Comparison of bone scan, computed tomography, and magnetic resonance imaging in the diagnosis of active sacroiliitis

Learning imaging in axial spondyloarthritis: more than just a matter of experience

OBJECTIVE

Reliable interpretation of imaging findings is essential for the diagnosis of axial spondyloarthritis (axSpA) and requires a high level of experience. We investigated experience-dependent differences in diagnostic accuracies using X-ray (XR), MRI and CT.

METHODS

This post hoc analysis included 163 subjects with low back pain. Eighty-nine patients had axSpA, and 74 patients had other conditions (mechanical, degenerative or non-specific low back pain). Final diagnoses were established by an experienced rheumatologist before the reading sessions. Nine blinded readers (divided into three groups with different levels of experience) scored the XR, CT and MRI of the sacroiliac joints for the presence versus absence of axSpA. Parameters for diagnostic performance were calculated using contingency tables. Differences in diagnostic performance between the reader groups were assessed using the McNemar test. Inter-rater reliability was assessed using Fleiss kappa.

RESULTS

Diagnostic performance was highest for the most experienced reader group, except for XR. In the inexperienced and semi-experienced group, diagnostic performance was highest for CT&MRI (78.5% and 85.3%, respectively). In the experienced group, MRI showed the highest performance (85.9%). The greatest difference in diagnostic performance was found for MRI between the inexperienced and experienced group (76.1% vs 85.9%, p=0.001). Inter-rater agreement was best for CT in the experienced group with κ=0.87.

CONCLUSION

Differences exist in the learnability of the imaging modalities for axSpA diagnosis. MRI requires more experience, while CT is more suitable for inexperienced radiologists. However, diagnosis relies on both clinical and imaging information.

Is it time to move on from pelvic radiography as the first-line imaging modality for suspected sacroiliitis?

PURPOSE OF REVIEW

Pelvic radiography in which structural lesions characteristic of sacroiliitis can be detected, is recommended as the first imaging modality when axial spondyloarthritis (axSpA) is suspected clinically. However, cross-sectional modalities like computed tomography (CT) and magnetic resonance imaging (MRI) are superior to radiographs for diagnosing sacroiliitis. Thus, we currently debate the role of radiography as first imaging modality in the diagnostic workup of axSpA.

RECENT FINDINGS

Diagnosing sacroiliitis on pelvic radiographs is challenging with large interobserver and intraobserver variation. Low-dose CT (ldCT) of the sacroiliac joints (SIJs) was proved to be more sensitive and reliable than radiographs with comparable ionizing radiation exposure. MRI is the preferred modality for detecting early SIJ inflammation, well before structural lesions evolve. New, promising MRI sequences sensitive to cortical bone improve erosion detection, making MRI a one-stop shop for the diagnosis of sacroiliitis.

SUMMARY

Given the debatable additive value of pelvic radiographs for the detection of sacroiliitis, and the presence of excellent alternatives for imaging the bony cortex of the SIJs such as ldCT and MRI with state-of-the-art sequences sensitive to cortical bone, it is high time to discuss the use of these more accurate modalities instead of radiographs.

Biomechanics of the Sacroiliac Joint: Surgical Treatments

BACKGROUND

Fixation is one of the most common surgical techniques for the treatment of chronic pain originating from the sacroiliac joint (SIJ). Many studies have investigated the clinical outcomes and biomechanics of various SIJ surgical procedures. However, the biomechanical literature points to several issues that need to be further explored, especially for the devices used in minimally invasive surgery of the SIJ. This study (part II) aims to assess biomechanical literature to understand the existing information as it relates to efficacies of the surgical techniques and the gaps in the knowledge base. Part I reviewed basic anatomy and mechanics of the SIJ joint, including difference between males and females, and causes of pain emanating from these joints.

METHODS

A thorough literature review was performed pertaining to studies related to SIJ fixation techniques and the biomechanical outcomes of the surgical procedures.

RESULTS

Fifty-five studies matched the search criteria and were considered for the review. These articles predominantly pertained to the biomechanical outcomes of the minimally invasive surgery with different instrumentation systems and surgical settings.

CONCLUSIONS

The SIJ is one of the most overlooked sources of lower back pain. The joint is responsible for the pain in 15% to 30% of people suffering from lower back pain. Various studies have investigated the clinical outcomes of different surgical procedures intended to improve the pain and quality of life following surgery. The data show that these techniques are indeed effective. However, clinical studies have raised several issues, like optimal number and positioning of implants, unilateral versus bilateral placements, adjacent segment disease, implant designs, and optimal location of implants with respect to variations in bone density across the SIJ. Biomechanical studies using in vitro and in silico techniques have addressed some of these issues. Studies also point out the need for additional investigations for a better understanding of the underlying mechanics for the improved long-term surgical outcomes. Further long-term clinical follow-ups are essential as well. This review presents pertinent findings.

