According to an article in the American Journal of Roentgenology (AJR), technological improvements, clinical practice changes, and growing experience among radiologists and referrers alike are contributing to the evolving role of dual-energy CT (DECT) in gout workup.
When comparing DECT examinations performed for gout in 2013 and 2019, the frequency of equivocal interpretations was significantly lower in 2019, “possibly related to interval technologic improvements,” says lead researcher Francis I. Baffour, MD, a diagnostic radiologist at Mayo Clinic in Rochester, Minn. “Negative examinations were less frequently followed by joint aspirations in 2019, possibly reflecting increasing clinical acceptance of the DECT results.”
Baffour and colleagues’ retrospective study included 100 consecutive adult patients who underwent DECT for gout evaluation in each of two periods, beginning in March 2013 and September 2019. DECT examinations in 2013 used a second-generation scanner (140 kV with 0.4 mm tin filter); in 2019, a third-generation scanner (150 kV with 0.6 mm tin filter) with improved spectral separation was used. Original DECT reports were classified as positive, negative, or equivocal for monosodium urate crystals indicative of gout. Joint aspirations occurring postexamination were recorded via medical record review.
Compared with the 2013 DECT examinations performed for suspected gout, those performed in 2019 had a significantly lower frequency of equivocal interpretations (16.0% vs. 33.0%, p<.001). Moreover, joint aspiration was significantly less likely to be performed after negative DECT interpretations in 2019 than in 2013 (2.1% vs. 17.4%, p=.02).
“The findings indicate an evolving role for DECT in the evaluation of gout following an institution’s routine adoption of the technology for this purpose,” the authors of the AJR article add.
Featured image: (A) Coronal image through forefoot and (B) coronal image through ankle. Green pixels (arrows) observed in association with first and fourth metatarsophalangeal joints (A) and tibiotalar joint (B), consistent with monosodium urate deposition. Examination interpreted as positive for gout. Final clinical diagnosis by referring service was gout. Confirmatory joint aspiration not performed after DECT examination.