Magnetic resonance imaging in ankylosing spondylitis

PURPOSE OF REVIEW: The past 18 months has seen considerable advances in the use of MRI for assessment of ankylosing spondylitis, to quantify active inflammation in the spine and sacroiliac joints which may not otherwise be detectable and to therefore measure change due to therapeutic interventions. RECENT FINDINGS: Characterization of the extension and morphology of inflammation in ankylosing spondylitis is now possible with MRI techniques. A number of randomized controlled trials of anti-tumour necrosis factor agents in ankylosing spondylitis have now been published showing regression of inflammatory lesions in the spine by MRI. Furthermore, the role of MRI for the early diagnosis of spondyloarthritis has become clearer. This review discusses the techniques used, the capabilities and the shortcomings of MRI in assessing ankylosing spondylitis patients. SUMMARY: MRI techniques have implications for early identification and intervention in patients with ankylosing spondylitis.     

Spondyloarthritis Research Consortium of Canada magnetic resonance imaging index for assessment of spinal inflammation in ankylosing spondylitis

OBJECTIVE: To develop a feasible magnetic resonance imaging (MRI)-based scoring system for spinal inflammation in patients with spondylarthropathy that requires minimal scan time, does not require contrast enhancement, evaluates the extent of lesions in 3 dimensional planes, and limits the number of vertebral levels that are scored because MRI demonstrates characteristic inflammatory lesions in the spine of patients with ankylosing spondylitis (AS) prior to the development of typical features on plain radiographic. METHODS: Our scoring method was based entirely on the assessment of increased signal denoting bone marrow edema on T2-weighted STIR sequences. Blinded MRI films were assessed in random order at 2 sites by 3 blinded readers at each of the 2 sites (the Universities of Alberta and Toronto). Intra- and interreader reliability was assessed by intraclass correlation coefficient. The 24-week response of patients with AS randomized to infliximab:placebo (8:3) was assessed by effect size and standardized response mean. RESULTS: An initial analysis of all discovertebral units (DVUs) in the spine of 11 patients demonstrated a mean of 3.2 (95% confidence interval 3.2, 5.2) affected units, while limiting the scoring to a maximum of 6 units captured most of the affected units. We scanned 11 patients with AS with clinically active disease and 20 additional patients randomized to a 24-week trial of either infliximab or placebo. Intraobserver reproducibility for the 6-DVU STIR score ranged from 0.93 to 0.98 (P < 0.0001). Interobserver reproducibility of scores by readers from both sites was 0.79 (P < 0.0001) for status score and 0.82 (P < 0.0001) for change score. Analysis of pretreatment and posttreatment scores for all 20 patients randomized to infliximab/placebo showed a large degree of responsiveness (standardized response mean = 0.87). Reproducibility and responsiveness were only slightly improved by using contrast enhancement with gadolinium diethylenetriaminepentaacetic acid. CONCLUSION: The Spondyloarthritis Research Consortium of Canada MRI index is a feasible, reproducible, and responsive index for measuring spinal inflammation in AS.     

Magnetic resonance imaging assessment of spinal inflammation in ankylosing spondylitis: Standard clinical protocols may omit inflammatory lesions in thoracic vertebrae

Objective

Radiologic assessment of spinal inflammation in patients with ankylosing spondylitis (AS) relies primarily on magnetic resonance imaging (MRI), although little is known about the distribution of inflammatory lesions within the structures of the spine. Our objective was to compare the distribution of inflammatory lesions centrally and laterally within the thoracic and lumbar spine vertebral bodies.

Methods

We studied 49 patients with AS who were scanned with STIR and T1‐weighted spin‐echo MRI of the whole spine. Scans were read by 2 musculoskeletal radiologists, with a third reader as the arbitrator. Controls included 6 age‐matched individuals. We recorded bone marrow edema on STIR images from each vertebral body, separately identifying central and lateral slices. The latter were defined as images that included or were lateral to the pedicle. Interreader reproducibility was assessed by kappa statistics.

