Ultrasound and MRI of the foot in children and adolescents newly diagnosed with juvenile idiopathic arthritis

Abstract

Aim: To evaluate the spectrum of inflammatory features in foot joints which may be detected on routinely performed ultrasound (US) and magnetic resonance imaging (MRI) in children newly diagnosed with juvenile idiopathic arthritis (JIA).

Material and methods: Two groups of children hospitalized in a reference center for rheumatology, newly diagnosed with JIA and suspected of foot involvement in the course of JIA were included in this retrospective study. In the first group of 47 patients aged 1-18 years, the imaging was restricted to US. The second group of 22 patients aged 5-18 years underwent only non-contrast MRI of the foot.

Results: The most frequent pathologies seen on US included effusion and synovial thickening in the first metatarsophalangeal joint (MTP1), followed by the tibiotalar joint. Synovial hyperemia on color Doppler US images was present most frequently in the Chopart and midtarsal joints (64%; 7/11 cases), followed by the tibiotalar joint (45%; 5/11), and MTP2-5 joint synovitis (40%; 4/10). Grade 3 hyperemia was present only in four cases; grades 1 and 2 were detected in the majority of cases. On MRI, bone marrow edema was the most frequent pathology, found mostly in the calcaneus (45%; 10/22 cases), while alterations of the forefoot were rare. No cases of bursitis, enthesitis, cysts, erosions or ankylosis were diagnosed in either of the analyzed groups.

Conclusions: Routine US of the foot is recommended for early detection of its involvement in JIA in daily clinical practice. Although MRI can identify features of various JIA stages, it is particularly useful for the detection of bone marrow alterations.

Keywords: foot arthritis; juvenile idiopathic arthritis; magnetic resonance imaging; ultrasound.

Fig. 1.

US of the MTP1 joint in longitudinal view in a patient diagnosed with JIA, presenting with thickened synovium with hyperemia on color Doppler in grade 2 (arrow)

Fig. 2.

US of the Chopart joint in a patient with JIA. A. Effusion and hypertrophied synovium in gray scale is shown dorsally in the talonavicular part of the Chopart joint. Note that both effusion and hypertrophied synovium may have hypoechoic appearance, and the ultrasound probe pressure maneuver may be helpful in discriminating both entities as fluid will be displaceable and compressible. B. Grade 2 vascularization is seen in microflow option in the talonavicular part medially

Fig. 3.

US of the interphalangeal joint of the big toe (IP) in longitudinal view in a patient diagnosed with JIA, presenting with thickened synovium with grade 2 hyperemia on color Doppler (arrow)

Fig. 4.

Short axis US of the flexor tendon at the level of the third toe in a patient diagnosed with JIA presenting with tendinopathy of the flexor tendon. On color Doppler, there is severe vascularization within the thickened tendon sheath (arrow) and inside the flexor tendon (curved arrow)

Fig. 5.

Proton density fat saturated MRI image of the foot in a patient diagnosed with JIA, A. sagittal view showing bone marrow edema in the calcaneus, navicular, and talus (arrows) and a small amount of effusion in the tibiotalar joint (star); B. on axial view bone marrow edema is detected in the calcaneus and cuboid (arrows)

Fig. 6.

Tenosynovitis of the tibias posterior, flexor hallucis longus, and flexor digitorum longus in patient with JIA. A. Gray-scale US in axial view at the level of the tibiotalar joint presenting with thickened tendon sheaths (arrows); B. vascularization is detected in the microflow SMI mode (right image) with only subtle hyperemia seen on power Doppler (left image); C. US of the peroneus longus tendon of the same patient in longitudinal view showing markedly thickened synovium within the tendon sheath with no hyperemia on power Doppler (left image) and detected vascularization in the microflow mode on the same level (right image)