Background:Only few articles evaluated the wrist in calcium pyrophosphate deposition disease (CPPD), although it is the second most frequent target of CPPD. Very recently, in a computed tomography (CT) study ligamentous calcifications were reported as a highly specific feature of CPPD at wrist level (1).Objectives:i) to determine the prevalence and distribution of the ultrasound (US) findings indicative of calcium pyrophosphate (CPP) crystal deposits at the wrist, with a particular focus on the dorsal aspect of the scapho-lunate ligament (SLL); ii) to investigate the diagnostic accuracy of US and conventional radiography (CR) in the evaluation of CPP crystal deposits at wrist level, iv) to assess the agreement between the different imaging techniques.Methods:Consecutive patients with a “definite” diagnosis of CPPD according to the Ryan and McCarty criteria and disease controls were prospectively included in this cross-sectional single-centre study. Dorsal part of the SLL, triangular fibrocartilage complex (TFCC), and volar recess of the radio-lunate joint were explored using US (according to EULAR standard scans and OMERACT definitions), CR and CT.Results:Sixty-one CPPD patients and 39 disease controls were enrolled. Two-hundred wrists were evaluated using both CR and US. CT data of 26 (13.0%) wrists were available: 20 wrists in CPPD patients and 6 wrists in controls. CPP crystal deposits were found by US in at least one wrist in 95.1% of CPPD patients and in 15.4% of controls (p<0.001). SLL calcification was reported in 83.6% of CPPD patients and in 5.1% of controls (p<0.001). CPP crystal deposits were observed by US at the SLL and/or radio-lunate joint in 5.7% of wrists and 6.6% of CPPD patients, but not at the TFCC of the same wrist. On CR, calcifications were found in at least one wrist in 72.1% of CPPD patients and in 0% of controls (p<0.001). Using the Ryan-McCarty criteria as a gold standard, the sensitivity, specificity and diagnostic accuracy were 0.72 (0.59-0.83), 1.0 (0.91-1.0) and 0.83 (0.74-0.90) for CR and 0.95 (0.86-0.99), 0.85 (0.69-0.94) and 0.91 (0.84-0.96) for US. Table 1 shows the agreement between the different imaging techniques.Tabel 1.Agreement between US and the other imaging techniques in the evaluation of CPP crystal deposits at the wrist.US-CR (n=200)US-CT (n=26)TFCC0.55 (0.43-0.67)0.70 (0.43-0.97)SLL0.23 (0.07-0.39)0.69 (0.41-0.97)RLJ0.25 (0.09-0.41)0.46 (0.12-0.80)Legend.n: number of the wrists,RLJ: volar recess of the radio-lunate joint. Values in brackets are the 95% confidence intervals of the Cohen’s kappa.Figure 1provides a pictorial evidence of the appearance of CPP crystal deposits in the SLL.A: CPP crystal deposits (curved arrow) at the TFCC. The SLL is not assessable due to superimposition of other bones.B: in the same patient of figure 1A, CT scan shows the presence of a calcification of the dorsal aspect of the SLL (arrow).C: dorsal longitudinal scan of the SLL: isolated hyperechoic spot (arrowheads) inside the ligament.D: dorsal longitudinal scan of the SLL showing the presence of a large aggregate extending towards the extensor tendons and hyperechoic spots (arrowheads) within it.Legend.iii: third extensor compartment,iv: fourth extensor compartment,l: lunate bone,s:scaphoid bone.Conclusion:This study supports the diagnostic accuracy of US in evaluating wrist involvement in CPPD patients. SLL calcifications are a specific US finding of CPPD at wrist level.References:[1]Ziegeler K, Diekhoff T, Hermann S, et al. Low-dose computed tomography as diagnostic tool in calcium pyrophosphate deposition disease arthropathy: focus on ligamentous calcifications of the wrist. Clin Exp Rheumatol 2019;37:826-33.Disclosure of Interests:Edoardo Cipolletta: None declared, Gianluca Smerilli: None declared, Riccardo Mashadi Mirza: None declared, Andrea Di Matteo Grant/research support from: the publication was conducted while Dr. Di Matteo was an ARTICULUM fellow, Fausto Salaffi Speakers bureau: Dr. Salaffi reports personal fees from Bristol Myers Squibb, personal fees from Pfizer, personal fees from Novartis, personal fees from AbbVie, personal fees from Roche, personal fees from Merck Sharp & Dohme Italia, outside the submitted work., Walter Grassi Speakers bureau: Prof. Grassi reports personal fees from AbbVie, personal fees from Celgene, personal fees from Grünenthal, personal fees from Pfizer, personal fees from Union Chimique Belge Pharma, outside the submitted work., Emilio Filippucci Speakers bureau: Dr. Filippucci reports personal fees from AbbVie, personal fees from Bristol-Myers Squibb, personal fees from Celgene, personal fees from Roche, personal fees from Union Chimique Belge Pharma, personal fees from Pfizer, outside the submitted work.
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