Sacroiliitis - early diagnosis is key

Sacroiliitis, inflammation of the sacroiliac joint (SIJ), may be associated with many rheumatic and nonrheumatic disorders. The diagnosis of sacroiliitis may be difficult in many patients, and awareness of its typical manifestations along with recognition of its diverse presentations and cognizance of the limitations of today’s imaging modalities are critical to good clinical practice. This review presents the didactic approach to the early diagnosis of sacroiliitis in patients with suspected axial spondyloarthritis and other nosologic entities, discussing also differential interpretation of information acquired from patients’ histories, physical examination, and imaging.

The Use of Imaging in Management of Patients with Low Back Pain

Lower back pain (LBP) is one of the most common chief complaints encountered in primary care. Advanced imaging studies, including computerized tomography (CT) and magnetic resonance imaging (MRI), are frequently ordered in the setting of LBP. Structural abnormalities are commonly identified by CT and MRI in patients complaining of low back pain, however, these findings are also found in asymptomatic patients. In the past decade, multiple guidelines have been published to help providers identify patients in whom the use of advanced imaging is appropriate. In this article, we review common conditions associated with LBP that require advanced imaging along with their clinical and associated imaging findings.

Bone Single Photon Emission/Computed Tomography in the Detection of Sacroiliitis in Seronegative Spondyloarthritis: A Comparison with Magnetic Resonance Imaging

OBJECTIVE

Seronegative spondyloarthritis (SpA) is characterized by chronic inflammation affecting the axial skeleton, entheses and occasionally peripheral joints. The involvement of the sacroiliac joints, sacroiliitis, is considered as a pathognomonic radiographic finding. Magnetic resonance imaging (MRI) is the method of choice for its early detection. Bone scintigraphy (BS) is characterized by high sensitivity in the diagnosis of bone and articular diseases. Limited value of BS in the diagnosis of sacroiliitis may be attributed to the use of planar imaging. In the present study, we aimed to investigate the role of SPECT in SpA, compared to MRI.

METHODS

Forty-three patients suffering from inflammatory back pain underwent MRI evaluation of the sacroiliac joints and BS, combined with SPECT in the same region, for the assessment of sacroiliitis.

RESULTS

Bone SPECT revealed no findings of sacroiliitis in 11 patients, with total agreement with MRI. Findings of chronic lesions were demonstrated from both modalities in 2 patients. Bone SPECT and MRI findings were in concordance regarding the investigation of active sacroiliitis, with the exception of one patient with mild SPECT findings and negative MRI examination; the diagnosis of AS however, was established one year later, after a positive follow-up MRI. The evaluation of the planar imaging of the whole skeleton and SPECT imaging, revealed additional lesions.

CONCLUSION

Bone SPECT is a reliable imaging method in the diagnosis of active sacroiliitis. Its application on planar BS, an economic and widely available diagnostic technique, appears to be a valuable aid for the clinician.

Prevalence and awareness of sacroiliac joint alterations on lumbar spine CT in low back pain patients younger than 40 years

Background Computed tomography (CT) examinations of the lumbar spine are commonly performed in patients aged ≤40 years due to low back pain (LBP). Purpose To investigate the prevalence and awareness of radiologists for the presence of structural post-inflammatory/other sacroiliac joint (SIJ) alterations on lumbar spine CTs of young patients with LBP. Material and Methods A total of 484 lumbar spine CT examinations (272 men, 212 women; average age, 31 years; age range, 18-40 years) of patients with LBP in which the entire SIJs were visualized were retrospectively reviewed. SIJs were scored (consensus) by two senior radiologists (study reading) for the presence of post-inflammatory structural SIJ findings or other SIJs alterations. The original reports were compared to the study reading. Fifty CT examinations were re-evaluated for reliability assessment (intra-class correlation coefficient [ICC]). Results A total of 150 (31%) abnormal SIJ examinations were registered (ICC: r = 0.7-0.8; P < 0.0001): suspected sacroiliitis = 50 (10.2%); definite sacroiliitis = 16 (3.3%); osteitis-condensans-ilii = 38 (7.8%); diffuse idiopathic skeletal hyperostosis = 24 (5%); degenerative changes = 22 (4.5%); accessory SIJ = 22 (4.5%); and tumor = 1. The SIJs were referenced 39 times (8.0%) in the original readings: pathological findings (n = 15); and normal SIJ (n = 24). Total diagnostic accuracy for these reports only and for the entire readings were 49% and 69%, respectively, and 13% and 1.3%, respectively, for the pathological findings. Conclusion Sacroiliitis and other SIJ alterations are prevalent in young individuals with LBP, albeit, the majority of these alterations are not recognized nor reported by senior radiologists thus may delay efficacious treatment.

[Inflammatory spinal diseases: axial spondyloarthritis : Central importance of imaging]

The diagnosis of axial spondyloarthritis (axSpA) includes classical ankylosing spondylitis (AS) as well as earlier stages and abortive courses of the disease, in which structural alterations have not yet occurred. These are classified as non-radiographic axSpA (nr-axSpa). Inflammatory changes in the entire axial skeleton are characteristic for axSpA and can be visualized by magnetic resonance imaging (MRI), while in most patients structural alterations, such as new bone formation with syndesmophytes and ankylosis develop in the later course of the disease. These bony alterations can best be visualized by conventional radiography and by computed tomography. Certain MRI sequences are nowadays considered as the standard method for depiction of inflammatory changes in axSpA. The introduction of MRI has led to a paradigm shift for this disease because the inflammatory lesions characteristic for the disease can be visualized at an early stage using appropriate MRI sequences.

