High-Frame Rate Vector Flow Imaging of the Carotid Bifurcation in Healthy Adults: Comparison With Color Doppler Imaging.

OBJECTIVES: To evaluate the carotid bifurcation in healthy adults using a commercial system equipped with high-frame rate vector flow imaging (VFI) based on the plane wave and to compare VFI with color Doppler imaging. METHODS: Carotid bifurcation diameters and flow characteristics of 60 vessels in 60 healthy volunteers were evaluated quantitatively and qualitatively to assess complex flow patterns and their extension and duration. RESULTS: Complex flow in the internal carotid artery (ICA) was associated with a statistically significant difference in the ΔICA sinus-to-common carotid artery (CCA) diameter ratio (the relative change in diameter between the CCA and ICA sinus.) Vector flow imaging and color Doppler imaging were in accordance when detecting complex flow in 96.7% of cases; in 3.3% of cases, only VFI identified small recirculation areas of short duration. Vector flow imaging highlighted a larger extension of the complex flow (mean ± SD, 47.7 ± 28.5 mm2 ; median, 45.5 mm2 ) compared with color Doppler imaging (mean, 29.2 ± 19.9 mm2 ; median, 29.5 mm2 ) and better depicted different complex flow patterns; a strong correlation (r = 0.84) was found between the ΔICA sinus-to-CCA diameter ratio and the complex flow extension. Vector flow imaging showed a longer duration of the flow disturbances (mean, 380 ± 218 milliseconds; median, 352.5 milliseconds) compared with color Doppler imaging (mean, 325 ± 206 milliseconds; median, 333 milliseconds), and there was a strong correlation (r = 0.92). CONCLUSIONS: Vector flow imaging is as effective as color Doppler imaging in the detection of flow disturbances, but it is more powerful in the assessment of complex flow patterns.

Identification of residual tumor with intraoperative contrast-enhanced ultrasound during glioblastoma resection.

OBJECTIVE: The purpose of this study was to assess the capability of contrast-enhanced ultrasound (CEUS) to identify residual tumor mass during glioblastoma multiforme (GBM) surgery, to increase the extent of resection. METHODS: The authors prospectively evaluated 10 patients who underwent surgery for GBM removal with navigated ultrasound guidance. Navigated B-mode and CEUS were performed prior to resection, during resection, and after complete tumor resection. Areas suspected for residual tumors on B-mode and CEUS studies were localized within the surgical field with navigated ultrasound and samples were sent separately for histopathological analysis to confirm tumor presence. RESULTS: In all cases tumor remnants were visualized as hyperechoic areas on B-mode, highlighted as CEUS-positive areas, and confirmed as tumoral areas on histopathological analysis. In 1 case only, CEUS partially failed to demonstrate residual tumor because the residual hyperechoic area was devascularized prior to ultrasound contrast agent injection. In all cases CEUS enhanced B-mode findings. CONCLUSIONS: As has already been shown in other neoplastic lesions in other organs, CEUS is extremely specific in the identification of residual tumor. The ability of CEUS to distinguish between tumor and artifacts or normal brain on B-mode is based on its capacity to show the vascularization degree and not the echogenicity of the tissues. Therefore, CEUS can play a decisive role in the process of maximizing GBM resection.

Velocity vector comparison between vector flow imaging and computational fluid dynamics in the carotid bifurcation.

It has been largely documented that local hemodynamic conditions, characterized by low and oscillating wall shear stresses, play a key role in the initiation and progression of vascular atherosclerotic lesions. Thus, investigation of the flow field in the carotid bifurcation can lead to early identification of vulnerable plaques. In this scenario, the development of novel non-invasive imaging tools that can be used in routine clinical practice to identify disturbed and recirculating blood flow becomes crucial. In this context, Vector Flow Imaging is becoming a relevant tool as it provides an angle independent assessment of blood flow velocity and multidimensional flow vector visualization. The purpose of the present study was to validate, in several locations of the carotid bifurcation, the high-frame rate vector flow imaging (HiFR-VFI) technique by comparing with computational fluid dynamic simulations (CFD). In all eight carotid bifurcations, HiFR-VFI accurately detected regions of laminar flow as well as recirculation and unsteady flow areas. An accurate and statistically significant agreement was observed between velocity vectors obtained by HiFR-VFI and those computed by CFD, both for vector magnitude (R = 0.85) and direction (R = 0.74). Our study demonstrated that HiFR-VFI is a valid technique for rapid and advanced visual representation of velocity field in large arteries. Thus, it has a great potential in research-based clinical practice for the identification of flow recirculation, low and oscillating velocity gradients near vessel wall. The use of HiFR-VFI may provide a great improvement in the investigation of the role of local hemodynamics in vascular pathologies, as well in the assessment of the effect of pharmacological treatments.

