Technological advancements improve the sensitivity of CEUS diagnostics. Martegani, MD, L. iani, MD Department of Diagnostic Imaging, Valduce Hospital, Como, Italy Characterization with Ultrasound B C D *mscect : Multislice Contrast Enhanced Computed Tomography. solid inhomogeneous FLL () to VII segment. t CEUS the lesion appears hypervascular during the arterial phase (B). In a late phase, it has a wash-out effect (C). Corresponding arterial phase in mscect* (D). Final diagnosis: Hepatocellular carcinoma (HCC) The contrast-enhanced ultrasound (CEUS) allows to represent in real time the vascularization dynamics of lesions, parenchyma and blood vessels. CEUS increases the diagnostic accuracy of US in the characterization of parenchymal and vascular diseases, not only at the abdominal structures but also at the superficial structures. Introduction The contrast-enhanced ultrasaund (CEUS) technique is based on the interaction between a contrast agent for ultrasounds (UC) and an ultrasound system with dedicated contrast algorithms. The UC consists of micro gas-bubbles stabilized by a membrane that allows them to survive in the bloodstream for at least 4-5 minutes. The micro-bubbles amplify the ultrasound signal coming from the blood. Their size, in the same order of magnitude of the red blood cells, allows them to pass through the blood-air barrier and to reach the circulatory system without penetrating the endothelial barrier, even when intravenously injected, so that they can be regarded as pure "blood pool" contrast agents. UC is known to have a very good safety profile as adverse events, which are generally characterized by allergic reactions, rarely occur.
Initially, UCs were developed to amplify Color-Doppler and Power-Doppler signals at the level of blood vessels that are too deep or whose flow is very slow. However, the development of specific algorithms at low acoustic pressure for the visualization of contrast agents even enabled the development of CEUS for the study of the micro- and macrovascularization of parenchymal tissues and lesions, as well as great vessels. s a new diagnostic technique, CEUS allows to amplify the acoustic signal of the micro-bubbles and to filter out the signal coming from the surrounding stationary tissues, leveraging on the nonlinear response properties of the UC. For these reasons, this method allows to identify only the bubbles distributed in the circulation of the target organ in real-time and thus to represent the microcirculation. Recent technological developments allow to use CEUS for real-time studies of deep parenchymal tissues, superficial tissues and vascular structures. In the following, we report cases obtained with Convex and Linear probes and a dedicated contrast algorithm available on RS80 (Samsung Medison Co. Ltd., Seoul, Korea). CEUS imaging in bdominal, Superficial and Vascular Study In the guidelines and recommendations proposed by European Federation of Societies for Ultrasound in Medicine and Biology(EFSUMB), CEUS finds application in many different pathological situations.. Characterization and monitoring of HCC treated with stce B C D E F Figure 1. solid and inhomogeneous nodule with peri- and intra-lesional vascular signs with Power Doppler analysis, localized to the right hepatic lobe (). CEUS examination proves intense arterial enhancement (B) with a progressive and sluggish wash-out (C), which becomes more evident in late phase (D). xial scans mscect-arterial phase (E) and MIP-3D reconstruction (F) show diagnostic signs that are compatible with HCC.
Figure 1-1. ngiographic demonstration of lesion vascularity (). Check after selective embolization (B): persistence of minimum residual disease sustained by tributary circle coming from right hepatic artery (red arrows). B C D E F G H I Follow-up ultrasound scan performed the day after, in B-mode (C) shows an intense hyperechoic nodule due to the presence of air spots. In CEUS compared to the B-mode (D) the nodule appears predominantly avascular (E) which confirms angiographic data of active tissue persistence to the periphery (F, G). Confirmation in mscect-arterial phase (H) and portal phase (I) images. Diagnostic signs compatible with sub-total treatment of HCC. CEUS shows high sensitivity in identifying hyper-vascular phenomena (especially microcirculation) in real-time, so it can play an important role in early and remote monitoring of oncologic therapies, particularly percutaneous ablation or angiography procedures. In this particular case, CEUS has enabled identification of lesions otherwise unlikely to be accessed through ultrasound scans. This supports the post-management of ablative treatment, especially for the case of persisting neoplastic phenomena or relapses of previously treated foci (Figure 1, 1-1).
