Medical imaging is certainly one of the areas that has advanced the most in the past twenty years. These recent discoveries allow for better diagnosis and facilitate the surgeon’s intervention. All procedures can usually be carried out within one week. Their interpretations are available to the specialist the day after their production.
Standard radiographs enable the visualization of traumatic bone lesions (dislocations, fractures), degenerative lesions (arthritis), calcifications of soft tissues, or the presence of radio-opaque foreign bodies. They showcase the importance of the displacement of a fracture, its articular extension, and the quality of the surgical correction (reduction). Wrist and left-hand x-rays can be used to estimate a child’s age. The overlapping bones, their three-dimensional structures, and sometimes the late appearance of fracture lines (especially in the scaphoid) explain that some fractures may not be visible initially. The side effects of X-rays are well established. The radiologist will ensure that the request for examination is duly justified and that the doses of radiation delivered are as low as possible, and with the protection of the areas not radiographed (using a lead apron). Periodic control of the radiological installations is provided for by law. Standard radiography takes about 5 minutes to complete.
An Ultrasound is an imaging technique based on, as the name suggests, an ultrasound. A probe ensures its emission and reception. Ultrasounds provide a detailed analysis of muscles, tendons, ligaments, and peripheral nerves (in addition to the standard X-ray assessment). This exam is painless, harmless, and can be repeated without problems. The measurements and quality of the images depend on the skill and competence of the radiologist. The duration of the exam ranges from 10 to 15 minutes.
The scanner uses the property of X-rays to be absorbed differently depending on the tissue they pass through. The patient is placed on a table which moves longitudinally through a ring comprising the X-ray tubes. The information obtained is stored sequentially in a computer: it allows, through complex mathematical calculations, reconstructions that ensure the formation of images. The scanner ensures the visualization of all the deep elements of the organism which are difficult to access with standard x-rays or ultrasounds. It allows the search for fractures, to assess the extent or degree of consolidation. It is particularly useful for analyzing bone and can be performed with a plaster. It requires the patient’s participation: he must be able to stop on the table for ten seconds. In the absence of the injection of contrast agents, there is no reason to be fasting. If the patient is pregnant, the justification (indication) of the examination and its benefit/risk ratio must be carefully evaluated. The fetus is particularly sensitive to radiation.
Magnetic resonance imaging (MRI) is an imaging technique used to obtain internal views of the wrist or fingers non-invasively with a relatively high resolution. The search for contraindications to MRI (claustrophobia, pacemaker, ventriculoperitoneal drains, and other devices sensitive to magnetic fields) is systematic. The presence of osteosynthesis material is not in itself a contraindication but is likely to potentially limit the quality of the images due to the production of artifacts. Avoid using MRI with pregnant women. The patient is placed in a mini-tunnel where a magnetic field prevails. The acquisition of images requires between 20 to 30 minutes depending on the pathologies considered. The tunnel producing the magnetic field is of variable size: depending on the organ to be explored, only limited portions of the body can be positioned within it. MRI is particularly useful for analyzing joints and soft tissue (tendons, nerves, synovium, etc.) and for finding or taking stock of tumors or other masses of soft tissue.
Sometimes, it is necessary to inject a contrast agent into a joint to identify the causes of dysfunction. The joint is thus distended: osteochondral lesions or intra-articular foreign bodies can be discovered. The leakage of contrast media may be indicative of a ligament rupture. Before the examination, the radiologist will check that the patient has not suffered from an allergic reaction to the injection of a radiological contrast medium in the past. The arthrography is performed in a codified and sequential manner. After disinfecting the periarticular area to be explored, the radiologist doctor instills the contrast product in the area (s) of interest- The positioning of the intra-articular puncture needle is done under radiological control. The whole process takes between 5 to 10 minutes. The injected product will fill the joint and mold the bone surfaces. When injecting, you may feel localized heat or a feeling of swelling. These effects are transient and disappear quickly. Once the injection has been performed, the doctor acquires the images either by MRI or by scanner depending on the structures to be explored (soft tissue, bone tissue, cartilage cover, etc.). Complications are rare (1 / 100,000): intraarticular bleeding and secondary infection are the main, the second being the most feared. Everything is being done, particularly in terms of asepsis, in order to limit the risk of it occurring.
This is an examination that uses nuclear medicine techniques (an injection of radioactive isotopes) to assess the bone metabolism of the entire skeleton. It is an additional examination for the search for bone diseases: fractures, joint diseases, sportsmen’s pathologies (cracks, periostitis), algodystrophy (Südek), bone infection, primary or secondary bone tumors. It is not necessary to be fasting. The examination takes place in two parts: First, an intravenous injection of the radioactive isotope is carried out (duration: 15 minutes). After the injection, the patient should drink 1 liter of water and go to urinate to facilitate the fixation of the product on the bone and its elimination by the kidneys. Three hours after the injection, the second part of the exam begins. It consists of placing the patient comfortably on the examination table (Gamma camera), which must remain immobile during the acquisition of the images (lasts 40 minutes).
Jaroslava Toman, MD
Service de Radiologie de l’Hôpital de la Tour