CEUS in abdominal trauma: multi-center study.

The objective of this study was to evaluate the concordance of US and contrast-enhanced US (CEUS) with CT in the assessment of solid organ injury following blunt trauma. Patients underwent complete US examination, including free fluid search and solid organ analysis. CEUS followed, using low-mechanical index techniques and SonoVue. CT was performed within 1 h. Among 156 enrolled patients, 91 had one or more abnormalities (n = 107) at CT: 26 renal, 38 liver, 43 spleen. Sensitivity, specificity, and accuracy for renal trauma at baseline US were 36%, 98%, and 88%, respectively, after CEUS values increased to 69%, 99%, and 94%. For liver baseline US values were 68%, 97%, and 90%; after CEUS were 84%, 99%, and 96%. For spleen, results were 77%, 96%, and 91% at baseline US and 93%, 99%, and 97% after CEUS. Per patient evaluation gave the following results in terms of sensitivity, specificity and accuracy: 79%, 82%, 80% at baseline US; 94%, 89%, and 92% following CEUS. CEUS is more sensitive than US in the detection of solid organ injury, potentially reducing the need for further imaging. False negatives from CEUS are due to minor injuries, without relevant consequences for patient management and prognosis.

Contrast enhanced ultrasound in the evaluation and percutaneous treatment of hepatic and renal tumors.

Image-guided percutaneous ablation techniques are increasingly being used for the treatment of malignant tumors of the liver and kidney. Contrast enhanced ultrasound (CEUS) is a real-time dynamic imaging technique that plays an important role in the pre-, intra-, and post-procedural management of these patients. This review will focus on the role of CEUS in the evaluation of patients undergoing treatment with percutaneous ablation for hepatic or renal tumors.

EVAR: Benefits of CEUS for monitoring stent-graft status.

Endo vascular aortic repair [EVAR] is performed with low peri-operative morbidity and mortality rate and short hospital stay. However, EVAR needs a close and lifelong imagining surveillance for a timely detection of possible complications including endoleaks, graft migration, fractures, and enlargement of aneurysm sac size with eventual rupture. Contrast enhanced computed tomography [CTA] is actually considered the gold-standard in EVAR follow-up, but it is accompanied with radiation burden and renal injury due to the use of contrast media. In the last two decades several studies have shown the role of contrast enhanced ultrasound [CEUS] in post-EVAR surveillance, with very good diagnostic performance, absence of renal impairment, and no radiation, accompanied by low costs, in comparison with CTA. In numerous prospective studies and meta-analyses the detection and characterization of endoleaks with CEUS is comparable to that of CTA imaging. Nowadays, in the EVAR surveillance novel strategies which involve CEUS with a central role, are suggested by several authors and applied in many institutions. In this review article we will present a comprehensive overview and analyses of the literature on the CEUS state-of-art imagining of EVAR follow-up, with its technique, findings, diagnostic accuracy, and its role in the follow up program.

Intraoperative contrast-enhanced ultrasound for brain tumor surgery.

