Contrast enhanced gray-scale sonography in assessment of joint vascularity in rheumatoid arthritis: results from the IACUS study group

What is the place of ultrasound in MSK imaging?

During the past four decades, ultrasound has become popular as an imaging modality applied to the musculoskeletal (MSK) system, particularly outside the USA, due to its low cost, accessibility, and lack of ionizing radiation. A basic requirement in performing these examinations is to have a core group of radiologists and ultrasound technologists with expertise in MSK ultrasound. The extent to which ultrasound will be part of the imaging offered by a particular radiology practice or in an academic institution will vary according to expertise, availability, and reimbursements. A brief discussion of the technical capabilities of the current generation of ultrasound scanners will be followed by a description of some of the more prevalent MSK ultrasound imaging applications. The extent to which training to perform these exams within and outside of Radiology plays a role is discussed. Applications that are unique to ultrasound, such as dynamic evaluation of musculoskeletal anatomy and some, US-guided interventions are an important part of MSK imaging. Ultrasound is increasingly important in the assessment of superficial structures, such as tendons, small joints, and peripheral nerves. These applications help to establish the place of ultrasound as an important part of the Radiologists approach to MSK imaging. Outside of radiology, for a variety of clinical subspecialties, ultrasound already plays an integral role in MSK imaging.

Musculoskeletal ultrasound: a technical and historical perspective

During the past four decades, musculoskeletal ultrasound has become popular as an imaging modality due to its low cost, accessibility, and lack of ionizing radiation. The development of ultrasound technology was possible in large part due to concomitant advances in both solid-state electronics and signal processing. The invention of the transistor and digital computer in the late 1940s was integral in its development. Moore's prediction that the number of microprocessors on a chip would grow exponentially, resulting in progressive miniaturization in chip design and therefore increased computational power, added to these capabilities. The development of musculoskeletal ultrasound has paralleled technical advances in diagnostic ultrasound. The appearance of a large variety of transducer capabilities and rapid image processing along with the ability to assess vascularity and tissue properties has expanded and continues to expand the role of musculoskeletal ultrasound. It should also be noted that these developments have in large part been due to a number of individuals who had the insight to see the potential applications of this developing technology to a host of relevant clinical musculoskeletal problems. Exquisite high-resolution images of both deep and small superficial musculoskeletal anatomy, assessment of vascularity on a capillary level and tissue mechanical properties can be obtained. Ultrasound has also been recognized as the method of choice to perform a large variety of interventional procedures. A brief review of these technical developments, the timeline over which these improvements occurred, and the impact on musculoskeletal ultrasound is presented below.

The Use of Superb Microvascular Imaging in Evaluating Rheumatic Diseases: A Systematic Review

Background and Objectives: Superb microvascular imaging is an advanced Doppler algorithm that seems to be useful in detecting low-velocity blood flow without using a contrast agent. Increasing evidence suggests that SMI is a more sensitive tool than conventional Doppler techniques for evaluating rheumatic diseases, especially inflammatory arthritis. We aimed to assess the use of SMI in evaluating joints and extraarticular structures. Materials and Methods: Two reviewers independently reviewed the literature to provide a global overview of the possibilities of SMI in rheumatology. Original English-language articles published between February 2014 and November 2022 were identified through database (PubMed, Medline, Ebsco, the Cochrane Library, and ScienceDirect) searching, and analysed to summarise existing evidence according to PRISMA methodology. Inclusion criteria covered original research articles reporting applications of SMI on rheumatic diseases and musculoskeletal disorders secondary to rheumatic conditions. Qualitative data synthesis was performed. Results: A total of 18 articles were included. No systematic reviews fulfilled our inclusion criteria. Most studies focused on characterising the synovial vascularity of rheumatoid arthritis. There have been several attempts to demonstrate SMI's value for evaluating extra-articular soft tissues (fat pads or salivary glands) and large-diameter vessels. The quantitative importance of SMI vascular indices could become a useful non-invasive diagnostic marker. Studies on therapeutic applications are still scarce, and the majority of studies have gaps in reporting the methodology (ultrasound performance technique and settings) of the research. Conclusions: SMI has proved to be useful in characterising low-flow vascularity, and growing evidence indicates that SMI is a non-invasive and lower-cost tool for prognostic assessment, especially in inflammatory arthritis. Preliminary findings also suggest potential interest in evaluating the effect of treatment.

The EFSUMB Guidelines and Recommendations for Musculoskeletal Ultrasound - Part II: Joint Pathologies, Pediatric Applications, and Guided Procedures

The second part of the Guidelines and Recommendations for Musculoskeletal Ultrasound (MSUS), produced under the auspices of EFSUMB, following the same methodology as for Part 1, provides information and recommendations on the use of this imaging modality for joint pathology, pediatric applications, and musculoskeletal ultrasound-guided procedures. Clinical application, practical points, limitations, and artifacts are described and discussed for every joint or procedure. The document is intended to guide clinical users in their daily practice.

Value of Contrast-enhanced Ultrasound in Evaluating Synovitis and Predicting Recurrent Joint Bleeding of Hemophilia

OBJECTIVE

Contrast-enhanced ultrasound (CEUS) is advantageous for evaluating microcirculation, and has been applied to assess arthritis in previous studies. However, CEUS examinations have not been studied for hemophilia arthritis. Hemophilia arthritis is different from other arthritis, because it is induced by spontaneous joint bleeding. Hence, CEUS may have special value in evaluating hemophilia arthritis. The present study assessed the value of CEUS in evaluating synovial hypertrophy and predicting recurrent joint bleeding in severe hemophilia A patients.

METHODS

From August 2016 to January 2017, 81 severe hemophilia A patients, who were referred to our hospital for ultrasound joint assessment with conventional ultrasound, were enrolled. Among these 81 patients, 46 patients consented for CEUS examinations on the same day.

RESULTS

Compared to color Doppler flow imaging (CDFI), four more joints presented with a blood flow signal under CEUS mode. In addition, the synovial hypertrophy measured by CEUS was thicker than that measured by conventional ultrasound. The ultrasound scores (including the total grey-scale ultrasound score, joint effusion/hemarthrosis, synovial hypertrophy, CDFI semi-quantitative score, and CEUS semi-quantitative score) were significantly higher in the joint bleeding group than in the no joint bleeding group (P<0.05). Furthermore, these ultrasound scores were positively correlated with the joint bleeding frequency, and had the highest correlation with the CEUS score (r=0.620, P<0.05).

CONCLUSION

CEUS can more accurately assess the degree of synovial hypertrophy and vascularization, and diagnose synovitis, when compared to conventional ultrasound. In addition, CEUS appears to be essential for evaluating the possibility of recurrent joint bleeding, and providing more reliable evidence for individualized treatment.

