Three-dimensional contrast-enhanced ultrasound of the liver: experience of 92 cases

3D-CEUS/MRI-CEUS fusion imaging vs 2D-CEUS after locoregional therapies for hepatocellular carcinoma: a multicenter prospective study of therapeutic response evaluation

OBJECTIVES

To compare the diagnostic accuracy of 3D contrast-enhanced ultrasound (CEUS)/MRI-CEUS fusion imaging with 2D-CEUS in assessing the response of hepatocellular carcinoma (HCC) to locoregional therapies in a multicenter prospective study.

MATERIALS AND METHODS

A consecutive series of patients with HCC scheduled for locoregional treatment were enrolled between April 2021 and March 2023. Patients were randomly divided into 3D-CEUS/MRI-CEUS fusion imaging group (3D/fusion group) or 2D-CEUS group (2D group). CEUS was performed 1 week before and 4-6 weeks after locoregional treatment. Contrast-enhanced MRI (CE-MRI) 4-6 weeks after treatment was set as the reference standard. CEUS images were evaluated for the presence or absence of viable tumors. Diagnostic performance criteria, including sensitivity, specificity, accuracy, and area under the curve (AUC), were determined for each modality.

RESULTS

A total of 140 patients were included, 70 patients in the 2D group (mean age, 60.2 ± 10.4 years) and 70 patients in the 3D/fusion group (mean age, 59.8 ± 10.6 years). The sensitivity of the 3D/fusion group was 100.0% (95% CI: 75.9, 100.0), higher than that of the 2D group (55.6%, 95% CI: 22.7, 84.7; p = 0.019). The specificity of the 3D/fusion group was 96.3% (95% CI: 86.2, 99.4), which was comparable to that of the 2D group (98.4%, 95% CI: 90.0, 99.9; p = 0.915). The AUC of the 3D/fusion group was 0.98 (95% CI: 0.95, 1.00), higher than that of the 2D group (0.77, 95% CI: 0.56, 0.98; p = 0.020).

CONCLUSION

3D-CEUS/MRI-CEUS fusion imaging exhibits superior diagnostic accuracy in evaluating the treatment response to locoregional therapies for HCC.

CLINICAL RELEVANCE STATEMENT

3D-CEUS/MRI-CEUS fusion imaging can be applied for post-treatment assessment of residual tumors in HCC undergoing locoregional treatment, offering potential benefits in terms of accurate diagnosis and clinical management.

KEY POINTS

Evaluating for HCC recurrence following locoregional therapy is important. 3D-CEUS/MRI-CEUS fusion imaging achieved a higher sensitivity than 2D-CEUS in assessing residual tumors after locoregional therapies. 3D-CEUS/MRI-CEUS fusion imaging can help clinicians intervene early in residual HCC lesions after locoregional treatment.

A noval noninvasive targeted therapy for osteosarcoma: the combination of LIFU and ultrasound-magnetic-mediated SPIO/TP53/PLGA nanobubble

Purpose

Osteosarcoma (OS) is the most common type of primary malignant bone tumor. Transducing a functional TP53 gene can effectively inhibit OS cell activity. Poly lactic acid-glycolic acid (PLGA) nanobubbles (NBs) mediated by focused ultrasound (US) can introduce exogenous genes into target cells in animal models, but this technique relies on the passive free diffusion of agents across the body. The inclusion of superparamagnetic iron oxide (SPIO) in microbubbles allows for magnetic-based tissue localization. A low-intensity-focused ultrasound (LIFU) instrument was developed at our institute, and different intensities of LIFU can either disrupt the NBs (RLI-LIFU) or exert cytocidal effects on the target tissues (RHI-LIFU). Based on these data, we performed US-magnetic-mediated TP53-NB destruction and investigated its ability to inhibit OS growth when combined with LIFU both in vitro and in vivo.

Methods

Several SPIO/TP53/PLGA (STP) NB variants were prepared and characterized. For the in vitro experiments, HOS and MG63 cells were randomly assigned into five treatment groups. Cell proliferation and the expression of TP53 were detected by CCK8, qRT-PCR and Western blotting, respectively. In vivo, tumor-bearing nude mice were randomly assigned into seven treatment groups. The iron distribution of Perls' Prussian blue-stained tissue sections was determined by optical microscopy. TUNEL-DAPI was performed to examine apoptosis. TP53 expression was detected by qRT-PCR and immunohistochemistry.

