software used was developed in-house from existing analytical software and interpolation programs and, according to Graeme Bydder (Professor of Radiology at the hospital) is “slow but flexible..”.

Using rigid body translations and rotations, sinc interpolation and iterative chi squared tests, the technique shows up changes between successive MR images of less than a hundredth of a millimetre in each of the three dimensions.

At Hammersmith, the technique has already been used on a number of patients with a variety of medical conditions (including Alzheimers and MS) and has proved particularly useful in the treatment of brain tumours. It has always been a puzzle that a significant number of patients who initially show a positive response to radiotherapy and chemotherapy, then relapse. MR imaging has shown, clearly and rapidly, situations in which some parts of the tumour are not responding.

Whilst the associated software is not yet commercially available, Professor Bydder believes that taking and comparing a series of images in this way will soon become routine clinical procedure.