A Review of Clinical Applications for Super-resolution Ultrasound Localization Microscopy

Microvascular structure and hemodynamics are important indicators for the diagnosis and assessment of many diseases and pathologies. The structural and functional imaging of tissue microvasculature in vivo is a clinically significant objective for the development of many imaging modalities. Contrast-enhanced ultrasound (CEUS) is a popular clinical tool for characterizing tissue microvasculature, due to the moderate cost, wide accessibility, and absence of ionizing radiation of ultrasound. However, in practice, it remains challenging to demonstrate microvasculature using CEUS, due to the resolution limit of conventional ultrasound imaging. In addition, the quantification of tissue perfusion by CEUS remains hindered by high operator-dependency and poor reproducibility. Inspired by super-resolution optical microscopy, super-resolution ultrasound localization microscopy (ULM) was recently developed. ULM uses the same ultrasound contrast agent (i.e. microbubbles) in CEUS. However, different from CEUS, ULM uses the location of the microbubbles to construct images, instead of using the backscattering intensity of microbubbles. Hence, ULM overcomes the classic compromise between imaging resolution and penetration, allowing for the visualization of capillary-scale microvasculature deep within tissues. To date, many in vivo ULM results have been reported, including both animal (kidney, brain, spinal cord, xenografted tumor, and ear) and human studies (prostate, tibialis anterior muscle, and breast cancer tumors). Furthermore, a variety of useful biomarkers have been derived from using ULM for different preclinical and clinical applications. Due to the high spatial resolution and accurate blood flow speed estimation (approximately 1 mm/s to several cm/s), ULM presents as an enticing alternative to CEUS for characterizing tissue microvasculature in vivo. This review summarizes the principles and present applications of CEUS and ULM, and discusses areas where ULM can potentially provide a better alternative to CEUS in clinical practice and areas where ULM may not be a better alternative. The objective of the study is to provide clinicians with an up-to-date review of ULM technology, and a practical guide for implementing ULM in clinical research and practice.

Contrast-enhanced ultrasound for musculoskeletal indications in children

The increasing use of contrast-enhanced ultrasound (CEUS) has opened exciting new frontiers for musculoskeletal applications in adults and children. The most common musculoskeletal-related CEUS applications in adults are for detecting inflammatory joint diseases, imaging skeletal muscles and tendon perfusion, imaging postoperative viability of osseous and osseocutaneous tissue flaps, and evaluating the malignant potential of soft-tissue masses. Pediatric musculoskeletal-related CEUS has been applied for imaging juvenile idiopathic arthritis and Legg-Calvé-Perthes disease and for evaluating femoral head perfusion following surgical hip reduction in children with developmental hip dysplasia. CEUS can improve visualization of the capillary network in superficial and deep tissues and also in states of slow- or low-volume blood flow. In addition, measurements of blood flow imaging parameters performed by quantitative CEUS are valuable when monitoring the outcome of treatment interventions. In this review article we present current experience regarding a wide range of CEUS applications in musculoskeletal conditions in adults and children, with emphasis on the latter, and discuss imaging techniques and CEUS findings in musculoskeletal applications.

A problem-based approach in musculoskeletal ultrasonography: central metatarsalgia

Ultrasonography (US) is a useful diagnostic method that can be easily applied to identify the cause of metatarsalgia. The superficial location of structures in the foot, dynamic capability of US, and the ability to perform direct real-time evaluations of the pain site are also strong advantages of US as a modality for examining the foot. Moreover, knowing the possible pain sources to investigate when a patient has a specific site of pain will enhance the diagnostic quality of US, and will help radiologists to perform US efficiently and effectively. The purpose of this article is to review the common etiologies of metatarsalgia including Morton’s neuroma, plantar plate injury, synovitis, tenosynovitis, bursitis, and metatarsal fractures, and to discuss their US features.

Longitudinal Changes in Knee Joint Synovial Vascularity in a Rabbit Model of Rheumatoid Arthritis: Quantification Using Power Doppler Ultrasound and Contrast-Enhanced Ultrasound

We studied a rabbit model of rheumatoid arthritis (RA) to examine the time course of changes in synovial neovascularization based on quantitative power Doppler ultrasound and contrast-enhanced ultrasound (CEUS). Twenty-five male New Zealand rabbits were in the ovalbumin-induced arthritis (OIA) group, and 5 were in the control group. Both rear knee joints of all rabbits were examined using conventional US and CEUS over 16 weeks. The knee synoviums of OIA rabbits were sampled by US-guided biopsy, and expression of CD31 and vascular endothelial growth factor (VEGF) was determined by immunohistochemistry. The correlation of joint damage based on multimodal US with microvessel density (CD31 positivity) and VEGF expression at different times was analyzed. OIA rabbits had increased synovial expression of CD31 and VEGF from weeks 6 to 12 (p < 0.01). During the early stage of CEUS enhancement, "dot enhancement" was more common at weeks 6 and 8, and "stripe enhancement" was more common at weeks 12 and 16 (p < 0.05). There were significant positive correlations of synovial CD31 and VEGF expression with power Doppler image grade, CEUS grade and peak intensity (p < 0.05 for all). Thus, OIA rabbits mimicked early-stage RA at 6 to 8 weeks, middle-stage RA at 8 to 12 weeks and late-stage RA at 12 to 16 weeks. Power Doppler image grade, CEUS grade and peak intensity, especially when combined with CD31 expression data, accurately characterized the extent of synovial vascularization in a rabbit model of RA. Increased vascularity based on CEUS may have value for the early diagnosis of RA.

Value of Contrast-Enhanced Ultrasonography in Evaluating Rheumatoid Arthritis: Preliminary Research Based on an Animal Model

BACKGROUND The aim of this study was to evaluate the effectiveness of grayscale ultrasound (GSUS), power Doppler imaging (PDI), and contrast-enhanced ultrasonography (CEUS) in early rheumatoid arthritis (RA) diagnosis through animal experiments. MATERIAL AND METHODS A rabbit RA model was constructed. The animals were randomly divided into 2 groups, namely, the RA model group and the control group. GSUS, PDI, and CEUS were performed in the model group during early RA and were compared with pathology of synovial biopsies. The consistency of 3 types of ultrasonography was evaluated in tandem with pathological grading. RESULTS 23 rabbits in the RA model group completed the experiment. GSUS showed that the synovial thickening of grades 1, 2 and 3 occurred in 12, 19, and 15 joints, respectively. The sensitivity, specificity, and accuracy of PDI in the diagnosis of knee joint synovitis in RA grades 1, 2, and 3 were 80.56% (29/36), 60.00% (6/10), and 76.09% (35/46), respectively, while those with CEUS were 94.44% (34/36), 90.00% (9/10), and 93.47% (43/46), respectively. The differences in diagnostic sensitivity, specificity, and accuracy of the 2 methods were statistically significant. Additionally, the thickness of the synovium measured with GSUS precontrast was greater than that of postcontrast. CONCLUSIONS RA evaluated with GSUS is often more hypertrophied than when evaluated with CEUS, while evaluation by PDI is less hypertrophied than that by CEUS. However, from a practical view point, GSUS and PDI are of sufficient practical value, except for in a few special cases.

Quantitative Musculoskeletal Ultrasound

Ultrasound (US) imaging plays a crucial role in the assessment of musculoskeletal (MSK) disorders. Several quantitative tools are offered by US systems and add information to conventional US imaging. This article reviews the quantitative US imaging tools currently available in MSK radiology, specifically focusing on the evaluation of elasticity with shear-wave elastography, perfusion with contrast-enhanced US and noncontrast superb microvascular imaging, and bone and muscle mass with quantitative US methods. Some of them are well established and already of clinical value, such as elasticity and contrast-enhanced perfusion assessment in muscles and tendons. MSK radiologists should be aware of the potential of quantitative US tools and take advantage of their use in everyday practice, both for clinical and research purposes.

