Contrast-enhanced ultrasound (CEUS) prediction of focal liver lesions in patients after liver transplantation in comparison to histopathology results

High resolution flow (HR Flow) and glazing flow in cases of hepatic flow changes: Comparison to color-coded Doppler sonography (CCDS)

AIM

To evaluate the possibilities of flow detection using high resolution flow (HR Flow) and Glazing Flow technique in patients with liver parenchymal changes and flow changes in comparison to colour coded Doppler sonography (CCDS).

MATERIAL AND METHODS

All examinations were performed using a multi frequency matrix convex probe with high resolution technique (SC6-1U/Resona7, Mindray, Shenzhen, China) by one experienced examiner to evaluate the venous, portal venous and arterial liver flow with digital documentation of the dynamic flow parameters like peak systolic flow, end-diastolic flow and resistance index. For liver parenchymal stiffness changes shear wave elastography was performed with at least 10 measurements. By two independent readers an elevation was performed to evaluate the image quality and the degree of flow artefacts, from 0 = not available to 5 points with excellent image quality without flow artefacts.

RESULTS

All 40 patients (24 men, 16 women, age 27-83 years, mean 56±5 years) showed morphology changes from B-Mode of the liver parenchyma to inhomogeneous tissue with higher stiffness evaluated by the shear wave elastography (1.45 m/s up to 2.79 m/s±1.79 m/s, considering F1 up to F4 fibrosis) and in 15 cases histopathologically proven liver cirrhosis. In 9 cases after non-acute thrombosis flow reduction of the portal vein was the reason for the diameter less than 5 mm. Flow parameters for the venous flow were between 8 cm/s up to 29 cm/s, mean 14±4 cm/s, for the hepatic portal vein 5 cm/s up to 57 cm/s, mean 17±5 cm/s, for the hepatic artery systolic flow between 50 cm/s up to 127±33 cm/s, end-diastolic flow from 22 cm/s up to 47 cm/s±8 cm/s. Resistance index for the hepatic artery was between 0.41 up to 0.73, mean 0.67±0.25. The image quality for CCDS over all cases was evaluated for CCDS between 1 up to 4. The mean quality was 2.5±0.5, for HR Flow in combination with Glazing flow 3±0.5, with significant differences for the 2 readers (P <  0.01).

CONCLUSION

Combination of HR Flow with Glazing Flow could be helpful to evaluate morphological und hemodynamic changes of liver arterial flow, portal venous and venous flow. Reduction of flow artefacts in combination with a higher image quality could be helpful for optimizing the digital measurements also for follow up examinations.

Molecular ultrasound imaging of neutrophil membrane-derived biomimetic microbubbles for quantitative evaluation of hepatic ischemia-reperfusion injury

Rationale: Early diagnosis of hepatic ischemia-reperfusion injury (HIRI), the major cause of early allograft dysfunction or primary non-function, is critical in orthotopic liver transplantation. However, liver biopsy is still the primary method for HIRI evaluation in clinical practice despite its numerous complications and shortcomings such as hemorrhage and inaccuracy. Herein, we aimed to develop a non-invasive, highly accurate, and specific method for detecting HIRI. Methods: We developed a top-down and bottom-up strategy to fabricate neutrophil biomimetic microbubbles (MB_neu). Neutrophil membrane was mixed with liposomes at a defined mass ratio by sonication. The air in the vial was exchanged with perfluoropropane, and then the solution was mechanically vibrated to form MB_neu. Results: MB_neu retained the neutrophil proteins, preferentially targeted inflamed hepatic tissue in a rat model of HIRI, and demonstrated physicochemical properties typical of liposome-based MBs because of its artificial phospholipid content. With MB_neu we can quantitively evaluate the severity of HIRI, which is helpful for early diagnosis and the prediction of outcome. In addition, MB_neu was shown to be safe and showed no immunogenicity. Conclusion: We demonstrated molecular ultrasound imaging of HIRI with MB_neu. This new synthesis strategy may be applied to different clinical scenarios using other cell types in the future.

[CEUS-diagnosis of benign liver lesions]

CLINICAL/METHODICAL ISSUE

Focal liver lesions are commonly seen during routine ultrasound examinations.

STANDARD RADIOLOGICAL METHODS

With native ultrasound there are lesions that cannot be sufficiently characterized. In these cases additional imaging might be necessary.

METHODICAL INNOVATIONS

With contrast-enhanced ultrasound (CEUS), focal liver lesions can be characterized with high diagnostic accuracy. After the ultrasound contrast agent has been injected into a peripheral vein, the examiner saves video loops of the arterial, portal venous and late contrast phases. Combing the findings of native and contrast-enhanced ultrasound allows not only assessment of the etiology as benign or malignant but also detailed characterization of the focal liver lesion in most cases.

PERFORMANCE

Using CEUS, focal liver lesions can be characterized with a sensitivity of over 95% and a specificity of about 83%.

ACHIEVEMENTS

The advantages of CEUS include that there is no radiation exposure and that the ultrasound contrast agent has no effects on the function of the liver, kidneys or the thyroid gland. The main limiting factors for CEUS are bowel gas and obesity of the patient.

PRACTICAL RECOMMENDATIONS

CEUS can visualize micro- and macrovascularization of benign focal liver lesions in real time. It is a useful imaging modality in unclear cases.

