Review of dynamic contrast-enhanced ultrasound guidance in ablation therapy for hepatocellular carcinoma

Basic Techniques and Technical Tips for Ultrasound-guided Needle Puncture

Ultrasound-guided needle puncture is essential for both vascular and nonvascular interventions. Ultrasound is widely available in various clinical settings, requires no ionizing radiation, offers color Doppler imaging, and enables real-time visualization of the needle position during puncture. However, ultrasound imaging has some limitations, such as signal attenuation in deeper tissues and the inability to penetrate bone or air, and it is a heavily operator-dependent modality. Here, we outline the basic techniques and technical tips for ultrasound-guided needle puncture.

Current trends in the characterization and monitoring of vascular response to cancer therapy

Tumor vascular physiology is an important determinant of disease progression as well as the therapeutic outcome of cancer treatment. Angiogenesis or the lack of it provides crucial information about the tumor's blood supply and therefore can be used as an index for cancer growth and progression. While standalone anti-angiogenic therapy demonstrated limited therapeutic benefits, its combination with chemotherapeutic agents improved the overall survival of cancer patients. This could be attributed to the effect of vascular normalization, a dynamic process that temporarily reverts abnormal vasculature to the normal phenotype maximizing the delivery and intratumor distribution of chemotherapeutic agents. Longitudinal monitoring of vascular changes following antiangiogenic therapy can indicate an optimal window for drug administration and estimate the potential outcome of treatment. This review primarily focuses on the status of various imaging modalities used for the longitudinal characterization of vascular changes before and after anti-angiogenic therapies and their clinical prospects.

Current status and future perspectives of contrast-enhanced ultrasound diagnosis of breast lesions

Advances in various imaging modalities for breast lesions have improved diagnostic capabilities not only for tumors but also for non-tumorous lesions. Contrast-enhanced ultrasound (CEUS) plays a crucial role not only in the differential diagnosis of breast lesions, identification of sentinel lymph nodes, and diagnosis of lymph node metastasis but also in assessing the therapeutic effects of neoadjuvant chemotherapy (NAC). In CEUS, two image interpretation approaches, i.e., qualitative analysis and quantitative analysis, are employed and applied in various clinical settings. In this paper, we review CEUS for breast lesions, including its various applications.

Contrast-enhanced ultrasonography-CT/MRI fusion guidance for percutaneous ablation of inconspicuous, small liver tumors: improving feasibility and therapeutic outcome

BACKGROUND

Percutaneous radiofrequency ablation (RFA) is pivotal for treating small malignant liver tumors, but tumors often remain inconspicuous on B-mode ultrasound (US). This study evaluates the potential of CEUS-CT/MRI fusion imaging (FI) to improve tumor visibility and the associated RFA outcomes for small (≤ 3 cm) malignant liver tumors that were inconspicuous on US.

METHODS

Between January 2019 and April 2021, a prospective study enrolled 248 patients with liver malignancies (≤ 3 cm) that were poorly visible on B-mode US. Tumor visibility and ablation feasibility were assessed using B-mode US, US-CT/MRI FI, and CEUS-CT/MRI FI, and graded on a 4-point scale. CEUS was employed post-registration of US and CT/MRI images, utilizing either SonoVue or Sonazoid. Comparisons between US-based and CEUS-based fusion visibility and feasibility scores were undertaken using the Friedman test. Moreover, rates of technical success, technique efficacy, local tumor progression (LTP), and major complications were assessed.

RESULTS

The cohort included 223 hepatocellular carcinomas (HCCs) (89.9%) and 23 metastases (9.3%), with an average tumor size of 1.6 cm. CEUS-CT/MRI FI demonstrated a significant advantage in tumor visibility (3.4 ± 0.7 vs. 1.9 ± 0.6, P < 0.001) and technical feasibility (3.6 ± 0.6 vs. 2.9 ± 0.8, P < 0.001) compared to US-FI. In 85.5% of patients, CEUS addition to US-FI ameliorated tumor visibility. Technical success was achieved in 99.6% of cases. No severe complications were reported. One and two-year post CEUS-CT/MRI FI-guided RFA estimates for LTP were 9.3% and 10.9%, respectively.

