Visualization of blood flow in hepatic vessels and hepatocellular carcinoma using B-flow sonography

A case of hepatocellular carcinoma with pseudoaneurysm formation upon lenvatinib administration

A 79-year-old man received treatment for multiple intrahepatic hepatocellular carcinoma with atezolizumab + bevacizumab. However, he developed lower back pain attributed to spinal metastases upon tumor enlargement; thus, he was admitted to our hospital for a change from atezolizumab + bevacizumab to lenvatinib and radiation therapy for the spinal metastases. On the 11th day after starting lenvatinib treatment, a pulsatile aneurysm appeared in the tumor, detected using abdominal ultrasonography Micro B-flow imaging, which visualized blood flow at a high frame rate; this was diagnosed as a pseudoaneurysm. The patient refused treatment for the pseudoaneurysm; therefore, he was carefully followed up. Fortunately, the pseudoaneurysm disappeared on the 17th day. One month later, the tumor had become completely necrotic. Lenvatinib demonstrated effectiveness in inhibiting angiogenesis in the tumor, as evidenced by a decrease in tumor blood flow. This case report suggests that pseudoaneurysm formation within the tumor occurs early after the administration of lenvatinib; thus, clinicians must be aware of the potential risk of pseudoaneurysm rupture.

Clinical Applications of B-Flow Ultrasound: A Scoping Review of the Literature

Coded excitation ultrasound investigations have the potential to augment the resolution, increase the efficiency, and expand the possibilities of noninvasive diagnostic imaging. B-Flow ultrasound, a type of digitally encoded imaging, was developed more than 20 years ago with the aim to optimize the visualization of blood flow. It has been investigated for a plethora of applications so far. A scoping review regarding its clinical applications was conducted based on a systematic literature research. B-Flow has been investigated in various anatomic locations and pathologies. However, previous research is limited by small sample sizes, the rare occurrence of elaborate study designs, the reliance on subjective reports and qualitative data, as well as several potential biases. While results are in general promising, it should therefore still be considered an emerging technology. Nevertheless, the limitations can be addressed in future research and the potential to expand its applications make B-Flow an interesting candidate for further investigations.

Targeting integrin αvβ3 by a rationally designed protein for chronic liver disease treatment

Chronic Liver Diseases (CLD) are characterized by abnormal accumulation of collagen fibrils, neo-angiogenesis, and sinusoidal remodeling. Collagen deposition along with intrahepatic angiogenesis and sinusoidal remodeling alters sinusoid structure resulting in portal hypertension, liver failure, and other complications. Efforts were made to develop treatments for CLDs. However, the success of such treatments is limited and unpredictable. We report a strategy for CLD treatment by induction of integrin αvβ3 mediated cell apoptosis using a rationally designed protein (ProAgio). ProAgio is designed to target integrin αvβ3 at a novel site. Integrin αvβ3 is highly expressed in activated Hepatic Stellate Cells (HSC), angiogenic endothelium, and capillarized Liver Sinusoidal Endothelial Cells (LSEC). ProAgio induces apoptosis of these disease causative cells. Tests with liver fibrosis mouse models demonstrate that ProAgio reverses liver fibrosis and relieves blood flow resistance by depleting activated HSC and capillarized LSEC. Our studies demonstrate an effective approach for CLD treatment.

A Method for Gray-Scale Imaging of Blood Flow Using High-Frequency Ultrasound

This paper presents a new method that complements current techniques available in the high-frequency blood imaging field. A comprehensive scattering model was established to determine the feasibility and frequency range of the blood flow imaging of superficial organs and tissues using high-frequency ultrasound. The transmitting and receiving modes and an algorithm were designed to obtain blood flow information based on differentiation between tissues and blood flow. The system was created and tested first with a model that simulates blood flow and was then used on human tissue. A fine-scale image of a blood vessel could be obtained with this system. Moreover, this method can obtain weak blood flow signal using single pulse rather than the traditional pulse-code method and maintains a high resolution that can be matched to high-frequency structural imaging. This study provides a reliable method for further applications related to diagnoses of superficial organs.

Evaluation of normal fetal ductus venosus using B-flow imaging with spatiotemporal image correlation and traditional color Doppler echocardiography

OBJECTIVE

To explore the feasibility of using four-dimensional echocardiography with B-flow and spatiotemporal image correlation (4DBF-STIC) imaging technology to detect fetal ductus venosus (DV), and establish the normal reference range for the ductus venosus diameter at 18-40 weeks gestation.

