Extended field-of-view sonography in musculoskeletal disorders

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.

Spatiotemporal Registration of 3-D Multi-perspective Ultrasound Images of Abdominal Aortic Aneurysms

Methods for patient-specific abdominal aortic aneurysm (AAA) progression monitoring and rupture risk assessment are widely investigated. Three-dimensional ultrasound can visualize the AAA's complex geometry and displacement fields. However, ultrasound has a limited field of view and low frame rate (i.e., 3-8 Hz). This article describes an approach to enhance the temporal resolution and the field of view. First, the frame rate was increased for each data set by sequencing multiple blood pulse cycles into one cycle. The sequencing method uses the original frame rate and the estimated pulse wave rate obtained from AAA distension curves. Second, the temporal registration was applied to multi-perspective acquisitions of the same AAA. Third, the field of view was increased through spatial registration and fusion using an image feature-based phase-only correlation method and a wavelet transform, respectively. Temporal sequencing was fully correct in aortic phantoms and was successful in 51 of 62 AAA patients, yielding a factor 5 frame rate increase. Spatial registration of proximal and distal ultrasound acquisitions was successful in 32 of 37 different AAA patients, based on the comparison between the fused ultrasound and computed tomography segmentation (95th percentile Haussdorf distances and similarity indices of 4.2 ± 1.7 mm and 0.92 ± 0.02 mm, respectively). Furthermore, the field of view was enlarged by 9%-49%.

Pectoralis Cross-Sectional Area can be Accurately Measured using Panoramic Ultrasound: A Validity and Repeatability Study

The objective of the current study was to examine the validity and repeatability of panoramic ultrasound in evaluating the anatomical cross-sectional area (ACSA) of the pectoralis major. Specifically, we aimed to quantify the measurement errors generated during the image acquisition and analysis (repeatability), as well as when comparing with magnetic resonance imaging (MRI) (validity). Moreover, we aimed to analyze the influence of the operator's experience on these measurement errors. Both sides of the chest of 16 participants (n = 32) were included. Errors made by two operators (trained and novice) when measuring pectoralis major ACSA (50% of sternum-areola mammae distance) were examined. Acquisition errors included the comparison of two images acquired 5 min apart. Acquisition 1 was analyzed twice to quantify analysis errors. Thereafter, acquisition 1 was compared with MRI. Statistics include the standard error of measurement (SEM), expressed in absolute (cm²) and relative (%) terms as a coefficient of variation (CV), and the calculation of systematic bias. Errors made by the trained operator were lower than those made by the novice, especially during the image acquisition (SEM = 0.25 vs. 0.66 cm², CV = 1.06 vs. 2.98%) and when compared with MRI (SEM = 0.27 vs. 1.90 cm², CV = 1.13 vs. 8.16%). Furthermore, although both operators underestimated the ACSA, magnitude and variability [SD] of these errors were lower for the trained operator (bias = -0.19 [0.34] cm²) than for the novice (bias = -1.97 [2.59] cm²). Panoramic ultrasound is a valid and repeatable technique for measuring pectoralis major ACSA, especially when implemented by a trained operator.

Panoramic ultrasound requires a trained operator and specific evaluation sites to maximize its sensitivity: A comprehensive analysis of the measurement errors