Results

SPIO/TP53/PLGA NBs with a particle size of approximately 200 nm were prepared successfully. For in vitro experiments, ultrasound-targeted transfection of TP53 overexpression in OS cells and efficient inhibition of OS proliferation have been demonstrated. Furthermore, in a tumor-bearing nude mouse model, RLI-LIFU-magnetic-mediated SPIO/TP53/PLGA NBs increased the transfection efficiency of the TP53 plasmid, resulting in apoptosis. Adding RHI-LIFU to the treatment regimen significantly increased the apoptosis of OS cells in vivo.

Conclusion

Combining LIFU and US-magnetic-mediated SPIO/TP53/PLGA NB destruction is potentially a novel noninvasive and targeted therapy for OS.

Loco-regional treatment of hepatocellular carcinoma: Role of contrast-enhanced ultrasonography

Hepatocellular carcinoma (HCC) is one of the few cancers for which locoregional treatments (LRTs) are included in international guidelines and are considered as a valid alternative to conventional surgery. According to Barcelona Clinic Liver Cancer classification, percutaneous treatments such as percutaneous ethanol injection, radiofrequency ablation and microwave ablation are the therapy of choice among curative treatments in patients categorized as very early and early stage, while transcatheter arterial chemoembolization is considered the better option for intermediate stage HCC. A precise assessment of treatment efficacy and surveillance is essential to optimize survival rate, whereas residual tumor requires additional treatment. Imaging modalities play a key role in this task. Currently, contrast-enhanced computed tomography/magnetic resonance imaging are considered the standard imaging modalities for this purpose. Contrast enhanced ultrasound (CEUS), using second generation contrast agents, plays an increasingly important role in detecting residual disease after LRTs. CEUS is a straightforward to perform, repeatable and cost-effective imaging modality for patients with renal failure or iodine allergies. Due to the ability to focus on single regions, CEUS can also provide high temporal resolution. Moreover, several studies have reported the same or better diagnostic accuracy as contrast-enhanced computed tomography for assessing tumor vascularity 1 mo after LRTs, and recently three-dimensional (3D)-CEUS has been reported as a promising technique to improve the evaluation of tumor response to therapy. Furthermore, CEUS could be used early after procedures in monitoring HCC treatments, but nowadays this indication is still debated, and data from literature are conflicting, especially after transcatheter arterial chemoembolization procedure.

Contrast-enhanced ultrasound-guided celiac plexus neurolysis in patients with upper abdominal cancer pain: initial experience

OBJECTIVES

The purpose of this study was to determine the efficacy and safety of contrast-enhanced ultrasound (CEUS)-guided celiac plexus neurolysis (CPN) in patients with upper abdominal cancer pain.

METHODS

Thirty-five patients with upper abdominal cancers tortured by intractable upper abdominal pain underwent CEUS-guided CPN with ethanol. The pain alleviation and opioid intake were observed and evaluated during a 3-month follow-up after CPN. The dispersion of alcohol around the aorta was evaluated on 3D-CEUS. Complications were assessed during CPN and at follow-up.

RESULTS

All of the 35 patients' CPN was successfully achieved. Pain relief was observed in 28 (80%), 20 (57.1%), 27 (77.1%), 20 (57.1%), and 10 (29.4%) patients immediately, 1 day, 1 month, 2 months, and 3 months after CPN, respectively. The agent dispersion around the aorta on CEUS images of 28 patients who showed pain relief was at least 90° of the circumference around the aorta. The median duration of pain alleviation was 2.7 months (95% confidence interval [CI], 2.5-2.9). Less than half of the patients had minor complications including irritant pain at the puncture site (8 of 35; 22.9%), diarrhea (4 of 35; 11.4%), nausea and vomiting (3 of 35; 8.6%), and post-procedural hypotension (1 of 35; 2.9%).

CONCLUSIONS

CEUS-guided CPN is a safe and effective method to alleviate refractory upper abdominal pain in patients with upper abdominal cancers. CEUS image allows the visualization of puncture path and observation of drug dispersion. The pain relief is relevant to the dispersion of neurolytic agent around the aorta.

KEY POINTS

• CEUS-guided celiac plexus neurolysis (CPN) is feasible and easy. • It allows direct visualization of the diffusion of the neurolytic agent in the retroperitoneal anatomic space. • CEUS-guided CPN improves safety of CPN by clearly delineating the needle path.