Imaging in the diagnosis and management of axial spondyloarthritis

Magnetic resonance imaging (MRI) is the imaging modality of choice for diagnosing axial spondyloarthritis (SpA) when the pelvic radiograph is normal or equivocal. Subchodral bone marrow edema (BME) is the primary feature of early SpA, although structural changes, particularly erosions, may also be seen at an early stage. It is unclear whether incorporation of structural lesions enhances the classification performance of a positive MRI definition based on BME alone. Neither spinal imaging nor contrast-enhanced imaging are useful for routine diagnostic evaluation. Fat metaplasia is a key intermediary in the pathway from inflammation to ankylosis, although the histopathology remains to be determined. Both active and structural lesions can be reliably detected and quantified on MRI. Tumor necrosis factor inhibitor therapies ameliorate inflammation; however, it is unclear whether complete suppression of inflammation is necessary to prevent structural damage. Structural lesions on MRI require further validation using computed tomography and prospective follow-up to determine their prognostic significance.

The diagnostic value of three sacroiliac joint pain provocation tests for sacroiliitis identified by magnetic resonance imaging

OBJECTIVES

The aim of the current study was to investigate the diagnostic value of three sacroiliac (SI) joint pain provocation tests for sacroiliitis identified by magnetic resonance imaging (MRI) and stratified by gender.

METHOD

Patients without clinical signs of nerve root compression were selected from a cohort of patients with persistent low back pain referred to an outpatient spine clinic. Data from Gaenslen's test, the thigh thrust test, and the long dorsal sacroilia ligament test and sacroiliitis identified by MRI were analysed.

RESULTS

The median age of the 454 included patients was 33 (range 18-40) years and 241 (53%) were women. The prevalence of SI joints with sacroiliitis was 5%. In the whole study group, only the thigh trust test was associated with sacroiliitis, the area under the receiver operating characteristic (ROC) curve (AUC) was 0.58 [95% confidence interval (CI) 0.51-0.65], sensitivity 31% (95% CI 18-47), and specificity 85% (95% CI 82-87). In men, sacroiliitis was associated with all the SI joint tests assessed and multi-test regimens, with the greatest AUC found for at least one positive out of three tests [AUC 0.68 (95% CI 0.56-0.80), sensitivity 56% (95% CI 31-79), and specificity 81% (95% CI 77-85)]. In women, no significant associations were observed between the SI joint tests and sacroiliitis.

CONCLUSIONS

Only in men were the SI joint tests found to be associated with sacroiliitis identified by MRI. Although, the diagnostic value was relatively low, the results indicate that the use of SI joint tests for sacroiliitis may be optimized by gender-separate analyses.

18F-fluoride PET/CT for detection of axial involvement in ankylosing spondylitis: correlation with disease activity

OBJECTIVES

Aim of the current study was to evaluate the relationships between the findings of 18F-fluoride PET/CT (F-PET/CT) reflecting osteo-proliferative processes and the clinical indexes related to the disease activity. The clinical indexes are Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) and Ankylosing Spondylitis Disease Activity Score (ASDAS).

METHODS

We studied 29 AS patients aged 26-69 years with a wide range of disease activity using F-PET/CT. The number of regions of high bone turnover or osteoarthritis features at the spine and at sacroiliac joints was counted.

RESULTS

The number of F-PET/CT positive sites was significantly higher in patients with severe functional impairment and higher disease activity and it was positively related to both BASDAI (r = 0.336; P = 0.036) and ASDAS (r = 0.408; P = 0.014) while the number of degenerative features (osteoarthritis) was related neither with functional impact nor with disease activity.

CONCLUSIONS

With a single examination, F-PET/CT accurately identifies the functional impairment and the clinical involvement of AS. The good correlation we found between the number of F-PET/CT positive sites and disease activity candidates this technique also for follow-up of AS.

Sacroiliac indicis increase the specificity of bone scintigraphy in the diagnosis of sacroiliitis

Objective: Bone scintigraphy is a highly sensitive method in the evaluation of sacroiliitis. Aim of this study is firstly to evaluate interobserver variation of partial and whole sacroiliac indicis, secondly investigation of clinical importance of these indicis in the diagnosis of sacroiliitis.

Methods: Fourty-six subjects (24 female: 35.4±11.9; 22 male: 43.1±12.4) without sacroiliitis 45 subjects with low back pain (33 female: 43.3±11.5, 11 male: 35.5±17.2) were included in the study. For right (R) and left (L) whole indices (WSI) irregular region of interest (ROI), for partial indices superior (S) and inferior (I) rectangular ROI were used. For background activity, rectangular ROI was drawn from the sacral region. Indices were calculated from ratio of average counts of sacroiliac and background regions. Two independent observers calculated sacroiliac indices. Interobserver agreement was evaluated by Pearson analysis.

