Ultrasonography in the evaluation of bone erosions

Abstract

Objective: To demonstrate the diagnostic efficacy of ultrasonography in depicting erosions in patients with rheumatoid arthritis and to compare sonographic and radiographic findings.

Methods: Sonographic images were obtained with an AU-4 Idea Esaote Biomedica (Genoa, Italy) equipped with a 13 MHz linear transducer.

Results: The images reported in this essay are representative examples of the ability of ultrasonography to detect and characterise even minimal bone margin changes in rheumatoid arthritis.

Conclusion: Ultrasonography with very high frequency transducers can depict bone erosions in early target areas of bone resorption. However, further studies are needed to validate this technique and to evaluate the relation between sonographic findings and those obtained with other imaging techniques (standard radiology, magnetic resonance).

Figure 1

Healthy subject. Metacarpophalangeal joint of the second finger: longitudinal (A) and transverse (B) dorsal scans. Metatarsophalangeal joint of the fifth toe: longitudinal (C) and transverse (D) dorsal scans. Articular cartilage appears as a clearly defined anechoic band delimited by sharp hyperechoic borders corresponding to the bone margin (arrowhead) and to the cartilage soft tissue interface (white triangle). mc = metacarpal head; mt = metatarsal head; ph = phalanx.

Figure 2

Rheumatoid arthritis. Longitudinal dorsal scans. Sonographic features of bone erosions of the metacarpal head. (A and B) Early disease. (C and D) Late disease. * = erosion; mc = metacarpal head; ph = phalanx.

Figure 3

Rheumatoid arthritis. Longitudinal dorsal views at different scanning planes as indicated on the corresponding standard radiogram (A). (B) Longitudinal dorsal scan shows a still well defined bone margin of the metacarpal head. (C) Longitudinal dorsal scan on a contiguous plane shows a clearly evident erosion (*). (D) Radial scan of the joint showing a large area of bone resorption (*). mc = metacarpal head; ph = phalanx.

Figure 4

Rheumatoid arthritis. Metacarpophalangeal joint of the second finger (same patient as fig 3). (A) Coronal scan. (B) Healthy subject. The coronal view demonstrates the good correspondence between radiographic (C) and sonographic (D) changes of the bone margin. * = erosion; mc = metacarpal head; ph = phalanx.

Figure 5

Rheumatoid arthritis. Metatarsal head of the fifth toe. Standard x ray (A) does not reveal clearly evident erosive changes (Sharp's score =1). (B and C) Off line digitalised radiograms show two areas of lower bone density (*) and loss of the normal sharp bone margin of the metatarsal head. (D) Longitudinal dorsal scan of metatarsal head does not reveal bone margin changes. (E) Coronal scan discloses clearly evident erosions of the metatarsal head, probably corresponding to the areas of low bone density on x ray. mt = metatarsal head.

Figure 6

Rheumatoid arthritis. Metatarsophalangeal joint of the fifth toe. Sonographic features of the metatarsal head at different scanning planes. These pictures demonstrate the potential role of multiplanar sonographic examination in detecting bone erosion (*). mt = metatarsal head.

Figure 7

Rheumatoid arthritis. Metatarsophalangeal joint of the fifth toe. Sonographic findings in late rheumatoid arthritis with cystic like areas of bone resorption on posteroanterior view. (A) Standard x ray. (B) Longitudinal dorsal scan between the two areas of bone erosions does not show any interruption of bone margin. (C) Sonographic scan on the border of the erosion. (D) Longitudinal scan in the centre of the area of bone resorption. (E) Coronal scan. * = erosion; mt = metatarsal head; ph = phalanx.

Figure 8

Rheumatoid arthritis. Metacarpophalangeal joint of the second finger. (A) Standard x ray. Multiplanar examination in patient with late disease. Ultrasonography is able to depict the extent of bone resorption both on longitudinal (B and C) and transverse scans (D). mc = metacarpal head; ph = phalanx; * = erosion.