Diagnostic errors in musculoskeletal ultrasound imaging and how to avoid them.

The article reviews the major challenges related to the principles of the correct technique of musculoskeletal ultrasound (MSK US). All the crucial aspects of correct MSK soft tissue diagnosis have been discussed, including equipment settings, use of recent image software innovations and ultrasound standoff pads, and correct transducer positioning. The importance of the fundamental principles of MSK US, facilitating good quality image and limiting the occurrence of artifacts, has been highlighted. The most common artifacts of the musculoskeletal system have been described, including those that diagnostically helpful, such as the presence of echo enhancement deep to a fluid-filled structure, or an acoustic shadow behind a calcification. The presence of acoustic shadow in the context of lesions of a different type has also been discussed. The common anisotropy-related artifacts, frequently leading to diagnosis of a pathological condition where none is present, have been elaborated on. The frequently encountered mirror reflection artifact has been described. Special attention has been paid to the means of either eliminating, or taking advantage of artifacts for the correct diagnosis of musculoskeletal lesions. The possibilities and technique of correct differentiation of hypoechoic or anechoic foci, commonly found in the pathological conditions of the musculoskeletal system, have been analysed. Non-typical ultrasound findings leading to misdiagnosis of given pathological conditions have been discussed.