Results

Inflammation was present in 263 (45%) of 588 thoracic and 86 (35%) of 245 lumbar vertebrae; the mean number of affected thoracic and lumbar vertebrae per patient were 5.4 and 1.8, respectively. Inflammation was present in the lateral aspect of 219 (37%) of 588 thoracic vertebrae and 45 (18%) of 245 lumbar vertebrae (P < 0.001). Lesions were more common laterally than centrally for all thoracic vertebrae except for T7. Involvement of only the lateral slices was observed in as many as 19.6% of thoracic vertebrae.

Conclusion

Evaluation of spinal inflammation by MRI may omit lesions in up to 20% of inflamed thoracic vertebrae if both scanning and image assessment do not include sagittal slices that extend to the lateral edges of all vertebrae.     

Magnetic resonance imaging and clinical assessment of temporomandibular joint pathology in ankylosing spondylitis

OBJECTIVE: To evaluate temporomandibular joint (TMJ) articular disc position and osseous degenerative changes using magnetic resonance imaging (MRI) as well as clinical symptoms of temporomandibular disorders in patients with ankylosing spondylitis (AS). METHODS: A sample of 43 patients with AS (38 males, age 45.9+/-10.7 years) and 16 controls (all male, age 41.3+/-6.3 years) were studied. All subjects completed a self-administered questionnaire and underwent clinical examination and MRI survey. Recorded variables included disease characteristics, subjective neck and TMJ disorder symptoms, and axial mobility measurements. MRI variables included TMJ disc position and severity of osseous degenerative change. RESULTS: TMJ disorder symptoms of headache duration and frequency, TMJ pain duration and frequency, and painful jaw movement were more frequent in patients with AS (p < 0.05). Significant differences were also observed in MRI indices for disc displacement (AS, 0.89; controls, 0.36; p = 0.005) and degenerative changes (AS, 0.55; controls, 0.06; p = 0.01). A total of 50 (62%) joints in the AS group had disc displacement compared to 11 (34%) joints in the controls. A total of 16 (20%) joints in the AS group had degenerative change compared to 2 (6%) joints in the controls. CONCLUSION: TMJ internal derangement, degenerative changes, and subjective pain complaints are frequent in patients with AS. Physicians should be aware of potential TMJ involvement in these patients, which may require specific assessment and therapy.     

Spondyloarthritis research Consortium of Canada magnetic resonance imaging index for assessment of sacroiliac joint inflammation in ankylosing spondylitis

OBJECTIVE: To develop a feasible magnetic resonance imaging (MRI)-based scoring system for sacroiliac joint inflammation in patients with ankylosing spondylitis (AS) that requires minimal scan time, does not require contrast enhancement, evaluates lesions separately at each articular surface, and limits the number of sacroiliac images that are scored. METHODS: A scoring method based on the assessment of increased signal denoting bone marrow edema on T2-weighted STIR sequences was used. MRI films were assessed blindly in random order at 2 sites by multiple readers. Intra- and interreader reliability was assessed by intraclass correlation coefficient (ICC); the 24-week response of patients with AS randomized to placebo:infliximab (3:8) was assessed by effect size and standardized response mean. The reliability and responsiveness of the scoring method were compared for STIR and gadolinium diethylenetriaminepentaacetic (Gd-DTPA)-enhanced MRI sequences. RESULTS: We scanned 11 patients with AS with clinically active disease and 11 additional patients randomized to the trial of infliximab therapy. ICC for total sacroiliac joint STIR score ranged from 0.90 to 0.98 (P < 0.00001) and interobserver ICC for combined readers from the 2 sites was 0.84 (P < 0.0001). ICC for change scores was lower for STIR (ICC 0.53) than for Gd-DTPA-enhanced sequences (ICC 0.79). Responsiveness was poor, although fusion was evident in one-third of patients who received treatment (placebo:infliximab) and inflammation scores were low. CONCLUSION: The Spondyloarthritis Research Consortium of Canada MRI index is a feasible and reproducible index for measuring sacroiliac joint inflammation in patients with AS.     

