CT foot is a method of radiation examination that allows to diagnose pathological changes in the anatomical structures that form the foot. It makes it possible to visualize the distal parts of the tibia and fibula; the tarsal (talus, calcaneus, navicular, cuboid and three wedge-shaped) and metatarsal bones; the phalanges of the fingers; the ankle joint and all regional bone joints. With the help of CT foot, traumatic injuries, dislocations of fragments and articular surfaces, inflammatory and dystrophic diseases, developmental anomalies, blood accumulations, pus can be determined. It is usually carried out natively, less often – with contrast enhancement.
Indications for CT foot are injuries, after which there is pronounced pain with axial load, movement or at rest, edema, hematomas, pathological mobility or bone crepitation; suspicion of penetration of radionegative foreign bodies; deformation of the foot and ankle joint; the appearance of neoplasms of uncertain etiology. Diseases that may require diagnosis include deforming osteoarthritis, gout, rheumatic arthritis, osteomyelitis, chronic and recurrent dislocations, X-ray negative fractures. To a lesser extent, this study is used to diagnose ligament and tendon injuries.
CT is also used to determine the tactics of surgical treatment and evaluate its effectiveness in the postoperative period; to monitor the condition of tissues in patients with autoimmune diseases, including against the background of a course of pharmacotherapy. CT with contrast enhancement may be required for differential diagnosis between benign and malignant tumors; with the development of dystrophic phenomena on the skin (hair loss, nails, pathological dryness), the formation of trophic ulcers that do not heal for a long time. The use of intravenous contrast makes it possible to detect damage to large vessels, internal hematomas in the tissues of the foot, hemarthrosis, etc.
CT foot is contraindicated in the following groups of patients: pregnant women due to the detrimental effect of X-rays on the fetus; preschool children. Diagnosis is not carried out for mental illnesses accompanied by increased motor activity, with severe pain syndrome and fear of confined space – persons of this category are not able to maintain the static position necessary for the study. In patients in critical condition or with severe cardiovascular insufficiency, computed tomography prevents continuous monitoring of hemodynamics and resuscitation measures. Pronounced obesity also serves as a relative contraindication to CT – most modern tomographs are able to withstand the patient’s weight up to 140-160 kg.
Contrast enhancement is not carried out with individual intolerance to iodine preparations or a burdened allergic history in relation to X-ray contrast preparations – these circumstances indicate the risk of anaphylactic reactions. Since most of the contrast agents used are metabolized and excreted by the liver and kidneys, the study is contraindicated in severe hepatic and renal insufficiency. In diabetes mellitus, iodine-dependent thyroid diseases, myeloma, contrast can cause their decompensation or severe metabolic disorders. After undergoing CT, nursing mothers are recommended to refrain from breastfeeding for the next 1-2 days.
Native research does not require prior preparation of the patient. If CT foot needs to be supplemented with contrast enhancement, then it is necessary to observe fasting 4-6 hours before the study, conduct a test for sensitivity to the injected drug, assess the excretory function of the kidneys (measurement of creatinine and blood urea, calculation of GFR) and the state of the liver (AlAT, AsAT, total bilirubin and its fractions). Immediately before the start of the study, the radiologist conducts a conversation, during which he finds out the complaints and the preliminary diagnosis of the patient; the presence of metal structures in the body (plates, spitz, screws); previously transferred operations in the study area.
Methodology of conducting
The patient is taken to the locker room, where it is necessary to change into a special robe and take off all jewelry and wearable metal objects. After that, the patient proceeds to a CT scan. Most devices have the form of a ring or tunnel with a horizontal couch for the patient, which is located in the center of the hole. For CT, the patient lies down on this couch, receives a brief briefing from a radiologist, after which the examined area is placed inside the scanner. The duration of the procedure, as a rule, is several minutes. The patient does not need to perform any actions during the study – it is only necessary to maintain a stationary position.
Native research is not accompanied by physical sensations. Most CT scanners emit clicks or a soft hum when scanning. Performing a CT scan foot with contrast can cause dizziness, mild nausea and general weakness. In some patients, these phenomena persist after the study. In such cases, it is not necessary to take any action – unpleasant symptoms go away on their own after a few hours. Tomography does not cause any other complications or adverse reactions.
Interpretation of results
Preparation of research materials can take from several hours to 1 day. As the results of the study, the patient may be given a paper report of a radiodiagnostic doctor, which includes a detailed description of all identified pathological changes and an X-ray diagnosis; images printed on film and recorded on a CD. By prior arrangement, all CT results of the foot can be sent to the e-mail of the patient or the attending specialist. Diagnostic data may indicate the following pathologies:
- fractures and fractures of bones (violation of structural integrity, formation of bone fragments and their displacement);
- complete and incomplete dislocations (displacement of articular surfaces relative to each other of varying degrees);
- deforming osteoarthritis, rheumatism, gout (deformity of the articular gap, osteoporosis);
- osteomyelitis (sequestration, pathological fractures);
- hematomas and abscesses (accumulations of blood or purulent masses).
Also, this study makes it possible to diagnose anomalies in the development of the bones of the foot and the foreign bodies present, including determining the nature of the object and its localization. Additional contrast enhancement during CT foot allows for differential diagnosis between benign neoplasms and cancerous tumors.