METHODS

This was a prospective observational study to detect the DV in 354 normal fetuses at 18-40 weeks of gestation using color Doppler echocardiography (CDE) and 4DBF-STIC imaging. CDE was performed on an oblique transverse plane of the fetal abdomen, with scanning around the long-axis view of the aortic arch. The DV inlet was measured on a two-dimensional gray-scale image of the long-axis view of the DV. Offline analyses of all datasets were performed.

RESULTS

The inlet diameter of the DV increased with increasing gestational age. There were no gender-related differences in the DV diameter. Data revealed that 4DBF-STIC was the best method to detect the DV between 18 and 29 weeks of gestation. The visualization rate was higher when scanning around the long-axis view of the aortic arch with CDE than when scanning around the oblique transverse plane throughout the gestational period.

CONCLUSIONS

Scanning around the long-axis view of the aortic arch using CDE was best suited for detecting the DV in clinical practice, whereas 4DBF-STIC was a feasible and promising technology to detect the fetal DV before 29 weeks of gestation.

Doppler ultrasound detection of preclinical changes in foot arteries in early stage of type 2 diabetes

BACKGROUND

There are few reports regarding the changes within the vessels in the initial stage of type 2 diabetes. The aim of this study was to estimate the hemodynamic and morphological parameters in foot arteries in type 2 diabetes subjects and to compare these parameters to those obtained in a control group of healthy volunteers.

MATERIAL/METHODS

Ultrasound B-mode, color Doppler and pulse wave Doppler imaging of foot arteries was conducted in 37 diabetic patients and 36 non-diabetic subjects to determine their morphological (total vascular diameter and flow lumen diameter) and functional parameters (spectral analysis).

RESULTS

In diabetic patients, the overall vascular diameter and wall thickness were statistically significantly larger when compared to the control group in the right dorsalis pedis artery (P=0.01; P=0.001), left dorsalis pedis artery (P=0.007; P=0.006), right posterior tibial artery (P=0.005; P=0.0005), and left posterior tibial artery (P=0.007; P=0.0002). No significant differences were observed in both groups in flow lumen diameters and blood flow parameters (PSV, EDV, PI, RI). In the diabetic group, the level of HbA1c positively correlated with flow resistance index in the right dorsalis pedis artery (r=0.38; P=0.02), right posterior tibial artery (r=0.38; P=0.02) and left posterior tibial artery (r=0.42; P=0.009). The pulsatility index within the dorsalis pedis artery decreased with increased trophic skin changes (r=-0.431, P=0.009).

CONCLUSIONS

In the diabetic group, overall artery diameters larger than and flow lumina comparable to the control group suggest vessel wall thickening occurring in the early stage of diabetes. Doppler flow parameters are comparable in both groups. In the diabetic group, the level of HbA1c positively correlated with flow resistance index and negative correlation was observed between the intensity of trophic skin changes and the pulsatility index.

B-flow imaging of vascular structure for the diagnosis of liver tumor

PURPOSE

B-flow is a non-Doppler-based technology for visualizing blood flow and has a high spatial resolution. The aim of this study is to evaluate the blood flow information of liver tumors using B-flow in comparison with color Doppler sonography (CDS).

METHODS

Seventy-nine patients with 82 hepatic nodules were studied using B-flow and CDS. The study group included 45 HCC nodules, 23 liver metastasis nodules, four intrahepatic cholangiocarcinomas (ICC), and 13 hemangiomas. The visualized vascularity and morphological findings of the hepatic tumor vessel were evaluated.

RESULTS

B-flow showed multiple vessels in 48 nodules (58.5 %) and a single vessel in 13 nodules (15.9 %). CDS showed multiple vessels in 44 nodules (53.7 %) and a single vessel in 23 nodules (28.0 %). Multivariate analysis showed basket pattern was significant for HCC (OR 49.263; p = 0.0002), and penetrating vessel was significant for liver metastasis or ICC (OR 14.545; p < 0.0001).

CONCLUSION

B-flow detects hepatic tumor blood flow with sensitivity as high as that of CDS. Vascular structure information obtained using B-flow could be potentially used to diagnose liver tumors.

