Medical imaging is used for many purposes including diagnosis, treatment and the planning of treatment. At the London Gastroenterology Centre, we are always keeping our eyes open for new ways of imaging. After all, if you are having an a private endoscopy in London or a colonoscopy, it is good to know that the specialists are keeping up to date with the latest developments!
Why Use Imaging At All?
An emerging area involves using different imaging modalities to help predict how an individual will respond to a particular therapy. PET (positron emission tomography) scanners can be used, for example, to help differentiate between benign (slow growing and relatively harmless) and malignant (rapidly growing, potentially fatal) tumours. This is done by estimating the total amount of radio-glucose taken up by these tumours. Radio-glucose is effectively a sugar molecule labelled with a radioactive substance. The reason for labelling the sugar is so that it can be detected by the PET scanner. The medical name for this special sugar is flurodeoxyglucose, more commonly abbreviated to FDG. FDG uptake correlates well with the amount of activity within the tumour, as more active tissues require more sugar (and hence take up more FDG). Malignant tumours are faster-growing than benign tumours and so their rate of FDG uptake will be higher, and this can be visualised using medical imaging. This technique has been successfully used to help differentiate benign tumours in several medical conditions including the genetic condition neurofibromatosis, and a type of lung cancer called non-small cell lung cancer (NSCLC).
A main advantage to this type of medical imaging is that it is non-invasive. It is still common practice to extract samples of the tumour by means of surgery prior to laboratory analysis. This procedure is not very pleasant for the patient and is very time consuming. Imaging, on the other hand, is a non-invasive and safe way of extracting this information.
Radiomics, A New Way to Analyse Images
More recently, a field called radiomics has been trying to determine how easy it is to predict the likely success of a particular therapy on the basis of heterogeneity of the tumour. In simple terms, heterogeneity refers to how much difference there is between the cells that make up the tumour. Imagine a ball pond with 1000 balls of varying colours. If the ball pond had 1000 balls, all of which were coloured blue, there would be no heterogeneity as all the balls are the same colour (and shape, weight etc…). If, on the other hand we had 100 blue balls, 100 red balls, 100 green balls, 100 orange balls…then the heterogeneity of the sample would be large as the characteristic features of the balls vary.
A similar outlook can be used to determine the heterogeneity of a tumour. Tumours are composed of basic building blocks called cells, which have an enormous number of properties, including size, blood flow and rate of sugar usage. It has been shown in a number of scientific studies that as the heterogeneity of the tumour increases, the aggressiveness of the tumour increases too. With this knowledge it may be possible to prescribe different treatments to different patients, on the basis of how aggressive their tumour is. The ultimate aim of this is to ensure all patients are given a treatment that will deal appropriately with their tumour. It is hoped that choosing different drugs for different patients will minimise the chance of therapy resistance, and maximise the chance of successful treatment.
Extracting more information from the images we already collect is an important and exciting goal. Radiomics is one way in which we can now start to do this.
