Imaging · General

MRI of the lower extremity (excluding joint) performed without contrast material

Verified May 8, 2026 · 6 sources ↓

Medicare: $222.45
Total RVUs: 6.66
Global, days
Region: General

Drawn from CMSCgsmedicareAAPCMdclarity

Documentation requirements

What must appear in the operative or office note to support the claim.

Source · Editorial brief grounded in 6 cited references ↓

Clinical indication specifying why the lower extremity (non-joint) is being imaged without contrast — medical necessity must be explicit
Order or referral identifying the anatomic region (e.g., thigh, calf, lower leg) and confirming non-joint site
Radiology report with named anatomic structures evaluated, imaging sequences used, and interpreting provider signature
ICD-10-CM diagnosis code(s) that support non-contrast imaging (e.g., soft tissue mass, bone lesion, vascular anomaly)
Documentation confirming no contrast was administered, consistent with the billed code level
If billing modifier 26, documentation must reflect a separate formal interpretation with findings, impression, and supervising radiologist attestation

Applicable modifiers

Modifiers commonly billed with this code.

Source · AMA CPT modifier descriptors · CMS NCCI Policy Manual

26 Professional component LT Left side RT Right side 52 Reduced services 59 Distinct service

What this code covers

Source · Editorial summary grounded in 6 cited references ↓

CPT 73718 covers a non-contrast MRI of the lower extremity — specifically structures other than a joint, such as the thigh, lower leg, or soft tissues of the leg. This distinguishes it from joint-specific codes (73721–73723 for knee, etc.) and from contrast-enhanced studies (73719 with contrast, 73720 with and without). Use 73718 when the clinical question involves soft tissue masses, bone marrow pathology, vascular lesions, or compartment evaluation that doesn't require a dedicated joint protocol.

The without/with contrast distinction is not interchangeable. CMS's RAC program explicitly flags billing a less extensive MRI (73718, no contrast) on the same anatomic site and same date as a more extensive study (73720, with and without contrast) — the less extensive code bundles into the more extensive one. If the order changes intraoperatively or contrast is added after scanning begins, document the clinical reason and bill only the most extensive code.

Site of service matters here. 73718 is billed in the office (POS 11) and on-campus outpatient hospital (POS 22) settings. In a facility setting, the interpreting radiologist or orthopedic surgeon bills modifier 26 for the professional component only; the facility bills the technical component separately. When billed globally (equipment + interpretation under one provider tax ID), no component modifier applies.

RVU & reimbursement

Component RVUs and Medicare national rate. Actual payment varies by GPCI locality.

Source · CMS Physician Fee Schedule, RVU26A · January 2026

Work RVU	1.32
Practice expense RVU	5.25
Malpractice RVU	0.09
Total RVU	6.66
Medicare national rate	$222.45
Global period	days

Payment by site of service

Medicare pays different rates by setting. HOPD typically pays substantially more than ASC for the same procedure.

Source · CMS OPPS Addendum B·ASC HCPCS payment rates·2026

Setting	Medicare rate (national)
Office (PFS non-facility) Procedure performed in physician's office	$222.45
HOPD (APC 5523) Hospital outpatient department	$243.77

Common denial reasons

The recurring reasons claims for CPT 73718 get rejected.

Source · Editorial brief grounded in CMS NCCI edits, AAOS coding appeals, and cited references ↓

Bundling denial when 73718 is billed same-day same-site with 73720 — less extensive study rolls into the more extensive code per CMS RAC policy
Medical necessity denial when the diagnosis code doesn't support non-contrast lower extremity imaging (e.g., payer LCD requires contrast for certain indications)
Wrong code family — billing 73718 for a knee or ankle MRI that should have been coded under the joint-specific series (73721–73723)
Missing or unsigned radiology report at time of claim submission
Component billing mismatch — global bill submitted when the facility already billed the technical component separately

Frequently asked questions

Source · Generated from the editorial pipeline, verified against 6 cited references ↓

01What's the difference between 73718 and 73721?

73718 is for MRI of the lower extremity excluding a joint — think thigh, lower leg, or soft tissue compartments. 73721 is specifically for MRI of a lower extremity joint (most commonly the knee). Billing 73718 for a knee MRI is a coding error that will trigger a mismatch denial or audit flag.

02Can 73718 and 73720 be billed together on the same date?

No. CMS's RAC program (Issue 0147) explicitly bundles 73718 into 73720 when both are billed for the same anatomic site on the same date. The more extensive study (73720, with and without contrast) subsumes the less extensive one. Bill only the most comprehensive code performed.

03When do I use modifier 26 with 73718?

Use modifier 26 when the interpreting physician is billing only for the professional component — i.e., reading and signing the report — and the technical component (equipment, technologist) is billed separately by the facility. Don't use 26 when the provider owns the equipment and is billing globally.

04Does 73718 require prior authorization?

Most commercial payers and many Medicare Advantage plans require prior auth for non-emergent MRI. Specific auth requirements vary by payer and plan. Confirm auth is tied to the correct code (73718, non-joint, no contrast) — an auth issued for 73721 won't cover this code.

05Is 73718 appropriate for a thigh soft tissue mass workup?

Yes, when the clinical question involves the soft tissue or bone of the thigh rather than a specific joint. If the ordering provider suspects a lesion that may require contrast for characterization, consider whether 73720 (with and without contrast) is more appropriate before submitting 73718.

06What ICD-10 codes typically support 73718 for orthopedic indications?

Common supporting diagnoses include soft tissue neoplasm codes (M79.89x), stress fracture of lower leg (M84.36x), bone lesion evaluation, compartment syndrome workup, and peripheral vascular or lymphatic assessment. The diagnosis must explicitly point to a non-joint lower extremity structure to avoid a site mismatch denial.

Sources & references

Editorial content was developed using the following public sources. Last verified May 8, 2026.

Mira AI Scribe

Mira's AI scribe captures the anatomic site (non-joint lower extremity), contrast status (without), laterality, and the clinical indication driving the order from dictation. That prevents the two most common denials: wrong code family (joint vs. non-joint) and missing medical necessity when the diagnosis doesn't match a non-contrast study. If the ordering provider dictates a joint-specific site like the knee or ankle, the scribe flags the potential mismatch with the 73718 code family before the claim is submitted.

See how Mira captures CPT 73718 documentation