O2087: Novel Surface Topographic Assessment of Pulmonary Function in Pediatric Spinal Deformity Patients

Background: Restrictive pulmonary disease is associated with severe spinal deformity, thought to result from thoracic distortions and lung-volume limitations. Though spirometry and body plethysmography are the gold standard for pulmonary function tests (PFTs), these tests are time-consuming and expensive, and certain patient populations cannot adhere to the instructions or breathing efforts necessary. Surface topographic (ST) scanning may offer a solution to such concerns, as these scans do not require radiation, anesthesia, significant patient compliance or external devices attached to the face or torso (i.e. mouthpieces or markers). As such, this study investigates whether ST measurements of body volume difference (BVD) between maximum inhale and exhale are predictive of forced vital capacity (FVC), vital capacity (VC) and total lung capacity (TLC) as measured by PFTs.

Methods: This retrospective study included pediatric patients (age 10-18 years) with idiopathic scoliosis and thoracic or thoracolumbar curves greater than or equal to 40˚. These patients received ST scans, standard clinical examinations and EOS biplanar radiographs as standard of care on the same day, and performed PFTs within 3 months of imaging studies. Patients were instructed to inhale and exhale to the fullest extent in the ST scan, which provided the volumetric measurements used to calculate BVD. Linear regression analysis was used to examine the relationships between PFT values, BVD and thoracic/thoracolumbar curves.

Results: Eighteen patients (14 ± 2 years, body mass index 21.4 ± 4.5 kg/m2, 72.2% female) with a mean thoracic/thoracolumbar curve of 61.5˚ ± 13.9˚ (45.1˚- 92.6˚) were assessed. All patients in this cohort had scoliosis: 16 idiopathic, 1 neuromuscular, and 1 thoracogenic. BVD measured by ST scanning displayed statistically significant positive correlations with FVC (R = 0.874, p < 0.0001), VC (R = 0.831, p < 0.0001) and TLC (R = 0.768, p < 0.0001) (Table 1). No significant correlations emerged between Cobb angle and ST BVD measurements or PFT values.

Conclusion: This study provides a proof-of-concept for the applicability of ST scanning to pulmonary function assessment given the significant positive correlations of ST BVD with FVC, VC, and TLC. ST scanning may serve as an inexpensive, reproducible non-contact method for analyzing thoracic volume that may include patients unable to cooperate with formal PFTs. Curve severity did not correlate to worsening BVD or PFT values. Further studies with a larger cohort, as well as healthy controls, must be conducted in order to validate this technology as an alternative diagnostic tool to spirometry. Moreover, a larger sample of scoliosis patients with more varied thoracic curve severity is needed to fully assess correlations between thoracic curve angle and pulmonary function.