This study aimed to examine the validity and repeatability of panoramic ultrasound to evaluate the anatomical cross-sectional area (ACSA) of quadriceps femoris muscles. Specifically, we aimed to quantify the errors generated during the image acquisition and analysis (repeatability), as well as when comparing with magnetic resonance imaging (MRI) (validity). Moreover, we analyzed the influence of the operator's experience, and the region of the thigh, on these errors. Both thighs of 16 subjects were included. The validity and repeatability study quantified the errors made by two operators (trained and novice) when measuring ACSA of vastus lateralis (VL), vastus medialis-intermedius (VMVI), and rectus femoris (RF), in six thigh regions (from 20% to 70%). Two ACSA images were acquired 5 min apart to examine acquisition errors, whereas acquisition #1 was analyzed twice to quantify analysis errors. Thereafter, ACSA of acquisition #1 was compared with that measured by MRI. Statistics included the standard error of measurement (SEM) expressed in absolute (cm²) and relative terms (%) as a coefficient of variation (CV). Measurement errors were lower for the trained operator than for the novice: Acquisition (SEM = 0.05-0.78 vs. 0.25-1.42 cm²), analysis (SEM = 0.13-1.93 vs. 0.30-3.05 cm²) and compared-with-MRI (SEM = 0.13-1.93 vs. 0.30-3.05 cm²). Regions with the lowest errors were those located at the middle of the thigh (40-50%), although slight between-muscle differences were found: VMVI (30-40%), VL (40-50%), RF (50-60%). The accurate implementation of panoramic ultrasound to measure ACSA of quadriceps femoris muscles requires a trained operator and specific evaluation sites.

Sonography of musculoskeletal infection in children

Musculoskeletal infection, especially in young children, often presents with non-specific clinical signs and symptoms necessitating early imaging to identify the source of infection. While MRI is the investigation of choice to demonstrate bone infection, it is expensive and often requires a general anaesthetic in the young child. Ultrasound can be a useful tool in the initial assessment due to its easy availability and portable equipment. It does not involve ionising radiation and is used to guide aspiration and drainage procedures. This review explains sonographic features of septic arthritis, osteomyelitis, pyomyositis and soft tissue infection in children and highlights advantages and limitations of sonography when assessing the child with suspected musculoskeletal infection.

Reliability and Validity of Ultrasonography for Measurement of Hamstring Muscle and Tendon Cross-Sectional Area

The purpose of this study was to determine the reliability and validity of ultrasonography for measurement of hamstring muscle and semitendinosus (ST) tendon cross-sectional area (CSA). On two consecutive days, muscle anatomical CSA (ACSA) and ST tendon CSA were measured at standardized positions (30%-80% of thigh length; half the distance from the distal muscle-tendon junction to the popliteal crease) on 12 legs using ultrasonography and compared with corresponding magnetic resonance imaging measures. Inter-day intraclass correlation coefficients were good-to-excellent (0.882-0.996) for all assessed muscle and tendon sites. The limits of agreement widths were narrowest (range: 17%-52%) when muscle ACSA was large but were wide at sites with relatively small ACSA (≤184%) and for ST tendon CSA (range: 72%). Results suggest ultrasound-based measures of individual hamstring muscle maximal ACSA are reliable and valid and ST tendon CSA measures are reliable but require comparison with cadaveric or intra-operative measurements to verify validity.

Scoliotic Imaging With a Novel Double-Sweep 2.5-Dimensional Extended Field-of-View Ultrasound

Extended field-of-view ultrasound (US EFOV) imaging is a technique used extensively in the clinical field to attain interpretable panorama of anatomy; 2.5-D US EFOV has recently been proposed for spine imaging. In the original 2.5-D US EFOV, it makes use of a six degrees-of-freedom positional sensor attached to the US probe to record the corresponding position of each B-scan. By combining the positional information and the B-scan images, the 2.5-D EFOV can reconstruct a panorama on a curved image plane when the scanning trajectory of the US probe is curved. In this paper, an improved method based on the Bezier interpolation is proposed to better reconstruct 2.5-D US EFOV imaging, producing the panoramas with smoother texture and higher quality. To make it more applicable for scoliosis patients, we designed a novel method called double-sweep 2.5-D EFOV to better image the spinal tissues and easily compute the Cobb angle. In vitro and in vivo experiments demonstrated that the 2.5-D EFOV images obtained by the proposed method can present anatomical structures of the scanning region accurately.

