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We thank Becciolini et al for their interest in our recent paper,1 in which we demonstrated that a focused ultrasound (US) examination of the classical sites for rheumatoid arthritis (RA) damage, in particular the fifth metatarsophalangeal (MTP) joints, may improve risk stratification for progression to RA in anticyclic citrullinated peptide antibody positive (CCP+) at-risk individuals.
Becciolini et al suggest that scanning the pisotriquetral joint (PTJ) could improve the US sensitivity for the assessment of inflammation in patients with early inflammatory arthritis (IA).2 The logic of this suggestion is based on the results of MRI studies showing that synovitis and bone erosions can be frequently found in the carpal bones, including the PTJ, in patients with early RA.3 4 The authors have also provided pictorial examples to show how US pathological findings (ie, synovitis and bone erosions) can be detected at this level in one patient with RA.
In recent years, US and MRI have shown the ability to predict progression to IA, and its timing, in at-risk individuals without clinical synovitis, raising important implications for the management of these individuals, including preventive approaches.5 The US studies carried out in at-risk cohorts have used comprehensive protocols evaluating multiple pathological findings (ie, power Doppler signal, grey scale synovitis and/or bone erosions) in most or all relevant joints. Although feasible in a research setting, this can be time-consuming and therefore challenging in daily clinical practice. Which joints, and indeed how many joints, need to be evaluated for optimum predictive accuracy in at-risk individuals is still an unanswered question.
In our study, we evaluated only the joints which have been reported as the most specific for the detection of US bone erosions in RA: the second and fifth metacarpophalangeal joints and the fifth MTP joint.6 Our study has the potential to provide to rheumatologists, who are now routinely being referred at-risk individuals in clinical practice, a valuable tool which can be readily used in the clinical setting for the management and risk stratification of these individuals. We acknowledge, however, that targeting US to only these sites of RA damage might potentially exclude other anatomical sites (ie, distal ulna or PTJ) from being evaluated which, as a result, might lead to underestimating the overall prevalence of bone erosions in CCP +at risk individuals.
Both the pisiform and triquetrum have been long known to be sites for early radiographic bone erosions in RA.7 During an US assessment, the triquetrum would normally be scanned as part of the existing EUropean League Against Rheumatism scanning views of the ulnar-carpal aspect of the wrist with the triquetrum forming the ‘carpal part’. The pisiform, however, has been a less favoured area to evaluate, unless there was a specific clinical indication to do so (eg, a site of significant pain). This practice is partly historical as US image resolution in the past was not good enough to clearly demonstrate this small region. In addition, older machines with larger transducers provided limited adequate transducer access. Anatomically, the positioning of the pisiform on the triquetrum, also precludes the comprehensive visualisation of the joint, especially in perpendicular planes, which is likely to have an impact on reliability. We also note that the PTJ, like other aspects of the wrist, is a frequent location for osteoarthritis and therefore prone to both degenerative-related bone irregularity/erosion and synovitis raising the question of lesion specificity in these areas.8 However, we agree with Becciolini et al,2 that US may visualise synovitis in the surrounding recesses of the PTJ but whether this offers any additional information to more conventional areas, needs to be further explored. In conclusion, this area warrants further investigation but more data is required before it is suggested as a standard site to evaluate.
Handling editor Josef S Smolen
Contributors All authors were involved in conception, drafting or revising the article. All authors approved the final version to be submitted for publication.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests This study was conducted while ADM was an ARTICULUM fellow. KM reports personal fees from Abbvie, UCB and Eli Lilly, outside the submitted work. RJW has received honoraria from Abbvie, Novartis and GE for ultrasound-related educational activities. PE reports consultant fees from BMS, AbbVie, Gilead, Galapagos, Lilly, MSD, Pfizer, Novartis, Roche, and Samsung outside the submitted work. He also reports research grants from UCB, AbbVie, Lilly, Novartis, BMS, Pfizer, MSD and Roche, outside the submitted work.
Patient and public involvement Patients and/or the public were not involved in the design, or conduct, or reporting, or dissemination plans of this research.
Patient consent for publication Not required.
Provenance and peer review Commissioned; internally peer reviewed.
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