The primary causes of scrotal trauma are blunt, penetrating, degloving, and electrical burn injuries to scrotal contents. Knowledge of the scrotal anatomy and appropriate imaging techniques are key for accurate evaluation of scrotal injuries. Ultrasonography (US) is the first-line imaging modality to help guide therapy for scrotal trauma, except in degloving injury, which results in scrotal skin avulsion. Blunt injury (eg, from an athletic accident or motor vehicle collision) is the most common cause of scrotal trauma, followed by penetrating injury from gunshot or other assault. Trauma often may result in hematoma, hydrocele, hematocele, testicular fracture, or testicular rupture. The timely diagnosis of rupture, based on a US finding of discontinuity of the echogenic tunica albuginea, is critical because emergent surgery results in salvage of the testis in 80%-90% of rupture cases. The radiologist should be familiar also with other nuances associated with penetrating trauma, iatrogenic and postoperative complications, and electrical injury. Color flow and duplex Doppler imaging are highly useful techniques not only for assessing testicular viability and perfusion but also for evaluating associated vascular injuries such as pseudoaneurysms. A thorough familiarity with the US findings of scrotal trauma helps facilitate appropriate management. Supplemental material available at radiographics.rsnajnls.org/cgi/content/full/27/2/357/DC1.

Incidental discovery of renal lesions on cross-sectional imaging studies performed for other indications is not uncommon. With the increased reliance on medical imaging, the number of incidentally detected renal lesions has also grown over time. While simple cysts account for the majority of these lesions, the presence of complex features within a cystic lesion, such as septations and solid components, can present a confusing picture. Solid lesions, too, can be indeterminate, and distinguishing between benign solid masses (like lipid-poor angiomyolipomas and oncocytomas) and renal cell carcinoma affects patient management and can prevent unnecessary interventions. Indeterminate renal lesions are traditionally further characterized by multiphase imaging, such as contrast-enhanced computed tomography and magnetic resonance imaging. Contrast-enhanced ultrasound (CEUS) is a new, relatively inexpensive technique that has become increasingly employed in the diagnostic workup of indeterminate renal lesions. With its lack of nephrotoxicity, the absence of ionizing radiation, and the ability to evaluate the enhancement pattern of renal lesions quickly and in real-time, CEUS has unique advantages over traditional imaging modalities. This article provides an overview of the current clinical applications of CEUS in characterizing renal lesions, both cystic and solid. Additional applications of CEUS in the kidney, including its roles in renal transplant evaluation and guidance for percutaneous biopsy, will also be briefly discussed.

Hepatic and renal lesions detected during ultrasound examinations frequently require subsequent contrast-enhanced computed tomography (CT) or magnetic resonance imaging (MRI) for characterization, delaying time to imaging diagnosis and increasing overall health care expenditures. Contrast-enhanced ultrasonography (CEUS) is a comparatively low-cost diagnostic tool that is underutilized in the evaluation of such indeterminate or suspicious hepatic and renal lesions. A retrospective chart review of CEUS examinations performed in our department demonstrated significantly shorter time to imaging diagnosis with CEUS compared to CT or MRI, largely due to the ability to perform the CEUS examination at the time of initial examination. For example mean time to completion for outpatient examinations was 5.2, 52.3, and 123.5 days for CEUS, CT, and MRI, respectively. The majority (78.4%) of CEUS examinations were completed the same day as the initial examination. Additionally, 66.7% of CEUS examinations were deemed diagnostic, abrogating further workup with CT or MRI in most cases. Annual imaging cost reduction of up to US $117,000 is anticipated in our institution based on projected reductions in follow-up CT and MRI examinations. These results indicate when CEUS was used as a first step to characterize both incidental lesions in patients without known risk factors for malignancy as well as suspicious lesions in patients with risk factors it can greatly reduce time to diagnosis and health care expenditures.

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