Arthritis & Rheumatism, Volume 62,
November 2010 Abstract Supplement

Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Atlanta, Georgia November 6-11, 2010.


The Dimorphic Vertebral Corner Inflammatory Lesion (CIL): A Magnetic Resonance Imaging Biomarker Associated with New Bone Formation in Patients with Ankylosing Spondylitis.

P. Maksymowych,  Walter, Morency,  Nathalie, G. W. Lambert,  Robert

Purpose:

One hypothesis proposed to explain the lack of impact of TNF blockers on radiographic progression in established AS is the activation of bone forming pathways in spinal lesions that have advanced from acute inflammation to more complex lesions. The latter may be visible on spinal MRI as a dimorphic corner inflammatory lesion (CIL) where the inflammatory signal at the vertebral corner (VC) on the STIR sequence does not itself extend all the way to the VC as in a typical CIL (Type A) but surrounds an area of decreased signal intensity at the VC which, on the T1 weighted images, may appear to be due to fat infiltration or erosion/bone sclerosis. It is proposed that the overall development of new bone during TNF blocker therapy may depend on the balance between the number of early and more mature inflammatory lesions. We tested the relative association between dimorphic or Type A CIL (lower and upper anterior VC in figure, respectively) and the subsequent development of new bone at the VC.

Method:

MRI scans were performed at baseline, 12, and 52 weeks while radiographs were done at baseline and 104 weeks in 76 AS patients randomized to receive either adalimumab (ADA) 40 mg every other week or placebo (PBO) for 24 weeks in a, double-blind, Phase III study of active AS. After the week 12 assessment, patients not achieving an ASAS20 response were eligible for early escape therapy with ADA and after 24 weeks all patients received ADA. The anterior VC of the cervical (C2 lower to T1 upper) and lumbar (T12 lower to S1 upper) spine were examined for new syndesmophytes and ankylosis (baseline, 104 weeks) on lateral radiographs of the cervical and lumbar spine by 2 readers scoring independently. Anonymized MR scans were read independently by 2 readers who recorded the presence/absence of Type A and dimorphic CIL at the same anterior VC that were assessed by radiography. The primary analysis was based on concordant radiographic and MRI data and compared proportions developing new bone using the Pearson's chi square.

Results:

Type A and dimorphic CIL were recorded in 155 (11.5%) and 56 (4.1%), respectively, of the 1351 VC analyzed both on MR and radiography. New syndesmophytes and/or ankylosis (from normal VC) was recorded in 45 (3.3%) of all VC. New bone developed significantly more frequently from VC that demonstrated dimorphic CIL (8 of 56 (14.3%)) as compared to Type A CIL (5 of 155 (3.2%), p = 0.007) or no CIL (32 of 1118 (2.9%), p = 0.0004) on the baseline MRI. This was also noted irrespective of whether the dimorphic CIL resolved or persisted at the 52 week follow up MRI.

Conclusion:

Our data confirm previous studies that inflammation at VC on baseline MRI is associated with subsequent new bone formation in established AS. More importantly, we show that this entirely reflects the presence of more complex inflammatory lesions, visualized as dimorphic CIL on MRI, where the process of bone formation may be autonomous from inflammation.

To cite this abstract, please use the following information:
P. Maksymowych, Walter, Morency, Nathalie, G. W. Lambert, Robert; The Dimorphic Vertebral Corner Inflammatory Lesion (CIL): A Magnetic Resonance Imaging Biomarker Associated with New Bone Formation in Patients with Ankylosing Spondylitis. [abstract]. Arthritis Rheum 2010;62 Suppl 10 :1957
DOI: 10.1002/art.29722

Abstract Supplement

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