BACKGROUND: Contrast-enhanced ultrasound (CEUS) is a dynamic and continuous modality that offers a real-time, direct view of vascularization patterns and tissue resistance for many organs. Thanks to newer ultrasound contrast agents, CEUS has become a well-established, live-imaging technique in many contexts, but it has never been used extensively for brain imaging. The use of intraoperative CEUS (iCEUS) imaging in neurosurgery is limited. OBJECTIVE: To provide the first dynamic and continuous iCEUS evaluation of a variety of brain lesions. METHODS: We evaluated 71 patients undergoing iCEUS imaging in an off-label setting while being operated on for different brain lesions; iCEUS imaging was obtained before resecting each lesion, after intravenous injection of ultrasound contrast agent. A semiquantitative, offline interobserver analysis was performed to visualize each brain lesion and to characterize its perfusion features, correlated with histopathology. RESULTS: In all cases, the brain lesion was visualized intraoperatively with iCEUS. The afferent and efferent blood vessels were identified, allowing evaluation of the time and features of the arterial and venous phases and facilitating the surgical strategy. iCEUS also proved to be useful in highlighting the lesion compared with standard B-mode imaging and showing its perfusion patterns. No adverse effects were observed. CONCLUSION: Our study is the first large-scale implementation of iCEUS in neurosurgery as a dynamic and continuous real-time imaging tool for brain surgery and provides the first iCEUS characterization of different brain neoplasms. The ability of CEUS to highlight and characterize brain tumor will possibly provide the neurosurgeon with important information anytime during a surgical procedure.

Intraoperative cerebral glioma characterization with contrast enhanced ultrasound.

BACKGROUND: Contrast enhanced ultrasound (CEUS) is a dynamic and continuous modality providing real-time view of vascularization and flow distribution patterns of different organs and tumors. Nevertheless its intraoperative use for brain tumors visualization has been performed few times, and a thorough characterization of cerebral glioma had never been performed before. AIM: To perform the first characterization of cerebral glioma using CEUS and to possibly achieve an intraoperative differentiation of different gliomas. METHODS: We performed CEUS in an off-label setting in 69 patients undergoing surgery for cerebral glioma. An intraoperative qualitative analysis was performed comparing iCEUS with B-mode imaging. A postprocedural semiquantitative analysis was then performed for each case, according to EFSUMB criteria. Results were related to histopathology. RESULTS: We observed different CE patterns: LGG show a mild, dotted CE with diffuse appearance and slower, delayed arterial and venous phase. HGG have a high CE with a more nodular, nonhomogeneous appearance and fast perfusion patterns. CONCLUSION: Our study characterizes for the first time human brain glioma with CEUS, providing further insight regarding these tumors' biology. CEUS is a fast, safe, dynamic, real-time, and economic tool that might be helpful during surgery in differentiating malignant and benign gliomas and refining surgical strategy.

Value of contrast-enhanced ultrasonography for detecting renal infarcts proven by contrast enhanced CT. A feasibility study.

The effectiveness of contrast-enhanced ultrasonography (CEUS) in the evaluation of patients with acute renal infarcts was investigated, using contrast-enhanced helical computed tomography (CT) as the reference imaging procedure. Twenty-seven consecutive patients with acute renal infarcts detected with contrast-enhanced helical CT underwent CEUS. Digital cine-clips of CEUS were evaluated by two independent readers blinded to CT findings. Image quality was rated subjectively on a four-point scale. Then, readers were asked to assign a confidence level in diagnosis of renal infarct at the upper pole, medium portion, and lower pole of each kidney according to a five-degree scale, ranging from definitely absent to definitely present. ROC curve analysis was employed to assess the overall confidence of diagnosis of infarct, and weighted kappa values were calculated to assess inter-reader agreement. The subjective image quality of CEUS was lower than the image quality of CT at the upper poles. However, the diagnostic performance of CEUS was excellent (area under receiver-operator characteristic curve 0.992 +/- 0.006 for reader 1; 0.991 +/- 0.007 for reader 2), with very good inter-reader agreement (weighted kappa value = 0.83). CEUS is a reproducible tool to detect acute renal infarcts in men, with a diagnostic performance approaching that of CT.

[A case of left ventricular thrombosis in a patient with beta-thalassemia major]. / Un caso di trombosi ventricolare sinistra in una paziente affetta da beta-talassemia maior.

