A Clearer Picture of the Gaps in Bones and Joints
A new twist on CT scanning software enables imaging of cartilage loss in osteoporosis
Doctors who treat bone and joint disorders such as osteoarthritis, rheumatoid arthritis and gout need clear pictures of affected areas. Typically they use X-rays, MRIs and ultrasound to acquire images, but the images are usually only two-dimensional and their interpretation is subjective.
In osteoarthritis, the standard measure of disease progression is a narrowing of the space between joints, indicating loss of cartilage as seen on X-rays. Currently X-rays are the only measure of bone and joint status approved by the U.S. Food and Drug Administration for clinical trials.
Computed tomography has rapidly gained popularity in rheumatology because it gives the clearest images of mineralized tissue, produces images rapidly, and can be assembled into 3D pictures. CT technology, though, cannot distinguish features below the device’s resolution limit, and the space between joints is usually below it. To improve image resolution, radiation dose must be raised. And nobody wants to do that.
A team of researchers from Cambridge University and Norwich University Hospital in the United Kingdom has developed a method of CT scan analysis they call “joint space mapping.” They published the results of a JSM experiment on a human femur in the June 18 issue of Scientific Reports.
First they acquired 3D images of the head of the femur and the acetabular bone, which is the concave area of the pelvis into which the femur fits. They labeled each part of the digital images as bone or other tissue -- a process called bone segmentation -- and then applied a new algorithm to detect and measure the space between the femur and the acetabulum with twice the sensitivity of an X-ray. While two other techniques for measuring joint space width using CT scans in rheumatoid arthritis have been described, both were restricted to the small joints of the hand, did not result in 3D images, and did not provide higher resolution than the standard method.
The authors believe the new method will improve the accuracy of osteoarthritis diagnoses and allow monitoring of joint changes over time. They have made the software they developed freely available for use by the medical community.