Soft tissue tumor imaging in adults: whole-body staging in sarcoma, non-malignant entities requiring special algorithms, pitfalls and special imaging aspects. Guidelines 2024 from the European Society of Musculoskeletal Radiology (ESSR).

OBJECTIVES: The revised European Society of Musculoskeletal Radiology (ESSR) consensus guidelines on soft tissue tumor imaging represent an update of 2015 after technical advancements, further insights into specific entities, and revised World Health Organization (2020) and AJCC (2017) classifications. This second of three papers covers algorithms once histology is confirmed: (1) standardized whole-body staging, (2) special algorithms for non-malignant entities, and (3) multiplicity, genetic tumor syndromes, and pitfalls. MATERIALS AND METHODS: A validated Delphi method based on peer-reviewed literature was used to derive consensus among a panel of 46 specialized musculoskeletal radiologists from 12 European countries. Statements that had undergone interdisciplinary revision were scored online by the level of agreement (0 to 10) during two iterative rounds, that could result in 'group consensus', 'group agreement', or 'lack of agreement'. RESULTS: The three sections contain 24 statements with comments. Group consensus was reached in 95.8% and group agreement in 4.2%. For whole-body staging, pulmonary MDCT should be performed in all high-grade sarcomas. Whole-body MRI is preferred for staging bone metastasis, with [18F]FDG-PET/CT as an alternative modality in PET-avid tumors. Patients with alveolar soft part sarcoma, clear cell sarcoma, and angiosarcoma should be screened for brain metastases. Special algorithms are recommended for entities such as rhabdomyosarcoma, extraskeletal Ewing sarcoma, myxoid liposarcoma, and neurofibromatosis type 1 associated malignant peripheral nerve sheath tumors. Satisfaction of search should be avoided in potential multiplicity. CONCLUSION: Standardized whole-body staging includes pulmonary MDCT in all high-grade sarcomas; entity-dependent modifications and specific algorithms are recommended for sarcomas and non-malignant soft tissue tumors. CLINICAL RELEVANCE STATEMENT: These updated ESSR soft tissue tumor imaging guidelines aim to provide support in decision-making, helping to avoid common pitfalls, by providing general and entity-specific algorithms, techniques, and reporting recommendations for whole-body staging in sarcoma and non-malignant soft tissue tumors. KEY POINTS: An early, accurate, diagnosis is crucial for the prognosis of patients with soft tissue tumors. These updated guidelines provide best practice expert consensus for standardized imaging algorithms, techniques, and reporting. Standardization can improve the comparability examinations and provide databases for large data analysis.

Combining morphological and functional imaging parameters to diagnose primary bone neoplasms in the skull base, spine and sacrum.

PURPOSE: Morphological magnetic resonance (MR) and computed tomography (CT) features are used in combination with histology for diagnosis and treatment selection of primary bone neoplasms. Isolated functional MRI parameters have shown potential in diagnosis. Our goal is to facilitate diagnosis of primary bone neoplasms of the skull base, mobile spine and sacrum, by a comprehensive approach, combining morphological and functional imaging parameters. MATERIALS AND METHODS: Pre-treatment MR of 80 patients with histologically proven diagnosis of a primary bone neoplasm of the skull base, mobile spine and sacrum were retrospectively analyzed for morphological and functional MRI parameters. Functional parameters were measured in 4 circular regions of interest per tumor placed on non-adjacent scan slices. Differences in values of functional parameters between different histologies were analyzed with Dunn's test. RESULTS: Chordomas were the predominant histology (60.0%). Most neoplasms (80.0%) originated in the midline and had geographical (78.2%) bone destruction. Amorphous-type calcification (pre-existing bone) was seen only in chordomas. Homogeneous contrast enhancement pattern was seen only in chondrosarcoma and plasmacytoma. Ktrans and Kep were significantly lower in both chordoma, and chondrosarcoma compared to giant cell tumor of the bone (p = 0.006 - 0.011), and plasmacytoma (p = 0.004 - 0.014). Highest diffusion-weighted MRI apparent diffusion coefficient (ADC) values corresponded to chondrosarcoma and were significantly higher to those of chordoma (p = 0.008). CONCLUSION: We identified the most discriminating morphological parameters and added functional MR parameters based on histopathological features that are useful in making a confident diagnosis of primary bone neoplasms in the skull base, mobile spine and sacrum.