Systematic assessment of inflammation by magnetic resonance imaging in the posterior elements of the spine in ankylosing spondylitis

Objective

Magnetic resonance imaging (MRI) is sensitive for scoring inflammatory lesions in the spine, but attention has primarily focused on vertebral bodies, and no study has systematically examined the posterior elements. We aimed to systematically determine the frequency and distribution of inflammatory changes in the posterior elements of the spine using MRI, and to assess the reliability of their detection and their impact on discrimination of spinal MRI.

Methods

We scanned 32 patients recruited to placebo‐controlled trials of anti–tumor necrosis factor therapy. Inflammatory lesions were detected by systematic review of consecutive sagittal STIR slices of the entire spine. Two readers evaluated pretreatment and posttreatment scans, blinded to treatment and time point. Inflammation was scored dichotomously (present/absent) in each posterior structure. Reproducibility was assessed by calculating random model variance components and generalizability coefficients, and discrimination by using Guyatt's effect size.

Results

Most patients (87.5%) had ≥1 lesion in the posterior elements (mean ± SD number of affected spinal levels per patient 6.7 ± 5.3), and they were detected most frequently in the thoracic spine. Interobserver reproducibility for total lesion count was very good to excellent for lesions in the thoracic spine and transverse and spinous processes. The addition of a simple dichotomous method for scoring posterior element inflammation substantially enhanced the discrimination observed using established MRI methods for scoring vertebral body inflammation.

Conclusion

Inflammatory lesions in the posterior elements were present in the majority of patients with AS, and standard MRI protocols of the spine should be modified to ensure adequate visualization of posterolateral structures.     

Magnetic resonance imaging of arachnoid diverticula associated with cauda equina syndrome in ankylosing spondylitis

Cauda equina syndrome is an uncommon complication of ankylosing spondylitis (AS), but results in significant morbidity in those patients affected. We report 2 patients who developed classical cauda equina syndrome, which was well visualized by magnetic resonance imaging. This technique allows accurate noninvasive diagnosis of this complication of AS.     

Inflammation on spinal magnetic resonance imaging is associated with poor bone quality in patients with ankylosing spondylitis

Abstract

Objective: To determine the association between inflammatory lesions on spinal magnetic resonance imaging (MRI) and trabecular bone score (TBS) in patients with ankylosing spondylitis (AS).

Methods: Ninety-seven patients with AS underwent spine MRI and dual energy X-ray absorptiometry of the lumbar spine to measure TBS and bone mineral density (BMD). Bone marrow edema (BME) on MRI was considered an inflammatory lesion. The presence, depth (>1?cm), and intensity of BME on MRI were scored for the 1st–4th lumbar spine segments. Inflammatory markers and spinal structural damage scores at the time of MRI examination were recorded. The association between inflammatory activity score on MRI and TBS was evaluated.

Results: Among the 97 patients, 52 had BME on spinal MRI (L1–L4). The mean TBS values were 1.38?±?0.11 and 1.43?±?0.11 for patients with and without BME, respectively (p?=?.022). Total inflammatory activity scores on spinal MRI correlated negatively with TBS, but not with BMD. Patients with a TBS value representing a high fracture risk had more deep BME (>1?cm) (p?=?.048) on MRI. After adjustment for age, symptom duration, and lumbar spinal structural damage, the TBS decreased as inflammation severity on MRI increased (p?=?.026).

Discussion: In AS patients, inflammation on spinal MRI was negatively correlated with TBS. The severity of local bone inflammation in the spine was associated with poor bone quality. These findings suggest that the control of active bone inflammation may be effective for preventing osteoporosis in AS patients.     

Spinal inflammation by magnetic resonance imaging in patients with ankylosing spondylitis: association with disease activity and outcome parameters