Contrast-Enhanced Ultrasound for Musculoskeletal Applications: A World Federation for Ultrasound in Medicine and Biology Position Paper

This World Federation for Ultrasound in Medicine and Biology position paper reviews the diagnostic potential of ultrasound contrast agents for clinical decision-making and provides general advice for optimal contrast-enhanced ultrasound performance in musculoskeletal issues. In this domain, contrast-enhanced ultrasound performance has increasingly been investigated with promising results, but still lacks everyday clinical application and standardized techniques; therefore, experts summarized current knowledge according to published evidence and best personal experience. The goal was to intensify and standardize the use and administration of ultrasound contrast agents to facilitate correct diagnoses and ultimately to improve the management and outcomes of patients.

Intraoperative Contrast-Enhanced Ultrasound Imaging of Femoral Head Perfusion in Developmental Dysplasia of the Hip: A Feasibility Study

OBJECTIVES

Developmental dysplasia of the hip (DDH) is one of the most common developmental deformities of the lower extremity. Although many children are successfully treated with a brace or harness, some require intraoperative closed or open reduction and spica casting. Surgical reduction is largely successful to relocate the hip; however, iatrogenic avascular necrosis is a major source of morbidity. Recent research showed that postoperative gadolinium-enhanced magnetic resonance imaging (MRI) can depict hip perfusion, which may predict a future incidence of avascular necrosis. As contrast-enhanced ultrasound (CEUS) assesses blood flow in real time, it may be an effective intraoperative alternative to evaluate femoral head perfusion. Here we describe our initial experience regarding the feasibility of intraoperative CEUS of the hip for the assessment of femoral head perfusion before and after DDH reduction.

METHODS

This single-institution retrospective Institutional Review Board-approved study with a waiver of informed consent evaluated intraoperative hip CEUS in children with DDH compared to postoperative contrast-enhanced MRI. Pediatric radiologists, blinded to prior imaging findings and outcomes, reviewed both CEUS and MRI examinations separately and some time from the initial examination both independently and in consensus.

RESULTS

Seventeen patients had 20 intraoperative CEUS examinations. Twelve of 17 (70.6%) had prereduction hip CEUS, postreduction hip CEUS, and postreduction gadolinium-enhanced MRI. Seven of 12 (58.3%) were evaluable retrospectively. All CEUS studies showed blood flow in the femoral epiphysis before and after reduction, and all MRI studies showed femoral head enhancement after reduction. The CEUS and MRI for all 7 patients also showed physeal blood flow.

CONCLUSIONS

Contrast-enhanced ultrasound is a feasible intraoperative tool for assessing adequate blood flow after hip reduction surgery in DDH.

[CEUS-application possibilities in the musculoskeletal system]

METHODICAL ISSUE

Contrast-enhanced ultrasound (CEUS) offers easily accessible visualization and quantification of the skeletal muscle microcirculation and other tissues in vivo and in real-time with almost no side effects.

AIM

The aim of this review is to present the increasing number of musculoskeletal CEUS applications.

METHODICAL INNOVATIONS/PERFORMANCE

CEUS applications regarding the musculoskeletal system include applications at bone and joints extending beyond the visualization of only the muscular microcirculation. Besides basic muscle physiology, impaired microcirculation in patients with peripheral artery disease or diabetes mellitus and the diagnosis of inflammatory myopathies have been the subject of previous CEUS studies. More recent studies in orthopedics and traumatology have focused on osseous and muscular perfusion characteristics, e. g., in differentiating infected and aseptic non-unions or the impact of different types of implants and prostheses on muscular microcirculation as a surrogate marker of clinical success.

PRACTICAL RECOMMENDATIONS

CEUS of the musculoskeletal system is used in clinical trials or off-label. Therefore, it is not well established in clinical routine. However, considering the increasing number of musculoskeletal CEUS applications, this could change in the future.

Role of Contrast-enhanced Ultrasound in the Evaluation of Inflammatory Arthritis

Objective:

Contrast-enhanced ultrasound (CEUS) is a well-established imaging modality which has been put into clinical use in recent years with the development of second-generation contrast agent and imaging devices, and its applications in the assessment of inflammatory arthritis, such as rheumatoid arthritis, psoriatic arthritis, and ankylosing spondylitis, have provoked abundant discussion and researches among radiologists and rheumatologists. To summarize the achievements of clinical studies on CEUS in the application of arthritis, and to keep up with the latest progresses of the imaging technique, we reviewed the literature in recent years, hoping to establish the role of CEUS in joint diseases.

Data Sources:

PubMed and EMBASE.

Study Selection:

We searched the database with the conditions “contrast-enhanced ultrasound AND arthritis” with the time limitation of recent 10 years. Clinical studies applying CEUS in inflammatory arthritis and review articles about development of CEUS in joint diseases in English were selected.

Results:

As it is proved by most studies in recent years, by delineating microvasculature within the inflamed joints, CEUS can indicate early arthritis with high sensitivity and specificity. Moreover, the imaging of CEUS has been proved to be consistent with histopathological changes of inflammatory arthritis. Quantitative analysis of CEUS permits further evaluation of disease activity. CEUS also plays a significant role in the therapeutic monitoring of the disease, which has been backed up by a number of studies.

Conclusions:

CEUS may be a new choice for the rheumatologists to evaluate inflammatory arthritis, because of its low price, ability to provide dynamic pictures, and high sensitivity to angiogenesis. It can also be applied in disease classification and therapeutic monitoring. More studies about CEUS need to be done to set up the diagnostic standards.

What is the added value of ultrasound joint examination for monitoring synovitis in rheumatoid arthritis and can it be used to guide treatment decisions? A systematic review and cost-effectiveness analysis

BACKGROUND

Synovitis (inflamed joint synovial lining) in rheumatoid arthritis (RA) can be assessed by clinical examination (CE) or ultrasound (US).

OBJECTIVE

To investigate the added value of US, compared with CE alone, in RA synovitis in terms of clinical effectiveness and cost-effectiveness.

DATA SOURCES

Electronic databases including MEDLINE, EMBASE and the Cochrane databases were searched from inception to October 2015.

REVIEW METHODS

A systematic review sought RA studies that compared additional US with CE. Heterogeneity of the studies with regard to interventions, comparators and outcomes precluded meta-analyses. Systematic searches for studies of cost-effectiveness and US and treatment-tapering studies (not necessarily including US) were undertaken.

MATHEMATICAL MODEL

A model was constructed that estimated, for patients in whom drug tapering was considered, the reduction in costs of disease-modifying anti-rheumatic drugs (DMARDs) and serious infections at which the addition of US had a cost per quality-adjusted life-year (QALY) gained of £20,000 and £30,000. Furthermore, the reduction in the costs of DMARDs at which US becomes cost neutral was also estimated. For patients in whom dose escalation was being considered, the reduction in number of patients escalating treatment and in serious infections at which the addition of US had a cost per QALY gained of £20,000 and £30,000 was estimated. The reduction in number of patients escalating treatment for US to become cost neutral was also estimated.

