What type of magnetic resonance imaging (MRI) is recommended for a 14-year-old female with chronic lower back pain, tingling, and numbness in her legs?

MRI Type for Adolescent with Chronic Lower Back Pain and Leg Symptoms

An MRI of the lumbar spine without contrast is the most appropriate imaging study for a 14-year-old female with chronic lower back pain and tingling/numbness in her legs. 1

Rationale for MRI Selection

Clinical Presentation Analysis

• The combination of chronic lower back pain with neurological symptoms (tingling and numbness in legs) suggests possible nerve root involvement
• These symptoms in an adolescent represent clinical "red flags" that warrant advanced imaging
• The radicular symptoms (leg tingling/numbness) indicate possible nerve compression that requires evaluation

Appropriate MRI Protocol

1. MRI lumbar spine without contrast

   • Fat-saturated imaging techniques are essential for proper evaluation 1
   • T2-weighted sequences with fat suppression are necessary to identify inflammatory changes and edema
   • Sagittal and axial views should be included to properly visualize neural structures

2. Why without contrast?

   • Contrast is not indicated for evaluation of chronic back pain due to suspected mechanical causes 1
   • The ACR Appropriateness Criteria specifically states: "There is little use for performing an MRI with contrast only. Contrast is not indicated in the evaluation of chronic back pain due to suspected mechanical causes." 1
   • Gadolinium contrast would only be indicated if there were concerns for inflammation, infection, or neoplasm 1, 2

Diagnostic Considerations

Potential Etiologies to Evaluate

• Spondylolysis (common in adolescents)
• Disc herniation (especially at L4-L5 or L5-S1 levels)
• Spinal stenosis
• Apophyseal ring fractures
• Intraspinous ligamentous injury
• Discogenic injury
• Scheuermann disease

MRI Advantages for This Patient

• MRI can directly visualize the spinal cord, nerve roots, ligaments, and intervertebral discs 1
• Superior for detecting active spondylolysis, which is common in adolescents 1
• Can evaluate radiculopathy from both spondylolytic and non-spondylolytic causes 1
• Can detect early stress reactions in the pedicles that may be missed by CT alone 1

Common Pitfalls to Avoid

1. Ordering contrast unnecessarily

   • Adding contrast provides no additional benefit for suspected mechanical causes of back pain 1
   • Exposes the patient to unnecessary risks associated with gadolinium administration

2. Starting with CT instead of MRI

   • While CT has high sensitivity for spondylolysis, it may miss early stress reactions 1
   • CT exposes the adolescent to radiation, which should be avoided when possible

3. Relying solely on radiographs

   • Radiographs have limited sensitivity (77.6%) for spondylolysis 1
   • They are insensitive to paraspinal and intraspinal soft tissue abnormalities

4. Overinterpretation of MRI findings

   • Many structural abnormalities on MRI appear in asymptomatic individuals 3
   • Findings must be correlated with clinical examination to provide meaningful judgments 4

Additional Considerations

• If the lumbar spine MRI is negative but symptoms persist, consider MRI of the lumbosacral plexus as the clinical diagnosis of plexopathy can overlap with radiculopathy 1
• Avoid routine imaging in acute uncomplicated low back pain without red flags 5, 6
• In this case, the presence of neurological symptoms (tingling and numbness) constitutes a red flag warranting immediate imaging 1, 5

MRI without contrast provides the most comprehensive evaluation for this adolescent patient with the least risk, offering the best opportunity to identify the cause of her symptoms and guide appropriate treatment.