Results: There was no significant interobserver difference (p>0.05). Significant correlation existed between all calculated indices. Among 45 patients with suspicion of sacroiliitis 15 had final diagnosis of sacroiliitis and all of the Tc-99m methilenediphosphonate planar and SPECT bone scintigraphy results of these patients were concordant with sacroiliitis. There were 8 false positive results in other 30 patients. Seven of these eight patients had normal index values. If the scintigraphy would be evaluated in conjuction with indicis the specificity would increase from 73% to 97% but sensitivity decreases from 100% to 80%. There was significant correlation between the observers calculated indicis (p<0.001).

Conclusion: Superior and inferior sacroiliac index values can be used with confidence. If we use sacroiliac index values to confirm positive results; index values can increase the specificity of bone scintigraphy.

The usefulness of bone SPECT/CT imaging with volume of interest analysis in early axial spondyloarthritis

Background

The role of conventional bone scintigraphy in diagnosing early axial spondyloarthritis (SpA) is yet controversial. Single positron emission computed tomography (SPECT) plus CT is an imaging modality that adds better anatomical information to scintigraphy of the sacroiliac (SI) joint. Our aim was to investigate the usefulness of bone SPECT/CT with volume of interest (VOI) analysis in early axial SpA patients.

Methods

Twenty patients (male: female ratio = 12:8; age range = 17–65 years) presenting with inflammatory back pain meeting the Amor criteria of early axial SpA were recruited from a single center in South Korea. Bone scintigraphy was performed 180 min after intravenous injection of 1110 MBq of Tc-99 m-HDP, followed by bone SPECT/CT. The ratio between the entire SI joint and sacrum (SIS ratio) was measured by both bone SPECT/CT and bone scintigraphy. Data from 13 controls were also evaluated. Receiver operating characteristic (ROC) curve was plotted for further analysis, and the correlation between the SIS ratio and SI joint grade by plain radiography was assessed.

Results

The SIS ratio of early axial SpA patients vs. control subjects was significantly increased in bone SPECT/CT (p < 0.001). However, no significant difference was detected in bone scintigraphy. ROC curve analysis showed a significant difference in the area under curve (AUC) of bone SPECT/CT vs. bone scintigraphy (0.862 vs. 0.523, respectively; p < 0.001). With a cut-off SIS ratio of 1.50, ROC curve analysis showed a sensitivity of 80.0% and specificity of 84.6% in bone SPECT/CT. The SIS ratio measured in SPECT/CT, but not that measured in bone scintigraphy, was significantly increased with a higher grade of SI joint changes in plain radiography (p = 0.014).

Conclusion

Bone SPECT/CT is more useful than conventional bone scintigraphy in identifying sacroiliitis in early axial SpA patients, even with mild SI joint changes in plain radiography. By combining CT, we can accurately delineate the sacrum and SI joint uptake with our VOI method.

The role of ultrasound in diagnosis of the causes of low back pain: a review of the literature

Context:

Low back pain (LBP) is among the most prevalent musculoskeletal conditions in the developed countries. It is a common problem causing disability and imposing a huge economic burden to individuals and state organizations. Imaging plays an important role in diagnosis of the etiology of LBP.

Evidence Acquisition:

The electronic databases included: PubMed (1950 to present), Ovid SP Medline (1950 to present) and ISI (1982 to present) and Google Scholar. In every search engine another search was performed using various permutations of the following keywords: ultrasonography, ultrasound imaging, low back pain, back muscles, paraspinal muscles, multifidus, transverse abdominis, muscle size, spinal canal, sacroiliac joint and spondylolisthesis.

Results:

Magnetic resonance imaging (MRI) is widely used in evaluation of patients with LBP; however, high costs, limited availability and contraindications for its use have restricted MRI utilization. In a quest for a less expensive and readily available tool to investigate LBP, clinicians and researchers found ultrasonography (US) as an alternative. In this review we discuss the US application in diagnosis of some common causes of non-specific chronic LBP. Discussed topics include evaluation of spinal canal diameter, paraspinal and transabdominal muscles, sacroiliac joint laxity, pregnancy related LBP, sacroiliitis, and spondylolisthesis using US in patients with LBP.

Conclusions:

While the first researches on employing ultrasound in diagnosis of patients with LBP had been focused on spinal canal diameter, recent studies have been mostly performed to evaluate the role of transabdominal and paraspinal muscles on core stability and thereby LBP occurrence. On the other side, Doppler ultrasonography has recently played an important role in objective measurement of joint laxity as a common etiology for LBP. Doppler imaging also in pregnant patients with LBP has been recommended as a safe and sensitive method. As conclusion, according to recent and most prestigious studies, focusing more on transabdominal muscle thickness can be considered as future approach in investigations.

