Whole-body imaging of the musculoskeletal system: the value of MR imaging

Bone marrow edema in children: chronic nonbacterial osteomyelitis and its mimickers

Bone marrow is a highly cellular tissue undergoing significant developmental and physiologic changes with age. Indeed, with maturation from pediatric to the adult age there is a progressive, centrifugal conversion from red to yellow bone marrow. Histological characteristics of bone marrow are reflected in MR image signal. MR is therefore extremely sensitive in detecting pathological changes which are mostly characterized by increased free water causing high signal intensity on T2. Among the numerous diseases causing bone marrow edema in children chronic nonbacterial osteomyelitis (CNO) certainly has to be mentioned. This idiopathic inflammatory disorder is characterized by nonspecific migrating symptoms like skeletal pain with phases of exacerbations and relapses with alternating acute and chronic MR signs and it is often a diagnosis of exclusion. Hence, with bone marrow edema, various features at imaging should be considered to differentiate malignancies such as osseous lymphoma, osteosarcoma, and Ewing's sarcoma as well as benign lesions like osteomyelitis, post-traumatic, or post-treatment bone marrow edema. The aim of this review is to recall the main characteristics of CNO and provide an overview of its main mimickers highlighting similarities and differences.

A literature survey of MR-based brain tumor segmentation with missing modalities

Multimodal MR brain tumor segmentation is one of the hottest issues in the community of medical image processing. However, acquiring the complete set of MR modalities is not always possible in clinical practice, due to the acquisition protocols, image corruption, scanner availability, scanning cost or allergies to certain contrast materials. The missing information can cause some restraints to brain tumor diagnosis, monitoring, treatment planning and prognosis. Thus, it is highly desirable to develop brain tumor segmentation methods to address the missing modalities problem. Based on the recent advancements, in this review, we provide a detailed analysis of the missing modality issue in MR-based brain tumor segmentation. First, we briefly introduce the biomedical background concerning brain tumor, MR imaging techniques, and the current challenges in brain tumor segmentation. Then, we provide a taxonomy of the state-of-the-art methods with five categories, namely, image synthesis-based method, latent feature space-based model, multi-source correlation-based method, knowledge distillation-based method, and domain adaptation-based method. In addition, the principles, architectures, benefits and limitations are elaborated in each method. Following that, the corresponding datasets and widely used evaluation metrics are described. Finally, we analyze the current challenges and provide a prospect for future development trends. This review aims to provide readers with a thorough knowledge of the recent contributions in the field of brain tumor segmentation with missing modalities and suggest potential future directions.

Diagnostic performance of computed tomography and diffusion-weighted imaging as first-line imaging modality according to the International Myeloma Working Group (IMWG) imaging algorithm for monoclonal plasma cell disorders

BACKGROUND

The latest International Myeloma Working Group (IMWG) guideline recommends low-dose whole-body (WB) computed tomography (CT) as the first-line imaging technique for the initial diagnosis of plasma cell disorders.

PURPOSE

To evaluate diagnostic performances of CT and diffusion-weighted imaging (DWI) as the first-line imaging modalities and assess misclassification rates obtained following the guideline.

MATERIAL AND METHODS

Two independent radiologists analyzed CT (acquired as PET/CT) and DWI (3-T; b-values = 50 and 900 s/mm²) of patients newly diagnosed with plasma cell disorder, categorizing the number of bone lesions. Diagnostic performance of CT and DWI was compared using the McNemar test, and misclassification rates were calculated with a consensus WB-MRI reading as the reference standard. Differences in lesion number categories were assessed using marginal homogeneity and kappa statistics.

RESULTS

Of 56 patients (36 men; mean age = 63.5 years), 39 had myeloma lesions. DWI showed slightly higher sensitivity for detecting myeloma lesions (97.4%) than CT (84.6%-92.3%; P > 0.05). CT showed significantly higher specificity (88.2%) than DWI (52.9%-58.8%; P<0.05). CT had a higher additional study requirement rate than DWI (7.7%-15.4% vs. 2.6%), but a lower unnecessary treatment rate (11.8% vs. 41.2%-47.1%). Both readers showed significant differences in categorization of the number of lesions on CT compared with the reference standard (P < 0.001), and one reader showed a significant difference on DWI (P = 0.006 and 0.098).

CONCLUSION

CT interpreted according to the IMWG guideline is a diagnostically effective first-line modality with relatively high sensitivity and specificity. DWI alone may not be an acceptable first-line imaging modality because of low specificity.

Fracture Risk in Men with Metastatic Prostate Cancer Treated With Radium-223

BACKGROUND

Radium-223 is a bone-seeking, alpha-emitting radionuclide used in metastatic castration-resistant prostate cancer (mCRPC). Radium-223 increases the risk of fracture when used in combination with abiraterone and prednisolone. The risk of fracture in men receiving radium-223 monotherapy is unclear.

PATIENTS AND METHODS

This was a prospective, multicenter phase II study of radium-223 in 36 men with mCRPC and a reference cohort (n = 36) matched for fracture risk and not treated with radium-223. Bone fractures were assessed using whole-body magnetic resonance imaging. The primary outcome was risk of new fractures.

RESULTS

Thirty-six patients were treated with up to six 4-week cycles of radium-223. With a median follow-up of 16.3 months, 74 new fractures were identified in 20 patients. Freedom from fracture was 56% (95% confidence interval, 35.3-71.6) at 12 months. On multivariate analysis, prior corticosteroid use was associated with risk of fracture. In the reference cohort (n = 36), 16 new fractures were identified in 12 patients over a median follow-up of 24 months. Across both cohorts, 67% of all fractures occurred at uninvolved bone.

CONCLUSIONS

Men with mCRPC, and particularly those treated with radium-223, are at risk of fracture. They should receive a bone health agent to reduce the risk of fragility fractures.

Low-field magnetic resonance imaging characteristics of multifocal vertebral lesions in dogs

BACKGROUND

There is a lack of information regarding magnetic resonance imaging (MRI) features of polyostotic vertebral lesions in dogs. The aim of this retrospective study was to identify and differenciate low-field MRI features of aggressive versus benign multifocal vertebral diseases in dogs.

METHODS

MRI examinations from 49 dogs with polyostotic vertebral lesions were reviewed. Images were evaluated for vertebral intensity changes, expansile lesions, new bone formation, cortical bone interruption, paravertebral musculature changes, lymphadenomegaly, spinal cord compression and spinal cord signal changes.

RESULTS

Twenty-nine dogs with non-aggressive bone lesions and 20 dogs with aggressive vertebral lesions were included. Non-aggressive lesions had variable T2-weighted fast spin-echo (T2W) signal intensity and the majority displayed low signal intensity on short tau inversion recovery (STIR). Aggressive lesions predominantly had high T2W and STIR signal intensity, with variable signal intensity on T1-weighted spin-echo and contrast enhancement. Aggressive lesions were associated with spinal pain (p < 0.01), new bone formation (p = 0.02), spinal cord compression (p < 0.01) and lymphadenomegaly (p < 0.01). Cortical interruption (p < 0.01) and paravertebral musculature changes (p < 0.01) were the strongest indicative imaging features for aggressive lesions.

CONCLUSION

Spinal pain, spinal cord compression, new bone formation, lymphadenomegaly and especially cortical interruption and paravertebral musculature signal intensity changes were the best discriminators for differentiating malignant from benign vertebral lesions.

Comparative accuracy of lower limb bone geometry determined using MRI, CT, and direct bone 3D models

Advancements in imaging and segmentation techniques mean that three dimensional (3D) modeling of bones is now increasingly used for preoperative planning and registration purposes. Computer tomography (CT) scans are commonly used due to their high bone-soft tissue contrast, however they expose subjects to radiation. Alternatively, magnetic resonance imaging (MRI) is radiation-free: however, geometric field distortion and poor bone contrast have been reported to degrade bone model validity compared to CT. The present study assessed the accuracy of 3D femur and tibia models created from "Black Bone" 3T MRI and high resolution CT scans taken from 12 intact cadaveric lower limbs by comparing them with scans of the de-fleshed and cleaned bones carried out using a high-resolution portable compact desktop 3D scanner (Model HDI COMPACT C210; Polyga). This scanner used structured light (SL) to capture 3D scans with an accuracy of up to 35 μm. Image segmentation created 3D models and for each bone the corresponding CT and MRI models were aligned with the SL model using the iterative closest point (ICP) algorithm and the differences between models calculated. Hausdorff distance was also determined. Compared to SL scans, the CT models had an ICP error of 0.82 ± 0.2 and 0.85 ± 0.2 mm for the tibia and femur respectively, whilst the MRI models had an error of 0.97 ± 0.2 and 0.98 ± 0.18 mm. A one-way analysis of variance found no significant difference in the Hausdorff distances or ICP values between the three scanning methods (p > .05). The black bone MRI method can provide accurate geometric measures of the femur and tibia that are comparable to those achieved with CT. Given the lack of ionizing radiation this has significant benefits for clinical populations and also potential for application in research settings.