Evaluation of response to neoadjuvant chemotherapy in osteosarcoma using dynamic contrast-enhanced MRI: development and external validation of a model.

OBJECTIVE: To identify which dynamic contrast-enhanced (DCE-)MRI features best predict histological response to neoadjuvant chemotherapy in patients with an osteosarcoma. METHODS: Patients with osteosarcoma who underwent DCE-MRI before and after neoadjuvant chemotherapy prior to resection were retrospectively included at two different centers. Data from the center with the larger cohort (training cohort) was used to identify which method for region-of-interest selection (whole slab or focal area method) and which change in DCE-MRI features (time to enhancement, wash-in rate, maximum relative enhancement and area under the curve) gave the most accurate prediction of histological response. Models were created using logistic regression and cross-validated. The most accurate model was then externally validated using data from the other center (test cohort). RESULTS: Fifty-five (27 poor response) and 30 (19 poor response) patients were included in training and test cohorts, respectively. Intraclass correlation coefficient of relative DCE-MRI features ranged 0.81-0.97 with the whole slab and 0.57-0.85 with the focal area segmentation method. Poor histological response was best predicted with the whole slab segmentation method using a single feature threshold, relative wash-in rate <2.3. Mean accuracy was 0.85 (95%CI: 0.75-0.95), and area under the receiver operating characteristic curve (AUC-index) was 0.93 (95%CI: 0.86-1.00). In external validation, accuracy and AUC-index were 0.80 and 0.80. CONCLUSION: In this study, a relative wash-in rate of <2.3 determined with the whole slab segmentation method predicted histological response to neoadjuvant chemotherapy in osteosarcoma. Consistent performance was observed in an external test cohort.

Mutation in the CCAL1 locus accounts for bidirectional process of human subchondral bone turnover and cartilage mineralization.

OBJECTIVES: To study the mechanism by which the readthrough mutation in TNFRSF11B, encoding osteoprotegerin (OPG) with additional 19 amino acids at its C-terminus (OPG-XL), causes the characteristic bidirectional phenotype of subchondral bone turnover accompanied by cartilage mineralization in chondrocalcinosis patients. METHODS: OPG-XL was studied by human induced pluripotent stem cells expressing OPG-XL and two isogenic CRISPR/Cas9-corrected controls in cartilage and bone organoids. Osteoclastogenesis was studied with monocytes from OPG-XL carriers and matched healthy controls followed by gene expression characterization. Dual energy X-ray absorptiometry scans and MRI analyses were used to characterize the phenotype of carriers and non-carriers of the mutation. RESULTS: Human OPG-XL carriers relative to sex- and age-matched controls showed, after an initial delay, large active osteoclasts with high number of nuclei. By employing hiPSCs expressing OPG-XL and isogenic CRISPR/Cas9-corrected controls to established cartilage and bone organoids, we demonstrated that expression of OPG-XL resulted in excessive fibrosis in cartilage and high mineralization in bone accompanied by marked downregulation of MGP, encoding matrix Gla protein, and upregulation of DIO2, encoding type 2 deiodinase, gene expression, respectively. CONCLUSIONS: The readthrough mutation at CCAL1 locus in TNFRSF11B identifies an unknown role for OPG-XL in subchondral bone turnover and cartilage mineralization in humans via DIO2 and MGP functions. Previously, OPG-XL was shown to affect binding between RANKL and heparan sulphate (HS) resulting in loss of immobilized OPG-XL. Therefore, effects may be triggered by deficiency in the immobilization of OPG-XL Since the characteristic bidirectional pathophysiology of articular cartilage calcification accompanied by low subchondral bone mineralization is also a hallmark of OA pathophysiology, our results are likely extrapolated to common arthropathies.