Translational paradigms in scientific and clinical imaging of cardiac development

Congenital heart defects (CHD) are the most prevalent congenital disease, with 45% of deaths resulting from a congenital defect due to a cardiac malformation. Clinically significant CHD permit survival upon birth, but may become immediately life threatening. Advances in surgical intervention have significantly reduced perinatal mortality, but the outcome for many malformations is bleak. Furthermore, patients living while tolerating a CHD often acquire additional complications due to the long-term systemic blood flow changes caused by even subtle anatomical abnormalities. Accurate diagnosis of defects during fetal development is critical for interventional planning and improving patient outcomes. Advances in quantitative, multidimensional imaging are necessary to uncover the basic scientific and clinically relevant morphogenetic changes and associated hemodynamic consequences influencing normal and abnormal heart development. Ultrasound is the most widely used clinical imaging technology for assessing fetal cardiac development. Ultrasound-based fetal assessment modalities include motion mode (M-mode), two dimensional (2D), and 3D/4D imaging. These datasets can be combined with computational fluid dynamics analysis to yield quantitative, volumetric, and physiological data. Additional imaging modalities, however, are available to study basic mechanisms of cardiogenesis, including optical coherence tomography, microcomputed tomography, and magnetic resonance imaging. Each imaging technology has its advantages and disadvantages regarding resolution, depth of penetration, soft tissue contrast considerations, and cost. In this review, we analyze the current clinical and scientific imaging technologies, research studies utilizing them, and appropriate animal models reflecting clinically relevant cardiogenesis and cardiac malformations. We conclude with discussing the translational impact and future opportunities for cardiovascular development imaging research.

Four-dimensional sonography with B-flow imaging and spatiotemporal image correlation for visualization of the fetal heart

PURPOSE

To use B-flow imaging with 4-dimensional (4D) sonography and spatiotemporal image correlation (STIC) in the evaluation of normal fetal heart and congenital heart disease during pregnancy.

METHOD

Volume data sets of the fetal heart were acquired with automated transverse and longitudinal sweeps of the anterior chest wall. We studied 13 normal fetuses and 2 fetuses with congenital heart disease (1 double-outlet right ventricle and 1 hypoplastic left heart syndrome) at gestation ages ranging from 13 to 39 weeks using transabdominal 4D B-flow sonography with STIC (4D BF-STIC).

RESULTS

4D BF-STIC demonstrated dynamic angiographic features in both normal and abnormal fetal hearts. 4D BF-STIC images could not be obtained in 2 normal fetuses at 18.1 and 33.1 weeks because of the high fetal heart rate and inappropriate fetal position. In normal fetal heart, characteristic hemodynamic changes in both atria and ventricles were clearly demonstrated in systole and diastole. 4D BF-STIC also allowed visualization of the relationship, size, and course of the outflow tracts, thus helping the examiner to better understand the relationships between the vessels. In a case of hypoplastic left heart syndrome, dramatic hemodynamic changes including the right atrium, right ventricle, and pulmonary artery were evident. In a case of double-outlet right ventricle with ventricular septal defect, left-to-right shunt flow through a ventricular septal defect was clearly shown, as were great arteries originating in parallel from the right ventricle.

CONCLUSION

4D BF-STIC provides a means of real-time 3-dimensional evaluation of fetal intracardiac and extracardiac hemodynamics in the second and third trimesters. This novel technique assists in the evaluation of fetal cardiac hemodynamics and may play an important role in future fetal cardiac research and in the evaluation of congenital heart disease in the fetus.

Real-time harmonic contrast material-specific US of focal liver lesions. Radiographics. 2005;25:333-349. [PMID: 15798053 DOI: 10.1148/rg.252045066]

Recent advances in contrast material-enhanced ultrasonography (US) mainly include (a) development of low-acoustic-pressure (low-mechanical-index) harmonic software, capable of obtaining real-time images without disrupting contrast material microbubbles, and (b) commercialization of new contrast media ("second-generation" contrast media), capable of producing intense echo signals in this low-mechanical-index setting. With use of low-mechanical-index continuous-mode contrast-enhanced US, the circulatory kinetic models of various focal liver lesions can be displayed dynamically. Hepatic lesions usually have typical perfusion characteristics and enhancement patterns through the various phases of parenchymal enhancement, which helps characterize lesions and, in most cases, allows definitive diagnosis, even among lesions that exhibit very similar baseline appearances. Because of the use of harmonic technologies at low emission frequencies, there is some loss of spatial resolution and overall image quality, typically resulting in a grainy appearance. In addition, lesion depth affects the detectability of vascularity to some degree in that poor signal arises from deep-seated lesions. Moreover, liver attenuation (eg, in patients with steatosis or chronic liver disease) further reduces the sensitivity of contrast-enhanced US. Nevertheless, with its unique capacity to provide images in real time, low-mechanical-index contrast-enhanced US is the dynamic imaging modality of choice in the differential diagnosis of focal liver lesions.