Comparison of Real-Time Two-Dimensional and Three-Dimensional Contrast-Enhanced Ultrasound to Quantify Flow in an In Vitro Model: A Feasibility Study

BACKGROUND This feasibility study aimed to compare real-time two-dimensional contrast-enhanced ultrasound (2D-CEUS) and three-dimensional contrast-enhanced ultrasound (3D-CEUS) to quantify flow in an in vitro model. MATERIAL AND METHODS Five polyvinyl chloride (PVC) tubes were used for the perfusion models and used SonoVue ultrasound contrast agent with a perfusion volume ratio of 1: 2: 4: 8: 16. The contrast was injected at a constant speed to compare the raw quantitative data of 2D-CEUS and 3D-CEUS at angles of 0°, 45°, and 90°. The coefficient of variation (CV) of the peak intensity (PI) in the model were compared and the correlations between weighted PI and perfusion volume were analyzed. RESULTS In the three angles used, real-time 3D-CEUS resulted in a more comprehensive view of the spatial relationships in the perfusion model. Using real-time 2D-CEUS, the mean CV was 0.92±0.36, and the mean CV in the real-time 3D-CEUS model was significantly less at 0.48±0.32 (p<0.001). Quantitative 3D-CEUS parameters showed a good correlation with those of 2D-CEUS with an r-value of 0.93 (p=0.02). The r-value of weighted PI and the perfusion ratio using 2D-CEUS was 0.66 (p=0.23) compared with values in 3D-CEUS of 0.84 (p=0.08). CONCLUSIONS The combination of real-time 3D-CEUS and quantitative analysis identified the spatial distribution of the changes in angle in the model, which was less influenced by sectional planes, and was more representative of the perfusion volume when compared with 2D-CEUS. Quantitative real-time 3D-CEUS requires in vivo studies to evaluate the potential role in the clinical evaluation of vascular perfusion of malignant tumors.

Preliminary study of real-time three-dimensional contrast-enhanced ultrasound of sentinel lymph nodes in breast cancer

PURPOSE

To investigate the clinical value of real-time three-dimensional contrast-enhanced ultrasound (3D-CEUS) in the detection of sentinel lymph nodes (SLNs) and drainage lymphatics in breast cancer patients.

METHOD

The prospective study was performed in women with pathology-confirmed T1/2 breast cancer between June 2016 and December 2017 who underwent sentinel lymph node biopsy and 3D-CEUS. The number, size, location, enhancement pattern of SLNs, and the lymphatic drainage patterns were reviewed. The routes, location of SLNs, and lymph channels (LCs) on the surface were marked. All patients underwent blue dye-guided sentinel lymph node biopsy (SLNB) finally.

RESULTS

According to the postoperative pathology findings and the blue dye staining of the lymphatic drainage routes, there are six patterns of lymphatic drainage routes and the coincidence rate of the 3D-CEUS was 97.4%; the sensitivity, specificity, positive predictive value, negative predictive value, the LN detection rate, and the correct diagnosis rate of the 3D-CEUS were 75%, 93.0%, 81.8%, 89.9%, 95.3%, and 87.7%, respectively.

CONCLUSION

3D-CEUS is a new feasible and useful approach to detect the SLNs and LCs. 3D-CEUS can accurately localize the LCs and SLNs and estimate the presence of metastatic lymph nodes.

KEY POINTS

• The three-dimensional contrast-enhanced ultrasound can detect the sentinel lymph nodes. • The three-dimensional contrast-enhanced ultrasound can show the stereo direction of sentinel lymph nodes and lymph drainage routes. • The three-dimensional contrast-enhanced ultrasound can accurately localize the LCs and SLNs and estimate the presence of metastatic lymph nodes.

Dynamic Three-Dimensional Contrast-Enhanced Ultrasound to Predict Therapeutic Response of Radiofrequency Ablation in Hepatocellular Carcinoma: Preliminary Findings

BACKGROUND & AIMS

To investigate the value of dynamic three-dimensional contrast-enhanced ultrasound (3D-CEUS) in the assessment of therapeutic response of hepatocellular carcinoma (HCC) treated with radiofrequency ablation (RFA).

METHODS

Forty-two patients (31 men and 11 women; mean age (52.1 ± 13.1 years)) with 42 clinical diagnosed HCC lesions (size range 14-48 mm; mean size 28.4 ± 9.9 mm) treated by RFA were included. All patients underwent two-dimensional contrast-enhanced ultrasound (2D-CEUS) and 3D-CEUS 1 month after treatment. Two radiologists assessed the absence (complete response, CR) or presence (residual tumor, RT) of any arterially hyperenhancing nodules within or along the margin of the treated HCC lesions. Complete response on magnetic resonance (MR) imaging acted as standard of reference (SOR).