Presurgical Perspective and Posttreatment Evaluation of Soft Tissue Tumors of the Ankle and Foot in Adults.

This article discusses soft tissue tumors of the ankle and foot region in adults, including tumors of the joints, and also briefly addresses tumor-simulating lesions. We offer general recommendations and describe specific aspects of common entities in that region, such as typical imaging appearance, therapeutic strategies, and posttherapeutic considerations. Focal masses and diffuse swelling are common in the foot and ankle region; most of them are non-neoplastic. Some of the tumors, such as plantar fibromatosis, tenosynovial giant cell tumor, synovial chondromatosis, or schwannoma, have a very typical appearance on magnetic resonance imaging. Sarcomas are rare among true soft tissue tumors; however, they can be small and well demarcated, may grow slowly, and are often misinterpreted as benign. This is especially true for synovial sarcoma, one of the most common sarcomas in this region. Densely packed tissues in the foot and ankle may hamper determining the tissue of origin. Adherence to diagnostic guidelines and cooperation with tumor centers is crucial including for posttherapeutic surveillance. We also describe typical posttherapeutic changes and complications after surgery, radiation therapy, and chemotherapy, as well as parameters for the detection and exclusion of recurrence of soft tissue tumors of the ankle and foot.

Can we use MRI to detect clinically silent recurrent soft-tissue sarcoma?

PURPOSE: The impact of MRI on early detection of local recurrence (LR) in high-grade soft-tissue sarcomas (STS) is unsubstantiated. To identify the contribution of MRI criteria including dynamic contrast-enhanced (DCE) MRI and knowledge of surgical margins that can be used in detecting recurrence prior to obvious proven presence of LR in soft-tissue sarcomas. The secondary aim was to determine causes for misdiagnosing LR. METHODS: MRI of 23 patients (12 men; mean age, 59.7 years ± 16.5 years) with LR of STS and that of 22 age- and histology-matched controls with STS but without LR were retrospectively analyzed by two musculoskeletal radiologists. Preoperative MRI characteristics (conventional and DCE) were compared to those of MRIs made after treatment, but before LR was proven. Likelihood of recurrence was rated on a 5-point Likert scale for morphological and dynamic assessment separately, before and after adding knowledge of surgical margins. Descriptive statistics and receiver operating characteristic analysis were performed. RESULTS: Differentiation of LR from post-therapeutic changes was the highest combining result of conventional MRI, DCE-MRI, and knowledge of surgical margins (area under the curve (AUC) 0.779), followed by DCE-MRI (AUC 0.706) and conventional MRI (AUC 0.648). Suboptimal MRI technique and overcalling post-therapeutic changes in microscopic positive margins were the main reasons for false negative and false positive results, respectively. CONCLUSION: MRI including DCE improves the detection of recurrent, clinically silent soft-tissue sarcoma when combined with knowledge of achieved surgical margins. LR may be missed on inadequate MRI protocols. KEY POINTS: • Dynamic contrast-enhanced MRI is useful in the differentiation of recurrent soft-tissue sarcoma and post-therapeutic fibrosis. • Knowledge of surgical margins substantially increases the value of MRI in detecting recurrent soft-tissue sarcoma. • MR with all three image orientations, covering the entire part of the extremity in at least one sequence and comparison to initial tumor characteristics and location, is beneficial.

Ten Commandments for the Diagnosis of Bone Tumors.

The diagnosis of tumors and tumorlike lesions of bone is a routine part of both general and specialist radiologic practices. The spectrum of disorders ranges from the small incidental lesion to the potentially life-limiting malignancies whether primary or secondary. In this review, authored by experts from several European orthopaedic oncology centers, we present a collection of pieces of advice in the form of 10 commandments. Adherence in daily practice to this guidance should help minimize adverse patient experiences and outcomes.

Soft Tissue Sarcoma Follow-up Imaging: Strategies to Distinguish Post-treatment Changes from Recurrence.

