Abstract
BackgroundA definite diagnosis of gout requires demonstration of monosodium urate crystals in synovial fluid or in tophi, which in clinical practice today seldom is done. Dual energy CT (DECT) has repeatedly been shown to be able to detect monosodium urate crystals in tissues, hence being an alternative method to synovial fluid microscopy. The vast majority of these studies were performed with CT scanners with two X-ray tubes. In the present study we aim to investigate if and at what locations DECT with rapid kilovoltage-switching source with gemstone scintillator detector (GSI) can identify MSU crystals in patients with clinically diagnosed gout. We also performed a reliability study between two independent readings.MethodsPatients with new or established gout who had been examined with DECT GSI scanning of the feet at Sahlgrenska University Hospital, Mölndal between 2015 and 2018 were identified. Their medical records were sought for gout disease characteristics using a structured protocol. Urate deposits in MTP1, MTP 2–5, ankle/midfoot joints and tendons were scored semiquantatively in both feet and presence of artifacts in nail and skin as well as beam hardening and noise were recorded. Two radiologists performed two combined readings and scoring of the images, thus consensus was reached over the scoring at each occasion (Espeland et al., BMC Med Imaging. 2013;13:4). The two readings were compared with kappa statistics.ResultsDECT GSI could identify urate deposits in the feet of all 55 participants with gout. Deposits were identified in the MTP-joints of all subjects but were also present in ankle/midfoot joints and tendons in 96 and 75% respectively. Deposition of urate was predicted by longer disease duration (Spearman’s Rho 0.64, p < .0001) and presence of tophi (p = 0.0005). Artifacts were common and mostly found in the nails (73%), a minority displayed skin artifacts (31%) while beam hardening and noise was rare. The agreement between the two readings was good (Κ = 0.66, 95% CI = 0.61–0.71).ConclusionThe validity of DECT GSI in gout is supported by the identification of urate in all patients with clinical gout and the good correlations with clinical characteristics. The occurrence of artifacts was relatively low with expected locations.
Highlights
Gout is world wide the most common inflammatory arthritis and is caused by the deposition of monosodium urate (MSU) crystals in joints, tendons and various tissues which may cause an inflammatory response, clinically recognized as an acute episode of gout
Patients with new or established gout who all fulfilled the ACR/EULAR classification criteria for gout [2] and had been examined with Dual energy CT (DECT) gemstone scintillator detector (GSI) scanning of the feet at Sahlgrenska University Hospital, Mölndal between 2015 and 2018 as part of clinical diagnostics or disease monitoring of gout were identified. They all had at least one ICD-10 diagnosis of gout (M10) in their medical records. Their medical records were examined according to a structured protocol for gout disease characteristics including information on onset of disease, presence of tophi, comorbidities (ischemic heart disease (IHD), hypertension (HT), dyslipidemia), treatment with loop or thiazide diuretics or urate lowering therapy (ULT), body mass index (BMI), serum urate level at time of DECT, and renal function described as eGFR calculated by the CKD-EPI formula [9]
We identified a total of 55 patients with a clinical diagnosis of new or established gout who had been examined with DECT GSI scanning of both feet, 43 men and 12 women, with a mean age of 60 (SD = 16) years for the men and 53 (SD = 14) years for the women (Table 1)
Summary
Gout is world wide the most common inflammatory arthritis and is caused by the deposition of monosodium urate (MSU) crystals in joints, tendons and various tissues which may cause an inflammatory response, clinically recognized as an acute episode of gout. In clinical practice joint aspiration is seldom performed [1] and the majority of patients do not have visible tophi. This is reflected in the ACR/EULAR classification criteria for gout from 2015 where imaging evidence of urate deposition by ultrasound or dual energy CT (DECT) is included as an important item [2]. A definite diagnosis of gout requires demonstration of monosodium urate crystals in synovial fluid or in tophi, which in clinical practice today seldom is done. In the present study we aim to investigate if and at what locations DECT with rapid kilovoltage-switching source with gemstone scintillator detector (GSI) can identify MSU crystals in patients with clinically diagnosed gout. We performed a reliability study between two independent readings
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