In patients with beta-thalassemia major cardiac events due to iron overload are the main cause of death. Moreover, a chronic hypercoagulable state has been described in these patients, which sometimes complicates with thromboembolic events, mainly cerebral ischemic accidents and deep venous thrombosis. We describe a case of cardiac hemochromatosis complicated with fatal massive multiorgan embolism due to a large left ventricular thrombus in a patient with beta-thalassemia major.

Parapancreatic Castleman disease: contrast-enhanced sonography and CT features.

Castleman disease is a rare lymphoproliferative disorder that can be classified into 3 types: hyaline-vascular, plasma cell, and mixed. We report a rare case of localized para-pancreatic hyaline-vascular Castleman disease that was evaluated using contrast-enhanced sonography and CT.

Economic assessment of contrast-enhanced ultrasonography for evaluation of focal liver lesions: a multicentre Italian experience.

BACKGROUND: The aim of this study was to evaluate the clinical and economic consequences of the introduction of contrast-enhanced ultrasonography (CEUS) into the diagnostic clinical algorithm for the characterization of incidental focal liver lesions (FLLs). METHODS: This prospective study enrolled 485 subjects at three hospitals in Italy. Two diagnostic algorithms were utilized: (1) a classic patient work-up, which included baseline US followed by a CT or MR examination, and (2) a new patient management scheme in which, following the baseline US, a CEUS examination was performed. For each pathway, both direct and indirect health costs for the National Health System (NHS) at two of the three hospitals involved in the study were calculated. Clinical outcome was measured in terms of number of cases correctly diagnosed, using contrast-enhanced CT/contrast-enhanced MR as the reference standard. RESULTS: CEUS correctly differentiated (benign vs. malignant) 559 of 575 lesions (97.2%), with a sensitivity of 98.1% and a specificity of 95.7%. Histological characterization was correct in 502 of 575 lesions (87%) with a sensitivity of 90.5% and a specificity of 85.4%. In terms of cost, the conventional diagnostic algorithm incurred for the NHS a total cost of Euro 134.576,60 vs. Euro 55.674,30 with CEUS, for a saving of Euro 78.902 (Euro 162 per patient). For the hospitals, the total cost was Euro 147.045 without CEUS vs Euro 61.979 with CEUS, for a saving of Euro 85.065,96 or Euro 175,39 per patient. CONCLUSION: The routine use of CEUS for the characterization of FLLs provides significant cost savings, both for the NHS and for the hospital.

[Current state of the use of sonographic contrast agents with low acoustic pressure techniques in the study of focal liver lesions].

Ultrasonography is the most commonly used screening modality for focal liver lesions in Europe. Over the past few years, to overcome the inherent limitations of B-mode imaging and colour-Doppler ultrasound in identifying and characterising focal liver lesions, intravenous agents capable of enhancing the ultrasound signal emitted by vascular and parenchymal structures have been developed. From December 1999 to December 2001, about 400 patients with a known tumour, HCV-related chronic cirrhotic liver disease, or with an indeterminate focal liver lesion discovered incidentally were evaluated by ultrasound of the liver parenchyma both in baseline conditions and after administration of contrast material. The ultrasound contrast agents used were: SonoVue (Bracco, Milan-Italy) and Optison (Mallinckrodt, London - UK). Our experience is based on low mechanical-index contrast-enhanced imaging, which acts conservatively, performed with different commercially available algorithms, in grey-scale mode alone (B-mode). We report the morphological patterns displayed by the main benign and malignant liver lesions after the administration of second-generation ultrasound contrast material, and review the main imaging patterns able to provide effective and practical guidance in formulating a diagnosis of benignity or malignancy. Our clinical experience confirmed the literature findings that the introduction of low mechanical index methods in grey-scale imaging has allowed qualitatively better results for detecting and characterising focal liver lesions than those obtained with baseline and colour-Doppler imaging. The ease of use, substantial repeatability and predictability of the enhancement effects obtainable with low mechanical index methods are the main reasons for the success of this approach. Broadening the scope of studies to obtain controlled data and comparisons with the other imaging modalities is crucial for the definitive validation of the method.