Although the diagnosis of arthritis and spondyloarthritis is based on clinical criteria, today the imaging methods are an indispensable aid to the rheumatologist. Imaging has not only the task of helping early diagnosis, but it has also a fundamental role in disease grading and therapeutic monitoring. In this scenario where many publications emphasize the importance of identifying synovitis and erosions at an early stage, it is essential to know the possible pitfalls which can determine both false positives and false negatives. The high variability of the musculoskeletal system anatomy makes it necessary to have a correct knowledge of all anatomical complexes, in order not to confuse them with the pathology. Moreover, the correct and standardized method of the execution and interpretation of the exams, such as ultrasound, is crucial to identifying and correctly monitoring the pathological hallmarks of the arthritis. This paper aims to provide an instrument to radiologists, highlighting the main imaging pitfalls in ultrasound and magnetic resonance which may be encountered in daily practice.
Keywords: Arthritis; Enthesitis; MRI; Pitfalls; Ultrasound.