RESULTS

After RFA treatment, 3D-CEUS was successfully conducted in 34 HCC lesions. CR was observed on both 2D-CEUS and 3D-CEUS in 25/42 (59.5%) HCC and RT in 6/42 (14.3%) HCC lesions. In 3/42 (7.1%) HCC lesion, RT was documented by SOR and 3D-CEUS, but it was not appreciable at 2D-CEUS. In 3/42 (7.1%) HCC lesion, the presence of peripheral RT was suspected by both 2D-CEUS and 3D-CEUS, but it was not confirmed by SOR. No statistically significant difference between 2D-CEUS and 3D-CEUS in depicting either CR or RT was found (P = 0.25). Combined with dynamic 3D-CEUS, the diagnostic accuracy was improved from 85.7% to 92.9%.

CONCLUSIONS

3D-CEUS might be helpful in better diagnostic performance in the assessment of therapeutic response of HCC treated after RFA.

Contribution of 3-Dimensional Contrast-Enhanced Ultrasonography (CEUS) Compared With 2-Dimensional CEUS in the Analysis of Liver Tumors

OBJECTIVES

In this study, we investigated the vascular characteristics of liver tumors on 3-dimensional (3D) and 2-dimensional (2D) contrast-enhanced ultrasonography (CEUS). The clinical value of these CEUS methods in the diagnosis of benign and malignant liver tumors was evaluated and compared.

METHODS

A total of 126 liver tumors were examined by conventional ultrasonography (US), 2D CEUS, and dynamic 3D CEUS (frequency range, 1-6 MHz; focusing ability, 2-25 cm in depth; mechanical index, 0.09). Dynamic 3D CEUS images were postprocessed with high-resolution intelligent tomographic technology. The sensitivity and specificity of the CEUS methods in differentiating benign and malignant liver tumors were compared, as were the vascular characteristics (including the number and spatial relationships of the tumor vessels, such as origin and continuity) of the tumors in the arterial phase.

RESULTS

The imaging methods did not significantly differ in their sensitivity and specificity for differentiating benign and malignant liver tumors (P > .05). Dynamic 3D CEUS was significantly better than 2D CEUS in revealing the vascular characteristics of the tumors (P < .05). The vascular morphologic characteristics of benign and malignant hepatic tumors in the arterial phase of dynamic 3D CEUS using intelligent tomographic technology differed significantly (P < .05).

CONCLUSIONS

Dynamic 3D CEUS of liver tumors provides a more intuitive and comprehensive view of the spatial relationships of their blood vessels, including their peripheral and internal distribution. The volume information obtained with dynamic 3D CEUS combined with intelligent tomographic technology can improve the US-based diagnosis of liver tumors and thus guide their treatment.

Quantitative Three-Dimensional Dynamic Contrast-Enhanced Ultrasound Imaging: First-In-Human Pilot Study in Patients with Liver Metastases

Purpose: To perform a clinical assessment of quantitative three-dimensional (3D) dynamic contrast-enhanced ultrasound (DCE-US) feasibility and repeatability in patients with liver metastasis, and to evaluate the extent of quantitative perfusion parameter sampling errors in 2D compared to 3D DCE-US imaging.

Materials and Methods: Twenty consecutive 3D DCE-US scans of liver metastases were performed in 11 patients (45% women; mean age, 54.5 years; range, 48-60 years; 55% men; mean age, 57.6 years; range, 47-68 years). Pairs of repeated disruption-replenishment and bolus DCE-US images were acquired to determine repeatability of parameters. Disruption-replenishment was carried out by infusing 0.9 mL of microbubbles (Definity; Latheus Medical Imaging) diluted in 35.1 mL of saline over 8 min. Bolus consisted of intravenous injection of 0.2 mL microbubbles. Volumes-of-interest (VOI) and regions-or-interest (ROI) were segmented by two different readers in images to extract 3D and 2D perfusion parameters, respectively. Disruption-replenishment parameters were: relative blood volume (rBV), relative blood flow (rBF). Bolus parameters included: time-to-peak (TP), peak enhancement (PE), area-under-the-curve (AUC), and mean-transit-time (MTT).

