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Magnetic resonance imaging (MRI) is one of the diagnostic examination procedures that provides detailing of the internal structures of the body without the use of radiation. The MRI method is based on measuring the electromagnetic response of the nuclei of hydrogen atoms when excited by electromagnetic waves in a constant magnetic field of high intensity and is a painless procedure.
Characteristics of the research method
Modern technologies used in magnetic resonance imaging (MRI) can provide detailed visualization of the studied areas of the body, such as hands and feet. The contrast resolution of soft tissue provided by MRI allows identification and characterization of various traumatic injuries, arthropathies, and neoplastic processes. Advances in gradient equipment, coil design and pulse trains allow very small images to be displayed at high resolution. Modern magnets provide increased signal-to-noise ratio and contrast-to-noise ratio. Dedicated multi-channel special coils further optimize the signal-to-noise ratio. In addition, these coils facilitate optimal patient positioning. When combined with appropriate imaging protocols, MRI imaging of the hand can offer improved diagnostic results for articular cartilage and the small supporting soft tissue structures of the hand.
Normal hand anatomy
The anatomy of the hand is quite complex and its integrity is absolutely essential for our daily functional life. A total of 27 bones make up the basic skeleton of the wrist and hand. The hand is innervated by three nerves—the median, ulnar, and radial nerves—each of which has sensory and motor components. The muscles of the hand are divided into internal and external groups, so any traumatic effects adversely affect the functioning of such a complex mechanism.
Hand MRI Preparation
Before a patient undergoes an MRI scan, personal items such as watches, wallets, car keys should not be taken into the office, and it is also important to inform the doctor about the presence of chronic diseases, such as kidney failure, or the presence of pregnancy.
Wear loose, comfortable clothing without metal snaps or zippers. If you have claustrophobia (fear of closed spaces) or an inability to lie still, you should check with your doctor before having an MRI for special instructions.
MRI is contraindicated if the patient has any of the following implanted metal objects:
- pacemaker;
- neurostimulator;
- cochlear (ear) implant;
- implantable drug for infusion;
- cardiac stent;
- artificial heart valve;
- metal fragments in the eye.
For some MRI tests, a gadolinium contrast agent is injected intravenously to better define the area being imaged. Unlike radiological contrast agents, MRI contrast does not contain iodine and therefore rarely causes allergic reactions.
Preparation for the study is not required. You can eat and take any medication prescribed by your doctor.
What diseases can be diagnosed with an MRI of the hand?
Traumatic hand injury
Contrast imaging of thin soft tissue MRI allows evaluation of tendons, ligaments and complex finger joint systems. Normal tendons and ligaments of the hands usually show low signal intensity on MRI. In contrast, these structures exhibit increased signal intensity or abnormal morphology upon injury.
Tendon injuries
Flexor tendon injuries most often occur secondary to a hand tear or sports injury. Rupture or partial damage to the tendons is usually the result of resistance to forced stretching or other types of trauma. MRI helps distinguish between a partial tear and a complete tear and displays the length of tendon retraction. This injury can occur anywhere along the flexor tendon and is classified according to the site of the injury.
Extensor tendon wounds
Extensor (extensor) tendon injuries can occur anywhere along the extensor tendons. A common example is a distal extensor tear from the distal phalanx. This occurs with forced flexion in the joint and active contraction of the extensor.
Osteoarthritis
Osteoarthritis (OA) is the most common joint disease of the hand, and the prevalence of the disease increases with age. More than 50% of men and women over 60 years of age have OA on a hand x-ray. Osteoarthritis is usually a slowly progressive disorder characterized by uneven narrowing of the articular cartilage, periarticular sclerosis, osteophytosis, and subchondral cysts. Erosive OA has the additional features of synovitis, tenosynovitis, and erosions, and is most commonly seen in postmenopausal women. When synovitis is observed in the presence of OA, synovitis is a marker of a secondary inflammatory response to cartilage damage and loose particles in the joint. The detection of synovitis in a patient with OA may help in diagnosing the risk of OA erosion, allowing for early preventive treatment.
