Supersonic shear imaging (SSI) is an ultrasound imaging modality that can provide insight into tissue mechanics by measuring shear wave propagation speed, a property that depends on tissue elasticity. SSI has previously been used to characterize the increase in Achilles tendon shear wave speed that occurs with loading, an effect attributable to the strain-stiffening behavior of the tissue. However, little is known about how shear wave speed varies spatially, which is important, given the anatomical variation that occurs between the calcaneus insertion and the gastrocnemius musculotendon junction. The purpose of this study was to investigate spatial variations in shear wave speed along medial and lateral paths of the Achilles tendon for three different ankle postures: resting ankle angle (R, i.e. neutral), plantarflexed (P; R − 15 deg), and dorsiflexed (D; R + 15 deg). We observed significant spatial and posture variations in tendon shear wave speed in ten healthy young adults. Shear wave speeds in the Achilles free tendon averaged 12 ± 1.2 m/s in a resting position, but decreased to 7.2 ± 1.8 m/s with passive plantarflexion. Distal tendon shear wave speeds often reached the maximum tracking limit (16.3 m/s) of the system when the ankle was in the passively dorsiflexed posture (+15 deg from R). At a fixed posture, shear wave speeds decreased significantly from the free tendon to the gastrocnemius musculotendon junction, with slightly higher speeds measured on the medial side than on the lateral side. Shear wave speeds were only weakly correlated with the thickness and depth of the tendon, suggesting that the distal-to-proximal variations may reflect greater compliance in the aponeurosis relative to the free tendon. The results highlight the importance of considering both limb posture and transducer positioning when using SSI for biomechanical and clinical assessments of the Achilles tendon.

Any promising minimally invasive therapy such as PRP deserves further investigation to avoid surgery. Diagnostic imaging outcome assessments, including ultrasound-guided needle precision, should be included in future investigations.

Sonography has high accuracy in the evaluation of superficial masses, particularly lipomas.

Juvenile idiopathic arthritis (JIA) and osteoarticular infection can cause nonspecific articular and periarticular complaints in children. Although contrast material-enhanced magnetic resonance imaging is the reference standard imaging modality, musculoskeletal ultrasonography (US) is emerging as an important adjunct imaging modality that can provide valuable information relatively quickly without use of radiation or the need for sedation. However, diagnostic accuracy requires a systemic approach, familiarity with various US techniques, and an understanding of maturation-related changes. Specifically, the use of dynamic, Doppler, and/or multifocal US assessments can help confirm sites of disease, monitor therapy response, and guide interventions. In patients with JIA, ongoing synovial inflammation can lead to articular and periarticular changes, including synovitis, tenosynovitis, cartilage damage, bone changes, and enthesopathy. Although these findings can manifest in adult patients with rheumatoid arthritis, important differences and pitfalls exist because of the unique changes associated with an immature and maturing skeleton. In patients who are clinically suspected of having osteoarticular infection, the inability of US to evaluate the bone marrow decreases its sensitivity. Therefore, the US findings should be interpreted with caution because juxtacortical inflammation is suggestive, but neither sensitive nor specific, for underlying osteomyelitis. Similarly, the absence of a joint effusion makes septic arthritis extremely unlikely but not impossible. US findings of JIA and osteoarticular infection often overlap. Although certain clinical scenarios, laboratory findings, and imaging appearances can favor one diagnosis over the other, fluid analysis may still be required for definitive diagnosis and optimal treatment. US is the preferred modality for fluid aspiration and administering intra-articular corticosteroid therapy. RSNA, 2017.

Infection of the musculoskeletal system is a common clinical problem. Differentiating soft tissue from osseous infection often determines the appropriate clinical therapeutic course. Radiographs are the recommend initial imaging examination, and although often not diagnostic in acute osteomyelitis, can provide anatomic evaluation and alternative diagnoses influencing subsequent imaging selection and interpretation. MRI with contrast is the examination of choice for the evaluation of suspected osteomyelitis, and MRI, CT, and ultrasound can all be useful in the diagnosis of soft tissue infection. CT or a labeled leukocyte scan and sulfur colloid marrow scan combination are alternative options if MRI is contraindicated or extensive artifact from metal is present. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Chronic knee pain is a condition that is frequently encountered. Imaging often plays an important role in narrowing down the potential causes and determining the most effective next steps. The ACR Appropriateness Criteria for Chronic Knee Pain provides clinicians with the best practices for ordering imaging examinations. The following narrative and accompanying tables should serve as useful guides to any clinician.The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Study Design Single cohort descriptive and correlational study. Objectives To investigate the relationships between tendon pathology, biomechanical measures, and self-reported pain and function in individuals with chronic lateral epicondylosis. Background Lateral epicondylosis has a multi-factorial etiology and its pathophysiology is not well understood. Consequently, treatment remains challenging and those with lateral epicondylosis are prone to recurrence. While tendon pathology, pain system changes, and motor impairments due to lateral epicondylosis are considered related, their relationships have not been thoroughly investigated. Methods Twenty-six participants with either unilateral (n = 11) or bilateral (n=15) chronic lateral epicondylosis participated in this study. Biomechanical (grip strength, rate of force development, and electromechanical delay), tendon pathology (magnetic resonance imaging [MRI] and ultrasound), and self-reported pain and function (Patient-rated Tennis Elbow Evaluation [PRTEE]) measurements were made. Partial Spearman correlations, adjusting for covariates (age, gender, weight, and height), were used to evaluate the relationship between self-reported pain, function, and biomechanical and tendon pathology measures. Results Statistically significant correlations between biomechanical measures and PTREE measures ranged in magnitude from 0.44 to 0.68 (P<0.05), but no significant correlation was observed between tendon pathology (MRI and ultrasound) measures and PRTEE (r = −0.02 – 0.31, P>.05). Rate of force development had a stronger correlation (0.54 – 0.68, P<0.05) with self-reported function score than grip strength (r = 0.35 – 0.47, P<.05) or electromechanical delay (r = 0.5, P<.05). Conclusion Biomechanical measures (pain free grip strength, rate of force development, electromechanical delay) have the potential to be used as outcome measures to monitor progress in lateral epicondylosis. In comparison, the imaging measures (MRI and ultrasound) were useful for visualizing the pathophysiology of lateral epicondylosis. However, the severity of the pathophysiology was not related to pain and function, indicating that imaging measures may not provide the best clinical assessment.

Ultrasound-guided corticosteroid injection of the quadratus femoris muscle shows promise as an effective treatment of IFI syndrome. However, larger longitudinal studies are needed to help establish the role of ultrasound-guided injection in the workup and care of patients presenting with both MRI findings and clinical findings of IFI.