Staging and Classification of Primary Musculoskeletal Bone and Soft Tissue Tumors Based on the 2020 WHO Update, From the AJR Special Series on Cancer Staging

Staging of primary musculoskeletal bone and soft tissue tumors is most commonly performed using the AJCC and the Enneking or Musculoskeletal Tumor Society (MSTS) staging systems. Radiologic imaging is integral in achieving adequate musculoskeletal neoplastic staging by defining lesion extent and identifying regional lymph node involvement and distant metastatic disease. Additional important features in surgical planning, though not distinct components of the staging systems, include cortical involvement, joint invasion, and neurovascular encasement; these features are optimally evaluated by MRI. In 2020, the WHO updated the classification of primary musculoskeletal tumors of soft tissue and bone. The update reflects the continued explosion in identification of novel gene alterations in many bone and soft tissue neoplasms. This has resulted in newly designated lesions, reclassification of lesion categories, and improved specificity of diagnosis. While radiologists do not need to have a comprehensive knowledge of the pathologic details, a broad working understanding of the most recent update is important to aid accurate and timely diagnosis given that histologic grading is a component of all staging systems. By approaching primary musculoskeletal neoplasms through a multidisciplinary approach with colleagues in pathology, orthopedic oncology, radiation oncology, and medical oncology, radiologists may promote improved diagnosis, treatment, and outcomes.

Imaging of Bladder Cancer: Standard Applications and Future Trends

The evolution in imaging has had an increasing role in the diagnosis, staging and follow up of bladder cancer. Conventional cystoscopy is crucial in the diagnosis of bladder cancer. However, a cystoscopic procedure cannot always depict carcinoma in situ (CIS) or differentiate benign from malignant tumors prior to biopsy. This review will discuss the standard application, novel imaging modalities and their additive role in patients with bladder cancer. Staging can be performed with CT, but distinguishing between T1 and T2 BCa (bladder cancer) cannot be assessed. MRI can distinguish muscle-invasive from non-muscle-invasive tumors with accurate local staging. Vesical Imaging-Reporting and Data System (VI-RADS) score is a new diagnostic modality used for the prediction of tumor aggressiveness and therapeutic response. Bone scintigraphy is recommended in patients with muscle-invasive BCa with suspected bony metastases. CT shows low sensitivity for nodal staging; however, PET (Positron Emission Tomography)/CT is superior and highly recommended for restaging and determining therapeutic effect. PET/MRI is a new imaging technique in bladder cancer imaging and its role is promising. Texture analysis has shown significant steps in discriminating low-grade from high-grade bladder cancer. Radiomics could be a reliable method for quantitative assessment of the muscle invasion of bladder cancer.

99mTc-dimercaptosuccinic acid scan versus MRI in pyelonephritis: a meta-analysis

PURPOSE

Tc-dimercaptosuccinic acid (DMSA) scan is the current gold standard in detecting parenchymal changes, particularly scarring, in pyelonephritis. Recently, magnetic resonance imaging (MRI) is gaining popularity in the diagnosis of pyelonephritis. The aim of this study is to perform a meta-analysis on studies directly comparing MRI to DMSA scan in patients with pyelonephritis.

MATERIALS

Systematic searches of PUBMED and EMBASE databases were performed to extract studies comparing MRI and DMSA scan in patients with pyelonephritis. The relevance of articles was assessed by two authors according to predefined inclusion and exclusion criteria. The pooled estimates of the sensitivities of MRI and DMSA scan were computed using random-effects meta-analysis model following DerSimonian and Laird's method. Subgroup analysis and publication bias were performed.

RESULTS

Seven studies were included (164 patients). Using random effect model, the pooled estimate of the sensitivities of MRI and DMSA scan were 0.62 (95%CI: 0.44 - 0.77) and 0.59 (95%CI: 0.48 - 0.70), respectively. The pooled estimates of sensitivities of MRI and DMSA scan for acute pyelonephritis were 0.73 (95%CI: 0.49- 0.89) and 0.66 (95%CI: 0.56 - 0.75), respectively, and for scar detection were 0.48 (95%CI: 0.31- 0.66), and 0.50 (95%CI: 0.30 - 0.71), respectively.

CONCLUSION

The overall sensitivities of MRI and DMSA scan were equivalent in detecting parenchymal changes in pyelonephritis. MRI and DMSA scan appeared to be equivalent to scar detection. In a small number of studies, MRI appeared to be better than the DMSA scan in acute pyelonephritis but this should be further studied in a larger number of patients.

Novel Muscle Imaging in Inflammatory Rheumatic Diseases-A Focus on Ultrasound Shear Wave Elastography and Quantitative MRI

In recent years, imaging has played an increasing role in the clinical management of patients with rheumatic diseases with respect to aiding diagnosis, guiding therapy and monitoring disease progression. These roles have been underpinned by research which has enhanced our understanding of disease pathogenesis and pathophysiology of rheumatology conditions, in addition to their key role in outcome measurement in clinical trials. However, compared to joints, imaging research of muscles is less established, despite the fact that muscle symptoms are very common and debilitating in many rheumatic diseases. Recently, it has been shown that even though patients with rheumatoid arthritis may achieve clinical remission, defined by asymptomatic joints, many remain affected by lingering constitutional systemic symptoms like fatigue, tiredness, weakness and myalgia, which may be attributed to changes in the muscles. Recent improvements in imaging technology, coupled with an increasing clinical interest, has started to ignite new interest in the area. This perspective discusses the rationale for using imaging, particularly ultrasound and MRI, for investigating muscle pathology involved in common inflammatory rheumatic diseases. The muscles associated with rheumatic diseases can be affected in many ways, including myositis-an inflammatory muscle condition, and myopathy secondary to medications, such as glucocorticoids. In addition to non-invasive visual assessment of muscles in these conditions, novel imaging techniques like shear wave elastography and quantitative MRI can provide further useful information regarding the physiological and biomechanical status of the muscle.

Non-hematologic diagnosis of systemic mastocytosis: Collaboration of radiology and pathology

Systemic mastocytosis (SM) is a hematologic disease with a wide range of clinical courses ranging from an indolent condition with normal life expectancy to exceedingly aggressive disorder with a poor prognosis. The symptoms and signs of SM result from the release of mast cell mediators with heterogeneous functions, and/or organ damage from neoplastic mast cell infiltration, or both. Diagnostic criteria for SM are well-defined by the World Health Organization (WHO). However, the diagnosis of SM can be difficult when especially it is not in the differential diagnosis. Routinely used radiologic techniques (e.g., X-ray, ultrasound, CT scans can show findings such as lytic-, sclerotic- or mixed-bone lesions, splenomegaly, hepatomegaly, retroperitoneal or periportal mesenteric lymphadenopathy, and omental thickening). It is essential to emphasize that the constellation of these radiologic findings should strongly concern of SM, especially in patients who also have a skin rash, allergic reactions, gastrointestinal tract symptoms (lasting, intermittent nausea, diarrhea), paroxysmal tachycardias, unexplained weight loss, persistent bone pain, cytopenias, liver dysfunction, eosinophilia. These findings, even coincidentally noted, will likely lead to a tissue biopsy, which reveals diagnosis (as we discussed and illustrated some tissue biopsies here). Moreover, the role of MRI and new techniques such as [18-fluorodeoxyglucose positron emission computed tomography, fibroscan] in the diagnosis of SM have been discussed. Furthermore, we reviewed the use of radiologic methods to evaluate treatment response and prognostication of SM..

