Sacroiliac joints MR: Finally a universal language for the sacroiliitis diagnosis

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1 Sacroiliac joints MR: Finally a universal language for the sacroiliitis diagnosis Poster No.: C-1836 Congress: ECR 2013 Type: Scientific Exhibit Authors: M. E. Banegas Illescas, C. López Menéndez, M. L. Rozas Rodríguez, C. Molino Trinidad; Ciudad Real/ES Keywords: Inflammation, MR, Musculoskeletal bone, Musculoskeletal joint DOI: /ecr2013/C-1836 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 20

2 Purpose To present the new classification for the diagnosis of axial spondyloarthropaties (SA) that the group ASAS/OMERACT (Ankylosing Spondylitis Assessment Studies/Outcome Measures in Rheumatoid Arthritis Clinical Trials) has developed, with special attention to the novel contribution of the MR findings as a diagnostic criterion. To describe the different alterations that we can find in the MR studies of sacroiliitis. To show practical examples for theirs application. Methods and Materials We performed a review of the role of the radiographic studies in the diagnosis spondyloarthropaties and the current situation of MR in the evaluation of the sacroiliac joint (SIJ) in these patients. We use the document elaborated by the ASAS/OMERACT group as the basis to describe the relevant findings in MR and to define those that can be considered, grouped or individually, diagnostic of sacroiliitis. We have compiled MR studies of SIJ performed at our institution during 2009 to illustrate the different kinds of active and structural lesions. Our studies consist of Spin Echo (SE), Turbo Spin Echo T2 and STIR/DP-SPR sequences as our usual protocol, adding according to the cases, a T1 with fat saturation sequence (SPIR) and paramagnetic contrast (Gadolinium) sequences. The images were obtained in a Gyroscan Intera equipment (Philips, Holland) of 1'5 Tesla using a Sinergy spine coil (Philips). Results A)Review of the subject. The term Spondyloarthropaty (SpA) refers to an heterogeneous group of chronic rheumatic inflammatory diseases that are characterized by the compromise of the spine (spondylitis), axial joints (sacroiliitis) and in some of them, the peripheral joints as an asymmetric oligoarthritis with a lower limbs dominance, that characteristically have a Page 2 of 20

3 negative rheumatoid factor (RF) and frequently are associated with the presence of HLA B27. We can distinguish 5 types: ankylopoyetic Spondylitis, reactive arthritis (Reiter s syndrome), psoriasic arthritis, arthritis associated to an inflammatory bowel disease and undifferentiated spondyloarthropaty. To know the different conditions of sacroiliac joints (SIJ) and the spine have an important role in the diagnosis, classification, evolutive evaluation especially in an ankylosing, spondylitis and also in the rest of SA. Traditionally plain radiography has been, and still is a very important tool in the detection of alterations in patients with SpA; so that the radiological findings have been part of the Rome diagnostic criteria (1961), the New York s modified criteria (1984) and later the Amor criteria (1990/1992) and the European Spondyloarthropaties Study Group (ESSG) that extended the criteria to include axial and peripheral spondyloarthropaties and also the initial stages of the disease where the changes are not detectable in X Rays. The detection of acute inflammation by MR, especially in the sacroiliac joints, in these patients have constituted an inflexion point because it allows to make an early diagnosis, with important therapeutic implications, because of the development of new biological therapies with tumoral necrosis factor antagonists (anti-tnf), and the monitoring of it. Besides the structural changes detected in MR, also play their role, not only in diagnosis but in the management and prognosis of the disease. That is why the MR study of the SIJ is currently, the main tool for the diagnosis and classification of the patients with incipient spondyloarthropaties. In spite of that, none of the mentioned classifications to the date included the MR findings as a criterion to take into account in the diagnosis, so while the equipment technology and radiology went forward with giant steps in this subject, the clinical management of spondyloarthropaties remains clung to the pre MR era. In the other hand, the radiological community during the last years have published studies about the usefulness and necessity to perform MR with contrast as a part of the regular protocol for the detection of active lesions as well as different, and occasionally complex, methods of scoring and classification of lesions with the final purpose of to homogenize and increase the interobserver reproducibility, that however none has demonstrate to be better than the other. In any case, we lacked the common and internationally accepted criteria, to diagnose sacroiliitis by MR. Owing to the necessity to actualize the clinical and radiological management of this entities and to homogenize criteria, the ASAS/OMERACT working group (OMERACT: Measures in Rheumatoid Arthritis Clinical Trials) in 2009 developed a new classification for axial SpA in which the imaging studies played an important role: they describe and establish the radiological findings that have to concur in a MR study to be considered Page 3 of 20

