Optimizing the Use of Ultrasound in Calcium Pyrophosphate Deposition (CPPD): A Review from the Ground Up

Ultrasound is a pivotal exam in calcium pyrophosphate deposition (CPPD) identification. It has been demonstrated to be feasible, accurate, and reliable for CPPD diagnosis. Even if standardized definitions and a scoring system for CPPD have been established by the OMERACT ultrasound working group, ultrasound is still considered one of the most operator-dependent techniques. This is because in ultrasound, both the acquisition and the interpretation phases of the diagnostic process are in the hands of one operator and are performed simultaneously, in contrast to what happens with other imaging exams, where the acquisition process is standardized and independent from the interpretation process. Therefore, the scanning technique and machine setting acquire a central role, almost as important as the interpretation of the images, as erroneous scanning may lead to interpretative mistakes. In this review, we will delve into the appearance of CPPD on ultrasound, based on the latest research findings, passing through its pathogenesis, and focusing on machine settings and ultrasound scanning techniques, providing some tips and tricks to facilitate accurate CPPD recognition in the most frequently affected sites.