Magnetic resonance imaging (MRI) has major contribution in early diagnosis of ankylosing spondylitis (AS). As it is difficult to determine disease activity owing to the lack of close relation between laboratory tests, clinical findings and imaging, MRI has been used as an objective outcome measure. The aim of this study is to investigate the relation between spinal MRI findings with disease activity and other outcome measures. Fifty patients fulfilling modified New York criteria for AS were enrolled to the study. All the patients were evaluated with Bath AS Disease Activity Index (BASDAI), AS Disease Activity Score (ASDAS), Bath AS Functional Index (BASFI), Bath AS Metrology Index (BASMI), Bath AS Radiology Index (BASRI) and As Quality of Life. Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) were measured as laboratory parameters, and ASspiMR scores were determined by spinal MRI. The median total ASspiMR-a score was 5.2. Spinal inflammation was evaluated in spinal segments, and thoracic segments had the highest mean ASspiMR-a level (3.1?±?5.94). Cervical and lumbar ASspiMR were correlated with only BASRI, and total ASspiMR score was correlated with BASRI, BASMI and CRP. Thoracic ASspiMR score was correlated with patient??s and doctor??s global assessments, BASFI, BASMI, BASRI, ASDAS A, ASDAS B, ASDAS C, ASDAS D, ESR and CRP (P?<?0.05). According to our results, the thoracic spine was the most related region with disease activity parameters and clinical outcome measures, so we suggest thoracic spine MRI evaluation in order to determine the disease activity.     

Magnetic resonance imaging of spinal infection

The findings on magnetic resonance imaging in various types of spinal infection are described, including disc space infection and osteomyelitis, epidural abscess, paraspinal abscesses, and meningitis. The characteristic appearance of spinal infection on both plain and gadolinium-enhanced magnetic resonance is contrasted with that of the normal spine.     

Persistent reduction of spinal inflammation as assessed by magnetic resonance imaging in patients with ankylosing spondylitis after 2 yrs of treatment with the anti-tumour necrosis factor agent infliximab

OBJECTIVES: Patients with ankylosing spondylitis (AS) benefit from anti-TNF therapy both on a clinical basis and as depicted by magnetic resonance imaging (MRI). It is not known whether spinal inflammation remains suppressed over time. Our objective was to assess spinal inflammation by MRI in AS patients after 2 yr of continuous infliximab treatment. METHODS: Twenty patients with active AS were examined by MRI at baseline, after 3 months (end of placebo-controlled-phase) and after 2 yr of continuous infliximab therapy (5 mg/kg/6 weeks). T1 pre- and post-gadolinium (T1/gadolinium-diethylenetriamine-pentaacetic acid) and short tau inversion recovery (STIR) MRI sequences were performed and read by one blinded reader using the ASspiMRI score. RESULTS: Spinal inflammation, detected by MRI in all patients at baseline, decreased after 3 months only in the infliximab group in both MRI sequences. Persistent improvement of spinal inflammation was seen after 2 yr by scoring STIR sequences, with a mean score of 4.6 +/- 5.9 vs 15.2 +/- 13.2 at baseline (P = 0.01). On an individual level, inflammatory spinal lesions decreased from 6.7 +/- 5.0 per patient at baseline to 2.2 +/- 1.8 after 2 yr (P = 0.003). Improvement in spinal inflammation was found in all patients by both MRI sequences. Only a minor degree but some spinal inflammation was still present after 2 yrs. CONCLUSION: Spinal inflammation in MRI was persistently reduced in all patients constantly treated with infliximab, but it was not completely eradicated. Disease activity parameters did not directly correlate with MRI, but both pointed in the same direction. Both types of information may be useful for the definition of response to anti-TNF therapy.     

Value of diffusion-weighted magnetic resonance imaging in early diagnosis of ankylosing spondylitis