4 positive for sacroiliitis, and besides, the result of the MR is included as a diagnostic criteria applied to very early conditions of SpA Table 1 on page 7. B) MR Findings. The expert international group (ASAS/OMERACT MRI Working group) formed by eight rheumatologists and two radiologists, has designed, with consensus, which findings found in MR are representative of inflammatory changes, and which are structural, as well as the more optimal sequences for their determination. We have to classify the radiological findings found in MR of the SIJ in patients with SpA as: inflammatory/active and structural lesions. The MR protocol of SIJ have to include a T1 turbo spin echo (TSE) that is usually sufficient to evaluate the chronic changes, as erosions and fat deposits, but to add a gradient echo T2 (GE) can help us for a better evaluation of the cartilage, and therefore a better detection of erosions. For the evaluation of active inflammatory lesions we should perform a STIR sequence, preferably to detect edema, adding a T1 sequence with fat saturation and contrast (gadolinium) to evaluate the rest Table 2 on page 7. The orientation especially in the last two sequences, has to be performed in semi coronal planes (parallel to the union line of the superior dorsal margins of the S1 and S3). 1. ACTIVE INFLAMMATORY LESIONS There are four types of active inflammatory lesions distinguishable in MR studies. BONE MARROW EDEMA/OSTEITIS Bone marrow edema (BME)/osteitis is an indicator of active sacroiliitis (90% specificity), but it can also be found in the other diseases. They typically affect periarticular areas or the subcondral bone. The BME is described as an increase of signal intensity in the STIR sequence, frequently hypo intense in T1w images. They can also have structural lesions Fig. 1 on page 8. By consensus, there should be 1 BME area in two consecutive images or if there s more than one focus, only in one image, whatever its size in both cases. The areas with an increase of signal in T1 with gadolinium and fat saturation reflect an increase in reactive perfusion to inflammation and are referred as an osteitis focus Fig. 2 on page 9 and Fig. 3 on page 10. As a reference we take the interforaminal sacral bone marrow signal. Page 4 of 20

5 SYNOVITIS Only using the STIR sequences we cannot differentiate synovitis from physiological joint fluid; that is why synovitis is identified in T1 Gd sequences with fat saturation as an increase in signal in the synovial margin of the SI joints that is twice the signal of the blood vessels Fig. 4 on page 11. Synovitis as an only finding is not enough to establish a sacroiliitis diagnosis. ENTHESITIS It is an increase of signal in STIR and/or T1Gd with fat saturation sequences at the bone insertion of tendons and ligaments Fig. 5 on page 12 including the space behind the joint (interosseous ligaments). This increase of signal can extend to the bone marrow and the soft tissues. CAPSULITIS Capsulitis shows findings very similar to synovitis but in this case the changes affect the anterior and posterior capsules Fig. 6 on page 13. There are other pathologies that can simulate these inflammatory lesions. It is very important to emphasize that inflammation in SIJ by SpA is limited to the subcondral bone and that do not cross other anatomical limits; by the contrary, inflammation secondary to an infection (septic sacroiliitis) normally crosses those limits and affect soft tissues. Other entities can go with BME and osteitis as for example fractures, typically by sacrum insufficiency and tumors as osteosarcoma. Osteoarthritis of the SIJ can also be associated with BME along the joint. Ligaments that are surrounded by blood vessels can appear hyper intense in the STIR sequence and be confused with an inflammatory lesion. Technical artifacts known as the so called "coil effect" can also confuse us in the interpretation of the increase of signal that it makes with a pathological area; in the semi coronal images this artifact typically appears in the inferior aspect of the sacrum, and sometimes the iliac bone and adjacent soft tissues. 1. STRUCTURAL LESIONS Page 5 of 20