RESULTS

Fifty-eight studies were included. Two randomised controlled trials compared adding US to a Disease Activity Score (DAS)-based treat-to-target strategy for early RA patients. The addition of power Doppler ultrasound (PDUS) to a Disease Activity Score 28 joints-based treat-to-target strategy in the Targeting Synovitis in Early Rheumatoid Arthritis (TaSER) trial resulted in no significant between-group difference for change in Disease Activity Score 44 joints (DAS44). This study found that significantly more patients in the PDUS group attained DAS44 remission (p = 0.03). The Aiming for Remission in Rheumatoid Arthritis (ARCTIC) trial found that the addition of PDUS and grey-scale ultrasound (GSUS) to a DAS-based strategy did not produce a significant between-group difference in the primary end point: composite DAS of < 1.6, no swollen joints and no progression in van der Heijde-modified total Sharp score (vdHSS). The ARCTIC trial did find that the erosion score of the vdHS had a significant advantage for the US group (p = 0.04). In the TaSER trial there was no significant group difference for erosion. Other studies suggested that PDUS was significantly associated with radiographic progression and that US had added value for wrist and hand joints rather than foot and ankle joints. Heterogeneity between trials made conclusions uncertain. No studies were identified that reported the cost-effectiveness of US in monitoring synovitis. The model estimated that an average reduction of 2.5% in the costs of biological DMARDs would be sufficient to offset the costs of 3-monthly US. The money could not be recouped if oral methotrexate was the only drug used.

LIMITATIONS

Heterogeneity of the trials precluded meta-analysis. Therefore, no summary estimates of effect were available. Additional costs and health-related quality of life decrements, relating to a flare following tapering or disease progression, have not been included. The feasibility of increased US monitoring has not been assessed.

CONCLUSION

Limited evidence suggests that US monitoring of synovitis could provide a cost-effective approach to selecting RA patients for treatment tapering or escalation avoidance. Considerable uncertainty exists for all conclusions. Future research priorities include evaluating US monitoring of RA synovitis in longitudinal clinical studies.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42015017216.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Rotator cuff calcific tendinopathy: from diagnosis to treatment

Rotator cuff calcific tendinopathy (RCCT) is a very common condition caused by the presence of calcific deposits in the rotator cuff (RC) or in the subacromial-subdeltoid (SASD) bursa when calcification spreads around the tendons. The pathogenetic mechanism of RCCT is still unclear. It seems to be related to cell-mediated disease in which metaplastic transformation of tenocytes into chondrocytes induces calcification inside the tendon of the RC. RCCT is a frequent finding in the RC that may cause significant shoulder pain and disability. It can be easily diagnosed with imaging studies as conventional radiography (CR) or ultrasound (US). Conservative management of RCCT usually involves rest, physical therapy, and oral NSAIDs administration. Imaging-guided treatments are currently considered minimally-invasive, yet effective methods to treat RCCT with about 80% success rate. Surgery remains the most invasive treatment option in chronic cases that fail to improve with other less invasive approaches. (www.actabiomedica.it)

Clinical utility of eco-color-power Doppler ultrasonography and contrast enhanced magnetic resonance imaging for interpretation and quantification of joint synovitis: a review

With the introduction of new biologics such as anti-TNF-alpha antibodies and other therapies in the treatment of inflammatory arthritis, capable of halting joint destruction and functional disability, there are new pressures on diagnostic and prognostic imaging. Early demonstration of pre-erosive inflammatory features and monitoring of the long-term effects of treatment are becoming increasingly important. Early detection of synovitis offers advantages in terms of allowing early instigation of therapy and may allow the identification of those patients displaying more aggressive disease who might benefit from early intervention with expensive DMARD therapy. Advanced imaging techniques such as ultrasound (US) and magnetic resonance imaging (MRI) have focussed on the demonstration and quantification of synovitis and allow early diagnosis of inflammatory arthropathies such as rheumatoid arthritis (RA) and psoriatic arthritis (PsA). Synovitis represents a potential surrogate measure of disease activity that can be monitored using either MRI or US; the techniques have, generally, focused on monitoring synovial volume or quality as assessed by its vascularity. However to achieve these goals, standardisation and validation of US and MRI are required to ensure accurate diagnosis, reproducibility and reliability. Each modality has different strengths and weaknesses and levels of validation. This article aims to increase the awareness of radiologists and rheumatologists about this field and to encourage them to participate and contribute to the ongoing development of these modalities. Without this collaboration, it is unlikely that these modalities will reach their full potential in the field of rheumatological imaging. This review is in two parts. The first part addresses the role of US and colour or power Doppler sonography (PDUS) in the detection and monitoring of synovitis in inflammatory arthropathies. The second part will look at advanced MR imaging and Dynamic contrast-enhanced MRI techniques and in particular how they are applied to the monitoring of the disease process.

Imaging of pediatric foot disorders

Infants and children undergo imaging studies to evaluate a wide variety of congenital and acquired disorders. Imaging protocols have to consider the patient’s comfort, level of anxiety, and smaller size. The first imaging study is usually made with plain radiographs. The routine radiographic examination of the foot includes the anteroposterior (AP), lateral, and oblique projections. Magnetic Resonance Imaging (RMI) provides excellent anatomic detail of cartilage, vasculature and soft tissue thanks to superior soft tissue contrast and spatial resolution, so is valuable in many cases. According to the clinical and objective signs, guided by the radiographs images, we can be oriented to perform Computed Tomography (CT), CT imaging or MRI imaging. CT imaging is useful to observe the bones but it has the disadvantage of using radiation and doesn’t adequately define the bone’s non-ossified portions. On the contrary, MRI imaging is very useful in identifying the cartilaginous parts and vascular and soft tissues, thanks to its superior contrast and spatial resolution. Finally, it is important to orientate the diagnostic process keeping in mind the clinical sign of the patient and to use the most appropriate diagnostic technique. (www.actabiomedica.it)

A Combined Ultrasonographic and Conventional Radiographic Assessment of Hemophilic Arthropathy

Hemophilic arthropathy (HA) can be diagnosed by a number of imaging studies. However, it is difficult with conventional radiography to find soft tissue structures around joints, and ultrasonography has limited effectiveness in evaluating internal bony structures. We attempt to determine whether a combination of ultrasonography for soft tissue around joints and conventional radiography for bony structures can be used as a cost-effective imaging tool for evaluating HA and whether it reflects the functional status of hemophilic patients. Thirty-six males (median age 16.5 years; severe 34, mild 2) with hemophilia were recruited. We evaluated the severity of HA using combined imaging score that consisted of modified Petterson X-ray score (mPXS) and the modified ultrasonographic score (mUS). Joint impairment was clinically assesses using the World Federation of Hemophilia-Physical Examination (WFH-PE) scale and the Hemophilic joint health score (HJHS). We assessed the Hemophilia activities list (HAL) for the functional level. We performed a comparative analysis between the combined imaging score and the joint impairment scores as well as the functional scores. The mean mUS was 4.97 ± 3.99 points, and the mean mPXS was 2.85 ± 2.91 points; the combined imaging score was 7.83 ± 6.31 points. The combined imaging score was significantly correlated with the HJHS (p = 0.006) and WFH-PE scores (p = 0.019) as well as the HAL score (p = 0.002). A combination of conventional radiological and ultrasongraphic study might ultimately impact the optimal evaluation of joint impairment and functional status in hemophilic patients.

