Performance of ultrasonography in diagnosis of calcium pyrophosphate deposition disease amongst Bangladeshi patients: an observational study

Due to protean presentations, poor sensitivity of radiographs and variable reliability of synovial fluid analysis, diagnosis of Calcium pyrophosphate deposition disease (CPPD) is a challenge. This study addressed the diagnostic performance of musculoskeletal ultrasound (MSK-USG) in identifying CPPD features in hyaline cartilage, fibrocartilage, tendon, and synovial fluid. We compared ultrasound findings in CPPD to those in osteoarthritis (OA) and gout and healthy control. In this retrospective exploratory study, MSK-USG performed between February 2022 and July 2023 were reviewed. Patients retrospectively fulfilled the ACR/ EULAR classification criteria 2023 (score ≥ 56) were included (n = 16). Clinical phenotypes included acute CPP arthritis (44%), CPPD with OA (44%), and chronic CPP arthritis (12%). Ultrasound images were evaluated at common CPPD target sites: hyaline cartilage and fibrocartilage of the knee, wrist triangular fibrocartilage, metacarpophalangeal joints, joint capsules, tendons, and synovial membranes. Ultrasound images of CPPD cases were compared to those of OA, gout, and healthy controls. Sensitivity, specificity, and predictive values were calculated for Ultrasound features. Compared to healthy controls, Ultrasound features showed a sensitivity of 94.12% (CI: 71.31–99.85), specificity of 100% (CI: 86.77–100), positive predictive value of 100%, and negative predictive value of 99.59% in diagnosing CPPD. Ultrasound findings in hyaline cartilage showed a sensitivity & a specificity of 100% each. Fibrocartilage involvement showed a sensitivity of 93.75% and specificity of 86.67%. Whereas these figures were lowest for tendons with sensitivity of 12.5% (CI: 1.55–38.35) and specificity of 86.67% (CI: 69.28–96.24), respectively. Compared to OA, sensitivity and specificity were 100% and 93.75%, respectively. Specificity was lower when compared to gout (40%). MSK-USG demonstrated high diagnostic accuracy in identifying CPPD, especially in hyaline cartilage and fibrocartilage. While these findings support the use of Ultrasound as an adjunctive diagnostic tool, particularly in distinguishing CPPD from OA, the small sample size and retrospective design limit generalizability. Prospective studies with larger cohorts and crystal-confirmed cases are needed for validation.