Ultrasonic biomedical technology; marketing versus clinical reality

Clinical ultrasound imaging is the most frequently used imaging modality in the world accounting for almost 25% of all imaging studies performed. Hence, manufacturers of commercial ultrasound equipment are committing significant engineering resources to advance the technology behind the modality and to improve the diagnostic capabilities of ultrasound imaging. Consequently, new imaging technologies are constantly being introduced to the market under a host of different trademarked names. Hence, this paper will review many of the recent advances in ultrasound imaging and try to differentiate between developments aimed at marketing and those providing real clinical improvements. In particular, we will describe the technologies behind concepts such as coded ultrasound imaging, real time spatial compounding, tissue harmonic imaging, extended field of view imaging as well as 3D and 4D (i.e., real time 3D) imaging. Some of the latest advances in blood flow imaging e.g., B-flow, advanced dynamic flow (ADF) and automatic optimization methods will also be described.

Potential for Differential Diagnosis with Gadolinium-Ethoxybenzyl-Diethylenetriamine Pentaacetic Acid-Enhanced Magnetic Resonance Imaging in Experimental Hepatic Tumors

RATIONALE AND OBJECTIVES

To investigate whether dynamic and delayed magnetic resonance imaging (MRI) with gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid (Gd-EOB-DTPA), a hepatobiliary MRI contrast agent, has potential for the differential diagnosis of experimental hepatic tumors.

METHODS

Twelve male rats received N-nitrosomorpholine solution as drinking water to induce hepatic tumors. After injection of Gd-EOB-DTPA, rats were subjected to dynamic and delayed MRI. The relative enhancement (RE) was calculated, and the time of the maximum RE (Tmax) was evaluated. After MRI, liver was histologically analyzed.

RESULTS

One hundred sixty-three hepatic tumors 3-12 mm in diameter were induced after 18 weeks of treatment with 0.01 wt/vol% of N-nitrosomorpholine, and 81 of them were evaluated. The RE in hyperplastic nodules (HPNs) was significantly higher than that in moderately or poorly differentiated hepatocellular carcinomas (HCCs) in the late phase, whereas there was no significant difference in RE between well-differentiated HCCs and HPNs. The average Tmax in HPNs was about 13 minutes, whereas that of each differentiated HCCs was about 1 minute.

CONCLUSIONS

It was possible to differentiate benign HPNs and malignant HCCs (especially well-differentiated HCCs) by evaluating the change of RE or comparison of Tmax with Gd-EOB-DTPA-enhanced MRI.

Evaluation of blood flow in carotid artery stenosis using B-flow sonography

B-flow ultrasonography can directly visualize blood streams by reflecting the intravascular red blood cells, and so can detect turbulent flow in vessels. B-flow sonography was used to evaluate flow abnormalities in patients with cervical carotid artery stenosis, and to investigate the mechanism of large embolus formation that may cause distal arterial occlusion. Twenty-two patients with > or = 60% stenosis of the cervical carotid artery excluding cardiovascular embolism were examined by B-flow and color Doppler sonography. Two patients had distal embolism as revealed by digital subtraction angiography, 16 patients had lacunar infarction, and four patients had transient ischemic attacks. B-flow sonography demonstrated reverse flow at the poststenotic site in patients with > or = 70% stenosis. Increased echogenicity at the site of the stenosis was seen in patients with at least 80% stenosis. Prestenotic reverse flow was seen in nine patients with > or = 85% stenosis. The two patients with distal embolism had decreased echogenicity and flow velocity, and diastolic flow was absent. B-flow sonography could detect various turbulent flow patterns and changes in echogenicity associated with cervical carotid artery stenosis. Prestenotic reverse flow and decreased flow velocity may be potential causes of distal embolism. B-flow sonography is a useful method for the evaluation of flow abnormality in patients with carotid artery stenosis.

