CT arthrography is an X-ray imaging test that allows the study of joint structures invisible to x-rays. It is thus used to diagnose certain joint lesions or to better highlight them before surgery.
What is an arthroscopy?
CT arthrography is an X-ray radiological examination which allows you to better see the intra- and para-articular structures (cartilage, ligaments, tendons, menisci, etc.) than with a conventional
CT arthrography is the combination of arthrography and a scanner. Arthrography consists of the intra-articular injection of an iodinated contrast product. The scanner uses X-rays to produce contiguous cross-sectional images of the joint, allowing reconstructions in three dimensions of space and in volume mode. “The iodized product will mold the structures of the joint and thus increase the differences in density and contrast between the different anatomical tissues on the CT sections obtained.explains Dr Yannick Carrillon, radiologist.
“In Europe, CT arthrography is a widely used examination, particularly before surgery. We can also speak of French specificity, because this technique is opposed to that more used in other countries: MRI arthrography. This technique is the same, except that gadolinium salts are injected instead of iodine and an MRI is performed instead of a CT scan.reports the specialist.
MRI arthrography has the advantage of not irradiating the patient and has a higher natural contrast than CT arthrography. On the other hand, to analyze cartilage lesions, CT arthrography is superior to MRI arthrography, explains Dr. Carrillon. “The arthrography scanner is particularly efficient because it provides very good resolution, and moreover, the examination lasts approximately two seconds, the patient does not move, whereas an arthrography MRI takes place over three to four minutes that can create motion artifacts. With the arthrography scanner, the image is therefore clearer.”
Why do an arthroscopy?
“CT arthrography is generally used as a third intention, after radiography, ultrasound, or even MRI. The goal is then to complete a diagnosis, by looking for lesions that are not seen on radio or MRI. ‘IRM’, underlines Dr Yannick Carrillon.
Regarding the joints, the indications for CT arthrography vary depending on the area to be explored. The rest with Dr. Carrillon:
- Shoulder arthroscopy has two main indications. The first is a rotator cuff tear. “The contrast product highlights the ruptures and their importance, thus allowing them to be better defined than MRI. Preoperatively, an arthroscopy is often performed. The second indication concerns instabilities, or dislocations. “The arthrography scan allows this time to highlight the lesions of the humerus and the scapula, called transitional lesions, and to make a more precise diagnosis, particularly with regard to the state of the cartilage, which is not possible. always show the x-rays”;
- Arthroscopy of the elbow allows you to explore the ligaments after a sprain. It is mainly used to explore possible osteoarthritis (wear of the cartilage). “We also look for intra-articular foreign bodies, because elbow osteoarthritis, in certain people, is not seen very well with x-rays”;
- Arthroscopy of the wrist allows, in the event of instability, to see damage to the ligaments and cartilage. “The wrist ligaments are extremely thin and difficult to observe with other imaging devices”;
- Arthroscopy of the hip is used to look for signs of femoroacetabular impingement, which could be the cause of early osteoarthritis of the hip in athletes, even amateurs, or in people who have hips that are a little too big in relation to the pelvis. , describes the specialist: “We will look for lesions in the cartilage that surrounds the hip, called the acetabular rim.. This is pre-osteoarthritis. Osteoarthritis is visible on the x-ray;
- Arthroscopy of the knee most often makes it possible to better describe meniscal lesions and cartilage lesions. It also makes it possible to detect possible intra-articular cartilaginous foreign bodies, or secondary osteochondromatosis, linked to the release of cartilage due to osteoarthritic wear. Primary osteochondromatosis concerns a disease of the synovial membrane which forms cartilaginous fragments;
- Ankle arthroscopy allows you to better observe the ligaments, but also the cartilage. “In these two indications, we also seek to know whether the cartilage lesion is mobile or not. If she is, she has chronic pain which may be an indication for surgery.”
Let us add that the arthroscopy is also used to inject at the same time, combined with iodine, an anti-inflammatory steroid (corticosteroid) directly in situ, that is to say in the painful joint. “In this case we are talking about arthrography with infiltration, specifies Dr. Carrillon. As soon as the patient is in pain, and before even knowing what the examination will reveal, we inject them with corticosteroids, which avoids having to give a second injection. Which also limits the risk of infection.
Finally, it should be noted that CT arthrography does not make it possible to diagnose all periarticular pathologies, in particular it does not allow the analysis of tendons and is less precise for ligaments than MRI.
How is an arthroscopy performed?
An arthroscopy takes place in 2 stages and in 2 locations.
- The first step consists of injecting the iodized contrast product, under fluoroscopic control, to precisely target the area to be explored. This therefore most often happens in the radiology room, where the patient lies on a table. “The patient’s skin, which corresponds to the area to be examined, is disinfected. Intra-articular contrast material is injected. Once the needle is removed, the patient’s joint is mobilized so that the iodine is distributed throughout the joint., describes Dr. Carrillon. It is not necessary to perform local anesthesia. It is not painful, assures the radiologist. On the other hand, as indicated previously, iodine can be coupled with an anti-inflammatory;
- The second stage takes the patient to the scanner room. The examination is very quick, around half a minute, the time for the X-rays to scan the area explored. “For the shoulder, we do two shoulder rotations, one external, the other internal. And for the other joints, we only do one pass”adds our interlocutor.
Allow a total of between 15 and 20 minutes for an arthroscopy.
What preparation?
This question applies especially in cases of allergy to iodine. “In this case there are two options, report to Dr Carrillon. Either we do not do an arthrography scan, or we prescribe the patient antihistamine medications or even corticosteroids beforehand.”
Another potentially problematic situation: a patient being treated for an infection, particularly ENT. It is then preferable to wait until it is cured before performing CT arthrography.
Remember that the iodine injection is given into the joint, not into the veins. People on anticoagulants do not have to temporarily stop their treatment, and prevention for people with kidney failure is no longer valid. But as it should be, before any examination, the patient is asked to indicate the pathologies for which he is possibly being treated. Same precaution if the person is pregnant.
If the origin of the pain is traumatic, Dr Carrillon does not recommend doing an arthroscopy at the acute stage of the accident: “The patient has a hematoma, it is very painful and therefore difficult to move..
For the rest, the person does not need to fast. And if to date, for the scan, the patient must purchase the contrast product themselves, from April 2024, the radiology centers will be responsible for providing it. “This will simplify the patient’s life and make us responsible for the product that is injected (batch number, origin, etc.), but the examination will cost a little more.”, summarizes the radiologist. However, you must bring your previous imaging shots and the medical prescription.
What about the results?
Once the arthrography scan is completed, the radiologist examines and analyzes the 3D images obtained. Good practice dictates that he then talks with the patient and explains to him what the images revealed, in short that he comments on them with him.
CT arthrography is often an opportunity to correct a diagnosis and therefore redirect treatment.
Then, a report with images is given to the person.
What recommendations afterwards?
Following a CT arthrogram with corticosteroid infiltration, the patient is asked to remain quiet for 48 hours: no physiotherapy, no gardening, no physical activity, etc.
In the case of CT arthrography without infiltration, the patient is asked to remain somewhat calm for a few hours, while the iodine is evacuated. “This is equivalent to two or three hours, no more,” specifies the radiologist. “Take advantage of this time to drink a lot. Likewise, in the event of an arthroscopy of the ankle, which is a small joint, the patient may experience temporary mobility difficulties, which disappear quickly.reassures Dr Yannick Carrillon.
Finally, watch for any bouts of fever in the days that follow or redness at the injection site, which could be early signs of an infection.