Quantitative Monitoring of Bone Formation in Ankylosing Spondylitis Using Computed Tomography
Author: Sovira Tan
Publisher: Springer International Publishing
Ankylosing Spondylitis, an inflammatory disease affecting mainly the spine, can be characterized by abnormal bone structures (syndesmophytes) growing at intervertebral disk spaces. Monitoring the evolution of these syndesmophytes has been a challenge because of their slow growth rate, a problem compounded by the use of radiography and a mainly qualitative rating system. To improve the low sensitivity to change of radiographic reading, we designed a computer algorithm that fully quantitates syndesmophytes in terms of volume using the 3D imaging capabilities of computed tomography. Its reliability was assessed by computing the difference between the results obtained from 2 scans performed on the same day in 9 patients. A longitudinal study performed over 2 years with 33 patients shows that the method holds promise for longitudinal clinical studies of syndesmophyte development and growth. At the end of the first year, 73 % of patients had a volume increase computed by the algorithm compared to only 12 % for the reading of radiographs.