B. Characterization of vascular nodular disseminated peritoneal metastases Today s technology advancements also allow the use of CEUS techniques in the study of surface structures by means of high frequency linear probes. Figure 2. Color-Doppler US module () proves the presence of nodules of the parietal peritoneum (white arrows) and of the parietal pleura (yellow arrows). Presence of ascites and some tiny vascular spots in the pleural nodule only. Selective study of the peritoneal nodule carried out with CEUS and a high frequency Linear transducer: compared to the baseline (B), an intense enhancement of the nodule can be noted in the early arterial phase (C) and the enhancement of the nodule and of the underlying liver parenchyma during the late phase (D). B C D E F Compared to the baseline CT image (E), the CE shows an increased enhancement (F) of the peritoneal nodule (before 49 HU, after CE 105 HU). Final diagnosis was peritoneal carcinomatosis. CEUS showed a greater sensitivity compared to Color-Doppler in the identification of vascular phenomena of the macro-and micro-circulation. This makes the identification of the solid and vascularized nature of the lesions possible; providing directions for the subsequent diagnostic steps (Figure 2).
rticle # WP201507-CEUS / Issue Date 17 July, 2015 C. Study of internal carotid artery - occlusion or pseudo-obstruction? CEUS can also be useful in studies involving large blood vessels, since it is more sensitive to slow flows and less exposed to the presence of artifacts. B C D Figure 3. In the US B-mode examination (), the internal carotid artery in the post-bulbar part reveals a presence of hyperechoic echo-structured material with stretches of heterogeneous appearance. Presence of small calcific plaque (white arrow) adhering to the bulb wall of the internal carotid artery. In the Color-Doppler examination (B), a low vascular signal is observed throughout the whole internal carotid lumen. In the transcranial Color-Doppler (TCD) examination, the ipsilateral Middle Cerebral rtery Doppler Spectrum (C) is characterized by a low systolic peak velocity and low systolic-diastolic modulation, especially compared with the contralateral artery (D). E F G The CEUS examination (E-F-G), performed with a high frequency linear probe, shows regular canalization of the carotid inside the bulb. The absence of contrast agent is confirmed in the post-bulbar part of the internal carotid artery. Final diagnosis: complete occlusion of the post-bulbar tract of the internal carotid artery.
s reported by many recent publications, CEUS is known to provide a more accurate measurement of the intima-media thickness, which is now considered an important parameter for defining cardiovascular risk of a patient. Moreover, contrast agent can be useful in differentiating very tight stenosis of the carotid and pseudo-occlusions from true occlusions, since it enables greater sensitivity to slow flows compared to the Doppler imaging (Figure 3). further application of CEUS to the carotid is the study of the carotid plaques not only at morphological but also at functional level, since the contrast may reveal the presence of "vasa vasorum" within the plaque in real-time. Several studies correlate the presence of the "vasa vasorum" in the atheromatous plaque with its increased instability. Consequently, CEUS can potentially become an important indicator of high risk of cardiovascular disease in the near future. Discussion In our daily practice, we frequently rely on CEUS for many clinical cases and for the study of several anatomical regions. The enhancement effect provided by CEUS is an important factor to plan a proper diagnostic and therapeutic path and also to exhaustively characterize the features of a lesion. potentially provides a comprehensive diagnostic toolset that can cover a wide range of anatomical structures. Conlcusion When correctly used, following proper guidelines, CEUS yields high accuracy and can even be comparable to CT and MRI images. Its low invasiveness and economic cost are also advantages over other imaging modalities. Recent technological advancements combined with valid CEUS investigations of the surface structures, CEUS may also be able to offer interesting perspectives even in the characterization of breast and prostate lesions. Supported Systems - RS80 with Prestige - RS80 - HS70 References 1. EFSUMB Study: Group The EFSUMB Guidelines and Recommendations on the Clinical Practice of Contrast Enhanced Ultrasound (CEUS): update 2011 on non-hepatic applications. Ultraschall Med. 2012; 33(1):33-59. 2. Guidelines and good clinical practice recommendations for Contrast Enhanced Ultrasound (CEUS) in the liver - update 2012: WFUMB-EFSUMB initiative in cooperation with representatives of FSUMB, IUM, SUM, FLUS and ICUS. Ultrasound Med. Biol. 2013;39(2):187-210. 3. Meloni MF, Livraghi T, Filice C, Lazzaroni S, Calliada F, Perretti L: Radiofrequency ablation of liver tumors: the role of microbubble ultrasound contrast agents. Ultrasound Q. 2006;22(1):41-47. 4. Bolondi L: The appropriate allocation of CEUS in the diagnostic algorithm of liver lesions: a debated issue. Ultrasound Med. Biol. 2013; 39(2):183-5. 5. Piscaglia F, Bolondi L. :The safety of Sonovues in abdominal applications: retrospective analysis of 23188 investigations. Ultrasound Med. Biol. 2006; 32 (9):1369 75. 6. Martegani, iani L, Borghi C: "The use of contrast-ehnancend ultrasound in large vessels". Eur. Radiol. 2004;14 Suppl 8:73-86. c 2015 Samsung Medison ll Rights Reserved. Samsung Medison Reserves the right to modify any design, packaging, specifications and features shown herein, without prior notice or obligation. Please visit www.samsungmedison.com