CONCLUSIONS

CEUS-CT/MRI FI significantly improves the visualization of tumors not discernible on B-mode US, thus augmenting percutaneous RFA success and delivering improved therapeutic outcomes.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT05445973. Registered 17 June 2022 - Retrospectively registered, http://clinicaltrials.gov/study/NCT05445973?id=NCT05445973&rank=1 .

Percutaneous ablation of colorectal liver metastases: a comparison between the outcomes of grayscale US guidance and Sonazoid CEUS Kupffer phase guidance using propensity score matching

PURPOSE

To assess the utility of Sonazoid contrast-enhanced ultrasound (CEUS) for guiding percutaneous microwave ablation (MWA) for colorectal liver metastases (CRLMs).

MATERIALS AND METHODS

The medical records of patients who had undergone ultrasound (US)-guided percutaneous MWA between July 2020 and June 2022, were reviewed. Propensity score matching (PSM) with a ratio of 1:1 was used to balance the potential bias between the grayscale US-guided and Sonazoid CEUS-guided groups. Local tumor progression (LTP), intrahepatic recurrence (IR), and complication rates were compared between the two groups.

RESULTS

Of 252 patients enrolled, 247 achieved complete ablation, and the technical effectiveness was 98.0% (247/252). Of these 247 patients, 158 were in the grayscale US-guided group and 89 in the Sonazoid CEUS-guided group. The median follow-up period was 14.6 months. After PSM, there were no significant differences in LTP, IR, or complication rates between the two groups (p = 0.100, p = 0.511, p > 0.99, respectively). Multivariate analysis identified tumor size ≥ 3 cm (hazard ratio [HR], 7.945; 95% CI, 2.591-24.370; p < 0.001), perivascular (HR, 2.331; 95% CI, 1.068-5.087; p = 0.034), and tumor depth > 8 cm (HR, 3.194; 95% CI, 1.439-7.091; p = 0.004) as significant factors associated with LTP. For tumors with poor vision on grayscale US, Sonazoid CEUS-guided ablation achieved a better LTP rate than grayscale US-guided ablation (3.7% vs.14.8%, p = 0.032).

CONCLUSION

For tumors with poor vision on grayscale US, Sonazoid CEUS guidance is recommended for better local tumor control.

Ultrasound fusion imaging for improving diagnostic and therapeutic strategies of focal liver lesions: A preliminary study

PURPOSE

To assess the effect of ultrasound (US) fusion imaging on the clinical diagnostic and therapeutic strategies of focal liver lesions, which are difficult to detect or diagnose by conventional US.

METHODS

From November 2019 to June 2022, 71 patients with invisible or undiagnosed focal liver lesions who underwent fusion imaging combining US with CT or MR were included in this retrospective study. The reasons for US fusion imaging were as follows: (1) lesions that were undetectable or inconspicuous on B-mode US; (2) post-ablation lesions that could not be assessed accurately by B-mode US; (3) to evaluate whether the lesions detected by B-mode US that were consistent with those presented on MRI/CT images.

RESULTS

Of the 71 cases, 43 cases were single lesions, and 28 cases were multiple lesions. Among the 46 cases which were invisible on conventional US, the display rate of lesions using US-CT/MRI fusion imaging was 30.8%, and that combined with CEUS was 76.9%. US-guided biopsy was performed in 30 patients after the detection and localization determined by fusion imaging, with a positive rate of 73.3%. Six patients with recurrence after ablation therapy were all detected and located accurately after fusion imaging, and 4 of them successfully underwent ablation therapy again.

CONCLUSION

Fusion imaging contributes to the understanding of the anatomical relationship between lesion location and blood vessels. Additionally, fusion imaging can improve the diagnostic confidence, be helpful to guide interventional operations, and hence be conducive to clinical therapeutic strategies.