Bayesian Quantification of Contrast-Enhanced Ultrasound Images With Adaptive Inclusion of an Irreversible Component

Contrast Enhanced Ultrasound (CEUS) is a sensitive imaging technique to assess tissue vascularity and it can be particularly useful in early detection and grading of arthritis. In a recent study we have shown that a Gamma-variate can accurately quantify synovial perfusion and it is flexible enough to describe many heterogeneous patterns. However, in some cases the heterogeneity of the kinetics can be such that even the Gamma model does not properly describe the curve, with a high number of outliers. In this work we apply to CEUS data the single compartment recirculation model (SCR) which takes explicitly into account the trapping of the microbubbles contrast agent by adding to the single Gamma-variate model its integral. The SCR model, originally proposed for dynamic-susceptibility magnetic resonance imaging, is solved here at pixel level within a Bayesian framework using Variational Bayes (VB). We also include the automatic relevant determination (ARD) algorithm to automatically infer the model complexity (SCR vs. Gamma model) from the data. We demonstrate that the inclusion of trapping best describes the CEUS patterns in 50% of the pixels, with the other 50% best fitted by a single Gamma. Such results highlight the necessity of the use ARD, to automatically exclude the irreversible component where not supported by the data. VB with ARD returns precise estimates in the majority of the kinetics (88% of total percentage of pixels) in a limited computational time (on average, 3.6 min per subject). Moreover, the impact of the additional trapping component has been evaluated for the differentiation of rheumatoid and non-rheumatoid patients, by means of a support vector machine classifier with backward feature selection. The results show that the trapping parameter is always present in the selected feature set, and improves the classification.

High-Resolution US of Rheumatologic Diseases

For the past 15 years, high-resolution ultrasonography (US) is being routinely and increasingly used for initial evaluation and treatment follow-up of rheumatologic diseases. This imaging technique is performed by using high-frequency linear transducers and has proved to be a powerful diagnostic tool in evaluation of articular erosions, simple and complex joint and bursal effusions, tendon sheath effusions, and synovitis, with results comparable to those of magnetic resonance imaging, excluding detection of bone marrow edema. Crystal deposition diseases including gouty arthropathy and calcium pyrophosphate deposition disease (CPPD) have characteristic appearances at US, enabling differentiation between these two diseases and from inflammatory arthropathies. Enthesopathy, which frequently accompanies psoriatic and reactive arthritis, also has a characteristic appearance at high-resolution US, distinguishing these two entities from other inflammatory and metabolic arthropathies. The presence of Doppler signal in examined joints, bursae, and tendon sheaths indicates active synovitis. Microbubble echo contrast agents augment detection of tissue vascularity and may act in the future as a drug delivery vehicle. Frequently, joint, tendon sheath, and bursal fluid aspirations and therapeutic injections are performed under US guidance. The authors describe the high-resolution US technique including gray-scale, color or power Doppler, and contrast agent-enhanced US that is used in evaluation of rheumatologic diseases of the wrist and hand and the ankle and foot in their routine clinical practice. This article demonstrates imaging findings of normal joints, rheumatoid arthritis, gouty arthritis, CPPD, psoriatic and reactive arthritis, and osteoarthritis.

Update in Musculoskeletal Ultrasound Research

CONTEXT

Musculoskeletal ultrasound (US) research is expanding due to increased clinical utility of sonography.

STUDY DESIGN

Clinical review.

LEVEL OF EVIDENCE

Level 4.

RESULTS

Ultrasound is widely applied in musculoskeletal imaging and sports medicine. The real-time capabilities and favorable cost profile of US make it ideal for use in diagnosis of musculoskeletal conditions. The enthusiasm for the use of US in musculoskeletal imaging has led to an increase in US research to broaden its applications.

CONCLUSION

Several recent advances have been made in conventional and novel US imaging techniques, quantitative US imaging, and US-guided interventions.

STRENGTH OF RECOMMENDATIONS TAXONOMY SORT

C.

Magnetic resonance and ultrasound contrast imaging of polymer-shelled microbubbles loaded with iron oxide nanoparticles

Dual-mode contrast agents (CAs) have great potential for improving diagnostics. However, the effectiveness of CAs is strictly related to both the solution adopted to merge the two agents into a single probe unit, and the ratio between the two agents. In this study, two dual-mode CAs for simultaneous magnetic resonance imaging (MRI) and ultrasound imaging (UI) were assessed. For this purpose, different densities of superparamagnetic iron oxide nanoparticles (SPIONs) were anchored to the external surface of polymer-shelled microbubbles (MBs) or were physically entrapped into the shell. In vitro static and dynamic experiments were carried out with a limited concentration of modified MBs (10⁶ bubbles ml^-1) by avoiding destruction during UI (performed at a peak pressure lower than 320 kPa) and by using a low-field MRI system (with a magnetic flux density equal to 0.25 T). Under these conditions, different imaging techniques, set-up parameters and SPION densities were used to achieve satisfactory detection of the CAs by using both UI and MRI. However, when the SPION density was increased, the MRI contrast improved, whereas the UI contrast worsened due to the reduced elasticity of the MB shell. For both UI and MRI, MBs with externally anchored SPIONs provided better performance than MBs with SPIONs entrapped into the shell. In particular, a SPION density of 29% with respect to the mass of the MBs was successfully tested.

Magnetic resonance and ultrasound contrast imaging of polymer-shelled microbubbles loaded with iron oxide nanoparticles

Dual-mode contrast agents (CAs) have great potential for improving diagnostics. However, the effectiveness of CAs is strictly related to both the solution adopted to merge the two agents into a single probe unit, and the ratio between the two agents. In this study, two dual-mode CAs for simultaneous magnetic resonance imaging (MRI) and ultrasound imaging (UI) were assessed. For this purpose, different densities of superparamagnetic iron oxide nanoparticles (SPIONs) were anchored to the external surface of polymer-shelled microbubbles (MBs) or were physically entrapped into the shell. In vitro static and dynamic experiments were carried out with a limited concentration of modified MBs (10⁶ bubbles ml^-1) by avoiding destruction during UI (performed at a peak pressure lower than 320 kPa) and by using a low-field MRI system (with a magnetic flux density equal to 0.25 T). Under these conditions, different imaging techniques, set-up parameters and SPION densities were used to achieve satisfactory detection of the CAs by using both UI and MRI. However, when the SPION density was increased, the MRI contrast improved, whereas the UI contrast worsened due to the reduced elasticity of the MB shell. For both UI and MRI, MBs with externally anchored SPIONs provided better performance than MBs with SPIONs entrapped into the shell. In particular, a SPION density of 29% with respect to the mass of the MBs was successfully tested.

Contrast-enhanced ultrasound in coxitis

OBJECTIVES

Hip involvement is common in rheumatological diseases but can be difficult to diagnose, especially in absence of MRI. B-mode ultrasound (US) detects joint capsule distention while distinguishing effusion from proliferative synovial tissue is strenuous since both appear hypoechoic. Power Doppler ultrasound (PDUS) often fails to detect vascularisation in the hip. We therefore evaluated contrast-enhanced ultrasound (CEUS) in the hip joint.

METHODS

We investigated 36 hip joints of patients with known rheumatological joint diseases presenting with hip pain and 5 hips of healthy controls using B-mode US, PDUS and CEUS. We assessed CEUS hypervascularisation semiquantitatively comparing to the periarticular tissue. In B-mode, we measured the distance between femoral neck and joint capsule (DNC) and compared the results to the avascular intraarticular margin (AIM) in CEUS using t-tests and crosstables.

RESULTS

PDUS signals were received in only 2/36 cases (5.6%). B-mode US established the diagnosis of coxitis in 64% of all symptomatic hip joints. In 4 cases (11%), the diagnosis was revised after the use of CEUS. In patients with definite coxitis, 14 hips (73.7%) showed CEUS hypervascularisation°2, five°1 (26.3%) and none°0 (χ²=3.277, P<0.001). The difference DNC/AIM was highly significant in patients with hip pain (P<0.001, 95% CI: 2.054-4.684) and those with definite coxitis (P<0.001, 95% CI: 3.268-7.258).