(18)F NaF PET/CT Versus Conventional Bone Scanning in the Assessment of Benign Bone Disease

Nuclear physicians in many centers nowadays have the choice of using different nuclear bone-imaging modalities. (18)F-labeled sodium fluoride (NaF) PET with computed tomography (PET/CT) is a promising tool for the evaluation of benign bone disease. The indications for NaF PET/CT in clinical practice are probably the same as those established for (99m)Tc-labeled methylene diphosphonate bone scintigraphy and single-photon emission computed tomography (SPECT)/CT. At present only preliminary data, often with a limited number of patients and lacking comparison with (99m)Tc-MDP SPECT/CT, are available. This article reviews the available literature and summarizes the authors' experience with NaF PET/CT in benign bone disease.

A systematic critical review on MRI in spondyloarthritis

Introduction

Magnetic resonance imaging (MRI) has been proven capable of showing inflammatory and structural changes in patients with spondyloarthritis (SpA) and has become widely used in the diagnosis of SpA. Despite this, no systematic reviews evaluate the diagnostic utility of MRI for SpA. Therefore, the objective of this systematic review was to determine the evidence for the utility of MRI in the clinical diagnosis of SpA. The aims were to identify which MRI findings are associated with the diagnosis of SpA and to quantify this association.

Methods

MEDLINE and EMBASE were electronically searched. Inclusion criteria were cross-sectional or longitudinal case-control or cohort MRI studies. The studies required a group with either SpA or inflammatory back pain (IBP) and a non-case group without SpA or IBP. Each group required a minimum of 20 participants. The included articles had to report results containing raw numbers suitable for the construction of two-by-two tables or report results by sensitivity and specificity for cross-sectional studies or odds ratios, relative risk ratios, or likelihood ratios for longitudinal studies. Method quality was assessed by using criteria based on the QUADAS tool.

Results

In total, 2,395 articles were identified in MEDLINE and EMBASE before November 2011. All articles were reviewed by title and abstract. Seventy-seven articles were reviewed by full text, and 10 met the inclusion criteria. Two were considered of high quality: one evaluated the sacroiliac joints, and the other, the spine. Because of the small number of high-quality studies, a meta-analysis was not performed. The two high-quality studies found a positive association between MRI findings (bone marrow edema, erosions, fat infiltrations, global assessment of sacroiliitis, and ankylosis) and the diagnosis of IBP and SpA.

Conclusion

In this review, several MRI findings were found to be associated with SpA. However, because of the small number of high-quality studies, the evidence for the utility of MRI in the diagnosis of SpA must be considered limited. Therefore, caution should be taken to ensure that inflammatory and structural MRI findings are not interpreted as being more specific for SpA than is supported by research.

18F-fluoride PET/CT for detection of sacroiliitis in ankylosing spondylitis

PURPOSE

The aim of this study was to evaluate the performance of (18)F-fluoride-PET/CT (PET/CT) for the diagnosis of sacroiliac joint (SIJ) arthritis in patients with active ankylosing spondylitis (AS).

METHODS

Included in the study were 15 patients with AS according to the modified New York criteria (AS group) and with active disease and 13 patients with mechanical low back pain (MLBP; control group) who were investigated with whole-body (18)F-fluoride PET/CT. The ratio of the uptake in the SIJ and that in the sacrum (SIJ/S) was calculated for every joint.

RESULTS

The mean SIJ/S ratio of 30 quantified joints in the AS group was 1.66 (range 1.10-3.07) with PET/CT, and the mean SIJ/S ratio of 26 quantified joints in the MLBP group was 1.12 (range 0.71-1.52). The area under the receiver operating characteristic curve for SIJ arthritis was 0.84. With plain radiography as a the gold standard and taking an SIJ/S ratio of >1.3 as the threshold, the sensitivity, specificity and accuracy on a per patient basis were 80%, 77% and 79%, respectively. On a per SIJ basis, the greatest sensitivity (94%) was found in grade 3 sacroiliitis (n = 16).

CONCLUSION

Our results suggest that quantitative (18)F-fluoride PET/CT may play a role in the diagnosis of sacroiliitis in active AS and is an alternative to conventional bone scintigraphy in times of molybdenum shortage.

Automatic computer-aided sacroiliac joint index analysis for bone scintigraphy

Bone scintigraphy helps to detect sacroiliitis before the radiographic changes. Nuclear medicine physicians interpret lesion on sacroiliac joint by the aid of sacroiliac joint-to-sacrum uptake ratios (sacroiliac joint index, SII). Usually, the SII is measured by manually drawing regions of interest (ROI) over the sacroiliac joints and sacrum, which is a tedious, time consuming, and highly operator dependent procedure. In this approach, we developed an automatic SII measurement program based on fuzzy sets histogram thresholding, anatomy-based image segmentation method and pelvis reference points located by morphological operations. To validate the program, the results of automatic SII measurement from 33 patients were compared with the results of manual SII measurement. For each patient, six SIIs representing the upper, middle, and low portions of the right and left SIIs were obtained. Totally, 198 SIIs were included for linear regression, bias, and precision analyses. The coefficient of determination (R(2)) between our approach and 2 medical experts' manual measurements are 0.923 and 0.917 respectively. The predictive performance (bias, precision) shows a good agreement result. From the result of this study, we expect that this automatic computer-aided approach may be applied to help nuclear medicine physicians in sacroiliitis interpretation.