Ultrasound imaging in musculoskeletal injuries-What the Orthopaedic surgeon needs to know

Patients with musculoskeletal complaints have either been ignored or advised investigations far beyond their means or comfort. Focusing attention only on spine and head restricted the evaluation in cases of trauma and were followed up only if the injuries were life threatening. In the same vein, the extremities often got overlooked or at best were evaluated only by plain radiographs. Soft tissue injuries were therefore often missed and not only raised the morbidity in the patient but also dissatisfaction towards the treating physician. Recent exponential improvement in medical ultrasound technology has revolutionised the field of musculoskeletal imaging. Cutting-edge technology using state-of-the-art machines and high-frequency transducers have placed it in a stronger position as compared to in the past in many aspects of musculoskeletal imaging. Also, with better techniques and understanding of the modality, under given set of circumstances MSK ultrasound has far reaching results allowing for detailed evaluation of soft tissues including nerves, ligaments and tendons.

Ultrasonographic assessment of articular cartilage of the femoral condyle in patients with an increased Q-angle

Introduction

The patella is a sesamoid for the quadriceps, which increases its power during knee extension and thus transfers considerable forces. The etiology of patellofemoral pain is multifactorial. In the absence of injury, the commonly accepted hypothesis is associated with increased compression of articulating surfaces.

Aim

The aim of the study was to perform an ultrasound evaluation of the thickness of articular cartilage covering the medial and lateral femoral condyle in patients with an increased Q-angle.

Materials and methods

The study included 26 women aged between 35 and 45 years. A total of 13 patients with Q >15° were included in the study group, and 13 patients with Q ≤15° were included in the control group. A goniometer was used for Q-angle measurement. The thickness of articular cartilage covering the medial and lateral femoral condyle of the femoral bone was measured using a HONDA HS-2200 ultrasound with a linear HLS-584M transducer. The Shapiro–Wilk test was used for the assessment of data distribution normality; the distribution was normal. The differences in the measured parameters were assessed with the ANOVA test for independent samples. The Bonferroni test was used for a multiple comparison.

Results

The statistical analysis showed statistically significantly reduced thickness of articular cartilage on the lateral femoral condyle (p = 0.00) in the Q >15° group. No statistically significant differences were demonstrated for the thickness of articular cartilage on the medial femoral condyle (p = 0.47).

Conclusions

The thickness of the articular cartilage on the lateral femoral condyle is lower than that of the medial femoral condyle in women aged between 35 and 45 years with the Q-angle >15°.

Ultrasonographic Imaging and Anti-inflammatory Therapy of Muscle and Tendon Injuries Using Polymer Nanoparticles

Ultrasonography is a reliable diagnostic modality for muscle and tendon injuries, but it has been challenging to find right diagnosis of minor musculoskeletal injuries by conventional ultrasonographic imaging. A large amount of hydrogen peroxide (H2O2) are known to be generated during tissue damages such as mechanical injury and therefore H2O2 holds great potential as a diagnostic and therapeutic marker for mechanical injuries in the musculoskeletal system. We previously developed poly(vanillyl alcohol-co-oxalate) (PVAX), which rapidly scavenges H2O2 and exerts antioxidant and anti-inflammatory activity in H2O2-associated diseases. Based on the notion that PVAX nanoparticles generate CO2 bubbles through H2O2-triggered hydrolysis, we postulated that PVAX nanoparticles could serve as ultrasonographic contrast agents and therapeutic agents for musculoskeletal injuries associated with overproduction of H2O2. In the agarose gel phantom study, PVAX nanoparticles continuously generated CO2 bubbles to enhance ultrasonographic echogenicity significantly. Contusion injury significantly elevated the level of H2O2 in skeletal muscles and Achilles tendons. Upon intramuscular injection, PVAX nanoparticles significantly elevated the ultrasound contrast and suppressed inflammation and apoptosis in the contusion injury of musculoskeletal systems. We anticipate that PVAX nanoparticles hold great translational potential as theranostic agents for musculoskeletal injuries.