MRI of Bladder Cancer: Local and Nodal Staging

Accurate staging of bladder cancer (BC) is critical, with local tumor staging directly influencing management decisions and affecting prognosis. However, clinical staging based on clinical examination, including cystoscopy and transurethral resection of bladder tumor (TURBT), often understages patients compared to final pathology at radical cystectomy and lymph node (LN) dissection, mainly due to underestimation of the depth of local invasion and the presence of LN metastasis. MRI has now become established as the modality of choice for the local staging of BC and can be additionally utilized for the assessment of regional LN involvement and tumor spread to the pelvic bones and upper urinary tract (UUT). The recent development of the Vesical Imaging-Reporting and Data System (VI-RADS) recommendations has led to further improvements in bladder MRI, enabling standardization of image acquisition and reporting. Multiparametric magnetic resonance imaging (mpMRI) incorporating morphological and functional imaging has been proven to further improve the accuracy of primary and recurrent tumor detection and local staging, and has shown promise in predicting tumor aggressiveness and monitoring response to therapy. These sequences can also be utilized to perform radiomics, which has shown encouraging initial results in predicting BC grade and local stage. In this article, the current state of evidence supporting MRI in local, regional, and distant staging in patients with BC is reviewed. LEVEL OF EVIDENCE: 3 TECHNICAL EFFICACY STAGE: 2 J. Magn. Reson. Imaging 2020;52:649-667.

Added Value of Contrast Medium in Whole-Body Hybrid Positron Emission Tomography/Magnetic Resonance Imaging: Comparison between Contrast-Enhanced and Non-Contrast-Enhanced Protocols

OBJECTIVE

To compare the diagnostic ability and time efficiency of contrast-enhanced (CE) whole body fluorodeoxyglucose (FDG) positron emission tomography/magnetic resonance imaging (PET/MRI) protocol and non-CE (NCE) protocol.

SUBJECTS AND METHODS

Ninety-three patients with known primary tumors underwent whole-body hybrid FDG PET/MRI during the follow-up of their malignancies with the use of NCE and CE protocols. The NCE PET/MRI protocol consisted of diffusion-weighted (b = 0 and 800 s/mm2) and T1-weighted Turbo Flash in the axial plane and T2-weighted HASTE sequence in the coronal planes (Σ = 25 min). The CE PET/MRI protocol was performed by acquiring axial serial CE 3D FS VIBE images in the upper abdomen, completing the whole body in the late phase in the axial plane (Σ = 30 min).

RESULTS

There was a statistically significant difference between the total number of lesions detected by the CE protocol (median 2, interquartile range (IQR) 0-14) and that detected by the NCE protocol (median 1, IQR 0-5; p < 0.001). More malignancies were detected in the abdomen (p < 0.001) and brain (p < 0.001) with the CE PET/MRI protocol, whereas no significant difference was present when comparing the 2 protocols in the detection of malignancies in the head and neck (p = 0.356), thorax (p = 0.09), lymph nodes (p = 0.196), and bone (p = 0.414).

CONCLUSION

The CE FDG PET/MRI protocol enables fast and accurate detection of malignancies compared to the NCE FDG PET/MRI protocol, particularly in the upper abdomen and brain. Diagnostic ability and time efficiency can be increased with the proposed short CE protocol in place of the whole body PET/MRI protocol including both NCE and CE imaging sequences.

What is the Diagnostic Performance of 18F-FDG-PET/MRI in the Detection of Bone Metastasis in Patients with Breast Cancer?

Objective

To evaluate the diagnostic performance of 18F-fluorodeoxyglucose (FDG)-positron emission tomography (PET)/magnetic resonance imaging (MRI) in the detection of bone metastasis in patients with breast cancer.

Materials and methods

From August 2018 to January 2019, a total of 23 patients with pathologically confirmed invasive breast cancer underwent whole-body hybrid 18F-FDG -PET/MRI for initial staging and follow-up of their malignancies. The number of the bone metastasis was recorded for each patient. The total 18F-FDG-PET/MRI protocol was compared with PET only and the contrast enhanced fused (CE) component for the detection of bone metastasis.

Results

Eight (26%) of 23 patients had bone metastasis. Bone metastases were dominantly localized in the spine (63%) and pelvis (25%). In terms of the total number of detected bone metastasis, there was a statistically significant difference between 18F-FDG-PET/MRI (mean 3.57; median 0; range, 0-2) and PET only component (mean 2.87; median 0; range, 0-1) (p=0.026), but no statistically significant difference was detected between 18F-FDG-PET/MRI and whole-body CE MRI (mean 3.43; median 0; range 0-2) (p=0.083).

Conclusion

Whole-body hybrid 18F-FDG-PET/MRI is superior to PET component only, but no statistically significant difference between hybrid 18F-FDG-PET/MRI and whole-body CE MRI is found for the detection of bone metastasis in patients with breast cancer.

Performance of an Automated Versus a Manual Whole-Body Magnetic Resonance Imaging Workflow

OBJECTIVES

The aim of this study was to evaluate the performance of an automated workflow for whole-body magnetic resonance imaging (WB-MRI), which reduces user interaction compared with the manual WB-MRI workflow.

MATERIALS AND METHODS

This prospective study was approved by the local ethics committee. Twenty patients underwent WB-MRI for myopathy evaluation on a 3 T MRI scanner. Ten patients (7 women; age, 52 ± 13 years; body weight, 69.9 ± 13.3 kg; height, 173 ± 9.3 cm; body mass index, 23.2 ± 3.0) were examined with a prototypical automated WB-MRI workflow, which automatically segments the whole body, and 10 patients (6 women; age, 35.9 ± 12.4 years; body weight, 72 ± 21 kg; height, 169.2 ± 10.4 cm; body mass index, 24.9 ± 5.6) with a manual scan. Overall image quality (IQ; 5-point scale: 5, excellent; 1, poor) and coverage of the study volume were assessed by 2 readers for each sequence (coronal T2-weighted turbo inversion recovery magnitude [TIRM] and axial contrast-enhanced T1-weighted [ce-T1w] gradient dual-echo sequence). Interreader agreement was evaluated with intraclass correlation coefficients. Examination time, number of user interactions, and MR technicians' acceptance rating (1, highest; 10, lowest) was compared between both groups.

RESULTS

Total examination time was significantly shorter for automated WB-MRI workflow versus manual WB-MRI workflow (30.0 ± 4.2 vs 41.5 ± 3.4 minutes, P < 0.0001) with significantly shorter planning time (2.5 ± 0.8 vs 14.0 ± 7.0 minutes, P < 0.0001). Planning took 8% of the total examination time with automated versus 34% with manual WB-MRI workflow (P < 0.0001). The number of user interactions with automated WB-MRI workflow was significantly lower compared with manual WB-MRI workflow (10.2 ± 4.4 vs 48.2 ± 17.2, P < 0.0001). Planning efforts were rated significantly lower by the MR technicians for the automated WB-MRI workflow than for the manual WB-MRI workflow (2.20 ± 0.92 vs 4.80 ± 2.39, respectively; P = 0.005). Overall IQ was similar between automated and manual WB-MRI workflow (TIRM: 4.00 ± 0.94 vs 3.45 ± 1.19, P = 0.264; ce-T1w: 4.20 ± 0.88 vs 4.55 ± .55, P = 0.423). Interreader agreement for overall IQ was excellent for TIRM and ce-T1w with an intraclass correlation coefficient of 0.95 (95% confidence interval, 0.86-0.98) and 0.88 (95% confidence interval, 0.70-0.95). Incomplete coverage of the thoracic compartment in the ce-T1w sequence occurred more often in the automated WB-MRI workflow (P = 0.008) for reader 2. No other significant differences in the study volume coverage were found.

CONCLUSIONS

In conclusion, the automated WB-MRI scanner workflow showed a significant reduction of the examination time and the user interaction compared with the manual WB-MRI workflow. Image quality and the coverage of the study volume were comparable in both groups.

