CPT
70450 — CT scan of head/brain without contrast
Same scan can cost 5x more at a hospital than at an imaging center.
Imaging
73721 — MRI lower extremity joint without contrast (knee)
MRI of a knee, ankle, or other lower-extremity joint without contrast. Workhorse code for orthopedic injury workup.
- Typical setting: Hospital outpatient or imaging center
- National avg charge (illustrative): Insurance allowed $400-$1,400; cash freestanding $350-$1,000; hospital $1,800-$6,000+.
- Most-disputed reason: Hospital pricing premium.
What it means
What 73721 actually means
CPT 73721 is an MRI of a lower-extremity joint (most commonly the knee) without IV contrast. It's used for ligament tears, meniscus injuries, cartilage assessment, and unexplained joint pain.
Common errors with this code
What goes wrong on real bills.
Most bills that look correct still contain at least one of these issues. Up to 49% of medical bills contain errors (CFPB).
- Hospital outpatient pricing several multiples of freestanding rate.
- Billed as 73723 (with-and-without-contrast) when only a non-contrast study was done.
- Out-of-network radiologist balance billing.
If you see 73721 on your bill
Three steps before paying.
1. Get the itemized bill. If your statement only shows a summary, request the CPT-level itemized bill before paying. Generate the request language →
2. Cross-check against the EOB. Compare what your insurer's Explanation of Benefits says you owe versus what the hospital is asking. They disagree more often than people think. Read the bill-vs-EOB guide →
3. Run a free Bill Scan. Upload the bill (and EOB if you have it) and BillBusted will flag the most likely issues with this specific code in your specific state. Run free scan →
Related codes
Other codes in this category.
People who land on 73721 often also see these adjacent codes on the same bill.
CPT
70470 — CT head/brain with and without contrast
If contrast wasn't given, 70470 is the wrong code.
CPT
70486 — CT maxillofacial area; without contrast material
Imaging — verify professional + technical components weren't double-billed.
CPT
70551 — MRI brain without contrast
Same scan can be 5x cheaper at a freestanding imaging center.
CPT
71045 — Chest X-ray, single view
Same image can cost 10x more at a hospital than a freestanding imaging center.
CPT
71046 — Chest X-ray, two views (PA + lateral)
Two-view CXR is standard. Watch the price gap between hospital and freestanding.
Related BillBusted guides
Plain-English reads if you see 73721 on a bill.
73721 FAQ
Plain-English answers.
Don't pay 73721 blindly.
The free scan tells you in under 60 seconds whether this charge looks reasonable for your situation.