Results: Clinical feasibility and repeatability of 3D DCE-US using both the destruction-replenishment and bolus technique was demonstrated. The repeatability of 3D measurements between pairs of repeated acquisitions was assessed with the concordance correlation coefficient (CCC), and found to be excellent for all parameters (CCC > 0.80), except for the TP (0.74) and MTT (0.30) parameters. The CCC between readers was found to be excellent (CCC > 0.80) for all parameters except for TP (0.71) and MTT (0.52). There was a large Coefficient of Variation (COV) in intra-tumor measurements for 2D parameters (0.18-0.52). Same-tumor measurements made in 3D were significantly different (P = 0.001) than measurements made in 2D; a percent difference of up to 86% was observed between measurements made in 2D compared to 3D in the same tumor.

Conclusions: 3D DCE-US imaging of liver metastases with a matrix array transducer is feasible and repeatable in the clinic. Results support 3D instead of 2D DCE US imaging to minimize sampling errors due to tumor heterogeneity.

High Resolution Ultrasound Superharmonic Perfusion Imaging: In Vivo Feasibility and Quantification of Dynamic Contrast-Enhanced Acoustic Angiography

Mapping blood perfusion quantitatively allows localization of abnormal physiology and can improve understanding of disease progression. Dynamic contrast-enhanced ultrasound is a low-cost, real-time technique for imaging perfusion dynamics with microbubble contrast agents. Previously, we have demonstrated another contrast agent-specific ultrasound imaging technique, acoustic angiography, which forms static anatomical images of the superharmonic signal produced by microbubbles. In this work, we seek to determine whether acoustic angiography can be utilized for high resolution perfusion imaging in vivo by examining the effect of acquisition rate on superharmonic imaging at low flow rates and demonstrating the feasibility of dynamic contrast-enhanced superharmonic perfusion imaging for the first time. Results in the chorioallantoic membrane model indicate that frame rate and frame averaging do not affect the measured diameter of individual vessels observed, but that frame rate does influence the detection of vessels near and below the resolution limit. The highest number of resolvable vessels was observed at an intermediate frame rate of 3 Hz using a mechanically-steered prototype transducer. We also demonstrate the feasibility of quantitatively mapping perfusion rate in 2D in a mouse model with spatial resolution of ~100 μm. This type of imaging could provide non-invasive, high resolution quantification of microvascular function at penetration depths of several centimeters.

3D analysis is superior to 2D analysis for contrast-enhanced ultrasound in revealing vascularity in focal liver lesions - A retrospective analysis of 83 cases

OBJECTIVE

To examine whether dynamic 3D contrast-enhanced ultrasound (CEUS) is superior to 2D imaging in revealing vascularization of focal liver lesions (FLLs).

METHODS

Dynamic 2D and 3D CEUS were used to assess the vascularity of FLLs in 83 patients. The two analyses were carried out sequentially following a bolus intravenous injection of SonoVue contrast agent, one injection of 1.5-2mL was given for each part of the study (one for the 2D and another for the 3D). Due to the large data volume for 3D analysis, only the arterial phase (20-25s) was recorded and analyzed. The data were analyzed by two independent analysts.

RESULTS

The current study included a total of 83 patients with FLL. The diagnosis was established based on histopathology, Computed Tomography (CT), and magnetic resonance imaging (MRI). Among the 83 cases, 61 were hepatocellular carcinomas (include 10 metastasis, 51 HCCs), and the remaining 22 were benign lesions: hemangiomas (n=15), focal nodular hyperplasias (n=4), and inflammatory lesions (n=3). The overall analysis showed similar patterns of enhancement between the 2D and 3D CEUS in the following features: morphological characteristics, and spatial relationships. In comparison to 2D imaging, 3D CEUS reveal more details of the boundary and feeding arteries of the lesions, as well as distorted features of supply vessels of hepatocellular carcinomas.

CONCLUSIONS

Dynamic 3D-CEUS is superior to 2D-CEUS in displaying the spatial relationship of FLLs and their vascularity patterns, and simultaneous imaging of FLL perfusion and anatomic features.

3D versus 2D contrast-enhanced sonography in the evaluation of therapeutic response of hepatocellular carcinoma after locoregional therapies: preliminary findings

OBJECTIVE

To investigate diagnostic performance of 3D contrast-enhanced ultrasound (CEUS) compared with 2D CEUS in the assessment of therapeutic response of hepatocellular carcinoma (HCC) treated with locoregional therapies (LRT).