Soft tissue sarcomas encompass multiple entities with differing recurrence rates and follow-up intervals. The detection of recurrences and their differentiation from post-therapeutic changes is therefore complex, with a central role for the clinical radiologist. This article describes approved recommendations. Prerequisite is a precise knowledge of the current clinical management and surgical techniques. We review recurrence rates and treatment modalities. An adequate imaging technique is paramount, and comparison with previous imaging is highly recommended. We describe time-dependent therapy-related complications on magnetic resonance imaging compared with the spectrum of regular post-therapeutic changes. Early complications such as seromas, hematomas, and infections, late complications such as edema and fibrosis, and inflammatory pseudotumors are elucidated. The appearance of recurrences and radiation-associated sarcomas is contrasted with these changes. This systematic approach in follow-up imaging of soft tissue sarcoma patients will facilitate the differentiation of post-therapeutic changes from recurrences.

Therapy-Related Imaging Findings in Patients with Sarcoma.

Knowledge of imaging findings related to therapy administered to patients with sarcoma is pivotal in selecting appropriate care for these patients. Imaging studies are performed as surveillance in asymptomatic patients or because symptoms, including anxiety, develop. In addition to detection of recurrent disease and assessment of response to therapy, diagnosis of conditions related to therapy that may or may not need treatment has a marked positive impact on quality of life. The purpose of this review is to assist radiologists, nuclear physicians, and others clinicians involved in the diagnosis and treatment of these patients in recognizing imaging findings related to therapy and not to activity of the previously treated sarcoma. Imaging findings are time dependent and often specific in relation to therapy given.

Hip and Pelvis Bone Tumors: Can You Make It Simple?

Although it is possible for any osseous tumor or tumorlike lesion to occur in and around the hip and pelvis, there are preferential lesions. Most tumors share many imaging features with those arising elsewhere in the skeletal system, but some may show specific morphological and imaging features. Furthermore, specific criteria and rules of thumb are related to this anatomical area that radiologists should know, which together with the imaging findings and clinical context will lead to a more confident diagnosis.In this article we review the basic anatomical and imaging principles in the hip and pelvis and their diagnostic criteria, describe the most common regional benign and malignant bone tumors and pseudotumors, and highlight their main imaging features and common differential diagnosis while keep this article as relatively simple and straightforward as possible. Soft tissue tumors are beyond the scope of this article.

Is fat suppression in T1 and T2 FSE with mDixon superior to the frequency selection-based SPAIR technique in musculoskeletal tumor imaging?

OBJECTIVE: To determine the image quality of fast spin echo (FSE) with mDixon relative to spectral attenuated inversion recovery (SPAIR) FSE sequences in musculoskeletal tumor imaging on a 1.5-T MRI system. MATERIALS AND METHODS: In a HIPAA-compliant prospective study, 265 patients requiring musculoskeletal tumor MRI scans were included. Patient consent was waived by the medical ethical committee. Two radiologists compared SPAIR and mDixon FSE water-only images in both T2- and T1-weighted gadolinium-enhanced (T1-Gd) sequences using a five-point scale (paired samples t test and visual grading characteristics curves (VGC)). Homogeneity of fat suppression, noise, contrast, several artifacts (motion, phase, edge blurring and water-fat swap) and subjective preference were evaluated. RESULTS: Readers did not have subjective preference for either sequence in 71% and 55% (reader 1 and 2, respectively). Scores for homogeneous fat suppression were significantly (p < 0.01) higher for mDixon (4.88 in T2 and 4.87 in T1-Gd) than for SPAIR (4.31 for T2 and 4.21 for T1-Gd). All VGC curves for homogeneity demonstrated preference for mDixon. In 57 individual mDixon cases, fat-suppression homogeneity was strikingly better (≥ 2 points higher), namely in areas with field heterogeneity. Average noise and contrast scores were slightly higher for mDixon, as were motion artifact scores for SPAIR (< 0.5 points difference). CONCLUSIONS: mDixon fat suppression was significantly more homogeneous than SPAIR on both T2 and T1-Gd FSE images in musculoskeletal tumor protocols. In areas of field inhomogeneity, mDixon outperforms SPAIR. SPAIR had slightly less motion artifacts than mDixon.

