Relationship between active inflammatory lesions in the spine and sacroiliac joints and new development of chronic lesions on whole-body MRI in early axial spondyloarthritis: results of the ESTHER trial at week 48

Abstract

Aim: To investigate the relationship between active inflammatory lesions on whole-body MRI (wb-MRI) and new development of chronic lesions on T1 MRI in patients with early axial spondyloarthritis (SpA) treated either with etanercept (ETA) or sulfasalazine (SSZ).

Methods: Wb-MRIs of 65 patients treated either with ETA (n=35) or SSZ (n=30) over 1 year were scored for active inflammation, fatty lesions, erosions and ankylosis in the 23 vertebral units (VUs) of the spine and in the sacroiliac joints (SI joints). Scoring was performed by two blinded radiologists.

Results: If there was no previous inflammation in the bone no new fatty lesions occurred in SI joint quadrants and only a few (0.6%) in spine VUs. There was a significant relationship between disappearance of inflammation and the appearance of fatty lesions: if baseline inflammation resolved fatty lesions occurred in 10.5% of SI joint quadrants and 17.9% of VUs. If inflammation did not resolve over 1 year, fatty lesions occurred less frequently: 2.4% (SI joint quadrants) and 7.2% (VUs). There was a significantly higher increase of the mean fatty lesion score between baseline and week 48 in the ETA (4.0 vs 4.8 for the SI joints and 1.9 vs 2.7 for the spine) compared to the SSZ (3.0 vs 3.2 for the SI joints and 1.1 vs 1.2 for the spine, respectively) group (p=0.001 and p=0.020 for the differences). No significant changes in the erosion or ankylosis score were observed in any of the two groups during this time.

Conclusions: These data indicate that there is a close interaction between inflammation, tumour necrosis factor blockade and the development of fatty lesions in subchondral bone marrow of patients with axial SpA.

Figure 1

Frequency of newly developed fatty lesions at the vertebral units of (A) the spine and (B) the sacroiliac joint quadrants at week 48 in relation to active inflammatory lesions. Percentages shown in the three groups in which (A) there was no active inflammation at baseline (BL) and no inflammation at week 48 (W48) vs (B) there was active inflammation at baseline but no inflammation at week 48 (disappearance of active inflammation) vs (C) there was inflammation present at week 48.

Figure 2

Cumulative probability of changes in MRI fatty lesion scores of (A) the spine and (B) the sacroiliac joints from baseline to week 48 in the etanercept and sulfasalazine treatment groups at the patient level. Each data point in figure 2A,B represents an individual patient.

Figure 3

Illustration of spine MRI of two patients treated with etanercept. (A) In patient A active inflammation (as shown by hyperintense signals in short tau inversion recovery sequence) in the spine decreased between (A-1) baseline and (A-2) week 48 but no new fatty lesions developed between (A-3) baseline and (A-4) week 48. (B) Patient B: active inflammatory lesions also decreased between (B-1) baseline and (B-2) week 48 and fatty lesions (as shown by hyperintense sequence in T1 sequence) newly occurred between (B-3) baseline and (B-4) week 48.