CONCLUSIONS

In most cases, clinical parameters together with B-mode US findings are sufficient to diagnose coxitis. However, CEUS is capable of visualizing and quantifying the degree of hypervascularisation and enables the discrimination between effusion and proliferative synovial tissue.

Pixel-based approach to assess contrast-enhanced ultrasound kinetics parameters for differential diagnosis of rheumatoid arthritis

Inflammatory rheumatic diseases are the leading causes of disability and constitute a frequent medical disorder, leading to inability to work, high comorbidity, and increased mortality. The standard for diagnosing and differentiating arthritis is based on clinical examination, laboratory exams, and imaging findings, such as synovitis, bone edema, or joint erosions. Contrast-enhanced ultrasound (CEUS) examination of the small joints is emerging as a sensitive tool for assessing vascularization and disease activity. Quantitative assessment is mostly performed at the region of interest level, where the mean intensity curve is fitted with an exponential function. We showed that using a more physiologically motivated perfusion curve, and by estimating the kinetic parameters separately pixel by pixel, the quantitative information gathered is able to more effectively characterize the different perfusion patterns. In particular, we demonstrated that a random forest classifier based on pixelwise quantification of the kinetic contrast agent perfusion features can discriminate rheumatoid arthritis from different arthritis forms (psoriatic arthritis, spondyloarthritis, and arthritis in connective tissue disease) with an average accuracy of 97%. On the contrary, clinical evaluation (DAS28), semiquantitative CEUS assessment, serological markers, or region-based parameters do not allow such a high diagnostic accuracy.

Effects of mud-bath therapy in psoriatic arthritis patients treated with TNF inhibitors. Clinical evaluation and assessment of synovial inflammation by contrast-enhanced ultrasound (CEUS)

OBJECTIVES

Despite the efficacy of TNF inhibitors, most patients with psoriatic arthritis maintain a residual synovial inflammation. The main aim of the study was to evaluate the effects of mud-bath therapy on clinical picture of PsA patients treated with TNF inhibitors. The secondary outcome was to assess synovial inflammation in hand joints detected by contrast-enhanced ultrasound. Other aims were to verify the risk of arthritis flare and to evaluate the effects of spa treatment on functional ability and on quality of life.

METHODS

Thirty-six patients with psoriatic arthritis, treated in the last 6 months with TNF inhibitors, were enrolled. After 1:1 randomisation, 18 patients (group A) underwent mud-bath therapy (12 mudpacks and 12 thermal baths), maintaining treatment with TNF inhibitors; 18 patients (group B) continued pharmacological therapy alone. CRP, PASI, DAS28, swollen and tender joint count, VAS pain, HAQ and SF-36 were evaluated at baseline (T0) and after 45 days (T1). Synovial inflammation detected by contrast-enhanced ultrasound, analysed by a software system, was also assessed.

RESULTS

A significant improvement in PASI (P<0.005), DAS28 (P<0.05), swollen joint count and tender joint count (P<0.001), and HAQ (P<0.001) between T0 and T1 was observed in group A. No patient underwent a flare-up of arthritis. Ultrasound videos demonstrated a significant appearance delay (P<0.05) and faster washout (P<0.02) of contrast dye in group A patients with respect to group B.

CONCLUSIONS

These data suggest a decrease of residual synovial inflammation and a beneficial clinical effect of spa therapy in psoriatic arthritis patients treated with TNF inhibitors.

Time-intensity curve parameters in rectal cancer measured using endorectal ultrasonography with sterile coupling gels filling the rectum: correlations with tumor angiogenesis and clinicopathological features

The primary aim of this study was to investigate the relationship between contrast-enhanced ultrasonography (CEUS) imaging parameters and clinicopathological features of rectal carcinoma and assess their potential as new radiological prognostic predictors. A total of 66 rectal carcinoma patients were analyzed with the time-intensity curve of CEUS. The parameter arrival time (AT), time to peak enhancement (TTP), wash-in time (WIT), enhanced intensity (EI), and ascending slope (AS) were measured. Microvessel density (MVD) was evaluated by immunohistochemical staining of surgical specimens. All findings were analysed prospectively and correlated with tumor staging, histological grading, and MVD. The mean values of AT, TTP, WIT, EI, and AS value of the rectal carcinoma were 10.84 ± 3.28 s, 20.61 ± 5.52 s, 9.78 ± 2.83 s, 28.68 ± 4.67 dB, and 3.20 ± 1.10, respectively. A positive linear correlation was found between the EI and MVD in rectal carcinoma (r = 0.295, P = 0.016), and there was a significant difference for EI among histological grading (r = -0.264, P = 0.007). EI decreased as T stage increased with a trend of association noted (P = 0.096). EI of contrast enhanced endorectal ultrasonography provides noninvasive biomarker of tumor angiogenesis in rectal cancer. CEUS data have the potential to predict patient prognosis.

Multi-planar dynamic contrast-enhanced ultrasound assessment of blood flow in a rabbit model of testicular torsion

To assess correlation between multi-planar, dynamic contrast-enhanced ultrasound (US) blood flow measurements and radiolabeled microsphere blood flow measurements, five groups of six rabbits underwent unilateral testicular torsion of 0°, 180°, 360°, 540° or 720°. Five US measurements per testis (three transverse/two longitudinal) were obtained pre-operatively and immediately and 4 and 8 h post-operatively using linear transducers (7-4 MHz/center frequency 4.5 MHz/10 rabbits; 9-3 MHz/center frequency 5.5 MHz/20 rabbits). Björck's linear least-squares method fit the rise phase of mean pixel intensity over a 7-s period for each time curve. Slope of fit and intervention/control US pixel intensity ratios were calculated. Means of transverse, longitudinal and combined transverse/longitudinal US ratios as a function of torsion degree were compared with radiolabeled microsphere ratios using Pearson's correlation coefficient, ρ. There was high correlation between the two sets of ratios (ρ ≥ 0.88, p ≤ 0.05), except for the transverse US ratio in the immediate post-operative period (ρ = 0.79, p = 0.11). These results hold promise for future clinical applications.

3D imaging options and ultrasound contrast agents for the ultrasound assessment of pediatric rheumatic patients

The application of 3D imaging in pediatric rheumatology helps to make the assessment of inflammatory changes more objective and to estimate accurately their volume and the actual response to treatment in the course of follow-up examinations. Additional interesting opportunities are opened up by the vascularity analysis with the help of power Doppler and color Doppler in 3D imaging. Contrast-enhanced ultrasound examinations enable a more sensitive assessment of the vascularity of inflamed structures of the locomotor system, and a more accurate analysis of treatment's effect on changes in vascularity, and thereby the inflammation process activity, as compared to the classical options of power and color Doppler. The equipment required, time limitations, as well as the high price in the case of contrast-enhanced ultrasound, contribute to the fact that the 3D analysis of inflammatory changes and contrast-enhanced ultrasound examinations are not routinely applied for pediatric patients.

The evolution of ultrasound in rheumatology

Musculoskeletal ultrasound is a powerful tool not only for evaluating joint and related structures but also for assessing disease activity. Ultrasound in rheumatology has rapidly evolved and been incorporated into routine clinical practice over the past decade. Moreover, technological development of equipment has made it more accessible for rheumatologists. We present a review of advances in ultrasound in rheumatology, focusing on major chronological developments.