Muscle injuries: ultrasound evaluation in the acute phase

Muscle injuries can be classified as extrinsic or intrinsic injuries as well as contusions and lacerations, and clinical assessment is composed of the history and physical examination. Diagnostic imaging, particularly ultrasound (US) examination, is essential to a correct assessment of the severity of the injury and to exclude important complications as these two elements influence treatment decisions, prognosis and time to return to unrestricted physical activity. This paper presents the main clinical and US features of acute muscle injuries.

Ultrasound measurements of the masseter muscle as predictors of cephalometric indices in orthodontics: a pilot study

This study investigated the potential of ultrasound measurements of the masseter muscle to accurately predict indices normally derived from cephalograms. Masseter muscle measurements on 11 adults (22 to 30 y) were made using lateral cephalometrics and extended field-of-view ultrasound. The ultrasound technique was validated in a simulation pilot study using 12 dry skulls and raw chicken breasts. Twenty cephalometric variables were analyzed against four ultrasound measurements of the masseter muscle. Highly significant correlations (r = 0.81-0.85, p = 0.001-0.002) between ultrasound measurements of the masseter muscle and cephalometric measurements representing the length of the superficial masseter muscle, the length and shape of the mandible and vertical facial proportions were demonstrated. Predictive equations from regression analyses were constructed to deduce ramus length and shape from the ultrasound measurements. The results provide pilot data suggesting that ultrasound is a potential clinical tool for sequential evaluation of masseter muscle length in orthodontics and facial muscle growth studies.

Extended Field-of-View Sonography: Evaluation of the Superficial Lesions

Objective

To evaluate the usefulness of extended-field-of-view 2-dimensional ultrasonography technique in superficial lesions.

Methods

During a 6-month period, 44 patients with superficial lesions on various parts of their bodies were evaluated with extended-field-of-view ultrasonography in addition to routine traditional 2-dimensional ultrasonography. If the diagnosis could not be made without the extended-field-of-view images, it was considered diagnostic. The radiologist decided if the extended-field-of-view ultrasonography helped spatial orientation, communicate findings, or compare the contralateral side in a single image, or if it was useful for follow-up evaluation.

Results

By using extended-field-of-view imaging including the surrounding anatomy, 22 musculoskeletal, 8 scrotal, 8 thyroid, 2 breast, and 4 abdominal wall lesions were documented successfully as a single image. Nevertheless, no new cases were diagnosed solely based on the extended-field-of-view images. Extended-field-of-view ultrasonography was considered helpful for spatial orientation in 25 cases (56.8%), for comparing the contralateral side in 16 cases (36.3%), and for communicating findings in 20 cases (45.4%). It was useful for follow-up evaluation in 13 cases (29.5%).

Conclusions

None of the extended-field-of-view images was diagnostic. However, they did provide valuable additional information and better documentation of the lesions.

New technologies applied to ultrasound diagnosis of sports injuries

INTRODUCTION

The aim of this study was to compare the ultrasound images of different soft tissue lesions from two different portable sonography devices: a conventional portable sonography device (ultrasound [US]-A, Micromaxx model; Sonosite Inc., Bothell, WA, USA), and a recently marketed compact device (US-B, Logiq e; General Electric Healthcare, Wauwatosa, WI, USA). The US-B device uses the new technologies of tissue harmonic imaging, real-time compound ultrasound, panoramic view, three-dimensional imaging, and virtual convex imaging.

METHODS

We compared ultrasound images of six different types of soft tissue lesions (muscle contusion, muscle strain, patellar tendinosis, calcifying patellar tendinosis, rupture of the lateral internal ligament of the knee, and deep infrapatellar synovial bursa), from six different subjects. Analysis of images was performed by the same ultrasound specialist. In accordance with the classical criteria for ultrasound studies, the following quantitative indicators and parameters of ultrasound quality were used to evaluate the images: degree of echogenicity, size of the lesion area, aspect, shape, borders, and overall visualization.

