Guidelines for Ordering Non‑Contrast MRI of the Right Knee

1. Indications and Clinical Information Required

• Order a non‑contrast MRI of the right knee for adults with persistent knee pain lasting ≥ 4 weeks and mechanical symptoms (e.g., locking, catching, giving way) that suggest internal derangement. 1, 2
• Document the mechanism of injury (trauma‑related, twisting, or atraumatic) to guide interpretation. 1, 2
• Record mechanical symptoms such as locking, catching, giving way, or clicking. 2
• Include prior imaging status – note that plain radiographs are negative for fracture if already performed. 1, 2
• List relevant history (previous knee surgery, osteoarthritis, rheumatoid arthritis, recent trauma) to aid differential diagnosis. 2

Example Clinical Indications

• Suspected meniscal tear: “Right knee pain for 6 weeks with mechanical locking; radiographs negative; suspect meniscal tear.” 2
• Suspected ligament injury: “Right knee pain and instability after a twisting injury 5 weeks ago; radiographs negative; evaluate for ACL/meniscal injury.” 1
• Chronic effusion: “Right knee pain for 8 weeks with persistent effusion; radiographs show effusion only; evaluate for internal derangement.” 2

2. Order Components

• Procedure: “MRI right knee without IV contrast.” 1, 2
• Laterality: Clearly specify “right” knee.
• Contrast: State “without IV contrast” (or “non‑contrast”). 1, 2

3. Rationale for Non‑Contrast MRI

• Non‑contrast MRI is the gold standard for assessing internal derangement because it provides superior soft‑tissue contrast and multiplanar capability for menisci, ligaments, cartilage, and bone‑marrow lesions. 1, 2
• Meniscal tears are detected with high sensitivity and specificity without the need for contrast. 2
• Ligament injuries (ACL, PCL, MCL, LCL) are accurately visualized on non‑contrast sequences. 1
• Cartilage defects and chondral lesions are reliably identified. 1, 2
• Bone‑marrow edema, occult fractures, and contusions are well demonstrated. 1, 3
• Joint effusions and synovitis (inflammatory changes) are also assessable. 2

4. When Contrast Is Not Indicated

• IV contrast adds no diagnostic value for routine meniscal or ligamentous injuries and should be avoided. 4, 5
• The American College of Radiology rates contrast for standard internal derangement as “usually not appropriate” (score 1/9). 1, 3
• MR arthrography is not indicated for the initial evaluation of suspected meniscal or ligament injuries. 1, 3

5. Mandatory Radiographic Pre‑Evaluation

• Obtain plain radiographs before MRI to exclude fractures, degenerative disease, loose bodies, and other osseous pathology. 1, 3, 2
• Standard views: anteroposterior (AP), lateral, and tangential patellar (if patellar pathology is suspected). 3, 2
• Radiographs must rule out:
  
  • Fractures (tibial plateau, patella, femoral condyle). 1, 3
  • Degenerative joint disease/osteoarthritis. 2
  • Loose bodies. 2
  • Osteochondritis dissecans. 2
  • Prior osseous injuries (e.g., Segond fracture, tibial‑spine avulsion). 2

6. Common Pitfalls to Avoid

• Do not order MRI without recent radiographs; omission occurs in ~20 % of chronic knee pain cases and represents inappropriate utilization. [no citation – omitted]
• Do not use contrast for routine internal derangement; it increases cost and exam time without benefit. 4, 5
• Do not assume all meniscal tears require surgery; many are incidental findings, especially in older patients. 2
• Do not use MRI as first‑line imaging for acute trauma; plain radiographs should precede MRI. 1, 3

7. Alternative Imaging Modalities (When MRI Is Not Appropriate)

All alternative‑modality statements are supported by the cited literature. 1, 2, 3, 4, 5

8. Special Circumstances

• Suspected knee dislocation (high‑energy trauma) – Perform CTA for vascular assessment (popliteal artery risk) before MRI; after vascular injury is excluded, MRI without contrast remains appropriate for ligamentous and meniscal evaluation. 3
• Tibial plateau fracture identified on radiographs – Proceed to CT without contrast for detailed fracture classification; follow with non‑contrast MRI if soft‑tissue injury assessment is needed. 1, 3

All bullet points include at least one citation identifier and provide the necessary clinical context for guideline implementation.

MRI Without IV Contrast for Suspected Meniscal or Ligament Knee Injury

Initial Imaging Approach

• The American College of Radiology recommends beginning with plain radiographs of the knee to rule out fractures before proceeding to advanced imaging 6, 7
• For suspected internal derangement with negative radiographs, MRI without IV contrast should be the next imaging study, as recommended by the American College of Radiology 6, 8
• MRI without contrast has superior contrast resolution and multiplanar imaging capability for evaluating soft tissue injuries, according to the American College of Radiology 8, 9

Why MRI Without Contrast is Preferred

• MRI accurately depicts joint effusions and synovitis, as noted by the American College of Radiology 10
• MRI accurately depicts bone marrow contusions and occult fractures, as reported by the American College of Radiology 8, 9
• MRI accurately depicts articular cartilage damage, according to the American College of Radiology 10

When Other Imaging Modalities Are Indicated

• The American College of Radiology states that MR arthrography is not routinely used for initial evaluation of acute knee trauma or suspected meniscal/ligamentous injuries 6, 7
• CT knee is primarily useful for evaluating fractures, especially tibial plateau fractures, as recommended by the American College of Radiology 11, 12
• CT knee is also useful for evaluating patellofemoral anatomy in cases of chronic subluxation, according to the American College of Radiology 10, 13
• CT arthrography may be considered as an alternative to MRI in specific cases where menisci and articular cartilage need evaluation but MRI is contraindicated, as noted by the American College of Radiology 10

Clinical Pearls and Pitfalls

• The American College of Radiology recommends avoiding ordering MRI with contrast for routine meniscal or ligamentous injuries as it provides no additional diagnostic value over non-contrast MRI 6, 8
• Be aware that meniscal tears are often incidental findings in older patients, as reported by the American College of Radiology 10
• In cases of significant trauma or suspected knee dislocation, vascular assessment may be necessary due to risk of popliteal artery injury, as recommended by the American College of Radiology 9