Application of a second-generation US contrast agent in infants and children--a European questionnaire-based survey

BACKGROUND

No US contrast agent (US-CA) is currently licensed for use in children.

OBJECTIVE

To survey the off-label use in children of a second-generation US-CA.

MATERIALS AND METHODS

Questionnaires were e-mailed to European paediatric radiologists, who were asked about their experience with the second-generation US-CA Sonovue® (Bracco, Milan, Italy). Number of examinations per indication and adverse effects were recorded. Examinations were categorised by intravenous or intracavitary use of US-CA.

RESULTS

Out of 146 respondents, 88 stated that they did not perform contrast-enhanced US in children, but 36 of these (44%) would appreciate paediatric approval. Forty-five centres reported 5,079 examinations in children (age mean: 2.9 years; range: birth-18 years, M/F: 1/ 2.8). The majority (4,131 [81%] in 29 centres) were intravesical applications. The minority (948 [19%] in 30 centres) were intravenous applications. No adverse effects had been recorded from intravesical use. Six minor adverse effects (skin reaction, unusual taste, hyperventilation) had been recorded after five intravenous studies (0.52%).

CONCLUSION

Responses suggest a favourable safety profile of this second-generation US-CA in children. It also demonstrates a demand for such US-CA from paediatric radiologists.

Diagnosis of early-stage rheumatoid arthritis: usefulness of unenhanced and gadolinium-enhanced MR images at 3 T

Forty-one consecutive unclassified arthritis patients with polyarthralgia including wrist joint were evaluated with 3-T MRI as possible early-stage rheumatoid arthritis (RA). After prospective follow-up, 21 of 41 patients fulfilled the American College of Rheumatology (ACR) criteria. Synovitis was detected in all 21 RA patients (sensitivity=100%) with postcontrast MRI and in 14 patients (67%) with unenhanced MRI when none of them fulfilled ACR diagnostic criteria. Fat-suppressed intermediate-weighted fast spin-echo (FSE) image showed high detection rate of synovitis and bone erosion, whereas FIESTA image clearly delineated joint fluid and bone trabeculae. MRI at 3 T is a potentially powerful tool for discriminating and managing early-stage RA patients.

Evaluation of finger joint synovial vascularity in patients with rheumatoid arthritis using contrast-enhanced ultrasound with water immersion and a stabilized probe

PURPOSE.: To assess synovial microvascularity in finger joints with rheumatoid arthritis (RA) by contrast-enhanced ultrasound (CEUS), distinguishing between cases of active disease and those in remission; to standardize the technique for software analysis. METHODS.: Fifty-two finger joints of RA patients (26 with active disease and 26 in remission) were immersed in water and examined by CEUS using a fixed probe. Signal intensity curves were calculated with the software. RESULTS.: Contrast enhancement was detectable in all 26 patients with active RA (100%), but not in 25 of 26 patients in remission (96%); one of the latter patients (4%) showed minimal enhancement. The method's sensitivity and specificity in distinguishing active disease from remission were 100% and 96%. The grades of synovial enhancement correlated with clinical disease activity and software flow parameters. The peak contrast levels correlated with clinical activity, a peak of 9% representing the cutoff between remission and active disease. CONCLUSIONS.: CEUS with a fixed probe on finger joints immersed in water detected synovial vascularization in RA, producing results suitable for standardized software analysis and avoiding artifacts.

Gray-scale contrast-enhanced ultrasonography for quantitative evaluation of the blood perfusion of the sciatic nerves with crush injury

RATIONALE AND OBJECTIVES

Blood perfusion of peripheral nerves plays an important role in regeneration after nerve injury. Functional recovery after a peripheral nerve injury depends not only on the survival of the affected neurons but also on the recovered blood perfusion. Previous studies have shown that it is possible to quantitatively assess blood perfusion of tissue using contrast-enhanced ultrasound (CEUS). The aim of this study was to evaluate the usefulness of CEUS for the quantitative evaluation of blood perfusion of the sciatic nerves with crush injury.

MATERIALS AND METHODS

Crush injuries were created in the left sciatic nerve of 30 New Zealand white rabbits. CEUS of the bilateral sciatic nerves was performed in six experimental rabbits at 3 days, 1 week, 2 weeks, 4 weeks, and 8 weeks after injury. Pulse-inversion harmonic imaging was used for real-time CEUS. The other six rabbits were used as a control group. Serial laser Doppler measurements of blood flow and quantitative histologic evaluation were performed parallel to CEUS on all animals.

RESULTS

Quantitative analysis of CEUS showed that the perfusion index of the crushed sciatic nerves was increased at 3 days after injury, with a peak at 1 week after injury (P = .000). The area under the curve for the crushed sites was increased at 3 days after injury, with a peak at 2 weeks after injury (P = .000). The mean transit time and maximum intensity of the crushed site of the left sciatic nerves were not significantly changed during the 2 months after injury (P = .335 and P = .157 respectively). The perfusion indices measured by CEUS correlated well with those measured by laser Doppler (r = 0.791, P = .000). Marked Wallerian degeneration was found at the crushed site of sciatic nerves at 3 days after injury. The percentage of degenerated myelinated axons was increased during the first 2 weeks after injury and then decreased during the following period. Regenerated axons with small diameter and thin myelin sheaths were found at 2 weeks after injury and during the following period.

CONCLUSIONS

CEUS may provide a new imaging method to quantitatively analyze blood perfusion of injured peripheral nerves.

The role of ultrasound in the diagnosis and follow-up of early inflammatory arthritis

The inflammatory arthritides are a group of chronic, often debilitating disorders characterized by synovial inflammation and progressive joint destruction. The primary diagnostic aim is to recognize the inflammatory arthritis at an early stage, such that therapies may be implemented before irreversible joint destruction has occurred. The radiologist now plays a pivotal role both in making an accurate and early diagnosis of inflammatory arthritis as well as assessing treatment response. This article reviews the current literature and presents our approach to the sonographic assessment of early inflammatory arthritis.

Contrast-enhanced, real-time volumetric ultrasound imaging of tissue perfusion: preliminary results in a rabbit model of testicular torsion

Contrast-enhanced ultrasound (US) imaging is potentially applicable to the clinical investigation of a wide variety of perfusion disorders. Quantitative analysis of perfusion is not widely performed, and is limited by the fact that data are acquired from a single tissue plane, a situation that is unlikely to accurately reflect global perfusion. Real-time perfusion information from a tissue volume in an experimental rabbit model of testicular torsion was obtained with a two-dimensional matrix phased array US transducer. Contrast-enhanced imaging was performed in 20 rabbits during intravenous infusion of the microbubble contrast agent Definity® before and after unilateral testicular torsion and contralateral orchiopexy. The degree of torsion was 0° in 4 (sham surgery), 180° in 4, 360° in 4, 540° in 4, and 720° in 4. An automated technique was developed to analyze the time history of US image intensity in experimental and control testes. Comparison of mean US intensity rate of change and of ratios between mean US intensity rate of change in experimental and control testes demonstrated good correlation with testicular perfusion and mean perfusion ratios obtained with radiolabeled microspheres, an accepted 'gold standard'. This method is of potential utility in the clinical evaluation of testicular and other organ perfusion.