RESULTS

In muscle lesions due to contusion, not only is the edematous area better visualized with the new system, but definition of hemorrhagic area borders and their content is especially increased. In lesions of the tendons, the new system affords better definition of the borders of the hypoechogenic area of tendinous degeneration and perfect visualization of the extension of the damaged area using a panoramic study. Sonographic study of ligaments with chronic lesions permits visualization of scar areas. Finally, use of the new system with a small synovial bursa shows the content of the bursa and thickness of the walls more clearly.

CONCLUSION

Overall, the quantitative indicators and parameters of image quality performed in this study of common sports lesions demonstrate the improvement in visualization of damaged soft tissues with the new technologies now incorporated into portable sonography devices.

Contrast enhanced ultrasound with second generation contrast agent for the follow-up of lower-extremity muscle-strain-repairing processes in professional athletes

PURPOSE

In literature, ultrasonographic potentials in traumatic muscle lesions have been codified, whereas the data about this method utility in follow-up are dissonant. The purpose of this work is to evaluate a second-generation ultrasound (US) contrast agent rule for the professional athletes' distractive lesions.

MATERIALS AND METHODS

Twenty professional athletes (18 men and two women, aged between 18 and 34 years) affected by different muscle lesions were examined. All the patients were evaluated within 48 h of the trauma by US device Esaote Technos MPX with a high-frequency linear probe. The examinations were carried out with and without contrast agent after 20, 40 and 60 days after the trauma; second-generation contrast agent was used (SonoVue).

RESULTS

In all athletes (nine first-grade lesions, 11 second-grade lesions), by using contrast agent intravenous injection done after 20 days, the appearance of contrast spots affecting part or all the lesioned area were observed. During the follow-up, after 40 days. the contrast spots widened to include the entire scar area, with haemorrhagic residual in three cases. After 60 days, in no case was a liquid haemorrhagic collection still present, and we found an important reduction of extension of vascular spots and US intensity and their total disappearance in seven cases.

CONCLUSIONS

US with a second-generation contrast agent, thanks to the neoangiogenesis identification, allows recognition, individuation and monitoring the repair processes in the muscle lesion and allows estimation of when athletes can return to competitive activity. This fact obviously reduces both relapses and complications.

Ultrasonography of the lower extremity

Ultrasonography is a useful imaging tool for various soft tissue and joint pathologies affecting the lower extremity. This article reviews the normal sonographic appearance of muscles, tendons, ligaments, nerves, bone, and cartilage. The ultrasound imaging appearance of various pathologic conditions affecting the hip, thigh, knee, lower leg, ankle,and foot are illustrated. The advantages of ultrasonography are highlighted.

The Complementary Roles of MR Imaging and Ultrasound of Tendons

The choice to use MR imaging or ultrasound to depict tendon pathology has traditionally depended on the imager's level of experience and comfort with the modality, and less so the individual strengths of either modality. Although this may be an acceptable rationale, it does not fully take advantage of the strength of either modality or the potential benefits of combining both modalities. This article demonstrates the complementary roles of these two modalities through a variety of clinical examples, based on experience working in a subspecialty hospital dedicated to orthopedic and rheumatologic diseases.

Imaging of the Achilles tendon

The Achilles tendon is the most commonly injured tendon in the foot and ankle; injuries commonly are related to sports/athletic activities. Imaging modalities that are used most commonly in the diagnostic assessment of the Achilles tendon include conventional radiography, ultrasonography, and MRI. This article reviews the normal and pathologic imaging features of the Achilles tendon, and highlights the potential usefulness and limitations of various imaging techniques in the noninvasive assessment of the tendon and the potential impact of imaging findings on clinical patient care.

Ultrasound of the elbow

The elbow is an important synovial hinge joint of the upper extremity. This joint represents a common site of musculoskeletal symptomatology, affecting all age groups. The advantages of ultrasound imaging of the elbow include easy availability, multiplanar capability and the ability to assess structures dynamically. Patient symptomatology and site of maximal tenderness can be directly correlated with imaging findings. Comparison is easily made with the contralateral side. Particular strengths include the ability to assess para-articular structures, such as regional tendons and ligaments, in addition to assessment of joint effusions, loose bodies and regional bursae. With operator experience and excellent technique, ultrasound is a valuable imaging tool for assessment of disorders of the elbow joint.

