# MRI CPT codes explained: 70551, 72148, 73221, 73721

The four CPT codes that describe the MRI scans people price most often: brain, lumbar spine, shoulder and knee, all without contrast. Learn what each code means and why the code decides the price.

Updated 2026-10-02. Country: United States. Also on the [web page](https://mriprices.fyi/guides/mri-cpt-codes-explained).

A Current Procedural Terminology (CPT) code is the way a hospital files, prices and bills a procedure. For MRI scans, each body part has its own code, and contrast changes the code within the same family. This page explains the four codes this directory tracks: brain, lumbar spine, shoulder and knee, all without contrast.

## The four scan types

- **CPT 70551 — brain MRI without contrast.** The standard scan for the head and brain. With contrast it becomes 70552; without and with contrast it is 70553.
- **CPT 72148 — lumbar spine MRI without contrast.** The standard scan of the lower back. With contrast it is 72149; without and with contrast it is 72150.
- **CPT 73221 — shoulder MRI without contrast.** The standard scan of the shoulder joint. With contrast it is 73222; without and with contrast it is 73223.
- **CPT 73721 — knee MRI without contrast.** The standard scan of the knee joint. With contrast it is 73722; without and with contrast it is 73723.

The "without contrast" code is the baseline in each family. A scan with contrast takes longer, uses a contrast agent, and usually has a higher price — which is why a hospital's price file lists them as separate rows.

## Why the code is the key to the price

Under the federal price transparency rule (45 CFR 180), every hospital must publish its standard charges in a machine-readable file, and the file is organized by item and service. For scans, the items are the CPT codes. So the cash price for a knee MRI is the row for 73721 in that hospital's file.

That is how a directory compares prices honestly: the same code, read from each hospital's own published file, next to the same code from another hospital. It is also how you get a quote that means anything. If you call a hospital and say "an MRI," the estimate desk cannot price it — say "CPT 73721, knee MRI without contrast" and the estimator can look it up.

## What the code does not tell you

The CPT code describes the scan, not the total bill. Two things are usually billed separately on top of the scan itself: the hospital's facility fee and the radiologist's professional fee for reading the images. Different radiologists may bill under their own codes. So a price keyed to 73721 may cover only the facility portion. Ask the hospital whether the quote is the total or just the scan, and get the written number.

On this site, each hospital page publishes the cash prices found in that hospital's own machine-readable file, tied to these four codes. Until a hospital's file is parsed, the page honestly reads "price undisclosed".

## Sources

- [AMA: CPT codes and descriptors](https://www.ama-assn.org/practice-management/cpt)
- [CMS: Hospital Price Transparency](https://www.cms.gov/priorities/key-initiatives/hospital-price-transparency)

## Questions

### What does 'without contrast' mean on an MRI code?

It means the scan is done without an injected contrast agent. The same body part has a separate code for with contrast, and a third for without and with. The codes sit together in one family and the with-contrast versions usually cost more.

### Which CPT code do I use for my scan?

Use 70551 for a head (brain) MRI without contrast, 72148 for a lumbar spine MRI, 73221 for a shoulder MRI and 73721 for a knee MRI. If your doctor orders contrast, use the matching with-contrast code from the same family.

### Why does the CPT code matter for the price?

Hospitals list their prices in a machine-readable file keyed by CPT code. The code is how you find your scan in the file, how the hospital quotes you, and how different hospitals' prices for the same scan can be compared.