Whole-body MRI and pathological findings in adult patients with myopathies

Magnetic resonance imaging (MRI) is considered the most sensitive and specific imaging technique for the detection of muscle diseases related to myopathies. Since 2008, the use of whole-body MRI (WBMRI) to evaluate myopathies has improved due to technical advances such as rolling table platform and parallel imaging, which enable rapid assessment of the entire musculoskeletal system with high-quality images. WBMRI protocols should include T1-weighted and short-tau inversion recovery (STIR), which provide the basic pulse sequences for studying myopathies, in order to detect fatty infiltration/muscle atrophy and muscle edema, respectively. High signal intensity in T1-weighted images shows chronic disease with fatty infiltration, whereas high signal intensity in STIR indicates an acute stage with muscle edema. Additional sequences such as diffusion-weighted imaging (DWI) can be readily incorporated into routine WBMRI study protocols. Contrast-enhanced sequences have not been done. This article reviews WBMRI as an imaging method to evaluate different myopathies (idiopathic inflammatory, dystrophic, non-dystrophic, metabolic, and channelopathies). WBMRI provides a comprehensive estimate of the total burden with a single study, seeking specific distribution patterns, including clinically silent involvement of muscle areas. Furthermore, WBMRI may help to select the "target muscle area" for biopsy during patient follow-up. It may be also be used to detect related and non-related pathological conditions, such as tumors.

How to report incidental findings from population whole-body MRI: view of participants of the German National Cohort

OBJECTIVES

In the German National Cohort (GNC), 30,000 individuals are examined with whole-body MRI (wbMRI), of which about 3000 participants are expected to receive an incidental finding (IF) disclosure. In order to get feedback from participants and to evaluate the IF-management procedure of the wbMRI substudy, a follow-up questionnaire was developed. This single-center pilot trial was aimed to get a first impression on feasibility reproducibility and validity of such a survey in order to take necessary adjustments before initiating the survey among several thousand participants.

METHODS

The questionnaires were sent out in test-retest manner to 86 participants who received a wbMRI examination in January-February 2016 at the imaging center in Neubrandenburg. The ratio of participants with and without IF notification was 1:1. Descriptive statistics was performed.

RESULTS

A first response of 94% and completion proportion of 99% were achieved. Participants were satisfied with the examination procedure. Ninety-five percent of participants considered it very important to receive notification of IFs. Participants reported minimal stress levels while waiting for a possible IF notification letter, but high stress levels when an IF letter was received. Phrasing of the IF reports was rated in 97% as well understandable and in 55% as beneficial to health status.

CONCLUSIONS

This questionnaire will serve researchers within the GNC as a fundamental instrument not only for quality management analyses but also for the investigation of still unacknowledged scientific and ethical questions contributing to evidence-based guidelines concerning the complex approach to IFs in future population-based imaging.

KEY POINTS

• Evidence-based guidelines for reporting incidental findings in population whole-body MRI are lacking. • Pilot-testing of a questionnaire for the evaluation of practical and ethical aspects of the procedure to report incidental findings in the German National Cohort shows a high level of acceptance and high return rate by participants. • Participants reported minimal stress levels while waiting for a possible incidental finding notification letter, which increased significantly, when such a letter was received.

Muscle fluorodeoxyglucose uptake assessed by positron emission tomography-computed tomography as a biomarker of inflammatory myopathies disease activity

OBJECTIVE

To devise a simple PET-CT score for measurement of muscle disease activity in patients with inflammatory myopathies (IMs) and to assess its validity.

METHODS

A total of 44 PET-CT examinations in 34 IM patients (performed during cancer screening) and 20 PET-CT examinations in matched controls (investigated for pulmonary nodules with a conclusion of benignity) were analysed. Maximal standardized uptake values (SUVmax) were recorded bilaterally in eight proximal muscles. The muscle SUVmax (mSUVmax) was defined as the average of the 16 muscle SUVmax values, normalized on the liver mean SUV. Reliability, validity and responsiveness were evaluated.

RESULTS

The mSUVmax was increased in IM patients compared with controls. This index allowed the identification of patients with high vs low muscle disease activity using the myositis intention to treat activity index as the gold standard. In patients with subsequent examinations, our method showed good accuracy to detect changes in muscle disease activity [area under the curve 0.96 (95% CI 0.84, 1)]. Responsiveness was strong. Interrater reliability was excellent.

CONCLUSION

PET-CT, a non-invasive tool useful for cancer screening, is also valuable to measure muscle disease activity and its evolution in IM patients.

Randomized placebo-controlled double-blind phase II study of zaltoprofen for patients with diffuse-type and unresectable localized tenosynovial giant cell tumors: a study protocol

Background

A tenosynovial giant cell tumor (TGCT) is a locally aggressive benign neoplasm arising from intra- or extra-articular tissue. Diffuse TGCT (D-TGCT) most commonly develops in the knee, followed by the hip, ankle, elbow, and shoulder. Surgical removal is the only effective treatment option for the patients. However, a local recurrence rate as high as 47% has been reported. Recently, we revealed that zaltoprofen, a nonsteroidal anti-inflammatory drug possessing the ability to activate peroxisome proliferator-activated receptor gamma (PPARγ), can inhibit the proliferation of TGCT stromal cells via PPARγ. PPARγ is a ligand-activated transcription factor that belongs to the nuclear hormone receptor superfamily. It plays an important role in the differentiation of adipocytes from precursor cells and exhibits antitumorigenic effects on certain malignancies. Therefore, we are conducting this investigator-initiated clinical trial to evaluate whether zaltoprofen is safe and effective for patients with D-TGCT or unresectable localized TGCT (L-TGCT).

Methods

This study is a randomized, placebo-controlled, double-blind, multicenter trial to evaluate the safety and efficacy of zaltoprofen for patients with D-TGCT or L-TGCT. For the treatment group, zaltoprofen 480 mg/day will be administered for 48 weeks; the placebo group will receive similar dosages without zaltoprofen. Twenty participants in each group are needed in this trial (40 participants total). The primary outcome is the progression-free rate at 48 weeks after treatment administration. “Progression” is defined as any serious events (1. Repetitive joint swelling due to hemorrhage, 2. Joint range of motion limitation, 3. Invasion of adjacent cartilage or bone, 4. Severe joint space narrowing, 5. Increase in tumor size) requiring surgical interventions. We hypothesize that the zaltoprofen group will have a higher progression-free rate compared to that of the placebo group at 48 weeks.

Discussion

This is the first study to evaluate the efficacy of zaltoprofen in patients with D-TGCT or unresectable L-TGCT. We believe that the results of this trial will validate a novel treatment option, zaltoprofen, to stabilize disease progression for TGCT patients.

Trial registration

University Hospital Medical Information Network (UMIN) Clinical Trials Registry (UMIN000025901) registered on 4/01/2017.

Surveillance for metastatic hemangiopericytoma-solitary fibrous tumors-systematic literature review on incidence, predictors and diagnosis of extra-cranial disease

BACKGROUND

Intracranial hemangiopericytomas (HPC) and solitary fibrous tumors (SFTs) (HPC-SFT) are rare vascular tumors that resemble meningioma on imaging and predominantly affect young adults. HPC-SFT have a high rate of local recurrence with well-known propensity for extracranial metastases. This provides clinical dilemmas frequently encountered in oncology: (i) How should these patients be monitored long term? (ii) Which primary tumors are more likely to metastasize?

OBJECTIVES

This systematic review aims to identify the incidence, common locations and time to presentation of extra-cranial metastases of HPC-SFT. We will assess the effect of primary tumor location, treatment, grade, patient age, gender and effect of local recurrence on rates of extra-cranial metastasis and discuss the ideal techniques by which patients with intracranial HPC-SFT should be monitored for extra-cranial metastases.

METHODS

Using PRISMA guidelines the authors searched Pubmed. Search terms included hemangiopericytoma, HPC, solitary fibrous tumor/ tumour, SFT, HPC-SFT, extra-cranial metastases, metastases, recurrence, monitoring, follow-up. Studies were identified up to 1st February 2018. Reference lists of identified articles were reviewed to detect other relevant citations. Data were extracted using a standard data collection form and results organized into (i) general study/patient characteristics, (ii) location of extra-cranial metastases, (iii) methods by which metastases were detected and followed up and (iv) characteristics of primary tumors.

