Exams
Your order asks for an MRI: what it is asking for and what the centre needs before it can book you
An MRI order is rarely written the same way twice. The doctor writes MRI lumbar spine, the centre's catalogue stores it as magnetic resonance imaging of the lumbar spine, and the exam order in your hand may say only MRI. All three name the same service, and the scheduling system recognises one.
What is an order that says MRI, MR or nuclear magnetic resonance actually asking for?
All three abbreviations point at the same machine. What changes the appointment are the two facts beside the acronym: which region of the body is being studied, and whether the study uses contrast material.
Catalogues spell out the full anatomy. In Chile's FONASA fee schedule, the service a patient would ask for as a brain MRI is listed as magnetic resonance imaging of the skull, brain or ears, bilateral. Someone has to translate one name into the other before a slot can exist.
How is it different from a CT scan?
| MRI | CT scan | |
|---|---|---|
| How the image is formed | Magnetic field and radio waves | X-rays |
| Metal and devices | Always asked about before you go in | Checked for other reasons |
| Appointment block | Long, dedicated scanner time | Short |
| Usual contrast type | Gadolinium-based | Iodine-based |
The RSNA reference on MRI describes MRI contrast as gadolinium-based, distinct from the iodine-based contrast used in CT. That is why an order for a CT scan and an MRI order for the same region are not interchangeable, even when a patient calls both a scanner.
What does the centre ask for before it confirms the appointment?
- A valid order and who issued it. Some insurance agreements also require the referral.
- A safety questionnaire. RSNA is blunt about it: always tell the technologist if you have any device or metal in your body. Pacemakers, clips and prostheses are declared beforehand, not in the scanner room.
- Prior images of the same region, for comparison.
- Instructions on exam preparation. On eating and drinking, RSNA notes the rules vary by facility: the sheet that governs is the one from the place treating you.
- If the order says with contrast, the centre reviews your history before confirming. What gets checked is set by each institution's contrast medium protocol.
How long is the appointment?
The block is longer than a plain X-ray or an ultrasound: the scanner is dedicated to one patient at a time. With contrast, extra time is reserved for the line and for observation afterwards. If you are claustrophobic, mild sedation is authorised in advance with the doctor who referred you.
Why does this order get dropped more often than others?
Because it stacks three filters before it becomes an appointment slot: map the name to a catalogue service, settle the contrast question and, sometimes, obtain the insurer's authorisation. Each filter is a phone call somebody has to make, and nobody owns that call.
Then there is the vocabulary gap: the patient types MRI, the catalogue indexes magnetic resonance imaging of the lumbar spine and the search comes back empty. The waiting list never learns the order exists.
What should you do if you are holding one?
- Read the whole order, margins included: that is usually where with contrast hides.
- When you call, state the body region and the word contrast even if nobody asks.
- Declare metal, devices and previous surgery on that same call.
- Ask whether you need prior images and whether your order expires.
Having the centre write to close this order, instead of it waiting folded on a bedside table, already happens. Ask at your health centre whether they work with Surface.