Gout: Using CT Scan to Diagnose Difficult Cases

Tim Bongartz, M.D. Associate Professor of Medicine Department of Rheumatology Mayo Clinic, MinnesotaMedicalResearch.com Interview with:
Tim Bongartz, M.D.
Associate Professor of Medicine
Department of Rheumatology
Mayo Clinic, Minnesota


MedicalResearch.com: What are the main study findings?

Dr. Bongartz:  Dual-energy computed tomography (DECT) is an imaging methods that has been in use for many years to classify the material of renal stones. Our study demonstrates that this technology can be useful in identifying monosodium urate deposits in and around joint, allowing to diagnose patients with gout with overall high sensitivity and specificity. Importantly, a stratified analysis of patient subgroups revealed that DECT is less accurate in diagnosing patients with a first flare of gout, emphasizing the importance of careful patient selection when using this new technology. In a “diagnostic-yield” substudy, we explored the question how much DECT could contribute to correctly diagnose patients where clinicians did have a high level of suspicion for gout, but synovial fluid aspiration results came back negative. In about a third of these patients with negative routine testing, we could confirm a diagnosis of gout through use of DECT.

MedicalResearch.com: Were any of the findings unexpected?

Dr. Bongartz:   We were impressed by the high number of patients in our diagnostic yield substudy who did have a negative synovial fluid analysis but found to have gout based on the DECT findings and subsequent targeted aspiration results. Many of these patients had unusual locations of their uric acid deposition, such as in tendon sheaths or around ligament/tendon attachment sites. These findings suggest that we really have to think about gout as an underlying pathology in a wide variety of inflammatory musculoskeletal conditions, even if the initial aspiration is negative.

MedicalResearch.com: What should clinicians and patients take away from your report?

Dr. Bongartz:   We believe that based on our findings, DECT should be considered as a second line test when gout is suspected but aspiration results come back negative. As part of our diagnostic yield study, DECT helped to correctly diagnose several patients with gout who had been falsely labeled with diagnoses such as “seronegative rheumatoid arthritis” because of synovial fluid analyses that had failed to detect monosodium urate crystals.

On the other hand, physicians should be aware of the lower sensitivity of DECT in patients with a first flare of gout and we don’t believe that DECT should replace joint aspiration and synovial fluid analysis as the first line test.

MedicalResearch.com: What recommendations if any do you have for future research as a result of this study?

Dr. Bongartz:   The ability to visualize the topography of monosodium urate deposition in patients with gout opens up a whole new avenue of research. We can now quantify the “burden” of monosodium urate deposits in individual patients and monitor their resolution as part of therapeutic studies. We are able to approach questions regarding the true extent and anatomy of monosodium urate deposition in patients with clinically overt as well as those with subclinical disease. And we may be able to better determine whom to treat with uric acid lowering agents early on, as this may be dependent on the extent of monosodium urate deposition at the time of a first flare of gout.

Citation:

Dual-energy CT for the diagnosis of gout: an accuracy and diagnostic yield study

  • Tim Bongartz,
  • Katrina N Glazebrook,
  • Steven J Kavros,
  • Naveen S Murthy,
  • Stephen P Merry,
  • Walter B Franz III,
  • Clement J Michet,
  • Barath M Akkara Veetil,
  • John M Davis III,
  • Thomas G Mason II,
  • Kenneth J Warrington,
  • Steven R Ytterberg,
  • Eric L Matteson,
  • Cynthia S Crowson,
  • Shuai Leng,
  • Cynthia H McCollough

Ann Rheum Dis annrheumdis-2013-205095Published Online First: 25 March 2014 doi:10.1136/annrheumdis-2013-205095