Imaging of the sacroiliac joint involvement in seronegative spondylarthropathies

Involvement of the sacroiliac joints is the first predominant finding of all seronegative spondylarthropathies (SpA) subsets, such as ankylosing spondylitis, psoriatic arthritis, and undifferentiated SpA. Although conventional radiography is indicated in the initial evaluation of sacroiliac joints diseases, it is often insensitive for demonstrating the early changes of sacroiliitis, so other imaging techniques typically are often necessary to clarify the pathology and for establishing the early diagnosis of seronegative SpA. Other imaging modalities, including computed tomography (CT), magnetic resonance imaging (MRI), ultrasonography (US), and bone scintigraphy have improved visualization of inflammatory changes at the sacroiliac joints (SIJ). CT scans are indicated for disease processes in which bony destruction or ossification may occur. MRI has been proposed as an imaging method to detect sacroiliitis earlier. MRI can identify both inflammation and structural changes caused by inflammation, while radiographs show only structural changes. MRI may be particularly useful in making a diagnosis of SpA. Musculoskeletal US has an increasing and relevant role in the evaluation of SpA mainly for its ability to assess joint and periarticular soft tissue involvement and in particular for its capacity to detect enthesitis. US assessment in general is safe, noninvasive, and comparably cheap, showing itself as a complimentary tool to clinical evaluation in SpA; nevertheless, it is very user dependent. Bone scintigraphy is at most of limited diagnostic value for the diagnosis of established AS, including the early diagnosis of probable/suspected sacroiliitis. The main aim of this study is to introduce the clinical and radiological aspects of the SIJ involvement in SpA, particularly the contribution of the different imaging techniques.

Review article: radiofrequency neurotomy for the treatment of sacroiliac joint syndrome

We review here the latest studies on efficacy of and techniques employed in radiofrequency neurotomy of the sacroiliac joint. Radiofrequency neurotomy has been shown to have limited evidence in treating sacroiliac joint syndrome. Variability in results has been attributed to individual nerve patterns, improper diagnosis, and selection of patients, as well as variability in the procedure itself. Future studies will be needed to focus on the type of radiofrequency neurotomy and positioning of electrodes to better evaluate efficacy.

Imaging of seronegative spondyloarthritis

Magnetic resonance imaging (MRI) and ultrasonography (US) are useful adjuncts in the diagnosis of seronegative spondyloarthritides (SpA); a group of diseases that present early at a stage when radiographic assessment is invariably normal. This chapter will review how MRI and US can be used in the evaluation of early SpA. The diffuse osteitis/enthesitis on MRI may serve as a diagnostic hallmark for SpA spinal disease, but needs confirmatory studies for comparison with other spinal pathologies. MRI is the modality of choice for monitoring axial disease in anti-tumour necrosis factor (TNF) therapy responses in the research environment, but it is not yet certain whether this will be relevant in clinical practice. Anti-TNF therapy may be associated with regression of MRI-determined osteitis, but retardation of associated bony fusion is debatable. MRI and US are still undergoing evaluation for the diagnosis of enthesitis of the appendicular skeleton; US, in particular, shows promise at these sites.

Early spondyloarthropathy: scintigraphic, biological, and clinical findings in MRI-positive patients

There are no specific diagnostic tests or a gold standard method for measuring disease activity and outcome in spondyloarthropathies (SpA). Many different methods have been developed to assess the signs and symptoms in SpA. The aim of this study was to evaluate the value of scintigraphy, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and Bath Ankilosing Spondylitis Disease Activity Index (BASDAI) in the evaluation of disease activity in early axial SpA diagnosed with magnetic resonance imaging (MRI). Thirty early MRI-positive axial SpA patients (23 males, 7 females) with a median age of 35 (18-55) years and a median duration of inflammatory low back pain of 24 (8-60) months were included in the study. In the patients with sacroiliitis, the sensitivity, specificity, and positive and negative predictive values of disease activity parameters were determined regarding MRI as the gold standard method. The sensitivities of quantitative scintigraphy, visual scintigraphy, ESR, CRP, and BASDAI were 32, 82, 35, 71, and 60%, respectively. The specificities of quantitative scintigraphy, ESR, CRP, and BASDAI were 100, 100, 50, and 100%, respectively. The positive predictive values of quantitative scintigraphy, visual scintigraphy, ESR, CRP, and BASDAI were 100, 92, 100, 95, and 100%, respectively. The negative predictive values of quantitative scintigraphy, ESR, CRP, and BASDAI were 9, 10, 11, and 15%, respectively. Regarding MRI as the gold standard in the evaluation of disease activity, combined visual and quantitative bone scintigraphy can be valuable in patients with MRI-incompatible implants. Additionally, use of cheaper, simple, and readily reproducible tests such as CRP and BASDAI together could be valuable and practical in detecting disease activity in long-term follow-up of these patients.