6 SUBCONDRAL SCLEROSIS. Sclerosis areas can be identified as hypo intense/signal void foci in all sequences without showing contrast enhancement Fig. 7 on page 14. Sclerosis attributable to SpA must extend at least 5 mm from the SI articular space, because small periarticular foci can be seen in healthy individuals. EROSIONS. Erosions are bone defects in the joint margin. Initially they appear as unique lesions and can give an appearance of joint pseudo widening Fig. 8 on page 15. They appear as low signal images in T1 sequences and high signal in STIR sequences if the lesion is active. The sequences that are more useful for its detection are T2GE and/or T1 TSE. PERIARTICULAR FAT DEPOSITS. Fat deposits are the result of the fatty acids esterification by inflammation more frequently in the periarticular region Fig. 9 on page 16. Fat deposits characteristically are in MR as an increase of the bone signal in T1 weighted sequences. Generally fat deposits are an unspecific finding. In SpA patients they reveal previously inflamed areas. BONE BRIDGES/ANKYLOSIS. Bone bridges or ankylosis of SIJ appear as low signal lesions in all MR sequences, occasionally surrounded with hyper intense areas in T1, corresponding with fat deposits. Initially the bone buds that face one to another, concur forming bridges that cross the joint and in some cases they "erase" the articular space Fig. 10 on page 16. However, once that we have described these lesions, which of those can be assumed, grouped or individually, diagnostic of sacroiliitis? Page 6 of 20

7 Between the MR findings of acute inflammation, the subcondral bone marrow edema evaluated with fat saturation techniques (FS, SPIR, STIR ) and osteitis, visible in post gadolinium sequences, they can constitute the key data to establish the MR diagnosis of sacroiliitis, while the rest (synovitis, capsulitis, enthesitis), and the structural findings are considered useful, but not diagnostic per se if they are not associated to the first two Table 3 on page 17. Images for this section: Table 1: Table 1. Page 7 of 20

8 Table 2: Table 2. Page 8 of 20

9 Fig. 1: Fig. 1a. Coronal T2 image in which we can see hyper intense areas in the periarticular margins of the right sacral edge(red arrow) and in both margins of the left SI joint (white arrows) that in the STIR sequence (Fig 1b) appear as hypo and hyper intense respectively and express fat deposits and edema. Page 9 of 20

10 Fig. 2: Fig. 2. Coronal T1 sequence in which it appears a decrease of signal intensity in the left iliac articular margin (white arrow) that enhances in the T1 + Gd with fat saturation sequence, corresponding to an osteitis area, The asterisk show an articular widening relating to the adjacent joint corresponding to an active erosion (Gd enhancement). Page 10 of 20

11 Fig. 3: Fig 3a and 3b. Axial oblique T1 sequence in which we can identify low signal in the periarticular bone of the sacral (green arrow a) and iliac margins (b) of the left SI joint. In T1 Gd SPIR sequence (Fig 3c) we can see enhancement in the described areas that corresponds to osteitis areas. Irregularity and pseudo widening of the left sacroiliac articular space comparing it to the right (asterisk). Page 11 of 20

12 Fig. 4: SYNOVITIS: Hyper intense content in the right SI joint (orange arrows) visualized in the coronal images of the sequences T2 (a) and STIR (b) with Gd enhancement in the T1-SPIR sequence (c) corresponding to synovitis. The green arrows show osteitis in the right periarticular iliac margin. White arrow showing a small articular erosion. Page 12 of 20

