When should a Magnetic Resonance Imaging (MRI) scan be ordered?

From the Guidelines

A Magnetic Resonance Imaging (MRI) scan should be ordered when detailed images of soft tissues, organs, and structures inside the body are needed for diagnosis or treatment planning, particularly in cases of suspected spine infection, neurological conditions, or when other imaging techniques are insufficient. MRIs are particularly valuable for examining the brain, spinal cord, nerves, muscles, ligaments, tendons, and internal organs. They should be considered when other imaging techniques like X-rays or CT scans don't provide sufficient information, or when radiation exposure is a concern. Specific indications include suspected neurological conditions (stroke, multiple sclerosis, tumors), joint or musculoskeletal injuries (torn ligaments, cartilage damage), spinal disorders (herniated discs, spinal stenosis), soft tissue abnormalities, and certain cancers.

Key Indications for MRI

• Suspected spine infection, such as epidural abscess or discitis osteomyelitis, especially in patients with new or worsening back or neck pain, with or without fever, and with red flags like diabetes mellitus, IV drug use, cancer, HIV, or dialysis 1
• Neurological conditions, including stroke, multiple sclerosis, and tumors
• Joint or musculoskeletal injuries, such as torn ligaments or cartilage damage
• Spinal disorders, including herniated discs and spinal stenosis
• Soft tissue abnormalities and certain cancers

Considerations for Ordering an MRI

• The procedure uses powerful magnets and radio waves rather than radiation to create detailed cross-sectional images, making it safer for repeated use
• However, MRIs are contraindicated for patients with certain metallic implants, pacemakers, or severe claustrophobia, and may require prior authorization from insurance companies due to their higher cost compared to other imaging techniques
• Recent studies, such as the one published in 2021 1, provide guidelines for the appropriate use of MRI in various clinical scenarios, emphasizing the importance of selecting the right imaging modality based on the patient's condition and needs.

Recent Guidelines and Recommendations

• The American College of Radiology (ACR) has published appropriateness criteria for the use of MRI in various conditions, including suspected spine infection 1 and seizures and epilepsy 1
• These guidelines highlight the importance of considering the clinical context and the potential benefits and risks of MRI in each patient
• For example, in patients with suspected spine infection, MRI is usually appropriate as the initial imaging modality, especially when there are red flags or abnormal lab values 1
• In patients with seizures and epilepsy, MRI is an important tool for identifying and characterizing focal causative lesions, and for assessing progression and determining prognosis 1

From the Research

Indications for MRI Ordering

The decision to order a Magnetic Resonance Imaging (MRI) scan depends on various clinical scenarios. Here are some instances where MRI might be considered:

• Osteonecrosis of the knee: MRI can be valuable in patients with suspected or proven osteonecrosis of the knee, especially for demonstrating bilateral disease, showing the extent of involvement, and establishing the presence or absence of bone marrow changes 2.
• Cervical spine trauma: While MRI can demonstrate ligamentous signal change, its findings should be interpreted with caution in the setting of trauma. Bony alignment and dynamic upright X-rays remain the gold standard for evaluating ligamentous integrity of the cervical spine 3.
• Femoral head osteonecrosis: MRI, along with plain radiographs, is sufficient for diagnosing and staging osteonecrosis of the femoral head using the Association Research Circulation Osseous (ARCO) staging system. Computed Tomography (CT) scans are not necessary for this purpose 4.
• Posttraumatic spinal ligament injury: MRI is an accurate method for assessing the integrity of spinal ligaments after acute trauma, with T2-weighted sequences being essential for detecting ligament injury 5.
• Multiple sclerosis: MRI can detect multifocal lesions of the white matter in patients with clinical multiple sclerosis and is more sensitive than CT scans in showing demyelinating lesions compatible with MS 6.

Key Considerations

When deciding to order an MRI, consider the following:

• The specific clinical question or diagnosis being investigated
• The availability and appropriateness of other imaging modalities (e.g., CT, X-rays)
• The potential benefits and limitations of MRI in the given clinical context
• The need for caution in interpreting MRI findings, especially in cases of trauma or when evaluating ligamentous integrity.