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Objectives: The intervertebral disk has traditionally been imaged by magnetic resonance imaging (MRI); however, advances in sonography mean it can now be visualized with this modality. The objectives of this human cadaveric study were to visualize the internal structure of the lumbar intervertebral disks and map any defects. Shear wave sonography was explored as a method for assessing the disks. Materials and Methods: In a human cadaver, L4-L5 and L5-S1 disks were imaged with sonography through the anterior abdominal wall and directly through the anterior longitudinal ligament. Gray-scale images and shear wave elastography velocities were obtained. An MRI was performed for image comparison. Results: Defects in the disks were clearly seen with sonography, imaging through the anterior abdominal wall and also directly through the anterior longitudinal ligament. The defects identified on sonography were less well visualized on MRI. Shear wave velocities could only be obtained from the anterior aspect of the disk and were unreliable, primarily owing to the stiffness of the tissues. Conclusion: Sonography can provide an accurate map of defects within the disk, corresponding with MRI. Shear wave elastography should be used with caution in the human cadaveric intervertebral disk, acknowledging the many confounding factors influencing the measurements.

To assess spinal stability in different physiological positions whilst weight-bearing.A cone beam CT scanner (CBCT) was used to identify any abnormal motion in the spine in different physiological positions whilst weight-bearing. The lumbar spine was assessed in 6 different patients with a comfortable neutral standing position and standing flexion and extension images in selected patients. Seated, weight-bearing flexion and extension images of the cervical spine were obtained in a further patient. Clinical indications included stability assessment post-trauma, post-surgical fusion and back pain. The projection images were reconstructed using bone and soft tissue algorithms to give isotropic CT images which could be viewed as per conventional multi-detector CT images. The flexion and extension CBCT data were fused to give a representation of any spinal movement between the extremes of motion.The flexion and extension weight-bearing images gave anatomical detail of the spine. Detail of the surgical constructs was possible. Dynamic structural information about spinal alignment, facet joints, exit foramina and paraspinal musculature was possible. The effective dose from the neutral position was equal to that of supine, multi-detector CT.CBCT can be used to image the lumbar and cervical spine in physiological weight-bearing positions and at different extremes of spinal motion. This novel application of an existing technology can be used to aid surgical decision making to assess spinal stability and to investigate occult back and leg pain. Its use should be limited to specific clinical indications, given the relatively high radiation dose.

Objectives To develop evidence-based recommendations on the use of MRI in the diagnosis of axial SpA (axSpA). Methods A working group comprising nine rheumatologists and nine musculoskeletal radiologists with an interest in axSpA was established, with support from the British Society of Spondyloarthritis (BRITSpA). Two meetings were held. In the first meeting, research questions were formulated. In the second meeting, the results of a systematic literature review designed to inform the recommendations were reviewed. An anonymized Delphi process was used to formulate the final set of recommendations. For each recommendation, the level of evidence and strength of recommendation was determined. The level of agreement was assessed using a 0–10 numerical rating scale. Results Two overarching principles were formulated, as follows: The diagnosis of axSpA is based on clinical, laboratory and imaging features (overarching principle 1), and patients with axSpA can have isolated inflammation of either the sacroiliac joints or the spine (overarching principle 2). Seven recommendations addressing the use of MRI in the assessment of patients with suspected axSpA were formulated, covering topics including recommended sequences, anatomical coverage, acquisition parameters and interpretation of active and structural MRI lesions. The level of agreement for each recommendation was very high (range 8.8–9.8). Conclusion A joint rheumatology and radiology consensus on the acquisition and interpretation of MRI in axSpA diagnosis was achieved, and a research agenda formulated. This consensus should help standardize practice around MRI and ensure a more informed, consistent approach to the diagnosis of axSpA.