Value of CEUS combined with feeding artery ablation in the microwave ablation of large solid benign thyroid nodules

OBJECTIVES

To investigate the value of contrast-enhanced ultrasound (CEUS) combined with feeding artery ablation in the microwave ablation (MWA) of large solid benign thyroid nodules (LSBTNs) with a diameter ≥ 4 cm.

METHODS

We retrospectively analyzed 122 patients with LSBTN ≥ 4 cm in diameter treated with MWA. During evaluations before and after MWA, 53 patients who underwent conventional ultrasound examination were classified as the routine group, and 69 patients who underwent CEUS combined with feeding artery ablation were classified as the union group. The differences in ablation energy required per milliliter (AERPM), complication rate, regrowth rate, and volume reduction rate (VRR) were compared between the two groups.

RESULTS

The AERPM of the union group was significantly less than that of the routine group (956.3 ± 38.5 J/mL vs. 1025.9 ± 121.5 J/mL, p < 0.001). The complication rate of the routine group was significantly higher than that of the union group (13.2% vs. 2.9%, p = 0.031). The regrowth rate of the routine group (22.6%, 12/53) was significantly higher than that of the union group (7.2%, 5/69) (p = 0.015). At the 1st, 3rd, 6th, 12th, 18th, and 24th month after ablation, the mean VRRs of the routine group were significantly less than those of the union group, with p values of < 0.001, < 0.001, 0.002, 0.007, 0.013, and < 0.001, respectively.

CONCLUSIONS

The application of CEUS combined with feeding artery ablation in the MWA of LSBTNs is helpful to reduce the regrowth rate, improve the ablation efficiency, and reduce bleeding.

KEY POINTS

• CEUS combined with feeding artery ablation in MWA of LSBTNs is helpful to reduce regrowth rate. • CEUS combined with feeding artery ablation can help improve ablation efficiency than conventional ultrasound in LSBTNs. • CEUS combined with feeding artery ablation helps reduce the incidence of bleeding during MWA.

MRI-guided fiducial marker implantation as a method of tagging an ultrasound- and non-enhanced CT-invisible liver tumor before thermal ablation

Some liver tumors are not visible on ultrasound or non-enhanced CT (NECT) which are main modalities used in image-guided ablations. This is a report of MR-guided implantation of fiducial marker to tag a neuroendocrine tumor metastasis in a patient with renal insufficiency precluding the use of contrast - enhanced CT during ablation. The marker was well visible on NECT which allowed for precise needle placement and complete ablation which was confirmed in 12-months follow-up.

Contrast-enhanced ultrasonography to guide diagnostic and therapeutic interventional procedures

Although not necessary for the vast majority of ultrasound-guided procedures, intravenous contrast agents can be useful for procedures aimed at lesions that require contrast enhancement to be seen on ultrasonography. Using contrast-enhanced ultrasonography to guide procedures has two drawbacks: first, because enhancement from ultrasound contrast agents is short lived, it is often necessary to plan several injections; second, because the needle is poorly seen on contrast-enhanced ultrasonography, a dual image display format is necessary. Contrast-enhanced ultrasonography can be used for planning and monitoring diagnostic and therapeutic procedures, for guiding the procedures, and for follow-up. Using contrast-enhanced ultrasonography enables better results in both types of procedures; moreover, it can be used within cavities.

Contrast-enhanced ultrasound in pediatric interventional radiology

There is growing interest in the use of contrast-enhanced ultrasound (CEUS) in diagnostic and interventional radiology. CEUS applications in interventional radiology are performed with intravascular or intracavitary administration of microbubble-based US contrast agents to allow for real-time evaluation of their distribution within the vascular bed or in body cavities, respectively, providing additional information beyond gray-scale US alone. The most common interventional-radiology-related CEUS applications in children have been extrapolated from those in adults, and they include the use of CEUS to guide lesion biopsy and to confirm drain placement in pleural effusions and intra-abdominal fluid collections. Other applications are emerging in interventional radiology for use in adults and children, including CEUS to optimize sclerotherapy of vascular malformations, to guide arthrography, and for lymphatic interventions. In this review article we present a wide range of interventional-radiology-related CEUS applications, emphasizing the current and potential uses in children. We highlight the technical parameters of the CEUS examination and discuss the main imaging findings.

