Bone marrow edema and osteitis in rheumatoid arthritis: the imaging perspective

Abstract

Magnetic resonance imaging bone marrow edema is an imaging feature that has been described in many conditions, including osteomyelitis, overuse syndromes, avascular necrosis, trauma, and inflammatory arthritides. In rheumatoid arthritis (RA), bone edema has special significance as it has been shown to be a common and widespread lesion that is often apparent at the hands and wrists but has also been described elsewhere, including the feet. It may occur in early or late disease and has been shown in several large cohort studies to have major negative implications for prognosis. It is the strongest predictor of erosive progression yet to be identified and characteristically occurs in those patients with the most aggressive and potentially disabling disease. In patients with undifferentiated arthritis, bone edema also predicts progression to criteria-positive RA, both independently and to a greater extent when combined with anti-cyclic citrullinated peptide status or rheumatoid factor positivity. Its histological correlate in the late stages of RA has been shown to be osteitis, in which the bone marrow beneath the joint is invaded by an inflammatory and vascular lymphoplasmacytic infiltrate. This lies adjacent to trabecular bone, where increased numbers of osteoclasts have been observed within resorption lacunae, suggesting a mechanistic link between inflammation and erosive bone damage. This could lead to erosion both of the overlying cortex, leading to classic radiographic rheumatoid erosions, and of local trabecular bone, possibly contributing to periarticular osteopenia and cyst formation. In addition to synovitis, osteitis is now regarded as a major rheumatoid lesion that is responsive to therapeutic intervention.

Juvenile Idiopathic Arthritis: Diagnosis and Treatment

“…A peculiar lesion detectable by MRI is periarticular bone marrow edema. This abnormality represents a key predictor of erosive joint damage in adults with arthritis [57], but its meaning is still debated in JIA, as some studies have shown that bone abnormalities on MRI resembling bone marrow edema can be seen in healthy subjects [58]. MRI identifies early changes in both sacroiliac joints and spine, especially in ERA and AS patients, as the most sensitive indicator of inflammation on these sites.…”

Efficacy of tocilizumab on MRI-determined bone oedema in rheumatoid arthritis

“…In a study investigating the efficacy of interleukin-6R inhibition in 31 patients with RA, RAMRIS bone oedema scores fell markedly among patients on tocilizumab, both as monotherapy and combined with methotrexate. The authors noted that using MRI bone oedema as an outcome measure allowed a therapeutic effect to be detected at 12 weeks, much earlier than the point at which radiographic abnormalities would have become apparent [13].…”

MRI in rheumatoid arthritis: a useful tool for the clinician?

“…Much interest is now focusing on the pre-RA state where patients are anti-CCP antibody positive and may have arthralgia but not yet true arthritis. Krabben et al recently reported 1.5 T MRI imaging of the hands and feet in 21 ACPA-positive arthralgia patients and found a correlation between the MRI inflammation score and anti-CCP positivity41 suggesting a pathological link between these parameters and their importance in disease initiation 42. In summary, MRI scanning can be most helpful in determining a diagnosis of RA, especially when there is difficulty discriminating between arthralgia in a pain sensitive patient and true inflammatory arthritis.…”

“…T2W images may also be relatively insensitive to minor changes in osteitis as the relative enhancement ratio of bone marrow in the study by Hodgson and colleagues fell significantly after 2 weeks of anti-TNFα treatment, while no effect was seen on the RAMRIS bone oedema score 56. Much remains unknown about how synovitis and bone oedema (osteitis) impact upon one another in RA and critically whether they occur as separate pathological processes operating in parallel or are linked causally 42. Very few studies have performed MRI and ultrasound systematically over time to determine how often osteitis and/or synovitis resolve completely in treated RA and most available data are currently owned by Pharma companies with commercial interests in how they are presented.…”