Introduction The aim of this study was to evaluate radiological measurements to establish the origin of giant cell tumours of bone. Methods A multi-centre retrospective review was conducted of patients with histologically confirmed giant cell tumours of bone. Images were analysed to estimate the centre of the tumour. Measured from the joint line, the ratio between the distance of the centre of the tumour and the physeal scar was calculated. Results Ninety-five patients were included in the study. Two observers found the tumour to be arising from the metaphyseal area in 94% - 97% of the cases. There was good agreement between the measurements of observers (interclass correlation coefficient 0.71). Conclusion Giant cell tumours of bone appear to be arising from the metaphyseal region.

OBJECTIVE: To predict accurately whether a soft tissue mass was benign or malignant and to characterize its type using ultrasound, shear wave elastography and MRI. We hypothesized that with the addition of shear wave elastography, it would be possible to determine a threshold velocity value to classify a lesion as benign or malignant. MATERIALS AND METHODS: A total of 151 consecutive, consenting adult patients were prospectively recruited to this study in a tertiary referral musculoskeletal oncology centre. All lesions were assessed with ultrasound, including B mode, Doppler and shear wave elastography measurements. One hundred thirty-eight patients also underwent MRI of the lesion. A histological diagnosis was obtained for all lesions. RESULTS: Malignant lesions were larger than benign lesions and had a greater Doppler activity. There was no useful threshold shear wave velocity to differentiate between benign and malignant lesions. Longitudinal and transverse shear wave velocities were strongly positively correlated with each other. An inverse correlation was shown with lesion size and depth, regardless of whether it was benign or malignant. A logistic regression model combining the ultrasound and MRI characteristics did not confidently classify a lesion as benign or malignant and was inferior to expert opinion. CONCLUSION: The strongest predictors of malignancy are large lesion size and high vascularity. The combination of all ultrasound characteristics (including shear wave elastography) and MRI features does not confidently classify a lesion as benign or malignant, and histological diagnosis remains the gold standard.

Paget disease (PD) is a common disease of bone associated with abnormal bone turnover that in turn is due to an imbalance between osteoclastic and osteoblastic activity. There is good evidence that PD is reducing in incidence, prevalence, and severity. The disease is most often asymptomatic and is usually detected incidentally on imaging examinations performed for other reasons. The features of PD are relatively specific on radiographs and computed tomography. However, the appearances on magnetic resonance imaging are subtle and nonspecific, although it has become the initial imaging choice for several clinical indications including back pain, neurologic dysfunction, and knee pain. It is therefore important to be familiar with the various imaging appearances of this relatively common disease in an increasingly aging population. In this article we discuss the various imaging appearances of PD and its complications.

Background The use of magnetic resonance imaging (MRI) has been instrumental in the early recognition and characterisation of axial spondyloarthritis (axSpA). However, a recent survey in the UK showed that there is diverse practice in the use of MRI and limited knowledge of MRI features suggestive of axSpA among radiologists.1 Objectives To develop clinical practice recommendations for the acquisition and interpretation of MRI of the spine and sacroiliac joints (SIJs) in the investigation of axSpA through a collaboration between rheumatologists and radiologists. Methods A working group comprising 9 rheumatologists and 9 musculoskeletal radiologists with an interest in axSpA was established. The EULAR standardised operating procedures were followed.2 Two working group meetings were held, the first to define the scope of the exercise and the second to review the results of the Systematic Literature Review that informed the recommendations. An anonymised Delphi process was used to formulate the final set of recommendations. The level of evidence and strength of recommendation was added to the recommendations. The level of agreement by working group members was assessed using a numerical rating scale. Results A total of 2 overarching principles and 7 recommendations were formulated (figure 1). The first 3 recommendations address the MRI acquisition protocol, namely anatomical areas to be scanned and sequences to be used. The remaining 4 recommendations address the interpretation of active and structural lesions of the spine and SIJs. Conclusions A UK joint rheumatology and radiology consensus on the most appropriate MRI acquisition protocol and interpretation of images in the investigation of axSpA was achieved. This consensus will help standardise practices and ensure prompt and effective patient management in the diagnosis and treatment of axSpA. References [1] Bennett, et al. J Rheumatol2017. [2] van der Heijde, et al. Ann Rheum Dis2015. Acknowledgements This work was financially supported by the British Society for Spondyloarthritis (BRITSpA). Disclosure of Interest None declared