New frontiers in liver ultrasound: From mono to multi parametricity

Modern liver ultrasonography (US) has become a “one-stop shop” able to provide not only anatomic and morphologic but also functional information about vascularity, stiffness and other various liver tissue properties. Modern US techniques allow a quantitative assessment of various liver diseases. US scanning is no more limited to the visualized plane, but three-dimensional, volumetric acquisition and consequent post-processing are also possible. Further, US scan can be consistently merged and visualized in real time with Computed Tomography and Magnetic Resonance Imaging examinations. Effective and safe microbubble-based contrast agents allow a real time, dynamic study of contrast kinetic for the detection and characterization of focal liver lesions. Ultrasound can be used to guide loco-regional treatment of liver malignancies and to assess tumoral response either to interventional procedures or medical therapies. Microbubbles may also carry and deliver drugs under ultrasound exposure. US plays a crucial role in diagnosing, treating and monitoring focal and diffuse liver disease. On the basis of personal experience and literature data, this paper is aimed to review the main topics involving recent advances in the field of liver ultrasound.

Contrast-enhanced ultrasonography to guide diagnostic and therapeutic interventional procedures

Although not necessary for the vast majority of ultrasound-guided procedures, intravenous contrast agents can be useful for procedures aimed at lesions that require contrast enhancement to be seen on ultrasonography. Using contrast-enhanced ultrasonography to guide procedures has two drawbacks: first, because enhancement from ultrasound contrast agents is short lived, it is often necessary to plan several injections; second, because the needle is poorly seen on contrast-enhanced ultrasonography, a dual image display format is necessary. Contrast-enhanced ultrasonography can be used for planning and monitoring diagnostic and therapeutic procedures, for guiding the procedures, and for follow-up. Using contrast-enhanced ultrasonography enables better results in both types of procedures; moreover, it can be used within cavities.

Interobserver agreement for contrast-enhanced ultrasound of liver imaging reporting and data system: A systematic review and meta-analysis

BACKGROUND

Hepatocellular carcinoma is the most common primary liver malignancy. From the results of previous studies, Liver Imaging Reporting and Data System (LI-RADS) on contrast-enhanced ultrasound (CEUS) has shown satisfactory diagnostic value. However, a unified conclusion on the interobserver stability of this innovative ultrasound imaging has not been determined. The present meta-analysis examined the interobserver agreement of CEUS LI-RADS to provide some reference for subsequent related research.

AIM

To evaluate the interobserver agreement of LI-RADS on CEUS and analyze the sources of heterogeneity between studies.

METHODS

Relevant papers on the subject of interobserver agreement on CEUS LI-RADS published before March 1, 2020 in China and other countries were analyzed. The studies were filtered, and the diagnostic criteria were evaluated. The selected references were analyzed using the “meta” and “metafor” packages of R software version 3.6.2.

RESULTS

Eight studies were ultimately included in the present analysis. Meta-analysis results revealed that the summary Kappa value of included studies was 0.76 [95% confidence interval, 0.67-0.83], which shows substantial agreement. Higgins I² statistics also confirmed the substantial heterogeneity (I² = 91.30%, 95% confidence interval, 85.3%-94.9%, P < 0.01). Meta-regression identified the variables, including the method of patient enrollment, method of consistency testing, and patient race, which explained the substantial study heterogeneity.

CONCLUSION

CEUS LI-RADS demonstrated overall substantial interobserver agreement, but heterogeneous results between studies were also obvious. Further clinical investigations should consider a modified recommendation about the experimental design.