General Practitioners Referring Adults to MR Imaging for Knee Pain: A Randomized Controlled Trial to Assess Cost-effectiveness.

Purpose To determine the cost-effectiveness of early referral by the general practitioner for magnetic resonance (MR) imaging compared with usual care alone in patients aged 18-45 years with traumatic knee symptoms. Materials and Methods Cost-utility analysis was performed parallel to a prospective multicenter randomized controlled trial in Dutch general practice. A total of 356 patients with traumatic knee symptoms were included from November 2012 to December 2015 (mean age, 33 years ± 8 [standard deviation]; 222 men [62%]). Patients were randomly assigned to usual care (n = 177; MR imaging was not performed, but patients were referred to an orthopedic surgeon when conservative treatment was unsatisfactory) or MR imaging (n = 179) within 2 weeks after injury. Main outcome measures were quality-adjusted life years (QALYs) and costs from a healthcare and societal perspective. Multiple imputation was used for missing data. The Student t test was used to assess differences in mean QALYs, costs, and net benefits. Results Mean QALYs were 0.888 in the MR imaging group and 0.899 in the usual care group (P = .255). Healthcare costs per patient were higher in the MR imaging group (€1109) than in the usual care group (€837) (P = .050), mainly due to higher costs for MR imaging, with no reduction in the number of referrals to an orthopedic surgeon in the MR imaging group. Conclusion MR imaging referral by the general practitioner was not cost-effective in patients with traumatic knee symptoms; in fact, MR imaging led to more healthcare costs, without an improvement in health outcomes.

Automatic quantification of bone marrow edema on MRI of the wrist in patients with early arthritis: A feasibility study.

PURPOSE: To investigate the feasibility of automatic quantification of bone marrow edema (BME) on MRI of the wrist in patients with early arthritis. METHODS: For 485 early arthritis patients (clinically confirmed arthritis of one or more joints, symptoms for less than 2 years), MR scans of the wrist were processed in three automatic stages. First, super-resolution reconstruction was applied to fuse coronal and axial scans into a single high-resolution 3D image. Next, the carpal bones were located and delineated using atlas-based segmentation. Finally, the extent of BME within each bone was quantified by identifying image intensity values characteristic of BME by fuzzy clustering and measuring the fraction of voxels with these characteristic intensities within each bone. Correlation with visual BME scores was assessed through Pearson correlation coefficient. RESULTS: Pearson correlation between quantitative and visual BME scores across 485 patients was r=0.83, P<0.001. CONCLUSIONS: Quantitative measurement of BME on MRI of the wrist has the potential to provide a feasible alternative to visual scoring. Complete automation requires automatic detection and compensation of acquisition artifacts. Magn Reson Med 79:1127-1134, 2018. © 2017 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

The diagnostic value of 18F-FDG-PET/CT and MRI in suspected vertebral osteomyelitis - a prospective study.

PURPOSE: The aim of this study was to determine the diagnostic value of 18F-fluorodeoxyglucose (FDG) positron emission tomography and computed tomography (PET/CT) and magnetic resonance imaging (MRI) in diagnosing vertebral osteomyelitis. METHODS: From November 2015 until December 2016, 32 patients with suspected vertebral osteomyelitis were prospectively included. All patients underwent both 18F-FDG-PET/CT and MRI within 48 h. All images were independently reevaluated by two radiologists and two nuclear medicine physicians who were blinded to each others' image interpretation. 18F-FDG-PET/CT and MRI were compared to the clinical diagnosis according to international guidelines. RESULTS: For 18F-FDG-PET/CT, sensitivity, specificity, PPV, and NPV in diagnosing vertebral osteomyelitis were 100%, 83.3%, 90.9%, and 100%, respectively. For MRI, sensitivity, specificity, PPV, and NPV were 100%, 91.7%, 95.2%, and 100%, respectively. MRI detected more epidural/spinal abscesses. An important advantage of 18F-FDG-PET/CT is the detection of metastatic infection (16 patients, 50.0%). CONCLUSION: 18F-FDG-PET/CT and MRI are both necessary techniques in diagnosing vertebral osteomyelitis. An important advantage of 18F-FDG-PET/CT is the visualization of metastatic infection, especially in patients with bacteremia. MRI is more sensitive in detection of small epidural abscesses.