Quantitative evaluation of the peripheral nerve blood perfusion with high frequency contrast-enhanced ultrasound

RATIONALE AND OBJECTIVES

The blood perfusion of peripheral nerves plays an important role in regeneration after nerve injury. Previous studies have shown that it is possible to quantitatively assess the blood perfusion of the tissue using contrast-enhanced ultrasound (CEUS). The aim of this study was to evaluate the feasibility of CEUS for quantitative assessment of the blood perfusion of the sciatic nerve in normal New Zealand white rabbits and to compare these parameters to those of surrounding skeletal muscle and the main artery in the thigh.

MATERIALS AND METHODS

CEUS of the bilateral sciatic nerves was performed in 12 normal New Zealand white rabbits after a bolus injection of SonoVue (0.13 mL/kg). Pulse-inversion harmonic imaging was used for real-time CEUS. The blood perfusion of the left sciatic nerve was compared to that of its surrounding muscle, the arterial branch in the thigh, and the contralateral side.

RESULTS

The supplying arteries in the sciatic nerve could be demonstrated during the early phase of CEUS, followed by the homogeneous enhancement of the whole nerve. The area under the curve and the perfusion index of the sciatic nerve were higher than those of the surrounding muscle and lower than those of the arterial branch in the thigh (both P values = .000). The maximum intensity of the sciatic nerve was similar to that of skeletal muscle and lower than that of the arterial branch. The time to peak was not significantly different among the sciatic nerve, skeletal muscle, and arterial branch (P = .551). There were no differences in area under the curve, mean transit time, perfusion index, maximum intensity, and time to peak between the left and right sciatic nerves (P > .05).

CONCLUSIONS

CEUS may be a feasible method for the quantitative assessment of blood perfusion of the peripheral nerves.

Ultrasound detects joint damage and bleeding in haemophilic arthropathy: a proposal of a score

Haemarthrosis triggers haemophilic arthropathy (HA) because bleeding starts synovitis immediately, damages cartilage and leads to loss of function and disability. The aim of our study was to investigate the capacity of ultrasonography (US) in detecting bleeding and joint damage in HA. The joints of 62 patients (pts) with haemophilia A or haemophilia B were consecutively evaluated and scored (score ranging from 0 to 21) for effusion (E), bone remodelling (BR), cartilage damage (CD), synovial hypertrophy (SH), haemosiderin (H), osteophytes (O), haemarthrosis (Hae), erosion (Er) and fibrotic septa (FS) with US. X-rays [Pettersson Score (PXS)] were performed in 61 patients and clinical evaluation [World Federation Haemophiliac orthopaedic score (WFHO)] was performed in all patients. A total of 20 healthy subjects and 20 patients affected by Rheumatoid Arthritis (RA) were used as controls. Power Doppler US (PDUS) was performed in all patients on the knee, ankle and elbow joints. A total of 83 joints were studied (50 knees; 12 elbows and 21 ankles). US showed effusion in 57 joint, bone remodelling in 62, cartilage damage in 64, synovial hypertrophy in 45, haemosiderin in 39, osteophytes in 30, haemarthrosis in 24, erosion in 5 and fibrotic septa in 3. The X-rays score showed remodelling in 47 joints, narrowing joint space in 44, displacement/angulation in 39, osteoporosis in 42, subchondral irregularity in 44, subchondral cyst formation in 37, osteophytes in 36 and erosions in 25. The US score in healthy subjects was always ≤ 5 (range 0 to 4). In haemophiliacs, 34 of 83 joints showed US score ≤ 5, and 49 US score > 5. Joints with US score ≤ 5 had a low PXS (SRCC = 0.375, P < 0.01) and joints with US score > 5 showed a high PXS (SRCC = 0.440, P < 0.01). A significant correlation between US score and PXS for bone remodelling [Spearman's rho Correlation Coefficient (SRCC) = 0.429, P < 0.01] and for osteophytes (SRCC = 0.308, P < 0.05) was found. The correlation between the US score and number of bleedings in 83 joints was very significant (SRCC = 0.375, P < 0.01). A total of 24 bleeding joints were identified and verified with aspiration of haematic fluid. US may detect bone and cartilage alterations and synovitis. Indeed, PDUS identified bleeding also in asymptomatic joints and was able to show different entity of haemarthrosis. US may be a feasible and reliable tool to evaluate joint modifications in HA.

Detection of vascularity in wrist tenosynovitis: power doppler ultrasound compared with contrast-enhanced grey-scale ultrasound

INTRODUCTION

We sought to assess vascularity in wrist tenosynovitis by using power Doppler ultrasound (PDUS) and to compare detection of intra- and peritendinous vascularity with that of contrast-enhanced grey-scale ultrasound (CEUS).

METHODS

Twenty-six tendons of 24 patients (nine men, 15 women; mean age ± SD, 54.4 ± 11.8 years) with a clinical diagnosis of tenosynovitis were examined with B-mode ultrasonography, PDUS, and CEUS by using a second-generation contrast agent, SonoVue (Bracco Diagnostics, Milan, Italy) and a low-mechanical-index ultrasound technique. Thickness of synovitis, extent of vascularized pannus, intensity of peritendinous vascularisation, and detection of intratendinous vessels was incorporated in a 3-score grading system (grade 0 to 2). Interobserver variability was calculated.

RESULTS

With CEUS, a significantly greater extent of vascularity could be detected than by using PDUS (P < 0.001). In terms of peri- and intratendinous vessels, CEUS was significantly more sensitive in the detection of vascularization compared with PDUS (P < 0.001). No significant correlation between synovial thickening and extent of vascularity could be found (P = 0.089 to 0.097). Interobserver reliability was calculated to be excellent when evaluating the grading score (κ = 0.811 to 1.00).

CONCLUSIONS

CEUS is a promising tool to detect tendon vascularity with higher sensitivity than PDUS by improved detection of intra- and peritendinous vascularity.

Developments in musculoskeletal ultrasound and clinical applications

OBJECTIVE

Ultrasound (US) technologies are rapidly advancing, offering several refined transducer technologies as well as soft and hardware facilities. The aim of this article is to outline US developments, from B-mode technologies over Doppler advances to more sophisticated technologies, and their potential clinical impact in the field of musculoskeletal (MSK) imaging.

NEW ADVANCES

When using B-mode ultrasound, compound imaging and beam-steering are of help to decrease anisotropy in tendons and ligaments, that are less well depicted due to their oblique course. Doppler imaging has become sensitive in the detection of flow in small vessels, which is of particular value in rheumatologic conditions, tumour and overuse assessment. The use of US microbubble contrast agents improves detection of low-volume blood flow in smaller vessels by increasing the signal-to-noise ratio and thereby facilitating detection of angiogenetic vessels in inflammatory conditions or tumours. The use of US blood pool contrast agents enables molecular imaging in real-time, and thus the diagnostic potential of US is expanded, opening up a new field of US applications. Objective quantification of altered tissue (e.g., synovial proliferation, tumours) is still demanding and might be improved by the use of three-dimensional imaging and software tools as parametric evaluation. Real-time sonoelastography (EUS) is a new development for visualization of tissue elasticity by measurement of tissue displacement in terms of tissue stiffness changes, promising new insights into tendon disorders. Image fusion is an exciting development that enables superimposition of CT/MRI data sets on real-time US scanning. This technique might be helpful in guiding injections under real-time conditions even in regions less easily accessible by US as, for instance, the axial skeleton, and can additionally provide an interesting tool for teaching MSK imaging and ways to guide interventions.

CONCLUSION

In summary, exciting developments are expanding the applications of US in the MSK field, offering the advantages of real-time performance, high tissue resolution and relative speed at a reasonable cost.