13 Fig. 5: Fig. 5.Alteration of the signal intensity of one of the posterior sacroiliac ligaments (white arrow) with hyper signal in the STIR sequence (Figure b). It is accompanied of edema in the insertion margins of the bone. Page 13 of 20

14 Fig. 6: Fig. 6. Superior capsular enhancement of the left SI joint in the T1 SPIR Gd sequence (yellow arrow) figure b) that do not corresponds to articular fluid or other signal alterations in the T2 sequence (figure a). We can see enhancement of both periarticular bone margins on the left side and sacrum on the right side corresponding to osteitis (white arrows). Page 14 of 20

15 Fig. 7: Fig. 7. Marked and extent hypo intensity of signal of both margins of the left sacroiliac joint (yellow circle) in the T2 sequence (Figure a) that do not show enhancement in the T1 SPIR Gd (figure b) that corresponds to sclerosis. The white arrow in figure b shows an enhancement area marginal to the sacral sclerosis that suggests an osteitis focus. Page 15 of 20

16 Fig. 8: Fig 8. Multiple subcondral erosions in both SI joints, hypo intense in the T1 sequence (figure a), whose confluence creates the appearance of left articular pseudo widening (white arrow), with enhancement in the T1 SPIR Gd sequence (figure b, white arrow). Fig. 9: Fig. 9. Areas of increase of periarticular bone signal in T1 sequence (Figure a, white arrows), whose signal is suppressed in the STIR sequence (figure b, yellow arrows), suggesting of fat deposits. In figure b, additionally we can identify bone edema limiting with periarticular sacral fat deposit (white arrowhead). Page 16 of 20

17 Fig. 10: Fig. 10. Ankylosis: We identify effacement of the right SI articular space (white arrows) with important sclerosis of the articular margins (figure b). Page 17 of 20

18 Table 3: Table 3. Page 18 of 20

19 Conclusion MR is a useful tool for the evaluation of the SI joints involvement in SA patients MR studies of the SI joints are included in the new classification proposed by the ASAS group for the diagnosis of SA, as an additional criterion. That implies an inflexion point because those criteria not only increase the importance of our role in the management of these pathologies, but because we also have common diagnostic criteria and therefore a universal language. Therefore as radiologists not only we must recognize the different changes (active or structural) but also include and manage these new criteria in our common practice. References Rudwaleit M. New approaches to diagnosis and classification of axial and peripheral spondyloarthritis. Current Opinion in Rheumatology 2010;22: Rojas-Vargas M, Muñoz-Gomariz E, Escudero A, Font P, Zarco P, Almodóvar R, et al. First signs and symptoms of spondyloarthritis - data from an inception cohort with a disease course of two years or less (REGISPONSER-Early). Rheumatology 2009;48: Martos Becerra JM, Carrasco Fernández JA, Cano Sánchez A. Monitorización y valor pronóstico por resonancia magnética de los tratamientos biológicos en las espondiloartritis. Reumatol Clín 2009; 5: Weber U, Maksymowych WP. Sensitivity and Specificy of Magnetic Resonance Imaging for axial spondyloarthritis. The American Journal of the Medical Sciences 2011; 341: Marzo-Ortega H, McGonagle D, O'Connor P, Hensor EM, Bennett AN, Green MJ et al. Baseline and 1-year magnetic resonance imaging of the sacroiliac joint and lumbar spine in very early inflammatory back pain. Relationship between symptoms, HLA-B27 and disease extent and persistence. Ann Rheum Dis 2009;68: Maksymowych WP. MRI in ankylosing spondylitis. Current Opinion in Rheumatology 2009;21: Marzo-Ortega H, McGonagle D, Bennet AN. Magnetic resonance imaging in spondyloarthritis. Current Opinion in Rheumatology 2010;22: Maksymowych WP, Weber U. Diagnostic utility of MRI in early spondyloarthritis. Curr Rheumatol Rep 2011;13: Page 19 of 20

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