Ultrasound provides a valuable tool for medical diagnosis offering real-time imaging with excellent spatial resolution and low cost. The advent of microbubble contrast agents has provided the additional ability to obtain essential quantitative information relating to tissue vascularity, tissue perfusion and even endothelial wall function. This technique has shown great promise for diagnosis and monitoring in a wide range of clinical conditions such as cardiovascular diseases and cancer, with considerable potential benefits in terms of patient care. A key challenge of this technique, however, is the existence of significant variations in the imaging results, and the lack of understanding regarding their origin. The aim of this paper is to review the potential sources of variability in the quantification of tissue perfusion based on microbubble contrast-enhanced ultrasound images. These are divided into the following three categories: (i) factors relating to the scanner setting, which include transmission power, transmission focal depth, dynamic range, signal gain and transmission frequency, (ii) factors relating to the patient, which include body physical differences, physiological interaction of body with bubbles, propagation and attenuation through tissue, and tissue motion, and (iii) factors relating to the microbubbles, which include the type of bubbles and their stability, preparation and injection and dosage. It has been shown that the factors in all the three categories can significantly affect the imaging results and contribute to the variations observed. How these factors influence quantitative imaging is explained and possible methods for reducing such variations are discussed.

Imaging is key in the accurate monitoring of response to cancer therapies targeting tumour vascularity to inhibit its growth and dissemination. Dynamic contrast enhanced ultrasound (DCE ultrasound) is a quantitative method with the advantage of being non-invasive, widely available, portable, cost effective, highly sensitive and reproducible using agents that are truly intravascular. Under the auspices of the initiative of the Experimental Cancer Medicine Centre Imaging Network, bringing together experts from the UK, Europe and North America for a 2-day workshop in May 2010, this consensus paper aims to provide guidance on the use of DCE ultrasound in the measurement of tumour vascular support in clinical trials. Key Points • DCE ultrasound can quantify and extract specific blood flow parameters, such as flow velocity, relative vascular volume and relative blood flow rate. • DCE ultrasound can be performed repeatedly and is therefore ideally suited for pharmacokinetic and pharmacodynamic studies evaluating vascular-targeted drugs. • DCE ultrasound provides a reproducible method of assessing the vascular effects of therapy in pre-clinical and early clinical trials, which is easily translatable into routine clinical practice.

Traditionally, stroke risk stratification has centred on the degree of internal carotid artery stenosis, and the presence of focal neurological symptoms. However, degree of stenosis alone is a relatively poor predictor of future stroke in asymptomatic patients; the Asymptomatic Carotid Surgery Trial highlighting the need to identify a subgroup of asymptomatics that may benefit from intervention. Attempting to define this subgroup has inspired imaging research to identify, in vivo, high-risk plaques. In addition to pre-operative risk stratification of carotid stenosis, contrast enhanced ultrasound (CEUS) may be employed in monitoring response to plaque-stabilising therapies. Unlike most contrast agents used for computed tomography and magnetic resonance imaging, microbubbles used in CEUS remain within the vascular space and can hence be used to study the vasculature. In addition to improving current carotid structural scans, CEUS has potential to add extra information on plaque characteristics. Furthermore, by targeting microbubbles to specific ligands expressed on vascular endothelium, CEUS may have the ability to probe plaque biology. This review describes the current carotid ultrasound examination and the need to improve it, rationale for imaging neovascularisation, use of CEUS to image neovascularisation, microbubbles in improving the structural imaging of plaque, potential problems with CEUS, and future directions.