MATERIALS AND METHODS

Twenty-three consecutive patients (13 men and 10 women; mean age 65.5 years) with 23 HCCs (size range 1.2-7.2 cm; mean size 2.9 ± 1.4 cm) treated by means of radiofrequency ablation (RFA n = 9), transarterial chemoembolization (TACE n = 8), combined RFA and TACE (n = 3), percutaneous alcoholization (n = 2), and wedge resection (n = 1) underwent 2D and 3D CEUS 1 month (30 ± 2 days) after treatment. Magnetic resonance (n = 17) and computed tomography (n = 6) acted as standard of reference (SOR). Two radiologists assessed the absence (complete response CR) or presence (residual tumor RT) of any nodular arterially enhancing area within or along the margin of the treated HCC.

RESULTS

Both 2D and 3D CEUS observed CR in 10/23 (43.5 %) HCCs and RT in 11/23 (47.8 %) HCCs. In 1/23 (4.3 %) HCC, RT was documented by SOR and 2D CEUS, but it was not appreciable at 3D CEUS. In 1/23 (4.3 %) HCC, the presence of peripheral residual tumor was suspected by both 2D and 3D CEUS, but it was not confirmed by SOR. No statistically significant difference between 2D and 3D CEUS in depicting either CR or RT was found (p > 0.05). Sensitivity, specificity, positive and negative predictive values, and accuracy of 3D CEUS were 91.7 % [95 % confidence interval (CI) 0.760-1.073], 90.9 % (95 % CI 0.739-1.079), 91.7, 90.9, and 91.3 %, respectively.

CONCLUSION

2D and 3D CEUS provided similar diagnostic performance in the assessment of therapeutic response of HCC treated with LRT.

Management of hepatocellular carcinoma: The role of contrast-enhanced ultrasound

Hepatocellular carcinoma (HCC) is the sixth most common neoplasm and the third cause of cancer death worldwide. Contrast enhanced ultrasound (CEUS) has been applied for more than ten years and plays increasingly important roles in the management of HCC. On the basis of the Guideline and Good Clinical Practice Recommendations for CEUS in the liver-update 2012 and related literature about the management of HCC, we summarize the main roles and applications of CEUS in the management of HCC, including HCC surveillance, diagnosis, CEUS-guided treatment, treatment response evaluation and follow-up. The diagnostic algorithm for HCC is also suggested. Meanwhile, the comparisons between CEUS and contrast enhanced computed tomography/magnetic resonance imaging (CECT/CEMRI) in these areas are made. Although CEUS is subject to the same limitation as ordinary US and is inferior to CECT/CEMRI in some aspects, CEUS has proved to be of great value in the management of HCC with inherent advantages, such as sufficient high safety profile making it suitable for patients with renal failure or allergic to iodine, absence of radiation, easy reproducibility and high temporal resolution. The tremendous application of CEUS to the diagnosis and treatment of HCC provides more opportunities for patients with HCC diagnosed at different stages.

Three-dimensional contrast-enhanced ultrasonography of intraductal papillary mucinous neoplasms of the pancreas: a comparison with magnetic resonance imaging

OBJECTIVES

The objective of this study was to prospectively compare the diagnostic accuracy of 3-dimensional contrast-enhanced ultrasonography (3D-CEUS) with that of magnetic resonance imaging (MRI) in the study of intraductal papillary mucinous neoplasms (IPMNs) of the pancreas.

METHODS

Thirty consecutive patients with IPMN were studied.

RESULTS

Three patients (10.0%) did not undergo diagnostic 3D-CEUS because of technical problems. Three dimensional CEUS identified 12 (44.4%) main-duct IPMNs versus no cases by MRI (P < 0.001). Intraductal papillary mucinous neoplasm localization showed poor agreement between 3D-CEUS and MRI (κ = 0.058), whereas good agreement was found in detecting the pancreatic calcifications (κ = 1.000). Significant differences between 3D-CEUS and MRI were found regarding the number of lesions detected (1.4 ± 0.8 vs 3.8 ± 3.6; P < 0.001), the detection of mucinous plugs (3.7% vs 50.0%; P < 0.001), chronic pancreatitis (7.4% vs 26.7%; P = 0.031), pancreatic atrophy (0% vs 50.0%; P < 0.001), thick septa (22.2% vs 53.3%; P = 0.004), and mural nodules (25.9% vs 3.3%; P = 0.016). Three dimensional CEUS showed similar results as compared with MRI in evaluating IPMNs smaller than 1 cm of diameter or greater than 2 cm.

