Official Proceedings - AIUM

American Institute of Ultrasound in Medicine Proceedings J Ultrasound Med 32(suppl):S1–S134, 2013Lumps, Bumps, and Extremity Pain in the EmergencyRoom: What Is the Role of Ultrasound?Moderator: Leslie Scoutt, MDSonography of Abdominal Wall HerniasLevon Nazarian Radiology, Thomas Jefferson UniversityHospital, Philadelphia, Pennsylvania USASmall abdominal wall hernias may be difficult to palpate onphysical examination; therefore, hernias are an often-overlooked cause ofpain or other complications. Because of its real-time nature, ultrasoundhas taken a central role in the evaluation of abdominal wall hernias, sincemany hernias are not present in the resting state. Since dynamic maneuversmay be necessary for diagnosis, many hernias go undetected by computedtomography or magnetic resonance imaging. This presentation willdiscuss the anatomy and technique pertinent to the diagnosis of abdominalwall hernias. Pathologic examples of the different hernia types will bepresented using both static images and video clips.Lumps and BumpsJason Wagner Radiological Sciences, University of Oklahoma,Edmond, Oklahoma USAThis presentation will describe an algorithm-based approach tothe ultrasound evaluation of a superficial mass, based on patient history,physical examination, lesion location, and sonographic findings. Specifictopics will include identification of fluid collections, distinguishing nonneoplasticcauses of a lump from neoplasms, and the differential diagnosisof superficial neoplasms.Peripheral Arterial DiseaseModerator: John Blebea, MD, MBAUltrasound in the Preintervention Stage of Patient EvaluationGowthaman Gunabushanam Diagnostic Radiology, YaleUniversity School of Medicine, New Haven, Connecticut USA;Radiology, VA Medical Center, West Haven, Connecticut USAThis presentation will review the noninvasive evaluation oflower extremity peripheral arterial disease (PAD) in the vascular laboratory,including ankle-brachial index (ABI), toe-brachial index (TBI), pulsevolume recording (PVR), segmental blood pressure measurement, and ultrasoundof native arteries and bypass grafts. ABI is used to confirm vascularetiology and provide prognostic information in symptomatic patients.ABI is also used to screen high-risk asymptomatic patients for PAD andto monitor the efficacy of therapeutic interventions. ABI 1.3 as digital arteriesare usually spared the medial calcinosis that affects the more proximalarteries. Segmental pressure measurements and PVR help determinethe level of stenosis. A gradient >20 mm Hg between adjacent segmentsor between the two sides at the same level is significant. PVR provides anarterial pressure waveform profile by measuring limb volume changeswith each cardiac cycle. A normal waveform has a rapid upstroke, a sharppeak, a dicrotic notch, and a downslope bowed toward the baseline. Aslower rise time, flattened or rounded peaks, absence of a dicrotic notch,and a downslope bowed away from baseline suggest a proximal stenosis.Velocity criteria are used for grading stenosis on ultrasound. Peak systolicvelocity (PSV) of 200 to 350 cm/s and PSV ratio of 2 to 3.5 are suggestiveof moderate stenosis. PSV >350 cm/s and PSV ratio >3.5 are consistentwith severe stenosis.Ultrasound-Guided ThrombolysisModerator: George Lewis Jr, PhDMedical Technology and Instrumentation for Sonothrombolysis:Current, Pipeline, and Future PlatformsGeorge Lewis Jr Zetroz, Ithaca, New York USAUltrasound technologies to provide and monitor sonothrombolysiscan currently be grouped into two broad categories: (1) catheterdirectedand/or delivered ultrasound and (2) extracorporeal focused and/orapplied ultrasound. The first class of technology is generally minimally invasiveand carried out with a sterile field in an interventional radiologysuite. The second class of device covers a much larger use case scenariorelative to where it can be applied and used. In both categories of technology,sonothrombolysis effectiveness in thrombus dissolution is mostregularly measured with precontrast and postcontrast fluoroscopy. Morerecently, however, ultrasound imaging including B-mode, Doppler flow,and intravascular ultrasound is making its way into fully integrated closedloopsonothrombolysis treatment and monitoring systems. This talk willreview current sonothrombolysis ultrasound technologies, their performancecharacteristics, methods of use, and basic mechanisms of action inwhich they rely on. Catheter-directed ultrasound technologies includecommercial systems such as Ekos and Omnisonics, as well as pipelinetechnologies still undergoing research in academia and the private sector.Extracorporeal noninvasive technologies, including power Doppler, lowintensitytherapeutic ultrasound, plane-wave pulsed ultrasound, high-intensityfocused ultrasound, and histotripsy, will be described along withtheir current use case scenarios, characteristics, and regulatory pathways.The catheter-directed sonothrombolysis approaches will be compared andcontrasted to noninvasive sonothrombolysis. Additionally, recent innovationsin closed-loop sonothrombolysis treatment monitoring and crossoversonothrombolysis platforms will be discussed as a gateway into clinical researchpresentations.Sonothrombolysis: Techniques, Mechanisms, and SafetyZhen Xu Biomedical Engineering, University of Michigan,Ann Arbor, Michigan, USAUltrasound has been shown to promote clot breakdown, as botha stand-alone procedure and in conjunction with thrombolytic drugs orcontrast agents. In this talk, 3 sonothrombolysis approaches and their underlyingmechanisms reported in the literature will be reviewed. First, lowintensityultrasound is combined with fibrinolytic enzymes (such asplasminogen activator) to accelerate the clot dissolution. The mechanismunderlying this approach includes the accelerated transport of drug moleculesinto the clot and alteration in fibrin structure to enhance enzymebinding. Both of these effects are caused by stable cavitation (ie, microstreamingand bubble translation) and inertial cavitation (ie, intense localizedstresses and microjets). Microbubble contrast agents can be usedin conjunction with fibrinolytic enzymes to enhance cavitation and furtheraugment thrombolysis. Second, higher-intensity ultrasound and microbubblecontrast agents are used together to cause clot fragmentation.The microbubbles that accumulate at the surface or within the clot serveas cavitation nuclei. For this approach, the primary mechanism is inertialcavitation, where energetic bubble growth and collapse induce high localstress and microjets, resulting in clot microfragmentation. Third, veryhigh-intensity focused ultrasound pulses are used alone to produce rapidclot fragmentation. Similar to the second approach, the mechanism forthis method is also inertial cavitation, where pre-exiting gas nuclei in clotsare used to generate cavitation. No contrast agents or drugs are required.To conclude, safety studies of sonothrombolysis techniques will be discussed,including damage to vessel walls and surrounding tissue, changesin blood chemistry, and embolization.S74