For some years now, significant progress has been made in diagnosis, treatment and surveillance of cancer patients, especially with the spectacular developments in medical imaging. This medical speciality uses both irradiation techniques such as standard X-rays, CT-scanner, angiogram and fluoroscopy, and non-irradiation techniques such as ultrasound and nuclear magnetic resonance. Each of these imaging methods has its characteristics, benefits and drawbacks, which radiologists and clinicians know and choose depending on the clinical context, the organ to be imaged or the type of tumour to be assessed.
X-rays must be used carefully, as they can damage effect organs examined if misused. In this field, major technological progress has been made in recent years to improve quality of X-ray images produced and reduce X-ray exposure times. The immediate effect of this progress has been a dramatic reduction in the time taken to obtain an image, combined with access to high resolution (with great fineness of detail). As patients have to hold their breath during examinations, these improvements allow much larger areas than before to be examined, with reduced breath-holding time. This means that CT scanner, which use X-rays, can image an entire thorax in a matter of seconds with sections less than 1 mm thick. As recently as 10 years ago, 30 seconds were needed to image the same region with sections about 5 mm thick.
Non-irradiation imaging techniques also have advantages and drawbacks. Ultrasound is quite harmless, but image quality and diagnosis depend heavily on the experience of the doctor conducting the test. Magnetic resonance imaging (MRI), in contrast to ultrasound, produces global sections of the organ to be studied and makes examination of that organ easy. Images are also obtained at various levels, to point out certain irregularities. The major benefit of this technique, compared with the CT scan, which also produces images in sections, is that it clearly distinguishes certain tissues, such as fat. MRI can be used repeatedly with no danger to the patient. However, patients who carry magnetic devices, such as pacemakers or certain bone-fixing materials, cannot have this type of examination. It should also be remembered that it is quite expensive.
A new medical imaging technique known as PET-CT has recently been introduced. This is a scan that combines medical imaging techniques (the CT or X-ray) with positron emission tomography or PET. In just one examination, this new technology gives an idea of the function and morphology of various organs. It is a happy combination, which, thanks to images of outstanding accuracy, provides a better diagnosis of certain conditions. For more details on PET-CT, click here (link to PET-CT).
There are many different medical imaging techniques, each of which has benefits and drawbacks. All, however, help to diagnose cancer and plan specific courses of treatment according to the case.
The decision to use a specific radiological technique to arrive at a diagnosis depends on the type of cancer. The section of the body to be explored will determine the course of action taken. For example, to search for a lung tumour in a smoker, the pneumologist examines the patient and then requests a standard X-ray. If there is a problem, he will request a CT-scan in an effort to determine whether the tumour found is benign or malignant. The scan also reveals any associated problems, such as involvement of ganglia or a bone irregularity. In most cases, the radiologist requests a guided puncture using fluoroscopy, ultrasound, endoscopy or CT scan to determine the type of cancer to be treated. He will also specify an examination to determine the extent of the tumour, using different imaging methods.
OUR SPECIFIC AREAS
To provide the high level of skill and performance needed by the multidisciplinary team caring for our patients, we have a technical centre fully equipped with thoroughly modern apparatus. The imaging specialist group working in this unit is constantly learning, as knowledge and techniques are evolving very fast indeed. Our image archiving system, which contains the patient’s entire history, is also worthy of note. Comparisons can be made between pictures taken at various stages in the disease, for example, to assess effects of treatment.
For radiologists, as for all other medical specialists confronted with cancer, high levels of skill and a team spirit within a multidisciplinary team are essential prerequisites. All radiologists specialise in specific organs, of which they have an in-depth knowledge and to which they dedicate most of their working time.
OTHER CONTRIBUTIONS MADE BY RADIOLOGY
Data obtained from examinations carried out using MRI, CT-scan or PET-CT may be used for planning radiotherapy treatment. In fact, these examinations give an idea on the size and contours of the tumour and of involvement of ganglia. Radiotherapists can thus produce dose profiles in order to treat targeted tumours better.
Radiology can also be used as a means of radio frequency guidance, a technique involving introduction of a probe into affected organs with the aim of eradicating a tumour.