Apparent diffusion coefficient as an indicator of spinal cord compression due to anterior atlanto-axial subluxation in rheumatoid arthritis patients

Małgorzata Mańczak,Grzegorz Pracoń,Iwona Sudoł-Szopińska,Robert Gasik

doi:10.1007/s00586-019-06058-2

Abstract

PurposeThe aim of this retrospective study was to evaluate the apparent diffusion coefficient (ADC) as a potential parameter of spinal cord damage in cervical spine instability at the atlanto-axial level in rheumatoid arthritis (RA) patients.MethodsOne hundred and six RA patients were included in the study. MRI examinations were performed with 1.5T scanner. The ADC was measured at six locations in the cervical spinal cord at the height of the first six cervical vertebrae (from C-1 to C-6). The ADC values were assessed in 2 groups: with and without anterior atlanto-axial subluxation (AAS) diagnosed on plain radiographs. Correlations between ADC values and radiographic measurements and RA activity indicators were evaluated.ResultsThe ADC values at C1 level (ADC1) was higher in the group with anterior AAS than in the group without AAS (p < 0.001). Statistically significant moderate positive correlation between ADC1 and anterior atlanto-axial diameter interval AADI (rho = 0.58; p < 0.008) was found as well as statistically significant weak negative correlation between ADC1 and posterior atlanto-axial diameter interval PADI (rho = − 0.34; p < 0.008).ConclusionsThe conducted study demonstrates the applicability of the ADC maps in the identification of spinal cord compression due to anterior AAS in RA patients. The results encourage the practical use of the ADC as an additional parameter in the qualification for surgical treatment.Graphic abstractThese slides can be retrieved under Electronic Supplementary Material.

Highlights

Rheumatoid arthritis (RA) is a chronic systemic inflammatory disease affecting 1–2% of the world’s population [1,2,3]
There is a significant difference in the apparent diffusion coefficient (ADC) at C1 level (p < 0.001): The ADC is higher in the group with the anterior axial subluxation (AAS)
No statistically significant correlation was found between ADC values at six levels of cervical spine and patient age, disease duration, erythrocyte sedimentation rate (ESR), C-reactive protein level (CRP) and DAS-28

Summary

Introduction

Rheumatoid arthritis (RA) is a chronic systemic inflammatory disease affecting 1–2% of the world’s population [1,2,3]. The cervical spine is the third most commonly affected. European Spine Journal (2019) 28:2352–2358 region, following hands and feet. Pathology in the cervical spine is observed in 44–86% of patients with RA [4, 5]. The most debilitating abnormality is the excessive movement at the junction between the atlas (C1) and axis (C2) called an atlanto-axial subluxation (AAS), which occurs in about 65% of patients and includes the anterior, posterior, lateral instability and the basilar invagination [6]. The diagnosis of the anterior AAS is based mainly on two imaging methods: plain radiography and magnetic resonance imaging (MRI). The initial evaluation of the atlanto-axial joint in relation to the anterior AAS is based on the functional lateral radiographs in neutral, flexion and extension positions. The assessment consists of measuring two distances: the anterior atlantodental interval (AADI) and the posterior atlantodental interval (PADI)

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