The AFSUMB Consensus Statements and Recommendations for the Clinical Practice of Contrast-Enhanced Ultrasound using Sonazoid

The first edition of the guidelines for the use of ultrasound contrast agents was published in 2004, dealing with liver applications. The second edition of the guidelines in 2008 reflected changes in the available contrast agents and updated the guidelines for the liver, as well as implementing some nonliver applications. The third edition of the contrast-enhanced ultrasound (CEUS) guidelines was the joint World Federation for Ultrasound in Medicine and Biology-European Federation of Societies for Ultrasound in Medicine and Biology (WFUMB-EFSUMB) venture in conjunction with other regional US societies such as Asian Federation of Societies for Ultrasound in Medicine and Biology, resulting in a simultaneous duplicate on liver CEUS in the official journals of both WFUMB and EFSUMB in 2013. However, no guidelines were described mainly for Sonazoid due to limited clinical experience only in Japan and Korea. The new proposed consensus statements and recommendations provide general advice on the use of Sonazoid and are intended to create standard protocols for the use and administration of Sonazoid in hepatic and pancreatobiliary applications in Asian patients and to improve patient management.

Perfluorobutane contrast-enhanced ultrasonography: a new standard for ultrasonography-guided thermal ablation of sonographically occult liver tumours?

INTRODUCTION

Image-guided thermal ablation, preferably with ultrasonography (US), is increasingly used for treatment of small liver tumours. Perfluorobutane-contrast enhanced US (pCEUS) is a promising tool that may allow for targeting of tumours that are otherwise imperceptible on greyscale US. Although pCEUS has been reported to be effective, the literature has been limited outside of Japan and South Korea. We aimed to provide data that supports the use of pCEUS in thermal ablation of sonographically occult liver tumours.

METHODS

We conducted a retrospective single-centre study of 35 consecutive patients who underwent pCEUS-guided ablation of 48 liver tumours with a median size of 1.2 cm. Periprocedural, one-month post-treatment, and relevant follow-up imaging studies were reviewed. Electronic records were also obtained, with long-term follow-up data of 12-28 months being available for 32 patients.

RESULTS

36 (75%) of tumours that were imperceptible on greyscale US became visible with pCEUS. Overall, complete tumour ablation at one month was 89%. 1 (3%) patient developed a major complication following treatment, while 6 (17%) had minor post-treatment complaints. The local tumour progression rate was 17% with a median time of 14 months.

CONCLUSION

pCEUS has a role in US-guided thermal ablation of liver tumours, offering a high technical success rate that is comparable to reported data. Additional benefits may include improved procedural time and freedom from ionising radiation.

The AFSUMB Consensus Statements and Recommendations for the Clinical Practice of Contrast-Enhanced Ultrasound using Sonazoid

The first edition of the guidelines for the use of ultrasound contrast agents was published in 2004, dealing with liver applications. The second edition of the guidelines in 2008 reflected changes in the available contrast agents and updated the guidelines for the liver, as well as implementing some nonliver applications. The third edition of the contrast-enhanced ultrasound (CEUS) guidelines was the joint World Federation for Ultrasound in Medicine and Biology-European Federation of Societies for Ultrasound in Medicine and Biology (WFUMB-EFSUMB) venture in conjunction with other regional US societies such as Asian Federation of Societies for Ultrasound in Medicine and Biology, resulting in a simultaneous duplicate on liver CEUS in the official journals of both WFUMB and EFSUMB in 2013. However, no guidelines were described mainly for Sonazoid due to limited clinical experience only in Japan and Korea. The new proposed consensus statements and recommendations provide general advice on the use of Sonazoid and are intended to create standard protocols for the use and administration of Sonazoid in hepatic and pancreatobiliary applications in Asian patients and to improve patient management.

Percutaneous Radiofrequency Ablation for Liver Tumors: Technical Tips

Percutaneous radiofrequency ablation (RFA) has been accepted as a minimally invasive therapeutic treatment for liver malignancies. Although RFA is usually applied for the treatment of small liver tumors (<3 cm), several technical developments have expanded the use of RFA. RFA is now used for the treatment of large liver tumors, and the number of complications associated with this treatment has decreased. These refinements may ultimately lead to better long-term prognosis. Here, we review recent refinements of liver RFA and provide technical tips.

Contrast-enhanced ultrasound of hepatocellular carcinoma: where do we stand?

