title: Spinal penetration index assessment in adolescent idiopathic scoliosis using EOS low-dose biplanar stereoradiography.
abstract: OBJECTIVE
  The spinal penetration index (SPI) quantifies the portion of the rib cage occupied by vertebrae. When measured by computed tomography (CT) or magnetic resonance imaging, SPI can only be determined in the reclining position, which modifies spinal and thoracic morphology. CT results in high radiation exposure. The authors studied rib cage and spinal morphology using low-dose biplanar stereoradiography and their impact on respiratory function in adolescent idiopathic scoliosis (AIS).
  
  
  METHODS
  In eighty thoracic AIS patients, a slot-scanning radiologic device allowing simultaneous acquisition of orthogonal images and 3D reconstructions with low exposure to radiation (EOS) was used to determine thoracic volume, mean spinal penetration index (SPIm), apical spinal penetration index (SPIa), main thoracic (MT) curve Cobb angle, T4-T12 kyphosis, and apical vertebral rotation (AVR).
  
  
  RESULTS
  Thoracic volume was correlated with thoracic kyphosis (r = 0.31, p = 0.006), but not with SPI, MT Cobb angle, or AVR. SPIm and SPIa were negatively correlated with thoracic kyphosis. Forced vital capacity and forced expiratory volume in 1 s were significantly lower in the hypokyphotic patients (p = 0.04, p = 0.03, respectively) and correlated with thoracic volume and T4-T12 kyphosis. No correlation was found between spinal penetration indices and pulmonary function tests, but SPIm was significantly greater in patients with obstructive syndrome (p = 0.01).
  
  
  CONCLUSIONS
  With little radiation exposure, EOS biplanar stereoradiography permits routine imaging is a functional standing position. Hypokyphotic patients had significantly decreased FEV1 and FVC. SPIm was significantly higher in patients with obstructive syndrome.
authors.affiliation: Pediatric Orthopaedic Department, Robert Debré Hospital, AP-HP, Paris Diderot University, 48 Bd Sérurier, 75019, Paris, France, i_brice@hotmail.com.
authors.forename: Brice
authors.initials: B
authors.lastname: Ilharreborde
authors.forename: Jean
authors.initials: J
authors.lastname: Dubousset
authors.forename: Wafa
authors.initials: W
authors.lastname: Skalli
authors.forename: Keyvan
authors.initials: K
authors.lastname: Mazda
mesh_terms: D000293:Adolescent; D005260:Female; D006801:Humans; D007738:Kyphosis / Q000000981:diagnostic imaging; D008171:Lung Diseases / Q000175:diagnosis / Q000209:etiology; D008297:Male; D059869:Radiostereometric Analysis; D012129:Respiratory Function Tests; D012600:Scoliosis / Q000150:complications / Q000000981:diagnostic imaging* / Q000503:physiopathology / Q000601:surgery; D013123:Spinal Fusion; D035441:Thoracic Wall / Q000000981:diagnostic imaging*