RESULTS

Seventy-one studies were identified. Mean recorded follow up ranged from 4 to 312 months. Mean age at diagnosis was 42.0 years. The overall rate of extra-cranial metastasis was 28% (n = 251/904). The minimum time to extracranial metastases was 3 months and the maximum time was 372 months. In the 71 studies identified, where site of extra-cranial metastasis was specified, there were 347 metastases in 213 patients. The most common sites for metastases were bone (location not specified) (19.6%) followed by lung and pleura (18.4%), liver (17.6%), and vertebrae (14.1%). Extra-cranial metastatic disease is typically diagnosed following symptomatic presentation. There is little documentation of methods used to monitor patients with extra-cranial HPC-SFT and no clear surveillance paradigm observed. Higher primary tumor grade (WHO Grade III) was associated with a 1.88 (p = 0.016) increased risk of extra-cranial metastasis. Location and treatment of primary tumor, local recurrence, patient age and gender were not.

CONCLUSION

Patients with intracranial HPC-SFT require periodic, long term monitoring for extra-cranial metastases. Metastases occur in any age group and can occur early and late. They vary in location and are typically diagnosed following symptomatic presentation. There is no suggested imaging modality for surveillance. Higher grade primary tumors have a greater risk of metastasis. Regular clinical review is essential with early imaging for symptoms of recurrence/metastasis with imaging modality dependent on clinical concern. Quality evidence for an imaging surveillance protocol in this heterogeneous group of patients is lacking. A multicenter study on appropriate surveillance may be of benefit.

Ultrashort Echo-Time Magnetic Resonance Imaging Is a Sensitive Method for the Evaluation of Early Cystic Fibrosis Lung Disease

RATIONALE

Recent advancements that have been made in magnetic resonance imaging (MRI) improve our ability to assess pulmonary structure and function in patients with cystic fibrosis (CF). A nonionizing imaging modality that can be used as a serial monitoring tool throughout life can positively affect patient care and outcomes.

OBJECTIVES

To compare an ultrashort echo-time MRI method with computed tomography (CT) as a biomarker of lung structure abnormalities in young children with early CF lung disease.

METHODS

Eleven patients with CF (mean age, 31.8 ± 5.7 mo; median age, 33 mo; 7 male and 4 female) were imaged via CT and ultrashort echo-time MRI. Eleven healthy age-matched patients (mean age, 22.5 ± 10.2 mo; median age, 23 mo; 5 male and 6 female) were imaged via ultrashort echo-time MRI. CT scans of 13 additional patients obtained for clinical indications not affecting the heart or lungs and interpreted as normal provided a CT control group (mean age, 24.1 ± 11.7 mo; median age, 24 mo; 6 male and 7 female). Studies were scored by two experienced radiologists using a well-validated CF-specific scoring system for CF lung disease.

MEASUREMENTS AND MAIN RESULTS

Correlations between CT and ultrashort echo-time MRI scores of patients with CF were very strong, with P values ≤0.001 for bronchiectasis (r = 0.96) and overall score (r = 0.90), and moderately strong for bronchial wall thickening (r = 0.62, P = 0.043). MRI easily differentiated CF and control groups via a reader CF-specific scoring system.

CONCLUSIONS

Ultrashort echo-time MRI detected structural lung disease in very young patients with CF and provided imaging data that correlated well with CT. By quantifying early CF lung disease without using ionizing radiation, ultrashort echo-time MRI appears well suited for pediatric patients requiring longitudinal imaging for clinical care or research studies. Clinical Trial registered with www.clinicaltrials.gov (NCT01832519).

Preclinical imaging methods for assessing the safety and efficacy of regenerative medicine therapies

Regenerative medicine therapies hold enormous potential for a variety of currently incurable conditions with high unmet clinical need. Most progress in this field to date has been achieved with cell-based regenerative medicine therapies, with over a thousand clinical trials performed up to 2015. However, lack of adequate safety and efficacy data is currently limiting wider uptake of these therapies. To facilitate clinical translation, non-invasive in vivo imaging technologies that enable careful evaluation and characterisation of the administered cells and their effects on host tissues are critically required to evaluate their safety and efficacy in relevant preclinical models. This article reviews the most common imaging technologies available and how they can be applied to regenerative medicine research. We cover details of how each technology works, which cell labels are most appropriate for different applications, and the value of multi-modal imaging approaches to gain a comprehensive understanding of the responses to cell therapy in vivo.

Advanced MRI Techniques for Muscle Imaging

Advanced magnetic resonance imaging (MRI) techniques can evaluate a wide array of muscle pathologies including acute or chronic muscle injury, musculotendinous response to injury, intramuscular collections and soft tissue masses, and others. In recent years, MRI has played a more important role in muscle disease diagnosis and monitoring. MRI provides excellent spatial and contrast resolution and helps direct optimal sites for muscle biopsy. Whole-body MRI now helps identify signature patterns of muscular involvement in large anatomical regions with relative ease. Quantitative MRI has advanced the evaluation and disease tracking of muscle atrophy and fatty infiltration in entities such as muscular dystrophies. Multivoxel magnetic resonance spectroscopy (MRS) now allows a more thorough, complete evaluation of a muscle of interest without the inherent sampling bias of single-voxel MRS or biopsy. Diffusion MRI allows quantification of muscle inflammation and capillary perfusion as well as muscle fiber tracking.

Whole-body MRI, dynamic contrast-enhanced MRI, and diffusion-weighted imaging for the staging of multiple myeloma

Magnetic resonance imaging (MRI) is the most sensitive imaging technique for the detection of bone marrow infiltration, and has therefore recently been included in the new diagnostic myeloma criteria, as proposed by the International Myeloma Working Group. Nevertheless, conventional MRI only provides anatomical information and is therefore only of limited use in the response assessment of patients with multiple myeloma. The additional information from functional MRI techniques, such as diffusion-weighted imaging and dynamic contrast-enhanced MRI, can improve the detection rate of bone marrow infiltration and the assessment of response. This can further enhance the sensitivity and specificity of MRI in the staging of multiple myeloma patients. This article provides an overview of the technical aspects of conventional and functional MRI techniques with practical recommendations. It reviews the diagnostic performance, prognostic value, and role in therapy assessment in multiple myeloma and its precursor stages.

Muscle MRI in pediatrics: clinical, pathological and genetic correlation

Pediatric myopathies comprise a very heterogeneous group of disorders that may develop at different ages and affect different muscle groups. Its diagnosis is sometimes difficult and must be confirmed by muscle biopsy and/or genetic analysis. In recent years, muscle involvement patterns observed on MRI have become a valuable tool, aiding clinical diagnosis and enriching pathological and genetic assessments. We selected eight myopathy cases from our institutional database in which the pattern of muscle involvement observed on MRI was almost pathognomonic and could therefore contribute to establishing diagnosis. Muscle biopsy, genetic diagnosis or both confirmed all cases.

An overview of PET/MR, focused on clinical applications

Hybrid PET/MR scanners are innovative imaging devices that simultaneously or sequentially acquire and fuse anatomical and functional data from magnetic resonance (MR) with metabolic information from positron emission tomography (PET) (Delso et al. in J Nucl Med 52:1914-1922, 2011; Zaidi et al. in Phys Med Biol 56:3091-3106, 2011). Hybrid PET/MR scanners have the potential to greatly impact not only on medical research but also, and more importantly, on patient management. Although their clinical applications are still under investigation, the increased worldwide availability of PET/MR scanners, and the growing published literature are important determinants in their rising utilization for primarily clinical applications. In this manuscript, we provide a summary of the physical features of PET/MR, including its limitations, which are most relevant to clinical PET/MR implementation and to interpretation. Thereafter, we discuss the most important current and emergent clinical applications of such hybrid technology in the abdomen and pelvis, both in the field of oncologic and non-oncologic imaging, and we provide, when possible, a comparison with clinically consolidated imaging techniques, like for example PET/CT.

An unusual metastasis of lung adenocarcinoma: Biceps brachii muscle

Skeletal muscle metastasis of nonsmall cell lung carcinoma (NSCLC) is a rare occurrence, and the most effective treatment modality is currently unknown. In this case presentation, we report a patient with NSCLC who underwent palliative radiotherapy for biceps muscle metastasis of NSLCS. Our case was a 49-year-old woman who had lung adenocarcinoma with biceps muscle metastasis. She had been followed up for 2 years due to Stage IV lung adenocarcinoma from whom a biopsy was taken from a painful mass in right arm that was found to be compatible with metastasis of lung adenocarcinoma. She had palliative radiotherapy for her painful mass and systemic chemotherapy was planned. After palliative radiotherapy, the pain originating from the metastatic mass in right biceps muscle alleviated. Palliative radiotherapy can be a valuable treatment option for cases with skeletal muscle metastasis.

