Information Technology Reference
In-Depth Information
Quantitative Monitoring of Bone
Formation in Ankylosing Spondylitis
Using Computed Tomography
Sovira Tan
Abstract Ankylosing Spondylitis, an in
ammatory 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
fl
first year, 73 % of patients had a volume
increase computed by the algorithm compared to only 12 % for the reading of
radiographs.
1 Introduction
Ankylosing Spondylitis (AS) is a progressive in
ammatory arthritis affecting pri-
marily the spine. It characteristically causes back pain and can lead to structural and
functional impairments. As a result, AS patients may suffer from work disability,
unemployment, and reduced quality of life. Estimates of prevalence rates range
from 0.1 to 1.4 % of the general population. AS is about twice as common in men
as in women. It has a known association with an important immunogenetic com-
ponent of DNA known as HLA-B27. The majority of patients affected by AS are
HLA-B27 positive. AS patients may also develop in
fl
fl
ammation of tendon
bone
-