Original report. Sonographic evaluation of shoulder arthroplasty

OBJECTIVE

The objective of our study was to review our experience using sonography to evaluate the rotator cuff after arthroplasty. Diagnostic reliability, with respect to surgical findings, as well as subjective assessment of the examinations, including the usefulness of applications such as extended field-of-view imaging, photopic imaging, and tissue harmonic imaging, were reviewed.

CONCLUSION

We found sonography to be a useful method of imaging the rotator cuff after arthroplasty. Extended field-of-view imaging and tissue harmonic imaging aided in diagnosis by improving visualization of regional anatomic landmarks and increasing conspicuity of small tendon tears.

The value of ultrasound in sports medicine

Musculoskeletal ultrasound is increasingly being used in the evaluation and treatment of sports-related injuries. This technique is widely available, rapid, and has a high patient acceptance. Its multiplanar capability and dynamic real-time imaging can be correlated with clinical symptoms and compared to contralateral asymptomatic structures.

Advances in ultrasound

Ultrasound (US) has undergone dramatic changes since its inception three decades ago; the original cumbersome B-mode gantry system has evolved into a high resolution real-time imaging system. This review describes both recent advances in ultrasound and contrast media and likely future developments. Technological advances in electronics and computing have revolutionized ultrasound practice with ever expanding applications. Developments in transducer materials and array designs have resulted in greater bandwidths with improvements in spatial and contrast resolution. Developments in digital signal processing have produced innovations in beam forming, image display and archiving. Technological advances have resulted in novel imaging modes which exploit the non-linear behaviour of tissue and microbubble contrast agents. Microbubble contrast agents have dramatically extended the clinical and research applications of ultrasound. Not only can Doppler studies be enhanced but also novel non-linear modes allow vessels down to the level of the microcirculation to be imaged. Functional and quantitative studies allow interrogation of a wide spectrum of tissue beds. The advent of tissue-specific agents promises to improve the sensitivity and specificity of ultrasound in the detection and characterization of focal liver lesions to rival that of computed tomography (CT) and magnetic resonance imaging (MRI). Ultrasound has recently moved into therapeutic applications with high intensity focused ultrasound (HIFU) and microbubble assisted delivery of drugs and genes showing great promise.

Ultrasound in pediatric musculoskeletal disease: techniques and applications

The increased ratio of nonossified cartilage to bone in children makes ultrasound (US) a particularly suitable technique for evaluating pediatric musculoskeletal disorders. US allows the examiner to compare quickly and meticulously an affected to unaffected area of interest in different orthogonal planes without a need for sedation. Developmental dysplasia of the hip is the most common indication for pediatric musculoskeletal US. Sonography is also a cost-effective, useful, and complementary imaging tool for evaluating pediatric musculoskeletal trauma, inflammation-infection, and masses.

Current concepts in imaging of tendinopathy

With the rising popularity of recreational sports, radiologists are being asked to image tendons with increasing frequency. Recognition of the critical link tendons provide between muscle and bone has also led to a better understanding of the processes leading to tendon damage. While plain radiography and CT have only a limited role to play in the diagnosis of tendon abnormality, the improvements in ultrasound and MRI technology mean that tendons can now be demonstrated in exquisite detail and previously undetectable abnormalities are readily demonstrated. This article reviews the structure and pathological processes affecting tendons and discusses the role of imaging in their assessment with an emphasis on ultrasound and MRI.