Skeletal muscle metastases on magnetic resonance imaging: analysis of 31 cases

Aim of the study

To investigate the magnetic resonance imaging (MRI) features of skeletal muscle metastases (SMM).

Material and methods

The records of 31 patients with proven SMM were retrospectively reviewed. Clinical history, type of primary malignancy, location of metastases, and MRI features of SMM were evaluated. Based on MRI findings, SMM were divided into three MRI types. The correlation between MRI types with ages and pathology category, between MRI types of SMM and ages, as well as MRI types of SMM and pathology category were analysed with Spearman's rho.

Results

The most common primary tumour was genital tumour (25.8%) and bronchial carcinoma (19.4%), and the most common cell type was adenocarcinoma (58.1%). SMM were located in the iliopsoas muscle (26.3%), paravertebral muscles (21.1%), and upper extremity muscles (18.4%). MRI features: (1) Type-I localised lesions (12.90%), round-like mass limited to local regions with heterogeneous iso-signal intensity in T1WI and heterogeneous hyper-intensity in T2WI; (2) Type-II diffuse lesions without bone destruction (35.48%), abnormal diffuse swelling of the muscle with irregular boundaries and slightly hypo- to iso-intensity in T1WI and hyper-intensity in T2WI; and (3) Type-III diffuse lesions with bone destruction (51.61%), distinct irregular lump with iso-intensity in T1WI and heterogeneous hyper-intensity in T2WI with adjacent bone invasion. There was positive correlation between MRI types and ages (r = 0.431, p < 0.05). There were no significant differences of MRI types with pathology category (p > 0.05).

Conclusions

SMM features on MRI can be broadly used to classify lesions, which is beneficial for SMM diagnosis.

MRI in multiple myeloma: a pictorial review of diagnostic and post-treatment findings

Magnetic resonance imaging (MRI) is increasingly being used in the diagnostic work-up of patients with multiple myeloma. Since 2014, MRI findings are included in the new diagnostic criteria proposed by the International Myeloma Working Group. Patients with smouldering myeloma presenting with more than one unequivocal focal lesion in the bone marrow on MRI are considered having symptomatic myeloma requiring treatment, regardless of the presence of lytic bone lesions. However, bone marrow evaluation with MRI offers more than only morphological information regarding the detection of focal lesions in patients with MM. The overall performance of MRI is enhanced by applying dynamic contrast-enhanced MRI and diffusion weighted imaging sequences, providing additional functional information on bone marrow vascularization and cellularity.

This pictorial review provides an overview of the most important imaging findings in patients with monoclonal gammopathy of undetermined significance, smouldering myeloma and multiple myeloma, by performing a ‘total’ MRI investigation with implications for the diagnosis, staging and response assessment.

Main message

• Conventional MRI diagnoses multiple myeloma by assessing the infiltration pattern.

• Dynamic contrast-enhanced MRI diagnoses multiple myeloma by assessing vascularization and perfusion.

• Diffusion weighted imaging evaluates bone marrow composition and cellularity in multiple myeloma.

• Combined morphological and functional MRI provides optimal bone marrow assessment for staging.

• Combined morphological and functional MRI is of considerable value in treatment follow-up.

Whole-body MRI in generalized cystic lymphangiomatosis in the pediatric population: diagnosis, differential diagnoses, and follow-up

OBJECTIVE

Generalized cystic lymphangiomatosis is a particularly rare disease with variable involvement of skeletal and extraskeletal sites. The key role of imaging in the diagnosis of this disease is no longer in doubt. The aim of our study was to demonstrate the contribution of whole-body magnetic resonance imaging (WB-MRI) at the diagnostic stage and during the follow-up in the pediatric population.

SUBJECTS AND METHODS

Three children were included from 2008. The inclusion criteria were radiological images (conventional radiographs, computed tomography, and MRI) compatible with histological confirmation. Each child included received WB-MRI at the diagnosis stage and during follow-up.

RESULTS

WB-MRI detected multiple hypointense T1 and hyperintense T2-STIR cystic bony lesions. One unnoticed mass in the retroperitoneum on computed tomography was easily detected by MRI. Mediastinal involvement was observed in one asymptomatic case. Histology was contributory in all cases. Preventive intramedullary nailings was done in one case. Follow-up WB-MRI detected new asymptomatic lesions in all cases. One child presented a third episode of lymphangitis of the right thigh during follow-up.

CONCLUSIONS

Due to its high sensitivity to diagnose, ability to eliminate differential diagnoses and make exhaustive lesions assessment, and its non-radiating character for long-term follow-up, WB-MRI is highly recommended for generalized cystic lymphangiomatosis in the pediatric population.

Bone marrow invasion in multiple myeloma and metastatic disease

Magnetic resonance imaging (MRI) of the spine is the imaging study of choice for the management of bone marrow disease. MRI sequences enable us to integrate structural and functional information for detecting, staging, and monitoring the response the treatment of multiple myeloma and bone metastases in the spine. Whole-body MRI has been incorporated into different guidelines as the technique of choice for managing multiple myeloma and metastatic bone disease. Normal physiological changes in the yellow and red bone marrow represent a challenge in analyses to differentiate clinically significant findings from those that are not clinically significant. This article describes the findings for normal bone marrow, variants, and invasive processes in multiple myeloma and bone metastases.

Whole-body magnetic resonance imaging in myxoid liposarcoma: A useful adjunct for the detection of extra-pulmonary metastatic disease

Myxoid liposarcomas (MLS) are a subgroup of soft-tissue sarcomas which have a propensity for extra-pulmonary metastases. Conventional radiological staging of soft-tissue sarcomas consists of chest radiographs (CXR) and thoracic computed tomography (CT) for possible chest metastases, supplemented by magnetic resonance imaging (MRI) for local disease. The optimal radiological modality to detect extra-pulmonary metastases for systemic staging has not been proven. We reviewed the efficacy of Whole-Body MRI (WBMRI) for this purpose. 33 WBMRI and simultaneous CT scans were performed in 28 patients suffering from MLS between 2007 and 2015. 38 metastases were identified in seven patients via WBMRI. Osseous lesions predominated (spine, pelvis, chest-wall and long bones), followed by soft-tissue and abdominal lesions. Of the 29 soft-tissue or osseous metastases that were within the field-of-view of the simultaneous CT scans, five soft-tissue and zero osseous metastases were identified using CT. Metastatic disease was detected in three patients solely using WBMRI, which directly influenced their management. WBMRI is a useful adjunct in the detection of extra-pulmonary metastatic disease, which directly alters patient management. WBMRI has demonstrated an ability to identify more sites of metastatic disease compared to CT. WBMRI should be used in two situations. Firstly, at diagnosis where ablative treatment will be required e.g. amputation, when the diagnosis of occult metastasis would change treatment planning. Secondly, at diagnosis of relapse to confirm if it is a solitary site of relapse prior to consideration of metastectomy.

Pre-treatment staging of multiple myeloma patients: comparison of whole-body diffusion weighted imaging with whole-body T1-weighted contrast-enhanced imaging

BACKGROUND

Multiple myeloma (MM) is a hematologic malignancy characterized by the clonal proliferation of plasma cells. Accurate staging is of pivotal importance in the management of MM. Advanced imaging techniques, such as magnetic resonance imaging (MRI), are increasingly used for the initial diagnosis and staging of MM.

PURPOSE

To compare whole-body (WB) MR diffusion-weighted imaging with background body signal suppression (DWIBS) with (WB) MR fat-suppressed T1-weighted contrast-enhanced imaging (T1-CE) in the pre-treatment staging evaluation of multiple myeloma (MM) patients.

MATERIAL AND METHODS

Thirty-six patients with MM were included in the study. T1-CE and DWIBS were performed using a 3 T scanner. The Durie-Salmon plus staging system was used. Kappa statistics was used to assess agreement.