CONCLUSIONS

Even if MRI remains the criterion standard technique for the diagnosis of IPMNs, 3D-CEUS can be safely used to follow patients with IPMNs of less than 1 cm.

Hepatocellular carcinoma after ablation: The imaging follow-up scheme

Percutaneous ablation using thermal or chemical methods has been widely used in the treatment of hepatocellular carcinoma (HCC). Nowadays, contrast-enhanced imaging modalities such as computed tomography (CT), magnetic resonance imaging (MRI), and contrast-enhanced ultrasound (CEUS) are widely used to evaluate local treatment response after ablation therapies. CEUS is gaining increasing attention due to its characteristics including real-time scanning, easy performance, lack of radiation, wide availability, and lack of allergy reactions. Several studies have documented that CEUS is comparable to CT or MRI in evaluating local treatment efficacy within 1 mo of treatment. However, little information is available regarding the role of CEUS in the follow-up assessment after first successful ablation treatment. Zheng et al found that in comparison with contrast-enhanced computed tomography (CECT), the sensitivity, specificity, positive predictive value, negative predictive value and overall accuracy of CEUS in detecting local tumor progression (LTP) were 67.5%, 97.4%, 81.8%, 94.4% and 92.3%, respectively, and were 77.7%, 92.0%, 92.4%, 76.7% and 84.0%, respectively for the detection of new intrahepatic recurrence. They concluded that the sensitivity of CEUS in detecting LTP and new intrahepatic recurrence after ablation is relatively low in comparison with CECT, and CEUS cannot replace CECT in the follow-up assessment after percutaneous ablation for HCC. These results are meaningful and instructive, and indicated that in the follow-up period, the use of CEUS alone is not sufficient. In this commentary, we discuss the discordance between CT and CEUS, as well as the underlying mechanisms involved. We propose the combined use of CT and CEUS which will reduce false positive and negative results in both modalities. We also discuss future issues, such as an evidence-based ideal imaging follow-up scheme, and a cost-effectiveness analysis of this imaging follow-up scheme.

Quantitative mapping of tumor vascularity using volumetric contrast-enhanced ultrasound

OBJECTIVE

The goal of this research project was to develop a volumetric strategy for real-time monitoring and characterization of tumor blood flow using microbubble contrast agents and ultrasound (US) imaging.

MATERIALS AND METHODS

Volumetric contrast-enhanced US (VCEUS) imaging was implemented on a SONIX RP US system (Ultrasonix Medical Corp, Richmond, BC) equipped with a broadband 4DL14-5/38 probe. Using a microbubble-sensitive harmonic imaging mode (transducer transmits at 5 MHz and receives at 10 MHz), acquisition of postscan-converted VCEUS data was achieved at a volume rate of 1 Hz. After microbubble infusion, custom data processing software was used to derive microbubble time-intensity curve-specific parameters, namely, blood volume (IPK), transit time (T1/2PK), flow rate (SPK), and tumor perfusion (AUC).

RESULTS

Using a preclinical breast cancer animal model, it is shown that millimeter-sized deviations in transducer positioning can have profound implications on US-based blood flow estimators, with errors ranging from 6.4% to 40.3% and dependent on both degree of misalignment (offset) and particular blood flow estimator. These errors indicate that VCEUS imaging should be considered in tumor analyses, because they incorporate the entire mass and not just a representative planar cross-section. After administration of an antiangiogenic therapeutic drug (bevacizumab), tumor growth was significantly retarded compared with control tumors (P > 0.03) and reflects observed changes in VCEUS-based blood flow measurements. Analysis of immunohistologic data revealed no differences in intratumoral necrosis levels (P = 0.70), but a significant difference was found when comparing microvessel density counts in control with therapy group tumors (P = 0.05).

CONCLUSIONS

VCEUS imaging was shown to be a promising modality for monitoring changes in tumor blood flow. Preliminary experimental results are encouraging, and this imaging modality may prove clinically feasible for detecting and monitoring the early antitumor effects in response to cancer drug therapy.

