Purpose: Three factors affect the projection of the breast after augmentation or reconstruction: breast tissue, implant, and underlying chest wall. While much has been written about tissue and implants, this is the first study that objectively examines anatomic variation and asymmetry in female anterior thoracic contour and evaluates their effect on breast projection.

Methods: A consecutive series of 50 female cross-sectional thoracic CT scans was examined at the level of the fourth rib. Specific measurements were taken to evaluate overall contour and asymmetry. There were no specific inclusion criteria; patients with thoracic wall surgery or trauma were excluded.

Results: The mean width:depth (WD) ratio was 1.46:1 (Range: 1.07-1.63, STDev: 1.46 +/- 0.14). All (100%) of patients showed asymmetry between their right and left thorax. Ages ranged from 21-91 years. As age increased, the WD ratio of the thorax increased (p<0.005).

Conclusion: Patients with lower WD ratios have sloped anterior chest walls and lateral appearance of the nipple, while higher WD ratios yield flatter anterior chest walls with the nipple closer to the mid-clavicular line. The average shape of the thorax of the women in our study was somewhere between the very flat shape seen with a high WD ratio and the very sloped shape seen with a low WD ratio. A wide amount of variation was seen in overall contour, which differs from previous studies. These results underscore the importance of clinical examination of the chest wall before surgery to help predict outcome and maximize patient satisfaction.