Evaluation of short-term efficacy of radiofrequency ablation for hepatocellular carcinoma by dynamic three-dimensional contrast-enhanced ultrasound

BACKGROUND

Radiofrequency ablation (RFA) plays an important role in non-surgical treatment of hepatocellular carcinoma (HCC). Accurate assessment of the residual status of HCC after operation is of great significance to the future treatment plan. The efficacy of RFA is often evaluated by various imaging methods in clinic. Ultrasound has attracted more and more attention in clinical evaluation of the efficacy of RFA, because of its non-invasive, convenient, and repeatable advantages. Dynamic three-dimensional contrast-enhanced ultrasound (3DCEUS) can dynamically display the blood perfusion status of tumor tissue in three-dimensional space, which is expected to provide a new imaging method for evaluating the efficacy of RFA.

AIM

To evaluate the short-term efficacy of RFA for HCC by 3DCEUS and the clinical value of 3DCEUS.

METHODS

We retrospectively analyzed 93 patients (including 117 tumors) with HCC who underwent ultrasound-guided RFA at our hospital from March 2016 to November 2018. All patients underwent 3DCEUS one month after operation. Enhanced magnetic resonance imaging (CEMRI) was used as the "golden standard" to analyze the efficacy of 3DCEUS in evaluating the efficacy of RFA.

RESULTS

CEMRI evaluation showed that 82.05% (96/117) of the tumors were completely ablated and 17.95% (21/117) were incompletely ablated. 3DCEUS evaluation showed that 82.91% (97/117) of the tumors were completely ablated and 17.09% (20/117) were incompletely ablated. The sensitivity, specificity, and accuracy of 3DCEUS in evaluating tumor residues after RFA were 90.48% (19/21), 98.96% (95/96), and 97.44% (114/117), respectively. There was no significant difference in diagnostic accuracy between 3DCEUS and CEMRI (P > 0.05).

CONCLUSION

3DCEUS can accurately evaluate the short-term efficacy of RFA for HCC and has high clinical value.

Clinical value of contrast-enhanced ultrasound in radiofrequency ablation for primary hepatocellular carcinoma undetectable by conventional ultrasound

BACKGROUND

Surgical resection is the first choice for the treatment of hepatocellular carcinoma (HCC). For patients who have unresectable HCC, radiofrequency ablation (RFA) is an important choice. RFA is usually guided by imaging methods including ultrasound, computed tomography (CT), and magnetic resonance imaging (MRI). CT has radiation damage, and MRI is not suitable for some patients (such as those who have pacemaker implantation, vascular stent implantation, or heart valve replacement). Ultrasound as a guidance method has the advantages of non-radiation, simplicity, and flexibility, and has been widely used in clinical practice. It has become an ideal and effective imaging method guiding RFA for liver tumors.

AIM

To investigate the clinical value of contrast-enhanced ultrasound (CEUS) in RFA for HCC undetectable by conventional ultrasound.

METHODS

A total of 52 patients with HCC undetectable by conventional ultrasound, but detected by contrast-enhanced MRI (CEMRI) and confirmed by pathology were selected as subjects (with a total of 75 tumors). All patients underwent CEUS and RFA guided by CEUS. CEMRI and CEUS were performed to evaluate the therapeutic effect after operation.

RESULTS

There was no significant difference in the detection rate between CEUS and CEMRI (P > 0.05). Time to starting enhancement and time to enhancement peak were significantly shorter in HCC tissues than in adjacent normal tissues, but peak intensity was significantly higher in HCC tissues than in adjacent normal tissues before operation (P < 0.05). Regardless of whether HCC was completely ablated or not, there was no significant difference in the accuracy rate between CEUS and CEMRI (P > 0.05). Serum alpha fetoprotein after operation was significantly lower than that before operation (P < 0.05).

CONCLUSION

CEUS can effectively detect and accurately locate HCC undetectable by conventional ultrasound and guide RFA, thus providing a reliable imaging method for evaluating RFA efficacy.

Multislice computed tomography/contrast-enhanced ultrasound image fusion as a tool for evaluating unclear renal cysts

Ultrasonography is a generally accepted imaging technique for diagnosing and monitoring cystic renal lesions. The widely used Bosniak classification (I-IV) categorizes renal cystic lesions into five distinctive groups according to ultrasonography and computed tomography (CT) image criteria. For solid renal lesions, determination of vascularity is discriminatory for malignancy in most instances. In indeterminate cases, contrast-enhanced ultrasound (CEUS) and magnetic resonance imaging/CT-ultrasound image fusion are able to detect and characterize difficult pathologies, with superior performance to either technique alone. In contrast to multislice CT (MS-CT), ultrasound image fusion is a real-time imaging technique that can be used in combination with other cross-sectional imaging modalities. This technical note describes state-of-the-art image fusion of CEUS and MS-CT to detect and characterize unclear renal pathologies.

Computational Modeling in Liver Surgery

The need for extended liver resection is increasing due to the growing incidence of liver tumors in aging societies. Individualized surgical planning is the key for identifying the optimal resection strategy and to minimize the risk of postoperative liver failure and tumor recurrence. Current computational tools provide virtual planning of liver resection by taking into account the spatial relationship between the tumor and the hepatic vascular trees, as well as the size of the future liver remnant. However, size and function of the liver are not necessarily equivalent. Hence, determining the future liver volume might misestimate the future liver function, especially in cases of hepatic comorbidities such as hepatic steatosis. A systems medicine approach could be applied, including biological, medical, and surgical aspects, by integrating all available anatomical and functional information of the individual patient. Such an approach holds promise for better prediction of postoperative liver function and hence improved risk assessment. This review provides an overview of mathematical models related to the liver and its function and explores their potential relevance for computational liver surgery. We first summarize key facts of hepatic anatomy, physiology, and pathology relevant for hepatic surgery, followed by a description of the computational tools currently used in liver surgical planning. Then we present selected state-of-the-art computational liver models potentially useful to support liver surgery. Finally, we discuss the main challenges that will need to be addressed when developing advanced computational planning tools in the context of liver surgery.