We reviewed all 717 manuscripts published in the 1997 issues of the British and American volumes of the Journal of Bone and Joint Surgery and in Clinical Orthopaedics and Related Research, from which 33 randomised, controlled trials were identified. The results and sample sizes were used to calculate the statistical power of the study to distinguish small (0.2 of standard deviation), medium (0.5 of standard deviation), and large (0.8 of standard deviation) effect sizes. Of the 33 manuscripts analysed, only three studies (9%) described calculations of sample size. To perform post-hoc power assessments and estimations of deficiencies of sample size, the standard effect sizes of Cohen (small, medium and large) were calculated. Of the 25 studies which reported negative results, none had adequate power (beta < 0.2) to detect a small effect size and 12 (48%) lacked the power necessary to detect a large effect size. Of the 25 studies which did not have an adequate size of sample to detect small differences, the average used was only 10% of the required number Our findings suggest that randomised, controlled trials in clinical orthopaedic research utilise sample sizes which are too small to ensure statistical significance for what may be clinically important results.

Ultrasonography (US) is often the first line of imaging for the examination of children suspected of having liver lesions. However, gray-scale US with color Doppler imaging has limitations. The use of US contrast agents has recently been approved by the U.S. Food and Drug Administration (FDA). Compared with other imaging modalities, contrast material-enhanced US (CEUS) enables the assessment of contrast enhancement patterns with a higher temporal resolution and is therefore becoming a valuable alternative imaging technique. CEUS is advantageous owing to its high safety profile; lower cost, compared with the costs of conventional contrast-enhanced computed tomographic and magnetic resonance imaging examinations; reliability; and reproducibility. Furthermore, US examinations obviate the use of sedation, ionizing radiation, and iodinated or gadolinium-based contrast agents. All of these are desirable attributes for an imaging examination for children, the most vulnerable of patients. Focal liver lesions in children are commonly discovered incidentally, and this can pose a dilemma in terms of diagnosis and management. Owing to the FDA's recent approval of the use of a specific US contrast agent for evaluation of focal liver lesions in pediatric patients, CEUS can now be used as a problem-solving tool that complements conventional imaging examinations and aids in the follow-up of lesions. The temporal resolution with CEUS enables US images to readily depict the real-time internal vascularity of a lesion. The characterization of a lesion during different phases of enhancement improves diagnostic confidence and treatment. In this article, the authors review the composition, physiologic properties, and safety profile of CEUS; describe the technique for performing CEUS; and highlight the utility of this examination in the assessment of common focal liver lesions in children. Online supplemental material is available for this article. RSNA, 2017.

Contrast-enhanced ultrasound (CEUS) is a radiation-free, safe, and in specific clinical settings, highly sensitive imaging modality. Over the recent decades, there is cumulating experience and a large volume of published safety and efficacy data on pediatric CEUS applications. Many of these applications have been directly translated from adults, while others are unique to the pediatric population. The most frequently reported intravenous abdominal applications of CEUS in children are the characterization of focal liver lesions, monitoring of solid abdominal tumor response to treatment, and the evaluation of intra-abdominal parenchymal injuries in selected cases of blunt abdominal trauma. The intravesical CEUS application, namely contrast-enhanced voiding urosonography (ceVUS), is a well-established, pediatric-specific imaging technique entailing the intravesical administration of ultrasound contrast agents for detection and grading of vesicoureteral reflux. In Europe, all pediatric CEUS applications remain off-label. In 2016, the United States Food and Drug Administration (FDA) approved the most commonly used worldwide second-generation ultrasound contrast SonoVue®/Lumason® for pediatric liver and intravesical applications, giving new impetus to pediatric CEUS worldwide.