Evaluation of the diagnostic accuracy of hand and foot MRI for early Rheumatoid Arthritis.

Objectives: To assess the diagnostic value of MRI for early RA. In some RA patients, a classifiable diagnosis cannot be made at first presentation; these patients present with unclassified arthritis (UA). The use of MRI for early diagnosis of RA is recommended, yet the evidence for its reliability is limited. Methods: MRI of hand and foot was performed in 589 early arthritis patients included in the Leiden Early Arthritis Clinic (229 presented with RA, 159 with other arthritides and 201 with UA). Symptom-free controls provided a reference for defining an abnormal MRI. In preliminary investigations, MRI of patients who presented with RA was compared with MRI of symptom-free controls and of patients with other arthritides. Thereafter, the value of MRI in early RA diagnosis was determined in UA patients using the 1-year follow-up on fulfilling the 1987 RA criteria and start of disease-modifying drugs as outcomes. Results: Preliminary investigations were promising. Of the UA patients, 14% developed RA and 37% started disease-modifying treatment. MRI-detected tenosynovitis was associated with RA development independent of other types of MRI-detected inflammation [odds ratio (OR) = 7.5, 95% CI: 2.4, 23] and also independent of age and other inflammatory measures (swollen joints, CRP) (OR = 4.2, 95% CI: 1.4, 12.9). Within UA patients, the negative predictive value of abnormal tenosynovitis was 95% (95% CI: 89%, 98%) and the positive predictive value 25% (95% CI: 17%, 35%). The performance was best in the subgroup of UA patients presenting with oligoarthritis (18% developed RA): the positive predictive value was 36% (95% CI: 23%, 52%), the negative predictive value was 98% (95% CI: 88%, 100%), the sensitivity was 93% (95% CI: 70%, 99%) and the specificity was 63% (95% CI: 51%, 74%). Conclusion: MRI contributes to the identification of UA patients who will develop RA, mostly in UA patients presenting with oligoarthritis.

Characterising arthralgia in the preclinical phase of rheumatoid arthritis using MRI.

BACKGROUND: The phase of arthralgia is the earliest moment to clinically recognize patients who may develop Rheumatoid Arthritis (RA). Previous imaging studies in the arthralgia phase have shown that inflammation precedes RA development. It is unknown which symptoms/characteristics relate to subclinical joint inflammation as measured by MRI. Among all patients with arthralgia, those with clinically suspect arthralgia (CSA) are suspected to progress to arthritis according to the clinical judgement of their rheumatologists. We determined the symptoms/characteristics of patients with CSA who had inflammation on MRI. METHODS: 102 patients with CSA and without clinical arthritis were included. They completed questionnaires, underwent joint counts and unilateral 1.5 T MRI of MCP joints 2-4, wrist and MTP joints 1-5. Synovitis, bone marrow oedema (BME) and tenosynovitis were scored according to the OMERACT rheumatoid arthritis MRI scoring system. Symptoms and signs were related to MRI inflammation (based on MRI scores in symptom-free controls; a sum of synovitis, BME and tenosynovitis scores ≥3 was considered positive). Whether certain clinical characteristics frequently occurred together with MRI inflammation was studied by partial least squares analysis. RESULTS: MRI was performed in 93 patients with CSA, 44% of whom had subclinical MRI inflammation. Synovitis was the most prevalent inflammatory feature on MRI (20%). Patients with MRI inflammation were older and were more frequently positive for anti-citrullinated peptide antibodies than patients without MRI inflammation (p<0.001 and 0.049). In PLS analysis, including 16 clinical and serological characteristics as independent variables and MRI inflammation as dependent variable, no clear clusters of patients with and without MRI inflammation were identified. CONCLUSIONS: Subclinical inflammation as measured by MRI is present in 44% of patients with CSA. A combination of symptoms/characteristics incompletely differentiated patients with and without MRI inflammation.

