Given a non‑contrast lumbar computed tomography that shows no acute fracture, mild leftward convex lumbar curvature, multilevel degenerative changes most severe at L4‑L5 and L5‑S1, no critical canal stenosis, and left‑sided foraminal narrowing at L5‑S1, should a magnetic resonance imaging (MRI) be ordered?

Should You Order an MRI After This CT?

No, do not routinely order an MRI based solely on these CT findings showing degenerative changes without red flags—MRI is only indicated if the patient has failed 6 weeks of conservative therapy AND is a candidate for surgery or intervention, OR if there are red flags suggesting serious pathology.

Clinical Decision Framework

The decision to proceed with MRI depends entirely on the clinical context that is missing from your question, not the CT findings themselves. Here's how to approach this:

When MRI Is NOT Indicated

According to the 2021 ACR Appropriateness Criteria, routine imaging provides no clinical benefit in uncomplicated low back pain with or without radiculopathy and can lead to increased healthcare utilization 1. The CT findings you describe—multilevel degenerative changes, foraminal narrowing, and mild scoliosis—are extremely common in asymptomatic individuals and do not by themselves warrant MRI 1.

Do NOT order MRI if:

• The patient has acute or subacute low back pain without red flags
• Conservative therapy has not been attempted or completed (minimum 6 weeks)
• The patient is not a surgical or interventional candidate
• There are no concerning neurologic findings

When MRI IS Indicated

Order MRI lumbar spine without contrast if ANY of the following apply:

1. Failed Conservative Therapy (6+ weeks) AND the patient is a surgical/interventional candidate with:

   • Persistent or progressive radiculopathy
   • Physical examination signs of nerve root irritation
   • Clinical signs of spinal stenosis with neurogenic claudication 1

2. Red Flags Present (immediate MRI regardless of treatment duration):

   • Suspected cauda equina syndrome (bladder/bowel dysfunction, saddle anesthesia, bilateral leg weakness) 1
   • Progressive neurologic deficits
   • Suspected infection, malignancy, or fracture
   • Multifocal neurologic deficits

Why CT Alone Is Insufficient for Surgical Planning

While your CT shows foraminal narrowing at L5-S1 and degenerative changes, CT has critical limitations 1:

• Cannot adequately visualize disc pathology, nerve root compression, or soft tissue structures
• Cannot distinguish between symptomatic and incidental findings
• CT is "equal to MRI for predicting significant spinal stenosis" 1, but this only addresses canal patency—not the soft tissue detail needed for surgical decision-making

MRI provides superior information for surgical candidates 1:

• Excellent soft-tissue contrast showing disc degeneration, herniations, and nerve root compression
• Visualization of the thecal sac and neural structures
• Correlation of anatomic findings with radicular symptoms

Common Pitfalls to Avoid

1. Ordering MRI based on imaging findings alone: The CT shows "foraminal narrowing" and "degenerative changes"—these are radiographic findings, not clinical diagnoses. Many asymptomatic people have identical findings 1.

2. Premature imaging: If conservative therapy hasn't been attempted for 6 weeks (physical therapy, NSAIDs, activity modification), imaging is premature and unhelpful 1.

3. Assuming all radiculopathy needs MRI: Only radiculopathy that persists despite conservative therapy in a surgical candidate warrants MRI 1.

The Bottom Line Algorithm

Ask yourself these questions in order:

1. Are there red flags (cauda equina, infection, malignancy, fracture, progressive deficits)?

   • YES → Order MRI immediately
   • NO → Continue to #2

2. Has the patient completed 6 weeks of optimal conservative management?

   • NO → Do NOT order MRI; continue conservative therapy
   • YES → Continue to #3

3. Does the patient have persistent/progressive symptoms AND is a candidate for surgery or intervention?

   • NO → Do NOT order MRI
   • YES → Order MRI lumbar spine without contrast 1

The CT findings you describe are incidental degenerative changes that require clinical correlation. Without knowing the patient's symptom duration, response to conservative therapy, and surgical candidacy, the default answer is no MRI 1.