The objective of this study is to estimate the value of diffusion-weighted MRI (DWI) in the detection of abnormalities in sacroiliac joints in the patients with early ankylosing spondylitis (AS) and investigate the feasibility of whole-body DWI (WB-DWI) in systemic evaluation of AS. Sixteen patients with early AS, 18 patients with simple low back pain (LBP), and 18 healthy volunteers were involved in this study. All subjects underwent conventional MRI and DWI. Apparent diffusion coefficient (ADC) in subchondral bone marrows of sacroiliac joints was measured. Independent-sample t test was used to statistically analyze the difference of ADC values between groups. WB-DWI was performed in additional 12 patients with clinically confirmed AS. The image results were analyzed by multiple post-processing techniques, as compared to conventional MRI. In AS patients, mean ADC values were (0.494?±?0.170)?×?10^?3?mm²/s in sacrum and (0.513?±?0.129)?×?10^?3?mm²/s in ilium, which were significantly higher than those of LBP ((0.306?±?0.057)?×?10^?3?mm²/s in sacrum and (0.323?±?0.083)?×?10^?3?mm²/s in ilium) and healthy volunteers ((0.315?±?0.009)?×?10^?3?mm²/s in sacrum and (0.319?±?0.012)?×?10^?3?mm²/s in ilium). No statistical differences were found between simple LBP and healthy volunteers. Mean ADC value of multiple lesions in AS was (0.932?±?0.299)?×?10^?3?mm²/s. By WB-DWI, abnormal signals of sacroiliac joints and extra-sacroiliac joint lesions were demonstrated in the locations corresponding with clinical findings. Mean ADC values of multiple lesions were (1.298?±?0.323)?×?10^?3?mm²/s in sacrum and (1.216?±?0.311)?×?10^?3?mm²/s in ilium. DWI and WB-DWI were shown to be effective in differentiation and systemic evaluation of early AS. Both techniques are likely to play an importance role in the early diagnosis of AS and assessment of treatment response.     

Major reduction in spinal inflammation in patients with ankylosing spondylitis after treatment with infliximab: results of a multicenter, randomized, double-blind, placebo-controlled magnetic resonance imaging study

OBJECTIVE: To determine whether the effects of anti-tumor necrosis factor alpha (TNFalpha) in reducing the signs and symptoms of ankylosing spondylitis (AS) coincide with a reduction in spinal inflammation as detected by magnetic resonance imaging (MRI). METHODS: Pre- and postgadolinium T1 and STIR MR images of the spine were acquired at baseline and at week 24 in patients with AS who participated in a multicenter, randomized, double-blind, placebo-controlled study. Patients were randomly assigned at an 8:3 ratio to receive infusions of infliximab (5 mg/kg) or placebo at weeks 0, 2, and 6 and then every 6 weeks thereafter. MR images were obtained and evaluated independently by 2 readers who were blinded to the treatment allocation and time sequence of the images. RESULTS: A total of 194 patients in the infliximab group and 72 patients in the placebo group had evaluable images at baseline and week 24. About 80% of the patients had at least 1 active spinal lesion at baseline, as assessed by MRI. The improvement in the MRI Activity Score after 6 months was significantly greater in the patients who received infliximab (mean 5.02, median 2.72) than in those who received placebo (mean 0.60, median 0.0) (P < 0.001). Almost complete resolution of spinal inflammation was seen in most patients who received infliximab, irrespective of baseline activity. CONCLUSION: Patients with AS who received infliximab therapy showed a decrease in spinal inflammation as detected by MRI, whereas those who received placebo showed persistent inflammatory spondylitis.     

Magnetic resonance imaging of sacroiliac joint inflammation

A consecutive series of 27 patients with symptoms compatible with sacroiliitis underwent magnetic resonance imaging (MRI) of the sacroiliac joints. The diagnostic sensitivity of MRI was similar to that of computed tomography or conventional radiography. However, MRI seems to have the potential of providing unique information about the disease process in sacroiliitis by demonstrating abnormalities in subchondral bone and periarticular bone marrow. The results of this study suggest that early inflammatory changes in sacroiliitis occur in the subchondral structures of the sacroiliac joints.     

MRI对肛瘘的评价

肛瘘术前要求外科医师必须清楚瘘管和肛门括约肌之间的关系,有无来源于原发管的继发管需要治疗处理。MRI在诊断肛瘘中的价值越来越受到临床重视,已成为术前瘘管分类的主要方法。MRI不仅能精确显示肛管及其肛管周围的解剖,而且能将瘘管分类、明确瘘管的类型、寻找内口位置,同时还能识别其他检查方法未能发现的疾病,如术后是否存在可能会导致复发的继发感染病灶。本文主要综述肛管及相关结构的MRI检查方法、影像解剖表现,以及MRI对肛瘘类型、瘘管形态走行及瘘口的显示价值及其对临床诊治及患者转归的影响。