RESULTS

For all MM stages good to very good agreement was found for both T1-CE and DWIBS. The unweighted kappa statistic indicated a moderate, good and very good agreement between T1-CE and DWIBS for stages I, II, and III, respectively. In particular, in 67% of patients the MM staging according to T1-CE was not different from DWIBS. In the remaining 33% of patients, the MM stage obtained with T1-CE was lower than that provided by DWIBS.

CONCLUSION

DWIBS and T1-CE were concordant in the majority of patients. In a minority of cases DWIBS evidenced areas of water restriction that did not correspond to contrast enhancement areas. Studies monitoring therapeutic response in relation to tumour burden and aggressiveness should be performed to assess the clinical relevance of DWIBS findings.

Whole-body magnetic resonance imaging in children: state of the art

Whole-body imaging in children was classically performed with radiography, positron-emission tomography, either combined or not with computed tomography, the latter with the disadvantage of exposure to ionizing radiation. Whole-body magnetic resonance imaging (MRI), in association with the recently developed metabolic and functional techniques such as diffusion-weighted imaging, has brought the advantage of a comprehensive evaluation of pediatric patients without the risks inherent to ionizing radiation usually present in other conventional imaging methods. It is a rapid and sensitive method, particularly in pediatrics, for detecting and monitoring multifocal lesions in the body as a whole. In pediatrics, it is utilized for both oncologic and non-oncologic indications such as screening and diagnosis of tumors in patients with genetic syndromes, evaluation of disease extent and staging, evaluation of therapeutic response and post-therapy follow-up, evaluation of non neoplastic diseases such as multifocal osteomyelitis, vascular malformations and syndromes affecting multiple regions of the body. The present review was aimed at describing the major indications of whole-body MRI in pediatrics added of technical considerations.

Whole-body MRI in adult inflammatory myopathies: Do we need imaging of the trunk?

OBJECTIVE

To evaluate whether imaging of the trunk could be omitted in patients with inflammatory myopathies without losing diagnostic accuracy using a restricted whole-body magnetic resonance imaging (rWB-MRI) protocol.

METHODS

After approval by the institutional review board, this study was performed in 63 patients (male/female, 13/50; median age, 52 years; range, 20-81 years) with new-onset myopathic symptoms (group 1, n = 41) or previously diagnosed inflammatory myopathy (group 2, n = 22). After performing whole-body MRI (WB-MRI) at 3.0 Tesla, myositis and fatty atrophy were evaluated in different muscles by two independent radiologists. The intra-class correlation coefficient (ICC) was calculated to evaluate inter-observer reliability.

RESULTS

Acquisition time was 56:01 minutes for WB-MRI and 37:37 minutes (32.8 % shorter) for rWB-MRI. In group 1, 14 patients were diagnosed with inflammatory myopathy based on muscle biopsy. rWB-MRI and WB-MRI showed equal sensitivity (42.9 %) and specificity (100 %) for myositis, and showed equal sensitivity (71.4 %) and similar specificity (63.0 % and 48.1 %, respectively) for fatty atrophy. No myositis was found in the body trunk in any patient. Inter-observer reliability was between substantial and perfect (ICC, 0.77-1.00).

CONCLUSIONS

rWB-MRI showed diagnostic accuracy similar to WB-MRI for inflammatory myopathy at markedly reduced overall acquisition time.

KEY POINTS

• Whole-body MRI (WB-MRI) is a time-consuming imaging modality. • A shortened MRI protocol was evaluated for inflammatory myopathies. • The proposed protocol showed diagnostic accuracy similar to WB-MRI.

Non-contrast-enhanced whole-body magnetic resonance imaging in the general population: the incidence of abnormal findings in patients 50 years old and younger compared to older subjects

Purpose

To assess and compare the incidence of abnormal findings detected during non-contrast-enhanced whole-body magnetic resonance imaging (WB-MRI) in the general population in two age groups: (1) 50 years old and younger; and (2) over 50 years old.

Materials and Methods

The analysis included 666 non-contrast-enhanced WB-MRIs performed on a 1.5-T scanner between December 2009 and June 2013 in a private hospital in 451 patients 50 years old and younger and 215 patients over 50 years old. The following images were obtained: T2-STIR (whole body-coronal plane), T2-STIR (whole spine-sagittal), T2-TSE with fat-saturation (neck and trunk-axial), T2-FLAIR (head-axial), 3D T1-GRE (thorax-coronal, axial), T2-TSE (abdomen-axial), chemical shift (abdomen-axial). Detected abnormalities were classified as: insignificant (type I), potentially significant, requiring medical attention (type II), significant, requiring treatment (type III).

Results

There were 3375 incidental findings depicted in 659 (98.9%) subjects: 2997 type I lesions (88.8%), 363 type II lesions (10.8%) and 15 type III lesions (0.4%), including malignant or possibly malignant lesions in seven subjects. The most differences in the prevalence of abnormalities on WB-MRI between patients 50 years old and younger and over 50 years old concerned: brain infarction (22.2%, 45.0% respectively), thyroid cysts/nodules (8.7%, 18.8%), pulmonary nodules (5.0%, 16.2%), significant degenerative disease of the spine (23.3%, 44.5%), extra-spinal degenerative disease (22.4%, 61.1%), hepatic steatosis (15.8%, 24.9%), liver cysts/hemangiomas (24%, 34.5%), renal cysts (16.9%, 40.6%), prostate enlargement (5.1% of males, 34.2% of males), uterine fibroids (16.3% of females, 37.9% of females).

Conclusions

Incidental findings were detected in almost all of the subjects. WB-MRI demonstrated that the prevalence of the vast majority of abnormalities increases with age.

The diagnostic value of SE MRI and DWI of the spine in patients with monoclonal gammopathy of undetermined significance, smouldering myeloma and multiple myeloma

OBJECTIVES

To evaluate DWI of the bone marrow in the differentiation of monoclonal gammopathy of undetermined significance (MGUS), smouldering myeloma (SMM) and multiple myeloma (MM).

METHODS

The retrospective study includes 64 patients with MGUS, 27 with SMM, 64 with new MM and 12 controls. Signal intensity (SI) of spinal SE-MRI and DWI (b0-1000) as well as apparent diffusion coefficients (ADC) were measured in the T10 and L3. Qualitative assessment of b-images was performed by one experienced radiologist.

RESULTS

ADC600 and ADC1000 are the best ADC values in differentiating patient groups (p < 0.030). SIT2, SIb1000 and ADC1000 are higher and SIT1 lower in L3 compared to T10 (p < 0.050). All quantitative parameters of L3 can differentiate significantly between MGUS and MM (p < 0.050) and between patients with percentage plasma cells (PC%) between 0-10 % compared to >50 % (p = 0.001). Only SIT2 for L3 can differentiate MGUS from SMM (p = 0.044) and PC%0-10 from PC%10-25 (p = 0.033). Qualitative interpretation of b1000 images allows differentiating MM patients from those with MGUS or SMM (p < 0.001).

CONCLUSIONS

Spinal SE-MRI can differentiate among MGUS, SMM, MM and control subjects. DWI based on the SI on b1000 images and ADC values is increased in MM compared to MGUS and SMM. Qualitative assessment of b-images can differentiate MM from MGUS or SMM.

KEY POINTS

• ADC values are higher in patients with MM compared to MGUS • DWI parameters change late in disease evolution • DWI is sensitive but not specific in diagnosing patients with MM • Qualitative DWI assessment is good in detecting myeloma patients.

Whole-body magnetic resonance imaging (WB-MRI) as surveillance for subsequent malignancies in survivors of hereditary retinoblastoma: a pilot study

BACKGROUND

Individuals with hereditary retinoblastoma (RB) are at very high risk of developing subsequent malignant neoplasms (SMNs) of which osteosarcoma (OS) is one of the most common. We hypothesized that annual surveillance using whole-body magnetic resonance imaging (WB-MRI) in asymptomatic survivors of hereditary RB would detect SMN of the bone and soft tissues at an early stage.

PROCEDURE

Retrospective review of the results of a WB-MRI screening program in hereditary RB survivors from February 2008 to August 2012. The primary outcome was to determine the sensitivity and specificity of WB-MRI in detecting SMNs.