Rheumatoid arthritis
Rheumatoid arthritis (RA) is a chronic systemic inflammatory arthropathy affecting approximately 0,5-1,0% of the population, although the prevalence appears to be increasing. RA manifests as a proliferative, hypertrophic synovitis that leads to the destruction of bones and cartilage. Within the upper extremity, RA predominantly affects the wrist joints. Characteristic radiographic findings of symmetrical or concentric narrowing of articular erosions indicate the presence of irreversible damage to cartilage and bone. The greater availability and positive outcomes associated with disease-modifying agents require the use of MRI to recognize RA at a very early stage before irreversible damage occurs. MRI allows you to more quickly and accurately detect synovitis, tendosynovitis, bursitis, early or small erosion and osteitis. Proliferating synovitis is the earliest recognized pathological indicator of RA and a poor prognosis for the patient.
Osteolysis, typically seen on MRI as a swollen bone marrow signal with insertion of a synovial membrane, is increasingly recognized as an early feature of RA that predicts cartilage and bone damage. Subcutaneous rheumatoid nodules are present in 30-40% of patients and may be seen on imaging of the hand.
Psoriatic arthritis and other inflammatory arthropathies
Psoriatic arthritis is an uncommon inflammatory arthropathy associated with psoriasis. This complication may occur in 30% of patients with psoriasis. On radiographs, arthritis usually presents as isolated tenosynovitis, especially from the flexor tendons, with associated soft tissue swelling that can be easily identified on MRI. The signal resembling cerebral edema is the earliest bone marker on MRI and tends to occur when the joint capsule on the phalanx is involved. This signal becomes more extensive as the disease progresses. Erosions eventually form at the edge of the bone, resulting in the deformity characteristic of psoriatic arthritis. Other systemic inflammatory diseases, such as systemic lupus erythematosus, may include evidence of tenosynovitis, synovitis, and bone marrow edema signal, as well as signals similar to early or seronegative RA.
Septic arthritis and osteomyelitis
Septic arthritis is an arthropathy caused by an intra-articular infection that leads to destruction of the joints. Risk factors include bacteremia, immunocompromised state, rheumatoid arthritis, and previous penetrating trauma. Septic arthritis should be considered in the setting of acute uniarticular arthritis, especially with accompanying clinical signs and symptoms of joint pain and fever. Early diagnosis and treatment are essential in making a diagnosis of septic arthritis with intact articular cartilage to prevent the immediate risk of irreversible damage and subsequent secondary osteoarthritis. On MRI, the presence of septic arthritis and synovitis with an associated signal of subchondral bone marrow edema is typical of septic arthritis in the corresponding clinical picture. Osteomyelitis usually occurs in the presence of a skin defect or previous penetrating injury and is characterized by edema and cortical destruction. MRI diagnostics is the most reliable method for accurately detecting osteomyelitis, since fluid-sensitive sequences can show similar signal changes in both non-infectious reactive changes and osteomyelitis.
Tumors
A wide variety of neoplasms can be found in the hand, although they are less common than elsewhere in the body. Injuries associated with the bones of the hands and fingers account for 6% of all benign and 0,5% of all malignant bone lesions. Lesions associated with the soft tissues of the hand and fingers account for 15% of all benign and 4% of all malignant soft tissue neoplasms. MRI can be a useful adjunct to radiographs of the hand and fingers given its ability to accurately delineate and differentiate tissue characteristics. MRI also provides layer-by-layer imaging, which allows you to determine the exact localization of damage in all planes. Soft tissue injuries are ideally assessed using MRI, as this study allows for precise localization of lesions and their relationship to surrounding structures. Tissue characterization by MRI is often sufficient to establish a diagnosis for injuries to the hand and fingers.
Recovery after MRI
The patient can immediately return to their normal lifestyle and activities. If a contrast was introduced, then its excretion from the body occurs naturally within 18-24 hours, it is colorless and odorless.
Modern methods of MRI of the hands and fingers provide accurate diagnostics for the assessment and characterization of traumatic injuries of small structures, various arthropathies and neoplastic processes. As the quality of examination continues to improve, the practicality and value of hand and finger MRI become more relevant in diagnosis.
Contrast enhancement with gadolinium is often useful for further definition and characterization. Magnetic resonance angiography can sometimes be helpful in identifying vascular involvement.