Current and future advances in medical imaging
What do you think of when someone mentions the terms ‘medical imaging’ and ‘radiology’? The first words you will think of are X-ray and CT scan. You will be right, but only partially. Because since its appearance at the beginning of the 20th century, medical radiology has diversified and become more complex with new techniques such as ultrasound and MRI.
Our society is becoming more and more technological with progress that is no longer counted in decades but in years and sometimes even in months. Everything is going fast, very fast sometimes, and the world of medical imaging is not spared.
Whether it is in the field of cell phones, computers or game consoles, it is very difficult to keep up with the exponential curve of the various developments. This is also the case in the field of medical imaging where each year new developments appear.
The progress observed currently (but also during the last few years) in the field of medical imaging is largely linked to Moore’s law which, without being a real physical law, describes the doubling of computer power every 18 to 24 months.
Thus, in recent years, the various techniques in radiology have improved significantly by offering increasingly precise and rapid examinations.
If we take for example the latest CT or MRI (Nuclear Magnetic Resonance) machines, we now have the possibility to make images of our organs with a resolution of less than a millimeter. We can also obtain 3D images that will help surgeons visualize the tissues to be operated on and even in some cases build 3D models of organs with 3D printers that will be used to simulate future operations.
Another important advance in the last few years concerns the world of ultrasound. Forget about the huge devices you may have seen at your doctor’s office. The current trend is towards portability and miniaturization. As a result, more and more doctors (specialists and non-specialists alike) can purchase a portable ultrasound machine and link it to their smartphone to perform their imaging exam. Obviously, the results are a little less good than the images obtained with large devices but this is only the beginning of the revolution. Within 5 to 10 years, these devices will be in the pocket of doctors and will (probably) replace their famous stethoscope. This advantage is undeniable in poor countries that cannot afford large ultrasound and imaging equipment.
In addition to this miniaturization, another technology that has already started to invade our everyday life is artificial intelligence. Under this esoteric name are software and other algorithms that allow, for example, vehicles to drive without a driver, or that, based on your food choices or your distractions, will suggest new ideas for meals or movies and series.
These artificial intelligence algorithms are slowly beginning to invade medical imaging equipment and will eventually improve the performance of current examinations and especially the interpretation of images by radiologists. The latest scientific publications show that these artificial intelligence software can in some cases provide precise assistance to the human being and even highlight anomalies that would have remained invisible to the human eye.
All of these tests are part of medical imaging. CT and MRI belong to radiology and PET-Scan belongs to the field of nuclear medicine.
CT scan and MRI allow the visualization of the structure of the tissues and organs (structural imaging), whereas the PET scan is a functional imaging technique that studies the functioning of the tissues.
The scanner uses X-rays (same as for radiography) and MRI does not use any ionizing radiation but a strong magnetic field. The PET-Scan examination uses radioactive tracers that must be injected intravenously into the patient’s body. These tracers emit gamma rays which are then ‘captured’ by the machine in order to give the final images which are interpreted by the doctor.
It is all a question of examinations and dosage. First of all, we need to talk about the so-called ‘non-ionizing’ imaging examinations such as MRI or ultrasound. These examinations are not harmful to the body. Then we have the examinations that are ionizing and that use either X-rays (CT scan) or gamma rays (scintigraphy and PET scan). In practice, these examinations are not dangerous for your health. However, it is recommended not to abuse this type of examination which, in the long run, could lead to an increased risk of cancer. For this reason, many countries have introduced a kind of radiological passport that takes into account all the imaging examinations and that makes it possible to know at a glance the number of examinations carried out on a patient and over what period of time these examinations are performed.
Before describing these examinations, it is important to remember what ionizing radiation is. Certain types of radiation that belong to the electromagnetic spectrum can interact with the electrons in atoms. If case of interaction, these rays can modify the structure of the atom and possibly cause molecular anomalies (DNA). Fortunately, our body has a whole system of defense and repair to counteract these molecular changes.
Not all imaging examinations are ionizing. The main examination that uses ionizing radiation is the X-ray scanner (CT-Scan). The most recent machines make it possible to considerably reduce the dose of X-rays used for an similar or even better result (low-dose CT). PET-Scan also uses gamma rays which are ionizing. The latest machines also make it possible to reduce the dose of radioactive tracers administered to patients.