Background The application and appropriate use of imaging-based scoring instruments is usually based on passive learning from published manuscripts while real-time interaction with instrument developers is often non-feasible. Moreover, most instruments lack knowledge transfer tools that would facilitate attainment of pre-specified performance targets for reader reliability. Objectives 1. To develop a web-based calibration module for the SPARCC MRI SIJ Inflammation Score based on consensus scores from these instrument developers, experiential game psychology, and real-time iterative feedback. 2. To test the feasibility and attainment of pre-specified performance targets for reader reliability. Methods The scoring of inflammatory lesions of the SIJ on MRI using the SPARCC method is based on SIJ quadrants and the calibration module is comprised of 50 DICOM cases, each with scans from baseline and 12 weeks after the start of TNF inhibitor therapy. Scans are scored blinded-to-time-point. Continuous visual real-time feedback regarding concordance/discordance of scoring per SIJ quadrant with expert readers is provided by a color-coding scheme. Reliability is additionally assessed by real-time intra-class correlation coefficient with the first ICC data being provided after 20 cases. Accreditation for SPARCC BME score is achieved with status and change score ICC of >0.8 and>0.7 and is based on the final 20 cases. 26 readers scored the SPARCC BME module (7 rheumatology fellows, 2 chiropracters, 1 undergraduate, 8 rheumatologists, 8 radiologists) with 21 having no prior experience. Feasibility was assessed by 8-item survey. Results The majority of readers achieved accreditation for SPARCC BME score on the basis of sufficient reliability with instrument developers for both status and change scores, irrespective of prior experience (table 1). All readers who completed the module a second time, 6 months after the first exposure, achieved accreditation for SPARCC BME score. All readers rated the modules as easy and intuitive with average time for reading each case for SPARCC BME being 8 min. Conclusions Experiential web-based learning is an effective and feasible calibration tool to achieve proficiency targets in the scoring of MRI scans for SIJ inflammatory lesions. Disclosure of Interest W. Maksymowych Shareholder of: CaRE Arthritis, S. Krabbe: None declared, D. Biko: None declared, P. Weiss: None declared, M. Maksymowych: None declared, J. Cheah: None declared, G. Krober: None declared, U. Weber: None declared, K. Danebod: None declared, P. Bird: None declared, P. Chiowchanwisawakit: None declared, J. Moeller: None declared, M. Francavilla: None declared, J. Stimec: None declared, T. Kogay: None declared, V. Zubler: None declared, M. Battish: None declared, N. Winn: None declared, D. Rumsey: None declared, R. Guglielmi: None declared, S. Pedersen: None declared, H. Boutrup: None declared, S. Shafer: None declared, J. Jaremko: None declared, F. Malik: None declared, E. Heffernan: None declared, M. Johansson: None declared, B. Trinh: None declared, J. Paschke: None declared, R. Lambert: None declared

Pigmented villonodular synovitis (PVNS) is normally treated by arthroscopic or open surgical excision. We present our initial experience with radiofrequency thermo-ablation (RF ablation) of PVNS located in an inaccessible location in the knee. Review of all patients with histologically proven PVNS treated with RF ablation and with at least 2-year follow-up. Three patients met inclusion criteria and were treated with RF ablation. Two of the patients were treated successfully by one ablation procedure. One of the three patients had a recurrence which was also treated successfully by repeat RF ablation. There were no complications and all patients returned to their previous occupations following RF ablation. In this study we demonstrated the feasibility of performing RF ablation to treat PVNS in relatively inaccessible locations with curative intent. We have also discussed various post-ablation imaging appearances which can confound the assessment for residual/recurrent disease.

