How should I write a non‑contrast MRI order for an adult with persistent right knee pain ≥4 weeks and mechanical symptoms, suspecting internal derangement (e.g., meniscal tear, ligament or chondral injury) and relevant history such as recent trauma, prior knee surgery, osteoarthritis, or rheumatoid arthritis?

How to Write an MRI Order for Right Knee Pain

Order "MRI right knee without IV contrast" for an adult with persistent knee pain ≥4 weeks and mechanical symptoms suggestive of internal derangement. 1, 2

Essential Components of the Order

Basic Order Format

• Procedure: MRI right knee without IV contrast 1, 2
• Laterality: Specify "right" knee 2
• Contrast: Explicitly state "without IV contrast" or "non-contrast" 1, 2

Clinical Information to Include

Mandatory elements for the radiologist:

• Duration of symptoms: Document that pain has persisted ≥4 weeks (distinguishes chronic from acute) 1
• Mechanism: Note whether trauma-related, twisting injury, or atraumatic 1
• Mechanical symptoms: Specify presence of locking, catching, giving way, or clicking 1, 2
• Prior imaging: State "radiographs negative for fracture" if already obtained 1, 2
• Relevant history: Include prior knee surgery, osteoarthritis, rheumatoid arthritis, or recent trauma 1, 3

Clinical Indication Examples

For suspected meniscal tear:

• "Right knee pain x 6 weeks with mechanical locking. Radiographs negative. Suspect meniscal tear." 1, 2

For suspected ligament injury:

• "Right knee pain and instability after twisting injury 5 weeks ago. Radiographs negative. Evaluate for ACL/meniscal injury." 1, 2

For chronic pain with effusion:

• "Right knee pain x 8 weeks with persistent effusion. Radiographs show effusion only. Evaluate for internal derangement." 1, 2

Why Non-Contrast MRI is the Correct Choice

MRI without contrast is the gold standard for evaluating internal derangement because it provides superior soft tissue contrast resolution and multiplanar imaging capability for assessing menisci, ligaments, cartilage, and bone marrow. 1, 2, 4

What Non-Contrast MRI Evaluates

• Meniscal tears: High sensitivity and specificity without need for contrast 1, 2, 5
• Ligament injuries: ACL, PCL, MCL, LCL tears and sprains 1, 2
• Cartilage damage: Articular surface defects and chondral lesions 1, 2
• Bone marrow edema: Occult fractures and contusions 1, 2
• Joint effusions and synovitis: Inflammatory changes 1, 2

When NOT to Order Contrast

• MRI with IV contrast adds no diagnostic value for routine meniscal or ligamentous injuries and should be avoided 1, 2
• Contrast is rated "usually not appropriate" (score 1/9) by the American College of Radiology for standard internal derangement 1, 2
• MR arthrography is similarly not indicated for initial evaluation of suspected meniscal or ligament injuries 1, 2

Critical Prerequisite: Obtain Radiographs First

Always obtain plain radiographs before ordering MRI to rule out fractures, degenerative changes, loose bodies, and other osseous pathology. 1, 3

Standard Radiographic Views

• Anteroposterior (AP) view 1
• Lateral view 1
• Tangential patellar view (if patellar pathology suspected) 1

What Radiographs Must Exclude

• Fractures (including tibial plateau, patella, femoral condyle) 1
• Degenerative joint disease/osteoarthritis 1, 3
• Loose bodies 1
• Osteochondritis dissecans 1
• Signs of prior osseous injury (Segond fracture, tibial spine avulsion) 1

Common Pitfalls to Avoid

Do not order MRI without recent radiographs – this occurs in approximately 20% of chronic knee pain cases and represents inappropriate utilization. 3

Do not order MRI with contrast for routine internal derangement – contrast provides no additional diagnostic benefit and increases cost and examination time. 1, 2

Do not assume all meniscal tears require surgery – meniscal tears on MRI are often incidental findings in older patients and should not automatically drive treatment decisions. 1, 3

Do not forget to rule out referred pain – hip or lumbar spine pathology can present as knee pain; document that examination localizes pain to the knee joint itself. 3

Do not order MRI for acute trauma as first-line imaging – radiographs should always be obtained first in the acute setting. 1

Alternative Imaging Modalities (When NOT to Use Them)

CT Knee Without Contrast

• Reserved for evaluating fracture classification (especially tibial plateau fractures already seen on radiographs) 1
• Useful for patellofemoral anatomy assessment in chronic subluxation 1
• Not appropriate for evaluating menisci or ligaments 1

CT Arthrography

• May be considered only when MRI is contraindicated (pacemaker, severe claustrophobia) 1
• Sensitivity 86-100% for meniscal tears but invasive 1

Ultrasound

• Not appropriate for internal derangement evaluation 1
• Limited role in knee imaging compared to MRI 1

MR Arthrography

• Not routinely indicated for suspected meniscal or ligament injuries 1, 2
• May have role in evaluating cartilage repair procedures (not relevant to initial diagnosis) 1

Special Circumstances

Post-Surgical Knee

• Non-contrast MRI can evaluate meniscal repair status without need for arthrography 5
• Specialized sequences can assess healing without intra-articular contrast 5

Suspected Knee Dislocation (High-Energy Trauma)

• If knee dislocation suspected, vascular assessment with CTA may be needed due to popliteal artery injury risk 1, 6
• MRI still appropriate for ligamentous and meniscal evaluation after vascular injury excluded 1, 6

Tibial Plateau Fracture on Radiographs

• CT without contrast is next study for fracture classification 1
• MRI without contrast follows if soft tissue injury assessment needed 1