RESULTS

Twenty-five patients had at least one WB-MRI performed (range: 1-5). First WB-MRI was performed at a median age of 16 years (range: 8-25 years). WB-MRI detected new osseous abnormalities suspicious for malignancy in five patients: two were diagnosed with localized high-grade OS of the extremity and three were found to have benign osseous abnormalities after dedicated imaging (n = 5/5) and/or biopsy (n = 3/5). One patient was diagnosed with secondary OS 3 months after a normal screening WB-MRI exam. Among a total of 41 WB-MRI screening tests performed in survivors of hereditary RB, the sensitivity of detecting SMN was 66.7% and the specificity was 92.1%.

CONCLUSIONS

Preliminary results suggest that annual WB-MRI surveillance detects SMN in survivors of hereditary RB, but with modest sensitivity. Further study is needed to assess the performance of annual surveillance WB-MRIs and whether this modality decreases SMN-related mortality in RB survivors.

Whole-body muscle MRI to detect myopathies in non-extrapyramidal bent spine syndrome

OBJECTIVE

Bent spine syndrome (BSS), defined as an abnormal forward flexion of the trunk resolving in supine position, is usually related to parkinsonism, but can also be encountered in myopathies. This study evaluates whole-body muscle MRI (WB-mMRI) as a tool for detecting underlying myopathy in non-extrapyramidal BSS.

MATERIALS AND METHODS

Forty-three patients (90 % women; 53-86 years old) with a non-extrapyramidal BSS were prospectively included. All underwent a 1.5-T WB-mMRI and a nerve conduction study. Muscle biopsy was performed if a myopathy could not be eliminated based on clinical examination and all tests. Systematic MRI interpretation focused on peripheral and axial muscle injury; spinal posture and incidental findings were also reported.

RESULTS

WB-mMRI was completed for all patients, with 13 muscle biopsies ultimately needed and myopathy revealed as the final etiological diagnosis in five cases (12 %). All biopsy-proven myopathies were detected by the WB-mMRI. Relevant incidental MRI findings were made in seven patients.

CONCLUSIONS

This study supports WB-mMRI as a sensitive and feasible tool for detecting myopathy in BSS patients. Associated with electroneuromyography, it can better indicate when a muscle biopsy is needed and guide it when required. Rigorous radiological interpretation is mandatory, so as not to miss incidental findings of clinical consequence.

PET/MR in Oncology: Non-18F-FDG Tracers for Routine Applications

PET/MR is a new multimodal imaging technique that is expected to improve diagnostic performance, especially in oncologic patients in certain indications. Apart from the clinical relevance of PET with ¹⁸F-FDG, various other tracers exist and are increasingly used, which allow insights into multiple physiologic and biologic processes. In this review, we discuss the current and potential future applications of hybrid PET/MR, focusing on non-¹⁸F-FDG tracers. The combination of PET and MR in hybrid whole-body PET/MR systems has the potential to combine excellent morphologic, functional, and biologic information in 1 imaging session with precise image coregistration, thus paving the way for the concept of multimodal multiparametric imaging for future more widespread clinical use.

Detection of skeletal muscle metastases on initial staging of lung cancer: a retrospective case series

PURPOSE

Estimation of skeletal muscle metastases (SMMs) at the time of diagnosis and/or initial staging of lung cancer.

MATERIALS AND METHODS

Retrospective evaluation of clinical charts and imaging data suggestive of SMMs of patients with histology-proved lung cancer over a 5-year period.

RESULTS

SMMs were identified in 46 out of 1,754 patients. Single and multiple (62.9% of cases) SMMs were detected by total body multi-detector computed tomography (MDCT). They were associated with poorly differentiated (43%) and advanced adenocarcinomas (52%) without clinically relevant symptoms and/or signs. Psoas and buttock muscles were most frequently involved (33.3%). MDCT findings consisted of well-defined homogeneously hyperdense oval masses (31%), lesions with ring-like enhancement and central hypoattenuation (68%), or large abscess-like necrotic lesions (24%). Sonography revealed well-defined hypoechoic masses (41.6%), ill-defined hypoechoic lesions (33.3%), or anechoic areas with a necrotic centre (25%). Positron emission tomography revealed that all SMMs were metabolically active.

CONCLUSIONS

SMMs are uncommon but not negligible in lung cancer, with an estimated prevalence of 2.62% in our series. Although histology remains the recommended method, use of high-performance imaging techniques and increased clinical suspicion may improve their early detection. Efforts addressing their effect on the natural history of lung cancer are needed.

Advances in musculoskeletal MRI: technical considerations

The technology of musculoskeletal magnetic resonance imaging (MRI) is advancing at a dramatic rate. MRI is now done at medium and higher field strengths with more specialized surface coils and with more variable pulse sequences and postprocessing techniques than ever before. These innumerable technical advances are advantageous as they lead to an increased signal-to-noise ratio and increased variety of soft-tissue contrast options. However, at the same time they potentially produce more imaging artifacts when compared with past techniques. Substantial technical advances have considerable clinical challenges in musculoskeletal radiology such as postoperative patient imaging, cartilage mapping, and molecular imaging. In this review we consider technical advances in hardware and software of musculoskeletal MRI along with their clinical applications.

Imaging features of primary and secondary adult rhabdomyosarcoma

OBJECTIVE

Rhabdomyosarcomas are rare and aggressive soft-tissue sarcomas in adults. The purpose of this article is to describe the imaging features of primary and secondary adult rhabdomyosarcomas utilizing MRI, CT, and (18)F-FDG PET/CT.

CONCLUSION

MRI is the imaging technique of choice for the evaluation of primary rhabdomyosarcoma involving most body sites (extremity, pelvis, head, and neck), with the added advantages of diffusion-weighted imaging and whole-body MRI for staging. CT and FDG PET/CT play major roles in the evaluation of metastatic disease. Because the imaging features of adult rhabdomyosarcoma are nonspecific, other parameters, such as clinical findings, age, site, lymphadenopathy, and metastatic disease, should be combined to narrow the differential diagnosis.

Diagnostic imaging and image-guided therapy of skeletal metastases

BACKGROUND

The high incidence of skeletal metastases in cancer patients warrants careful detection with imaging and follow-up. Efforts are needed to manage pain associated with skeletal metastases as part of overall patient management.

METHODS

This article reviews the current methods of diagnostic imaging in the evaluation of skeletal metastases and image-guided treatment of bone metastases for the palliation of pain based primarily on the assessment of imaging and interventional radiologic literature.

RESULTS

Approaches to diagnostic imaging of skeletal metastases are summarized. Skeletal scintigraphy provides high sensitivity for detecting skeletal metastases, but targeted computed tomography (CT) or magnetic resonance imaging (MRI) may be needed to increase specificity. Newer imaging modalities, such as positron emission tomography (PET)/CT, improve detection of both lytic and blastic metastases. Minimally invasive percutaneous ablative treatment techniques, including radiofrequency ablation, microwave ablation, and cryoablation, are examined. They provide alternative approaches to radiation therapy to effectively palliate pain of bone metastases. Preliminary results of MR-guided focused ultrasound surgery (MRgFUS) demonstrate its effectiveness in palliating pain from skeletal metastases.

CONCLUSIONS

Skeletal scintigraphy is the most common imaging modality for detecting skeletal metastases. Additional imaging may be required based on the type of tumor, the disease state, or treatment options. External-beam radiation therapy remains the mainstay for palliation of pain from bone metastases. Alternative minimally invasive and noninvasive image-guided treatment options can provide effective pain palliation.

Advanced imaging of skeletal manifestations of systemic mastocytosis

Systemic mastocytosis comprises a group of clonal disorders of the mast cell that most commonly involves the skeletal system. Imaging can be helpful in the detection and characterization of the osseous manifestations of this disease. While radiography and bone scans are frequently used for this assessment, low-dose multidetector computed tomography and magnetic resonance imaging can be more sensitive for the detection of marrow involvement and for the demonstration of the various disease patterns. In this article, we review the pathophysiological and clinical features of systemic mastocytosis, discuss the role of imaging for staging and management, and illustrate the various cross-sectional imaging appearances. Awareness and knowledge of the imaging features of this disorder will increase the accuracy of image interpretation and can contribute important information for management decisions.