Objective.To assess feasibility and reliability of scoring bone marrow lesions (BML) on knee magnetic resonance imaging (MRI) in osteoarthritis using the Outcome Measures in Rheumatology Knee Inflammation MRI Scoring System (KIMRISS), with a Web-based interface and online training with real-time iterative calibration.Methods.Six readers new to the KIMRISS (3 radiologists, 3 rheumatologists) scored sagittal T2-weighted fat-saturated MRI in 20 subjects randomly selected from the Osteoarthritis Initiative data, at baseline and 1-year followup. In the KIMRISS, the reader moves a transparent overlay grid within a Web-based interface to fit bones, then clicks or touches each region containing BML per slice, to score 1 if BML is present. Regional and total scores are automatically calculated. Outcomes include the interreader intraclass correlation coefficients (ICC) and the smallest detectable change (SDC).Results.Scoring took 3–12 min per scan and all readers rated the process as moderately to very user friendly. Despite a low BML burden (average score 2.8% of maximum possible) and small changes, interobserver reliability was moderate to high for BML status and change in the femur and tibia (ICC 0.78–0.88). Four readers also scored the patella reliably, whereas 2 readers were outliers, likely because of image artifacts. SDC of 1.5–5.6 represented 0.7% of the maximum possible score.Conclusion.We confirmed feasibility of knee BML scoring by new readers using interactive training and a Web-based touch-sensitive overlay system, finding high reliability and sensitivity to change. Further work will include adjustments to training materials regarding patellar scoring, and study in therapeutic trial datasets with higher burden of BML and larger changes.

Objective.To assess reliability and feasibility of using a Web-based interface and interactive online calibration tool for magnetic resonance imaging (MRI) scoring of bone marrow lesions (BML) in osteoarthritis (OA), applied to the Hip MR Inflammation Scoring System (HIMRISS).Methods.Seven readers new to HIMRISS (3 radiologists, 4 rheumatologists) scored coronal short-tau inversion recovery MRI from a hip OA observational study obtained pre- and 8-week poststeroid injection (n = 40 × 2 scans × 2 hips = 160 hips). By crossover design, Group B (4 readers) scored 20 patients (40 hips) using conventional spreadsheet-based methods and then another 20 using a Web-based interface and an online real-time iterative calibration (RETIC) training module. Group A (3 readers) reversed the order, scoring the first 20 subjects by the new method and the final 20 conventionally. Outcomes included ICC and reader survey.Results.Interobserver reliability for BML status was high by both spreadsheet and Web-based methods (0.84–0.90), regardless of the order in which scoring was performed. Reliability of change scores was moderate and improved with training. Improvement was greater in readers who began with the spreadsheet method and then used the Web-based method than in those who began with the Web-based method, especially at the acetabulum. Readers found Web-based/RETIC scoring more user-friendly and nearly 50% faster than traditional spreadsheet methods.Conclusion.HIMRISS offers reliable BML scoring in OA, whether by conventional spreadsheet-based scoring or by a Web-based interface with interactive feedback. The new method allowed faster readings, provided a consistent training environment that helped inexperienced readers achieve reliability equivalent to that of conventional methods, and was preferred by the readers.

Imaging evaluation of the spine can be challenging. Awareness of the limitations of the different imaging modalities allows one to take a considered approach to their interpretation. The modalities of radiography, computed tomography, and magnetic resonance imaging are often complementary to each other in the information they provide. There are many pitfalls to be avoided. Familiarity with normal radiological anatomy, an awareness of technical factors which can lead to confusion in interpretation, and knowledge of normal ossification and normal variants will minimize the risk of over- or, indeed more seriously, underreporting radiological findings.

Paget's disease of bone is a disorder of bone remodelling, leading to changes in the architecture and overall appearance of the bone. The disorder may be monostotic or polyostotic and affect any bone in the body, although most commonly it involves the spine, pelvis, skull and femur. This article explores the different imaging modalities used in the assessment of Paget's disease of bone in its different phases. The relative merits of each imaging modality is discussed with illustrative examples, in particular with respect to radiographs, nuclear medicine bone scan, computed tomography (CT) and magnetic resonance imaging (MRI).