Purpose:To determine if the number of nontargeted microbubbles retained in human carotid plaque is suffi cient to be detected with ultrasonography (US). Materials and Methods:The study protocol was approved by the local research ethics committee. Informed consent was obtained. A total of 37 subjects with carotid atherosclerosis (mean age, 69.9 years; age range, 49-86 years), of whom 27 (73%) were men (mean age, 69.7 years; age range, 58-86 years) and 10 (27%) were women (mean age, 70.3 years; age range, 49-86 years), were studied between December 2008 and May 2009 with late-phase (LP) contrast material-enhanced US by using fl ash imaging with a nonlinear mode at an intermediate mechanical index of 0.34 6 minutes after bolus contrast agent injection. Plaques were defi ned as symptomatic if symptoms consistent with stroke, transient ischemic attack, or amaurosis fugax had occurred in the neurovascular territory of the plaque studied within 12 months prior to entry into the study. Plaques were defi ned as asymptomatic if no such events had ever occurred within the neurovascular territory. Raw linear data were used to quantify echogenicity of the plaque, which was normalized to lumen echogenicity. Gray-scale median score was also calculated. Results:Of the 37 subjects, 16 (43%) had symptomatic plaques and 21 (57%) had asymptomatic plaques. All examinations yielded evaluable LP contrast-enhanced US data. Normalized LP plaque echogenicity was greater in the symptomatic group (0.39; 95% confi dence interval: 2 0.11, 0.89) than in the asymptomatic group (0.69; 95% confi dence interval: 2 1.04, 2 0.34) ( P = .0005). There was a moderate ( r = 2 0.44, P = .016) inverse correlation between normalized LP plaque echogenicity and gray-scale median score. Conclusion:By quantifying microbubble retention within the carotid plaque, LP contrast-enhanced US depicts clear differences between groups of subjects with plaque ipsilateral to symptoms and asymptomatic plaques. This technique has promise as a tissue-specifi c marker of infl ammation and a potential role in the risk stratifi cation of atherosclerotic carotid stenosis.q RSNA, 2010

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BackgroundCompetency‐based hiring is beginning to catch on as employers insist on having a clearer understanding of an applicant's abilities before extending an offer of employment. Microcredentialing offers employees a mechanism to articulate their competency, and they offer employers a profound way to certify an applicant's abilities.PurposeTo seek an understanding of the value of a microcredentialing structure through employer perspectives. The central research question is, do employers see value in a postsecondary micro‐credentialing structure?MethodThis qualitative case study uses Skill Acquisition Theory and cultivated twenty‐two industry professionals from various sectors, primarily from the early childhood education industry.ResultsSeveral themes emerged from the data: The industry is not satisfied with employee skills, competency is the new currency, seat time does not equal education, a policy for issuing and securing microcredentials is necessary.DiscussionEmployers were questioning the validity of a college transcript and suggested that applicants present microcredentials for key employment elements along with their transcript to certify further their ability to apply knowledge and skills.ConclusionsIt is concluded that microcredentials would be beneficial to the holder and employers. To increase the value of these credentials, the participants suggested using a registry to track and report microcredentials earned. It was further concluded that institutions need to develop governing rules for issuing a microcredential, rules similar to those governing transcripts to ascertain and protect the validity of the credential.

Ultrasound-based elastography may be a promising tool for displaying the ablation zone created by expandable RFA probes.

Background and Purpose-Development of translational functional imaging modalities for atherosclerosis risk stratification is sought for stroke prediction. Our group has developed late-phase contrast-enhanced ultrasound (LP-CEUS) to quantify microbubble contrast retention within carotid atherosclerosis and shown it to separate asymptomatic plaques from those responsible for recent cerebrovascular events. We hypothesized that microbubbles are retained in areas of plaque inflammation, aiming to examine whether LP-CEUS signal reflects plaque biology. Methods-Subjects awaiting carotid endarterectomy (nϭ31) underwent axial LP-CEUS and diseased intimal segments were symmetrically divided in the long axis. Half-specimens underwent quantitative immunohistochemical analysis for CD68 (macrophages) and CD31 (angiogenesis). Half-specimens were processed for atheroma cell culture and supernatant collected at 24 hours for multianalyte profiling for 34 analytes. Results-Percentage area immunopositivity was significantly higher in subjects in which normalized plaque late-phase intensity was Ն0 versus Ͻ0 (CD68 mean 11.8 versus 6.68, Pϭ0.004; CD31 mean 9.45 versus 4.82, Pϭ0.025).Interleukin-6, matrix metalloproteinase-1, and matrix metalloproteinase-3 were significantly higher by multianalyte profiling when LP-CEUS was Ն0. Conclusions-LP-CEUS