Prevalence of cartilaginous tumours as an incidental finding on MRI of the knee.

OBJECTIVES: The purpose was to determine prevalence of enchondromas and atypical cartilaginous tumour/chondrosarcoma grade 1 (ACT/CS1) of the knee on MRI in a large cohort study, namely the Netherlands Epidemiology of Obesity (NEO) study. METHODS: Participants aged 45 to 65 years were prospectively included, oversampling overweight and obese persons. Within a subgroup of participants, MRI of the right knee was performed and screened for incidental cartilaginous tumours, as defined by their characteristic location and appearance. RESULTS: Forty-nine cartilaginous tumours were observed in 44 out of 1285 participants (estimated population prevalence 2.8 %, 95 % CI 2.0-4.0 %). Mean largest tumour diameter was 12 mm (range 2-31 mm). Eight participants with a tumour larger than 20 mm or a tumour with aggressive features were referred to rule out low-grade chondrosarcoma. One was lost to follow-up, three had histologically proven ACT/CS1 and four had dynamic contrast MRI findings consistent with benign enchondroma. CONCLUSIONS: Incidental cartilaginous tumours were relatively common on knee MRI and may be regarded as a normal concurrent finding. However, more tumours than expected were ACT/CS1. Because further examination was performed only when suspicion of chondrosarcoma was high, the actual prevalence might be even higher. KEY POINTS: • Incidental cartilaginous tumours are relatively common on knee MRI. • Most incidental cartilaginous tumours are small and lack suspicious features. • Small cartilaginous tumours without suspicious findings may be a normal concurrent finding. • Large tumours and/or those with suspicious findings should be further investigated. • Atypical cartilaginous tumour/chondrosarcoma grade 1 was found more often than expected.

Aiming for a simpler early arthritis MRI protocol: can Gd contrast administration be eliminated?

PURPOSE: To evaluate whether intravenous gadolinium (Gd) contrast administration can be eliminated when evaluating synovitis and tenosynovitis in early arthritis patients, thereby decreasing imaging time, cost, and invasiveness. MATERIALS AND METHODS: Wrist MRIs of 93 early arthritis patients were evaluated by two readers for synovitis of the radioulnar, radiocarpal, and intercarpal joints, according to the Rheumatoid Arthritis MRI Scoring method (RAMRIS), and for tenosynovitis in ten compartments. Scores of MRI images without Gd contrast enhancement were compared to scores obtained when evaluating all, including contrast-enhanced, MRI images as reference. Subsequently, a literature review and pooled analysis of data from the present and two previous studies were performed. RESULTS: At the individual joint/tendon level, sensitivity to detect synovitis without Gd contrast was 91 % and 72 % for the two readers, respectively, with a specificity of 51 % and 81 %. For tenosynovitis, the sensitivity was 67 % and 54 %, respectively, with a specificity of 87 % and 91 %. Pooled data analysis revealed an overall sensitivity of 81 % and specificity of 50 % for evaluation of synovitis. Variations in tenosynovitis scoring systems hindered pooled analyses. CONCLUSION: Eliminating Gd contrast administration resulted in low specificity for synovitis and low sensitivity for tenosynovitis, indicating that Gd contrast administration remains essential for an optimal assessment. KEY POINTS: • Eliminating gadolinium contrast administration results in low specificity for synovitis • For tenosynovitis, sensitivity is low without gadolinium contrast administration • Gadolinium contrast administration remains essential for evaluating synovitis and tenosynovitis in early arthritis.