The clinical usefulness of multidetector computed tomography of the sacroiliac joint for evaluating spondyloarthropathies

BACKGROUND

Due to the low sensitivity of plain radiography, the diagnosis of early stage ankylosing spondylitis (AS) is often difficult since many patients do not meet the radiographic criteria. The objective of our study was to investigate the diagnostic value of performing multidetector computed tomography (MDCT) of the sacroiliac (SI) joint in the evaluation of AS patients.

METHODS

Thirty seven patients with definite or probable AS were evaluated. Plain radiography and MDCT imaging of the pelvis were performed for evaluating the SI joints. Two radiologists analyzed the images, and they graded the sacroiliitis on a scale of 0-4 according to the modified NY criteria. The clinical variables we analyzed included the disease duration, the treatment duration, the prescribed drugs, peripheral joint involvement, enthesopathy, the functional limitations and the BASDAI.

RESULTS

MDCT detected more bilateral sacroiliitis as compared to the plain radiography (86.5% vs. 75.7%, respectively), and MDCT yielded a higher grade of disease in 32.4% (right SI joint) and 24.3% (left SI joint) of the patients. More patients satisfied the modified NY criteria with using MDCT as compared with that when using the plain radiography (81.1% vs. 54.1%, respectively, p=0.002).

CONCLUSIONS

Visualization of the sacroiliac joint by MDCT provided a better diagnosis of AS, and especially during the early stage of the disease.

A study of ten Japanese patients with seronegative spondylarthropathy: a tentative proposal

We reviewed ten patients with seronegative spondylarthropathy (SNSA), who all fulfilled the European Spondylarthropathy Study Group criteria for spondylarthropathy (SpA); seven patients also met the Amor criteria for SpA. Seronegative spondylarthropathy was not a uniform syndrome but rather a wide spectrum of complex disease with characteristics of sacroiliitis and enthesopathy. The most frequent symptom at diagnosis of SNSA was inflammatory low back pain, followed by asymmetric oligoarthralgia and Achilles tendonitis and/or plantar fasciitis. Systemic complications were revealed as eye and skin involvement. Imaging methods including pelvic radiography, scintigraphy, and computed tomography scanning were useful in detecting spondylarthropathic changes, which were characteristic of SNSA. Human leukocyte antigen (HLA) typing showed various patterns among patients, in which HLA-B27 was positive in three patients with ankylosing spondylitis. HLA-B51, which is a well-known genetic factor associated with Behçet's disease (BD), was positive in two patients who were apparently distinct from BD. Two patients with palmoplantar pustulosis showed symptoms and signs characteristic of SNSA. Although we have few SNSA patients in the present study, we would like to propose that HLA-B51 positive SpA would be considered as a subset of SNSA, and that pustulotic SpA also would be classified as a member of SNSA. This led us to suggest the possibility to change the concept of SNSA proposed by Moll et al. The optimal treatment remains to be defined, but sulfasalazine was effectively used with almost all patients in combination with nonsteroidal anti-inflammatory drugs.

Sacroiliíte: avaliação por imagem

Sacroiliíte é o processo inflamatório não-infeccioso das articulações sacroilíacas, sendo critério diagnóstico das espondiloartropatias soronegativas. O diagnóstico desta enfermidade requer confirmação pelos métodos de imagem. O presente trabalho faz um revisão de casos do arquivo didático e de artigos da literatura para ilustrar a anatomia, a técnica e os principais achados de imagem na radiografia, tomografia computadorizada e ressonância magnética, na determinação do diagnóstico de sacroiliíte, abordando inclusive os seus principais diagnóstico diferenciais.

Validation of the Spondyloarthritis Research Consortium of Canada magnetic resonance imaging spinal inflammation index: Is it necessary to score the entire spine?

OBJECTIVE

The Spondyloarthritis Research Consortium of Canada (SPARCC) magnetic resonance imaging (MRI) spinal inflammation index has been developed to objectively measure inflammation in ankylosing spondylitis (AS) and to assess change in response to therapeutic intervention. Scoring of the entire spine limits feasibility and a scoring method that records inflammation in only the more severely affected spinal segments may improve feasibility without sacrificing performance.

METHODS

MRI films of 68 patients with AS were assessed in random order by 2 blinded readers. Interreader reliability was assessed by intraclass correlation coefficient. Pre- and posttreatment MRI films of 29 patients randomized to placebo or anti-tumor necrosis factor alpha (anti-TNFalpha) therapy were read by readers blinded to chronology, and responsiveness was assessed by effect size and standardized response mean. The performance of scores based on 6, 8, 10, and all 23 spinal discovertebral units (DVU) was compared.

RESULTS

The median number of affected spinal levels per patient was 6.0 and 62% of all affected levels were included when analysis was limited to only the 6 most severely affected levels per patient. Comparison of DVU scores that were limited to only the more severely affected DVU (6-, 8-, 10-DVU score) with scores for all 23 spinal DVU showed excellent interreader reliability for status and change scores (Spearman's correlation >0.90) as well as similar construct validity. Responsiveness to anti-TNFalpha therapy was greater when the more limited scoring methods were used and was greatest with the 6-DVU score.

