Ultrasound in pediatric musculoskeletal disease: techniques and applications

Musculoskeletal imaging in neonates: use of ultrasound

High-resolution US is a practical, cost-effective modality to evaluate the musculoskeletal system in neonates. US can be performed portably in the neonatal intensive care unit so that the critically ill infant can be evaluated with minimal distress. Sonography is noninvasive and does not require sedation; typical questions that might require the use of MRI or CT in older children can be rapidly resolved with US. Dynamic imaging can be used in real time to stress joints and see how articular structures relate. Given the advantages of US within the neonatal population, it has been widely used to evaluate for neonatal fractures, congenital joint abnormalities, limb deficiencies as well as muscular and soft-tissue abnormalities.

Musculoskeletal ultrasound in children: Current state and future directions

Juvenile idiopathic arthritis (JIA) is a heterogeneous group of chronic inflammatory arthritides that if inadequately treated, may be associated with chronic disability and deformity. Early diagnosis and treatment initiation is essential in the management of patients with JIA. Conventional means of evaluation of disease presence, disease activity and response to therapy including physical exam, labs and x-rays are at times limited and may be insufficient in making an accurate assessment. Musculoskeletal ultrasound (MSUS) is a well-established modality that is patient and family-friendly, non-invasive, does not require sedation and can be performed at the bedside in real-time. MSUS offers information that cannot be attained by standard outcome measures, and may help to advance both diagnosis and treatment of patients with JIA ultimately improving patient outcomes. This review explores the background of MSUS and the current evidence to support its potential role as a diagnostic, disease activity monitoring and interventional tool.

Toward Standardized Musculoskeletal Ultrasound in Pediatric Rheumatology: Normal Age-Related Ultrasound Findings

OBJECTIVE

The Outcome Measures in Rheumatology Ultrasound Task Force has recently started to work on the validation and standardization of musculoskeletal ultrasound (MSUS) examination in children in order to improve its applicability to joint examination.

METHODS

This was a prospective multicenter study performed by 4 experts in pediatric MSUS, who independently collected representative images using predefined scanning procedures of 4 joints (knee, ankle, wrist, and second metacarpophalangeal joint) in different predefined age groups. Researchers were allowed to use their own settings (B-mode and Doppler) in order to get the best quality image and highest sensitivity for low blood flow. Images were evaluated for quality parameters and an atlas was created with the best images. An equipment comparative study was performed by a single examiner using 2 different types of machines.

RESULTS

Sixty-four healthy children were scanned. The quality of evaluated images, obtained by predefined scanning positions, was highly comparable among the examiners. The B-mode images clearly showed age-related variations of joint findings, while Doppler images showed the presence of blood flow, particularly within the epiphyseal cartilage of the children at a younger age. There was a high to good level of consistency between images obtained from the 2 different ultrasound machines.

CONCLUSION

The study shows a systematic method for ultrasound examination of children at different age groups. Additionally, a baseline collection of images was developed, showing blood vessels in the joints examined. The present study could provide a framework for ongoing MSUS studies as well as for clinical practice in pediatric rheumatology.

Measuring myofiber orientations from high-frequency ultrasound images using multiscale decompositions

High-frequency ultrasound (HFU) has the ability to image both skeletal and cardiac muscles. The quantitative assessment of these myofiber orientations has a number of applications in both research and clinical examinations; however, difficulties arise due to the severe speckle noise contained in the HFU images. Thus, for the purpose of automatically measuring myofiber orientations from two-dimensional HFU images, we propose a two-step multiscale image decomposition method. It combines a nonlinear anisotropic diffusion filter and a coherence enhancing diffusion filter to extract myofibers. This method has been verified by ultrasound data from simulated phantoms, excised fiber phantoms, specimens of porcine hearts, and human skeletal muscles in vivo. The quantitative evaluations of both phantoms indicated that the myofiber measurements of our proposed method were more accurate than other methods. The myofiber orientations extracted from different layers of the porcine hearts matched the prediction of an established cardiac mode and demonstrated the feasibility of extracting cardiac myofiber orientations from HFU images ex vivo. Moreover, HFU also demonstrated the ability to measure myofiber orientations in vivo.

[Acute limping in children between 1 and 4 years old]

Recent limping in children aged between 1 and 4 years old are often a diagnostic problem because the young child may not be able to show the area of pain. Dominated by the traumatic causes like hairline fracture, the physician should eliminate the most severe, including infectious etiologies that require urgent treatment. The clinical examination is fundamental and simple complementary investigations like standard X-rays and biology (blood count cell, C reactive protein) looking for increased inflammatory parameters will help to find the cause in the majority of cases. The persistence of a limp beyond a week involves the realization of bone scan or MRI imaging.

Musculoskeletal ultrasonography of the lower extremities in infants and children

Ultrasonography is a powerful diagnostic imaging tool for evaluating lower extremity anatomy and pathology in children. Indications for pediatric musculoskeletal lower extremity sonography include developmental dysplasia of the hip, hip joint sonography for the child with a painful hip, evaluation and characterization of superficial soft-tissue masses, evaluation for deep venous thrombosis, and foreign body localization, characterization and removal. This review highlights these established indications, but primarily focuses on additional US applications for evaluation of the lower extremities, including diagnosis and characterization of arthritis and monitoring of therapy, evaluation of tendon tears and muscle strain injuries, characterization of soft-tissue masses and evaluation of certain congenital abnormalities of the lower extremities. Techniques for optimal utilization of musculoskeletal US in children are also discussed.

[The chronically limping child]

Chronic limping in children usually indicates the presence of an underlying organic lesion. Clinical evaluation establishes the site and type of limping. It may suggest a neurological or mechanical lesion or locoregional etiology at the level of the hip or pelvis. Plain radiographs and ultrasound are firstline imaging techniques. The diagnosis may be delayed either due to ignorance of age-specific entities or false positive or negative results on plain films and ultrasound. MRI now plays a major role for diagnosis. Multiple potential underlying etiologies including trauma, infections, arthritides or tumors are best evaluated with MRI. The MRI examination should not be limited only to the hip joint.

Role of power Doppler sonography in early diagnosis of osteomyelitis in children

We describe 2 children complaining of leg pain associated with elevated C-reactive protein levels in whom power Doppler (PD) sonography suggested the diagnosis of early osteomyelitis. PD sonography detected increased blood flow that resulted in a high-intensity signal area adjacent to the symptomatic tibia surface. Antibiotic therapy led to prompt improvement. These cases suggest that PD sonography is useful in the evaluation of possible early osteomyelitis in children.

Gray-scale and Doppler characteristics of fibrous cortical defects in a child

We report the case of a 9.5-year-old boy who underwent sonographic and radiographic examinations because of knee pain. Two fibrous cortical defects were discovered, in his right femur and left tibia; the femoral lesion was seen more easily on sonography than on radiography. On gray-scale sonography, the lesions were characterized as a scalloped indentation of the cortical surface containing hypoechoic soft tissue. On color Doppler sonography, discrete vessels were found at the periphery and within the substance of the lesions, and on spectral Doppler analysis, low-resistance arterial flow was detected in those vessels. Follow-up examinations performed 10 and 19 months after our initial examination showed signs that the lesions were healing. The diagnosis of fibrous cortical defect was suggested by the gray-scale and Doppler sonographic characteristics and confirmed on radiography. Although radiography is required to document these lesions if found incidentally on sonography, follow-up examinations using only sonography may be feasible.