Real-time spatial compound imaging: application to breast, vascular, and musculoskeletal ultrasound

Real-time spatial compound imaging (SonoCT) is an ultrasound technique that uses electronic beam steering of a transducer array to rapidly acquire several (three to nine) overlapping scans of an object from different view angles. These single-angle scans are averaged to form a multiangle compound image that is updated in real time with each subsequent scan. Compound imaging shows improved image quality compared with conventional ultrasound, primarily because of reduction of speckle, clutter, and other acoustic artifacts. Early clinical experience suggests that real-time spatial compound imaging can provide improved contrast resolution and tissue differentiation that is beneficial for imaging the breast, peripheral blood vessels, and musculoskeletal injuries. Future development of real-time spatial compound imaging will help address the bulk of general imaging applications by extending this technology to curved array transducers, tissue harmonics, panoramic imaging, and three-dimensional sonography.

Extended field-of-view ultrasound

When ultrasound became a clinical reality in the 1970s, extended field of view was the only form of imaging available because all ultrasound images were created with articulated arm scanners that encompassed the area of interest in its entirety. With the advent of high-quality real-time imaging in the 1980s, the extended field of view was lost, and with it went an important diagnostic component as well as an important means of communicating diagnostic findings to referring clinicians. Through the magic of computer technology, extended field of view imaging is back! Extended field of view images can now be created very easily and conveniently, in real time. The convenience and accuracy of real-time imaging is maintained while important anatomical perspectives are added. This article reviews the status of real-time extended field of view sonography. The technical details as well as the clinical relevance of this method are summarized. The day-to-day clinical utility of extended field of view imaging is liberally illustrated.

Ultrasound of the adult hip

The adult hip is a new and challenging site for evaluation with ultrasound (US). Clinically, diseases involving the hip region may be difficult to diagnose without the help of imaging. The hip region is a crossroad for numerous vascular, nervous, and muscular structures that pass between the trunk and the lower extremity. Thus, inflammatory processes and neoplasms may spread to and from the hip, buttock, thigh, pelvis, and retroperitoneum, and trauma may also effect the adjacent areas of the trunk and thigh. Because it is a crossroad, many conditions that are not specific to the hip occur in this area, including inguinal lymphadenopathy, pathology from the abdomen or the genitalia (intestinal hernia, inflammation, and infection), and even referred pain from spinal disorders. The goals of US imaging are the detection and localization of these pathological processes, the differentiation of intra-articular andextra-articular pathology, and the performance of diagnostic and therapeutic interventional procedures. This article reviews the hip anatomy, followed up by a discussion of the US evaluation and differential diagnosis of common pathology occurring in the hip area. This includes joint effusion, arthritis, loose bodies, bursitis, pseudoaneurysm, muscle and tendon diseases, as well as tumor and tumor-like lesions such as hematoma, abscess, and lymphadenopathy.

Foot and ankle sonography

Sonography of the foot and ankle offers many advantages. Currently, sonographic evaluation rivals or exceeds MR imaging for evaluation of tendons, joint and bursal pathology, and specific soft tissue pathology. The advantages of sonographic evaluation provide a strong impetus for applying this modality to imaging of foot and ankle pathology. Those who accept the challenge will have an expanded repertoire to offer in the pursuit of efficient and effective patient care.

Future and new developments in musculoskeletal ultrasound

Improvements in high-resolution gray-scale imaging and clinical expertise performing musculoskeletal ultrasound will undoubtedly continue. Development of digital beam formers, two-dimensional arrays along with exploitation of nonlinear techniques to achieve higher resolution and use of ultrasound contrast to improve flow sensitivity will all contribute to the utility of ultrasound in the musculoskeletal system. It behooves the radiologic community to become familiar with these techniques, not only for economic reasons, but also because of the rich complement of future applications of this modality. The few potential applications mentioned here may only scratch the surface of what is possible. In addition to improved images of tissue morphology, ultrasound may play a role in functional and quantitative assessment of soft tissues. It may likewise play a role in the evaluation of prosthetic implants, bone mineralization, and cartilage integrity. Thus, the role of this modality in future musculoskeletal applications may significantly impact clinical diagnosis and therapy.