X-Ray Imaging for Scoliosis
For suspected scoliosis, order standing posteroanterior (PA) and lateral radiographs of the complete spine (cervical through lumbar) as the initial imaging study. 1, 2, 3
Standard Initial Imaging Protocol
- Radiographs of the complete spine are the primary imaging modality for diagnosing scoliosis, measuring curve severity (Cobb angle), classifying curve type, and monitoring progression 1, 2, 3
- The American College of Radiology recommends both PA and lateral views of the entire spine to fully evaluate the three-dimensional spinal deformity 1, 2
- Standing films are essential (not supine) to assess the true weight-bearing curvature and functional deformity 4
- PA projection is preferred over AP when possible to reduce breast radiation exposure, particularly in adolescent females 1
What These Films Must Show
The complete spine radiographs should include:
- Cervical spine through sacrum to identify all curve patterns and compensatory curves 1, 2
- Visualization of the iliac crests to assess skeletal maturity (Risser sign) 4
- Clear vertebral body margins to measure Cobb angle and assess vertebral rotation 4
When to Add MRI to Initial Imaging
MRI of the complete spine without contrast should be obtained alongside radiographs in these specific situations:
Mandatory MRI Indications:
- All patients with congenital scoliosis (21-43% have intraspinal anomalies) 1, 2
- Early onset idiopathic scoliosis (age 0-9 years) 1
- Before any surgical intervention to rule out neural axis abnormalities 1, 2
Red Flag Indications for MRI:
- Left thoracic curve pattern (atypical for idiopathic scoliosis) 1, 2, 3
- Short segment curve 1, 2, 3
- Rapid curve progression (>1° per month) 1, 3
- Functionally disruptive pain 1, 2, 3
- Any focal neurological findings on examination 1, 2, 3
- Male sex with idiopathic scoliosis 1, 2
- Pes cavus deformity 1, 2
- Absence of apical segment lordosis or presence of hyperkyphosis 1, 2
Critical Pitfall to Avoid
Never assume a normal neurological examination rules out intraspinal abnormalities - physical exam accuracy is only 62% for detecting intraspinal anomalies in congenital scoliosis, and 2-4% of adolescents with idiopathic scoliosis have intraspinal abnormalities detectable only by MRI 1, 2
Follow-Up Imaging Intervals
For serial monitoring after initial diagnosis:
- Maximum frequency of once every 6 months for skeletally immature patients with congenital or early onset scoliosis to minimize radiation exposure 1, 3
- Once every 12 months for adolescents at Risser stages 0-3 under observation 1
- Every 18 months for Risser stages 4-5 1
- Low-dose imaging protocols should be used when available to reduce cumulative radiation exposure in pediatric patients 1, 2
What NOT to Order Initially
- CT is not routinely indicated for initial scoliosis evaluation; reserve CT for presurgical planning to visualize bony malformations and reduce screw misplacement 1, 2, 3
- Oblique sacroiliac views add no diagnostic value over standard PA views 5
- Thoracic spine-only films are inadequate due to difficulty assessing overlying structures and missing compensatory curves 5