CONCLUSION

The SPARCC MRI spinal inflammation index performs better when analysis is limited to a maximum of 6 most severely affected levels compared with assessment of the entire spine. This should improve its feasibility in clinical trials and research.

Imaging in ankylosing spondylitis

The introduction of symptomatically highly effective anti-tumour necrosis factor alpha therapies for ankylosing spondylitis (AS) has generated interest in the use of imaging to evaluate the potential structure-modifying properties of these agents. Several approaches have been developed to score the plain radiographic abnormalities in AS. Of these, the modified Stoke AS Spinal Score is the most responsive to change, although responsiveness is limited and requires a minimum of 2 years before significant change becomes apparent in patients on standard therapies. Magnetic resonance imaging (MRI) is the most sensitive imaging abnormality, and the advent of fat-suppression imaging allows detection of bone marrow inflammation in the sacroiliac joints as one of the earliest abnormalities in AS. Limited studies have shown that spinal inflammation can be scored reliably using either a system that evaluates the entire spine or a system that limits evaluation to only the most severely affected spinal segments. Both methods also demonstrate excellent responsiveness. The prognostic significance of acute changes on MRI remains unclear. Reliable approaches to the evaluation of chronic changes are yet to be developed. MRI represents a major advance in the diagnostic evaluation of AS.

Low grade radiographic sacroiliitis as prognostic factor in patients with undifferentiated spondyloarthritis fulfilling diagnostic criteria for ankylosing spondylitis throughout follow up

OBJECTIVE

To determine the rate and factors associated with ankylosing spondylitis in a cohort of patients with undifferentiated spondyloarthritides (SpA).

METHODS

62 consecutive patients with undifferentiated SpA seen between 1998 and 1999 underwent clinical and imaging evaluations throughout follow up. The main outcome measure was a diagnosis of ankylosing spondylitis.

RESULTS

50 patients with peripheral arthritis (n = 35) and inflammatory back pain (n = 24) (26 male; mean (SD) age at onset, 20.4 (8.8) years; disease duration 5.4 (5.7) years) were followed up for 3-5 years. At baseline, >90% of patients had axial and peripheral disease, while 38% had radiographic sacroiliitis below the cut off level for a diagnosis of ankylosing spondylitis (BASDAI 3.9, BASFI 2.9). At the most recent evaluation, 21 patients (42%) had ankylosing spondylitis. Two factors were associated with a diagnosis of ankylosing spondylitis in multivariate analysis: radiographic sacroiliitis grade <2 bilateral, or grade <3 unilateral (odds ratio (OR) = 11.18 (95% confidence interval, 2.59 to 48.16), p = 0.001), particularly grade 1 bilateral (OR = 12.58 (1.33 to 119.09), p = 0.027), and previous uveitis (OR = 19.25 (1.72 to 214.39), p = 0.001). Acute phase reactant levels, juvenile onset, and HLA-B27 showed a trend to linkage with ankylosing spondylitis (NS).

CONCLUSIONS

Low grade radiographic sacroiliitis is a prognostic factor for ankylosing spondylitis in patients originally classified as having undifferentiated SpA. Low grade radiographic sacroiliitis should be regarded as indicative of early ankylosing spondylitis in patients with undifferentiated SpA.

Sacroiliac joint dysfunction: evaluation and management

Sacroiliac joint dysfunction is believed to be a significant source of low back and posterior pelvic pain.

METHODS

To assess the clinical presentation, diagnostic testing, and treatment options for sacroiliac joint dysfunction, a systematic literature review was performed using MEDLINE.

RESULTS

Presently, there are no widely accepted guidelines in the literature for the diagnosis and treatment of sacroiliac instability. Establishing management guidelines for this disorder has been complicated by the large spectrum of different etiologic factors, the variability of patient history and clinical symptoms, limited availability of objective testing, and incomplete understanding of the biomechanics of the sacroiliac joint.

CONCLUSIONS

A reliable examination technique to identify the sacroiliac joint as a source of low back pain seems to be pain relief following a radiologically guided injection of a local anaesthetic into the sacroiliac joint. Most patients respond to non-operative treatment. Patients who do not respond to non-operative treatment should be considered for operative sacroiliac joint stabilization.

Imaging in early arthritis

Imaging can play a vital role in the evaluation of patients with early arthritis. Various imaging methods can be utilized to aid with diagnosis, predict prognosis and follow disease progression and treatment response. Previously, conventional radiography was the principal method used to evaluate and follow bone damage in patients with inflammatory arthritis. More recently the use of magnetic resonance imaging and ultrasonography has gained wider acceptance and popularity due to the ability of these multiplanar techniques to image both bone changes and soft tissue abnormalities, including synovitis. This chapter discusses the current imaging modalities used in the evaluation of patients with early arthritis, as well as the use of imaging in establishing the extent of disease, in prognosis and in monitoring disease course. Current data on imaging of patients with early arthritis due to rheumatoid arthritis, psoriatic arthritis and ankylosing spondylitis is reviewed.