Era of diagnostic and interventional ultrasound

It is an era of diagnostic and interventional ultrasound (US). Various new techniques such as three-dimensional US (3D US), interventional US, and contrast-enhanced US (CEUS) have been introduced into clinical practice. Dr. Xu and his colleagues have taken advantage of these techniques and carried out a series of relevant studies. Their use of 3D US in the liver, gallbladder, liver tumor volumetry, guidance for ablation, and 3D CEUS has widened the application of 3D US in the clinic. They found that prognosis in patients with hepatocellular carcinoma (HCC) after thermal ablation with curative intent was determined by treatment response to ablation, pretreatment serum AFP, and liver function reserve. Tumor response to treatment was the most predictive factor for long-term survival. They compared the use of percutaneous microwave ablation and radiofrequency ablation for the treatment of HCC and found that both are effective methods in treating HCCs. The local tumor control, complications related to treatment, and long-term survival were equivalent for the two modalities. They first compared the enhancement patterns of HCC and intrahepatic cholangiocarcinoma (ICC) and proposed the diagnostic clues for ICC, liver angiomyolipoma (AML), gallbladder cancer, renal carcinoma, and renal AML, which have greatly enhanced the role of CEUS in the clinic. They also evaluated the diagnostic performance of CEUS in characterizing complex cystic focal liver lesions and the agreement between two investigators with different experience levels; and found that CEUS is especially useful for the young investigator. They assessed the effect of anti-angiogenic gene therapy for HCC treated by microbubble-enhanced US exposure and concluded that gene therapy mediated by US exposure enhanced by a microbubble contrast agent may become a new treatment option for HCC.

Contrast-enhanced ultrasound: The evolving applications

Contrast-enhanced ultrasound (CEUS) is a major breakthrough for ultrasound imaging in recent years. By using a microbubble contrast agent and contrast-specific imaging software, CEUS is able to depict the micro- and macro-circulation of the targeted organ, which in turn leads to improved performance in diagnosis. Due to the special dual blood supply system in the liver, CEUS is particularly suitable for liver imaging. It is evident that CEUS facilitates improvement for characterization of focal liver lesions (FLLs), detection of liver malignancy, guidance for interventional procedures, and evaluation of treatment response after local therapies. CEUS has been demonstrated to be equal to contrast-enhanced computed tomography or magnetic resonance imaging for the characterization of FLLs. In addition, the applicability of CEUS has expanded to non-liver structures such as gallbladder, bile duct, pancreas, kidney, spleen, breast, thyroid, and prostate. The usefulness of CEUS in these applications is confirmed by extensive literature production. Novel applications include detecting bleeding sites and hematomas in patients with abdominal trauma, guiding percutaneous injection therapy and therefore achieving the goal of using interventional ultrasonography in managing splenic trauma, assessing the activity of Crohn’s disease, and detecting suspected endoleaks after endovascular abdominal aneurysm repair. Contrast-enhanced intraoperative ultrasound (US) and intracavitary use of CEUS have been developed and clinically studied. The potential use of CEUS involves sentinel lymph node detection, drug or gene delivery, and molecular imaging. In conclusion, the advent of CEUS has greatly enhanced the usefulness of US and even changed the status of US in clinical practice. The application of CEUS in the clinic is continuously evolving and it is expected that its use will be expanded further in the future.

Treatment response evaluation with three-dimensional contrast-enhanced ultrasound for liver cancer after local therapies

OBJECTIVE

To investigate the potential usefulness of three-dimensional contrast-enhanced ultrasound (3D-CEUS) in evaluating the treatment response for liver cancer after local therapies.

METHODS

A total of 107 lesions in 95 consecutive patients with liver cancer underwent local therapies and thereafter received low acoustic power 3D-CEUS examination. The LOGIQ 9 ultrasound scanner and a volume transducer were used and the ultrasound contrast agent was SonoVue. The image quality of 3D-CEUS images was evaluated and the influence of 3D-CEUS to clinical outcome was investigated.

RESULTS

The image quality of 3D-CEUS was defined as high in 102 (102/107, 95.3%) lesions and common in 5 (5/107, 4.7%) lesions. 3D-CEUS did not change the diagnosis in any patient compared with 2D-CEUS. However, 3D-CEUS changed the management in 3 (2.8%) of 107 lesions, increased confidence but made no change in diagnosis in 85 (79.5%) lesions, added some information but did not change management or diagnosis in 15 (14.0%), and made no change in 4 (3.7%), respectively, in comparison with 2D-CEUS.

CONCLUSION

3D-CEUS enhances the diagnostic confidence in the majority of the patients and even changes the management in some patients. 3D-CEUS has potential usefulness in evaluating treatment response for liver cancer after local therapies.