The knee is a common area of the body to undergo interventional procedures. This article discusses image-guided interventional issues specific to the knee area. The soft tissues in and around the knee are frequently affected by sport-related injuries and often need image-guided intervention. This article details the specific technical issues related to intervention in these soft tissues, including the iliotibial tract, fat pads, patellar tendon and other tendons, bursae and the meniscus. Most often, simple procedures such as injection and aspiration are performed without image guidance. Rarely image-guided diagnostic arthrography and therapeutic joint injections are necessary. The technique, indications and diagnostic considerations for arthrography are discussed in this article. Primary bone and soft-tissue tumours may involve the knee and adjacent soft tissues. Image-guided biopsies are frequently necessary for these lesions; this article details the technical issues related to image-guided biopsy around the knee. A number of newer ablation treatments are now available, including cryoablation, high-frequency ultrasound and microwave ablation. Radiofrequency ablation, however, still remains the most commonly employed ablation technique. The indications, technical and therapeutic considerations related to the application of this technique around the knee are discussed here. Finally, we briefly discuss some newer, but as of yet, unproven image-guided interventions for osteochondral lesions and Brodie's abscess.

Background: CT guided lung biopsy is a commonly performed procedure to obtain tissue for a histological diagnosis in cases of suspected lung cancer. Methods: This is a prospective cohort study to obtain information directly from patients about their experiences of the biopsy procedure, thus obtaining a more accurate picture of complications compared with previously performed retrospective reviews. Patients participated in a post-procedure telephone interview and information was gathered about any procedural complications and personal experiences. We also compared the patient reported complications with those obtained from a retrospective review of hospital databases, analogous to previously performed retrospective studies. Results: In our patient group, reported procedural complication rates were 10% pneumothorax rate (4% requiring a chest drain) and 10% haemoptysis. Post-procedural pain and shortness of breath showed positive correlation, with one patient experiencing prolonged pain. No statistical difference was found between the patient reported complication rates and those obtained from retrospective review of the hospital database. Conclusions: Our study demonstrates CT guided lung biopsy is a safe procedure and is generally well tolerated. Some patients may experience significant and lasting pain and therefore should be counselled about this pre-procedure.

Objective.To compare the utility of radiography and magnetic resonance imaging (MRI) for the diagnosis of juvenile-onset spondyloarthritis in pediatric patients presenting with low back and/or sacroiliac (SI) pain of potentially inflammatory etiology.Methods.Radiographs and MRI studies of the SI joints in 26 patients with juvenile spondyloarthritis (JSpA) and 35 controls were assessed independently by 2 radiologists, with discrepancies arbitrated by a third. Radiographs and MRI were blinded and read in separate batches in random order.Results.Erosion was common and was the most useful diagnostic feature on radiography [positive likelihood ratio (LR) = 3.5] and was especially diagnostic of SpA on MRI (LR = 6.7). Subchondral sclerosis was common but was the least specific feature for both modalities. Joint space narrowing had some utility on radiography (LR = 2.0) and MRI (LR = 2.7) but was uncommon and had poor reader reliability. Bone marrow edema (LR = 3.1) and subarticular fat infiltration (LR = 4.5), detectable only on MRI, were both useful features. Global diagnostic impression of MRI (LR = 9.4) had very high utility for the diagnosis of JSpA, exceeding radiography (LR = 4.4) because of superior specificity. In addition, global diagnosis of SpA is much more reliably made on MRI (κ = 0.80) compared to radiography (κ = 0.30).Conclusion.Specificity and reliability of MRI of the SI joints are superior to radiography for the diagnosis of juvenile-onset SpA and, where available, MRI should replace radiography as the first line of investigation.

Ultrasound is an essential modality within musculoskeletal imaging, with the recent addition of elastography. The elastic properties of tissues are different from the acoustic impedance used to create B mode imaging and the flow properties used within Doppler imaging, hence elastography provides a different form of tissue assessment. The current role of ultrasound elastography in the musculoskeletal system will be reviewed, in particular with reference to muscles, tendons, ligaments, joints and soft tissue tumours. The different ultrasound elastography methods currently available will be described, in particular strain elastography and shear wave elastography. Future directions of ultrasound elastography in the musculoskeletal system will also be discussed.