Ultrasound, CT and MRI: ask what the image will change

Different images answer different questions

Ultrasound, CT and MRI are not interchangeable versions of the same checkup. Ask which body area will be examined, what clinical question the scan is meant to answer, and who will interpret the images. A list of available machines says little about which investigation is appropriate for you.

Bring previous imaging reports and, if available, the original image files. Ask whether they can be reviewed before another scan is ordered. The date, body area and reason for earlier imaging help the clinician decide whether a comparison or repeat examination would add useful information.

Ultrasound has strengths and limits

Ultrasound uses sound waves and does not expose you to ionising radiation. It can show many soft tissues, but gas and bone limit what can be seen. The suitability of an examination depends on the organ and the question being investigated; it is not a scan that excludes every disease.

Preparation may differ between examinations. Ask whether you should eat or drink beforehand and whether bladder filling is required. Do not apply instructions from one type of ultrasound to another. If an internal examination is proposed, request a clear explanation of the procedure and consent process.

MRI needs a safety discussion

MRI also avoids ionising radiation, but uses a strong magnetic environment. Tell the team about implants, medical devices and any metal-related safety concern before the appointment. The exact device must be checked; do not assume all implants have the same MRI conditions.

Ask whether contrast or sedation is planned, how long you need to remain still, and what to do if enclosed spaces are difficult for you. These details can change preparation, transport and the price. A scan without radiation is not automatically necessary or free of other risks.

Evaluate an add-on before paying

CT uses X-rays and therefore involves ionising radiation. For CT or any other proposed scan, ask about the expected benefit, relevant risks and a reasonable alternative. Explain pregnancy possibility and previous reactions to contrast before agreeing to imaging. The treating team should determine whether a particular examination is suitable.

Request the written report and an accessible copy of the images where appropriate. Confirm whether interpretation and a follow-up consultation are included. If a finding is uncertain, ask what additional appointment could be needed and whether it can be arranged within your travel plans.

• What would a normal result change?
• What would an incidental or uncertain finding mean for me?
• Can my usual clinician access the report and image files?