1. Intra-articular discontinuity of the bone surface is visible in 2 perpendicular planes OMERACT, Wakefield and coll. J Rheumatol 2005. ULTRASOUND DEFINED EROSION IN RA dorsal longitudinal (A) and transverse longitudinal (B) scans A B

2. Erosion of the 2 MC visible in two perpendicular planes: dorsal longitudinal (A) and transverse longitudinal (B) scans A B METACARPAL HEAD

3. Erosion of the 2 MC visible in a longitudinal dorsal scan METACARPAL HEAD

4. Erosion of the 2 MC visible in a longitudinal dorsal scan with inflammatory synovitis and vessels inside the erosion METACARPAL HEAD

5. Erosion of the 2 MC visible in a longitudinal dorsal scan with inflammatory synovitis and vessels inside the erosion

6. METACARPAL HEAD Erosion of the 2 MC visible in a longitudinal dorsal scan in B mode (A) and with Doppler (B): inflammatory synovitis and vessels inside the erosion A B

7. METACARPAL HEAD A B Erosion of the 5 MC visible in two perpendicular planes: dorsal longitudinal (A) and transverse longitudinal (B) scans

8. Several coalescent erosions of the 2 MC visible in two perpendicular planes: dorsal longitudinal (A) and transverse longitudinal (B) scans METACARPAL HEAD A B

9. Several coalescent erosions of the 3 MC visible in two perpendicular planes: dorsal longitudinal (A) and transverse longitudinal (B) scans A B

10. Dorsal Radius: large erosion in a transverse scan WRIST

11. Lunatum: several coalescent erosions in longitudinal (A) and transverse (B) palmar scans A B

12. Dorsal Ulna, transverse scan: several coalescent erosions WRIST

13. Processus Styloideus of ulna: several coalescent erosions: longitudinal dorsal (A) and transverse dorsal (B) scans A B

14. ELBOW Radial head in anterior longitudinal scan : large erosion

15. Actual limitations Acoustic window Pitfalls –physiological vessel bone channels, normal irregularities of cortical bone, grooves, sesamoids Co-existent OA may be confused with erosions – pseudo-erosions, osteophytes

16. ENTHESOPHYTES Enthesophyte of the 2 MC visible in a longitudinal dorsal scan (arrow)

17. IRREGULARITIES, EROSION OR PRE-EROSION ? Radial aspect of 2 nd MC : longitudinal scan (A) and transverse scan (B) A B