MRI and CT scan: which is better?

CT uses X-rays to create cross-sectional images quickly, making it useful when speed, bones, bleeding, or detailed views of the chest and abdomen matter. MRI uses a magnetic field and radio waves, often giving strong contrast between soft tissues such as the brain, spinal cord, muscles, and many tumours. MRI does not use ionising radiation, but it can take longer and is sensitive to movement. Both tests can be performed with or without a contrast agent, depending on the question. A scan shows anatomy; it may need to be combined with examination, laboratory tests, or biopsy before a diagnosis is confirmed.

Tell the imaging team about pregnancy, kidney problems, allergies or prior reactions to contrast, implanted devices, metal fragments, and difficulty staying still. For MRI, remove metal items and follow instructions about devices and clothing. For CT, follow any fasting or contrast instructions given by the department. The team chooses the protocol, positioning, and contrast decision for the clinical question.

After contrast, seek urgent help for trouble breathing, swelling of the face or throat, or fainting. Contact the imaging service about a spreading rash, persistent vomiting, or worsening pain at an injection site. If the scan was arranged for sudden weakness, confusion, severe headache, or major injury, follow the urgent-care instructions you were given rather than waiting for a routine appointment.

Ask what the scan is intended to show, whether contrast is needed, how quickly the result is required, and whether a previous scan can answer the same question. Ask how the findings will affect the next decision.