NEWS | July 10, 2012

UC Davis researchers demonstrate usefulness of a novel PET/CT device in inflammatory arthritis


UC Davis researchers have shown that their specially constructed PET/CT scanner enables better monitoring of the course of inflammatory arthritis - a costly and painful disease.

The custom-built device is designed to improve upon existing imaging techniques such as whole-body PET scans, which do not adequately reveal the effects of inflammatory arthritis such as rheumatoid and psoriatic arthritis in small joints.

PSA finger © UC Regents
High resolution PET/CT: image of the finger joints in a psoriatic arthritis patient; top - CT, bottom - PET, center - fusion of PET/CT.

Abhijit Chaudhari, assistant professor of radiology at UC Davis, presented his findings at a recent meeting of the Society of Nuclear Medicine and Molecular Imaging. The presentation was covered by, a leading radiology research news resource.

Inflammatory arthritis affects over 2 percent of the world's population of a cost estimated at more than $40 billion, according to the article. The disease can erode cartilage and bone and result in permanent disability.

"Dr. Chaudhari's novel imaging techniques allow clinicians and patients to visualize inflammation in the joint early in the disease process and to follow this inflammation during treatment," said Nancy Lane, endowed professor of medicine and rheumatology at UC Davis. "This should allow clinicians to determine if patients are resopnding to therapies sooner and to make therapy adjustments as necessary."

Because the radiotracer used in PET scanning accumulates in areas of the body where inflammation occurs, Chaudhari and colleagues thought it might be a good marker for inflammatory arthritis.

For their study, Chaudhari tested four men and five women (five with rheumatoid arthritis and three with psoriatic arthritis). Each patient lay atop the scanning device gantry, with his or her hand or arm hanging down through a hole in the table. A PET/CT scanner rotated around the affected limb. 

Radiological evaluations of the images found that classic symptoms associated with inflammatory arthritis were clearly identified from the PET scan on anatomical images captured from the CT.  They found that the uptake of the radiotracer correlated with findings on an MRI scan at areas in the limb where changes in the bone had occurred. Erosive changes in bone were better detected from the CT than from MRI scans. The findings suggest that PET/CT is useful for disease monitoring as well as determining whether a given treatment is working.

While there are new drugs effective in treating inflammatory arthritis, not every patient responds well to the treatment.

"Our initial studies with PET/CT show that the device can separate responders from non-responders at an early time point, which is critical, because non-responders can try other drugs before their disease progresses, while responders can avoid the cost and toxicity associated with some of the more aggressive treatments," Chaudhari said.

The system appeared to be sensitive to  early, albeit small changes in disease status, demonstrating that high resolution PET/CT is a potential tool for optimizing treatment and improving outcomes for inflammatory arthritis. In addition, PET/CT can produce detailed molecular and anatomical pictures of the status of disease, giving physicians and scientists new insights into the pathology responsible for inflammatory arthritis. One high-resolution picture from the device, for example, was chosen as the still image of the year by the American College of Rheumatology. The image showed the possible mechanism of inflammation of the nail bed typical in patients with psoriatic arthritis.

Chaudhari's research and clinical trials using the device are being conducted with colleagues in the UC Davis departments of radiology, medicine and the Sacramento VA Medical Center. The multidisciplinary team consists of rheumatologists, scientists, clinical radiologists, physicians and biomedical engineers.