Background Contrast imaging, in general, involves the use of an agent to enhance the contrast of structures or fluids in the human body. A variety of contrast agents have been employed in medical imaging over many decades, beginning with the use of air and barium in the early days and evolving into the complex pharmacologic agents currently in use in computed tomography (CT), magnetic resonance, positron emission tomography, and nuclear medicine imaging modalities. Through various physical interactions between the agent and the energy used by the modality creating the image, dissimilarities in tissue types and boundaries are accentuated, which permits better differentiation between them. Ultrasound Contrast Agents Ultrasound contrast agents (UCAs) consist of gaseous microbubbles suspended in an aqueous solution that is injected into the human venous vascular system. They are composed of an inert inner gas bubble surrounded by a stabilizing outer shell (Figure 1). Different UCA manufacturers use various gas/shell combinations. As the microbubbles are "blood pool" agents, they remain intravascular at all times and do not permeate into adjacent tissues. As such, they act effectively as red blood cell tracers. The great acoustic mismatch between gas and surrounding blood results in dramatic and predictable physical responses when the microbubbles are exposed to an acoustic energy field. Reflection, backscatter and nonlinear harmonic responses create a returning acoustic data set that can be processed in ways that permit the 715221J DMXXX10.

Ovarian torsion is the complete or partial rotation of the ovary upon its vascular pedicle with subsequent vascular compromise; it is one of a few gynecologic surgical emergencies requiring prompt diagnosis and treatment. The commonly accepted diagnostic sonographic finding in ovarian torsion is the absence of ovarian parenchymal blood flow using color or power Doppler imaging. However, since not all cases of ovarian torsion cause complete vascular obstruction, the presence of ovarian blood flow cannot eliminate this diagnosis in symptomatic patients with other positive sonographic findings. The case presented demonstrates the potential for a missed diagnosis of ovarian torsion when relying predominantly on Doppler findings.

Critical thinking is a learned, scientific method of directing and using cognitive functions to achieve a well-defined goal or answer questions that require the use of judgment. It can also be defined as "active sustained cognitive effort directed at solving a complex problem." 1 Critical thinking has the following characteristics. It

Ultrasound imaging continues to break through scientific and engineering ceilings that have formerly restricted the type and quality of information available. Limited by the temporal, data acquisition, and processing constraints inherent in traditional beamforming technology, ultrasound systems did not have the capacity to acquire and process large amounts of raw acoustic data fast enough to move beyond standard imaging modalities. While traditional beamforming capabilities can provide high-quality and high-resolution images, sensitive Doppler modes, and other advanced imaging applications, there have been limitations to creating new applications that use the information contained within the received acoustic data set. This has all changed with the introduction of ultrasound imaging systems that acquire and process significantly more acoustic data quickly. Upgraded, state-of-the-art digital signal processing (DSP) capabilities have made new imaging possibilities, including enhanced B-mode tissue characterization. This modality helps to differentiate areas within a region of interest based on the unique acoustic characteristics of the tissues insonated.

Accurate, reliable, and easily obtainable quantification of peripheral arterial hemodynamic states has long been a holy grail of vascular ultrasound. While conventional Doppler modalities have been relied upon for decades to provide velocity, directionality, and flow volume data for integration into patient management schema, they carry limitations in accurately and reproducibly quantifying complex arterial hemodynamic patterns. Advances in ultrasound imaging architecture, such as virtual beamforming, integration of “big data” capabilities, and the use of enhanced digital signal processing methods have opened the door for a novel approach to arterial hemodynamic mapping and quantification—ultrasound vector flow imaging (VFI). This article presents an overview of the technological underpinnings of VFI, compares it with conventional pulsed wave and color Doppler methods, and describes the potential clinical benefits of this emerging vascular ultrasound modality.