Ultrasound in the diagnosis of calcium pyrophosphate dihydrate deposition disease. A systematic literature review and a meta-analysis

Abstract

US is potentially a useful tool for the diagnosis of CPPD but universally accepted definitions and further testing are necessary in order to assess the role of the technique in the diagnostic process.

Diagnosis of calcium pyrophosphate deposition by imaging – current state and challenges remaining

“…In fact, there are currently no definitions available for US features of BCP crystal deposition deep within joints (fibrocartilage, hyaline cartilage, and synovial fluid) and, to date, no study has conclusively proven that US detected lesions in tendons according to OMERACT definitions were indeed true pure CPP deposits. This might explain the lower agreement for tendon involvement, both here and in previous US studies 12,13 , and the comparable prevalence of "CPP" deposits in the patellar tendon and synovial fluid between cases and controls in this study.…”

“…In contrast, ultrasound (US) has generated much more interest and been increasingly used for the diagnosis of CPPD over the past decade. Ultrasound has proven useful in identifying calcifications in peripheral joints, particularly the knee, yielding higher pooled sensitivity (34e77%) and specificity (92e100%) than conventional radiography when considering each joint structure and variable reference standards 12 . However, this recent systematic literature review with meta-analysis also emphasized that although the diagnostic accuracy of US in CPPD was relatively high in all studies, the definitions used for US characteristics of CPPD varied considerably 12 .…”

“…Ultrasound has proven useful in identifying calcifications in peripheral joints, particularly the knee, yielding higher pooled sensitivity (34e77%) and specificity (92e100%) than conventional radiography when considering each joint structure and variable reference standards 12 . However, this recent systematic literature review with meta-analysis also emphasized that although the diagnostic accuracy of US in CPPD was relatively high in all studies, the definitions used for US characteristics of CPPD varied considerably 12 . This prompted the formation of the outcome measures in rheumatology (OMERACT) US CPPD task force with the aim of first agreeing on the US features and definitions of CPP deposits in joints and periarticular tissues, and then assessing their reliability 13 .…”

“…While the authors are to be commended for having accomplished such an exciting piece of work sparking new insights into the diagnostic role of US in CPPD of the knee, the study by Lee et al also raises a few comments and concerns. First, a major issue is, as with previous US studies 12,13 , the concern for exposure misclassification since the reference standard used was synovial fluid analysis. As previously mentioned, compensated polarized light microscopy of synovial fluid can be challenging and is not the ideal 100%-accurate gold standard 4 CPP crystal deposits in various joint structures.…”

Identification of calcium pyrophosphate deposition disease (CPPD) by ultrasound: reliability of the OMERACT definitions in an extended set of joints—an international multiobserver study by the OMERACT Calcium Pyrophosphate Deposition Disease Ultrasound Subtask Force

“…Since then, the group has produced a systematic literature review and meta-analysis12 on the use of US in the identification of CPPD and has created the US definitions for the identification of CPPD 7. First, reliability assessment of the definitions was then carried out in 2015 in Siena involving the fibrocartilage of the knee and wrist (TFC), the hyaline cartilage of the knee, the quadriceps/patellar/Achilles tendons and the synovial fluid of the knee and wrist.…”