Early assessment of the therapeutic response to radio frequency ablation for hepatocellular carcinoma: utility of gray scale harmonic ultrasonography with a microbubble contrast agent

OBJECTIVE

To evaluate the utility of gray scale harmonic ultrasonography with a microbubble contrast agent in the early assessment of the therapeutic response to radio frequency ablation for hepatocellular carcinoma.

METHODS

Seventy-five patients with 81 nodular hepatocellular carcinomas (1.3-4.8 cm) treated with percutaneous radio frequency ablation were evaluated with contrast-enhanced gray scale harmonic ultrasonography after intravenous bolus injection of a galactose-based microbubble contrast agent. The vascularity within the ablation zones was evaluated with a continuous scan for 3 to 5 seconds between 15 and 30 seconds after initiation of contrast agent injection. To evaluate the perfusion of the ablation zones, intermittent stimulated acoustic emission imaging was performed with a rapid sweeping technique from the end of the continuous scan. All patients underwent follow-up 3-phase helical computed tomography at 1 month after radio frequency ablation and were followed for at least 1 year. The results of contrast-enhanced ultrasonography were compared with those of follow-up computed tomography in terms of the presence or absence of residual unablated tumors.

RESULTS

In 10 (12%) of the 81 treated hepatocellular carcinomas, contrast-enhanced ultrasonography showed either nodular or crescentic enhancing foci at the margins of ablation zones, suggesting residual unablated tumors. Contrast-enhanced computed tomography obtained 1 month after radio frequency ablation confirmed the residual unablated tumors in the same 10 lesions. Diagnostic agreement between 1-month follow-up computed tomography and contrast-enhanced ultrasonography was achieved in all 81 cases (100%).

CONCLUSIONS

Contrast-enhanced gray scale harmonic ultrasonography can be a reliable alternative to contrast-enhanced computed tomography in the early assessment of the therapeutic response to radio frequency ablation for hepatocellular carcinoma.

B-Flow, a Non-Doppler Technology for Flow Mapping: Early Experience in the Abdomen

B-flow imaging is a non-Doppler technology for blood flow imaging that was introduced on high-frequency transducers at the end of the last decade. It has only recently become available on convex array and sector transducers suitable for abdominal examination. B-flow technology is not plagued by some of the troublesome pitfalls often encountered during color and power Doppler flow imaging, and appears promising as an adjunct to Doppler evaluation of blood flow in the abdomen. This article introduces the author's early experience using B-flow in the abdomen, and illustrates the potential advantages this technique offers relative to Doppler flow mapping.

Focal hepatic lesions: evaluation with contrast-enhanced gray-scale harmonic US

OBJECTIVE

To determine the findings of various focal hepatic lesions at contrast-enhanced gray-scale ultrasound (US) using a coded harmonic angio (CHA) technique and emphasizing lesion characterization.

MATERIALS AND METHODS

The study involved 95 patients with 105 focal hepatic lesions, namely 51 hepatocellular carcinomas (HCCs), 22 metastases, 22 hemangiomas, four cases of focal nodular hyperplasia (FNH), and six nontumorous nodules. After the injection of a microbubble contrast agent (SH U 508A), gray-scale harmonic US studies using a CHA technique were performed with a combination of continuous scanning to assess the intratumoral vasculature (vascular imaging) and interval-delay scanning to determine the sequential enhancement pattern (acoustic emission imaging). Each imaging pattern was categorized and analyzed.

RESULTS

At vascular imaging, 69% of HCCs (35/51) showed irregular branching vessels, while in 91% of metastases (20/22) a peripherally stippled pattern was observed. Intratumoral vessels were absent in 95% of hemangiomas (21/22) and all nontumorous lesions (6/6), while in 75% of FNHs (3/4) a spoke-wheel pattern was evident. At acoustic emission imaging, 71% of HCCs (36/51) showed heterogeneous enhancement and 86% (19/22) of metastases showed rim- or flame-like peripheral enhancement during the early phase, with washout occurring in all HCCs and metastases (100%, 73/73) during the late phase. In hemangiomas, enhancement was either peripheral and nodular (19/22, 86%) or persistent and homogeneous (3/22, 14%), and 75% of FNHs (3/4) became isoechoic during the late phase.

CONCLUSION

At contrast-enhanced gray-scale US using a CHA technique, a period of continuous scanning depicted the intratumoral vasculature, and interval-delay scanning demonstrated the sequential enhancement pattern. The characteristic findings of various focal hepatic lesions were thus determined.