Contrast-enhanced ultrasound (CEUS) represents a significant breakthrough in ultrasonography (US), and it is being increasingly used for the evaluation of focal liver lesions (FLLs). CEUS is unique in that it allows non-invasive assessment of liver perfusion in real time throughout the vascular phase, which has led to dramatic improvements in the diagnostic accuracy of US in the detection and characterization of FLLs, the choice of therapeutic procedures, and the evaluation of response. Currently, CEUS is included as a part of the suggested diagnostic work-up of FLLs, including in cirrhotic patients with hepatocellular carcinoma, resulting in better patient management and cost-effective delivery of therapy.

Evaluation of Contrast-Enhanced Intraoperative Ultrasound in the Detection and Management of Liver Lesions in Patients with Hepatocellular Carcinoma

AIM

To evaluate the role of contrast-enhanced intraoperative ultrasound (CE-IOUS) during liver surgery in the detection and management of liver lesions in patients with hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

From December 2016 to December 2017, 50 patients with HCC, who were candidates for liver resection, were evaluated with intraoperative ultrasound (IOUS). For all patients, MRI and/or CT were performed before surgery. During surgery, IOUS was performed after liver mobilization, and when nodules that had not been detected in the preoperative MRI and/or CT were observed, CE-IOUS scans were carried out with the dual purpose of better characterizing the unknown lesion and discovering new lesions.

RESULTS

In 12 patients, IOUS showed 14 nodules not detected by preoperative MRI and/or CT, before surgery. Out of the 12 lesions, five presented vascular features compatible with those of malignant HCC to the evaluation with CE-IOUS and four of these were simultaneously treated with intraoperative radiofrequency ablation (RFA). The fifth lesion was resected by the surgeon. The remaining nine lesions recognized by IOUS were evaluated as benign at CE-IOUS and considered regenerative nodules. The last diagnosis was confirmed during follow-up obtained by means of CT and/or MRI after 1, 3, 6, or 12 months.

CONCLUSION

In our experience, CE-IOUS is a useful diagnostic tool in both benign pathologies, such as regenerative nodules, and malignant liver lesions. The advantage of this approach is the possibility of intraoperatively characterizing, based on vascularization patterns, lesions that could not be diagnosed by preoperative imaging, resulting in modification of the surgical therapy decision and expansion of the resection or intraoperative ablation.

Defeating Cancers' Adaptive Defensive Strategies Using Thermal Therapies: Examining Cancer's Therapeutic Resistance, Ablative, and Computational Modeling Strategies as a means for Improving Therapeutic Outcome

BACKGROUND

Diverse thermal ablative therapies are currently in use for the treatment of cancer. Commonly applied with the intent to cure, these ablative therapies are providing promising success rates similar to and often exceeding "gold standard" approaches. Cancer-curing prospects may be enhanced by deeper understanding of thermal effects on cancer cells and the hosting tissue, including the molecular mechanisms of cancer cell mutations, which enable resistance to therapy. Furthermore, thermal ablative therapies may benefit from recent developments in computer hardware and computation tools for planning, monitoring, visualization, and education.

METHODS

Recent discoveries in cancer cell resistance to destruction by apoptosis, autophagy, and necrosis are now providing an understanding of the strategies used by cancer cells to avoid destruction by immunologic surveillance. Further, these discoveries are now providing insight into the success of the diverse types of ablative therapies utilized in the clinical arena today and into how they directly and indirectly overcome many of the cancers' defensive strategies. Additionally, the manner in which minimally invasive thermal therapy is enabled by imaging, which facilitates anatomical features reconstruction, insertion guidance of thermal probes, and strategic placement of thermal sensors, plays a critical role in the delivery of effective ablative treatment.

RESULTS

The thermal techniques discussed include radiofrequency, microwave, high-intensity focused ultrasound, laser, and cryosurgery. Also discussed is the development of thermal adjunctive therapies-the combination of drug and thermal treatments-which provide new and more effective combinatorial physical and molecular-based approaches for treating various cancers. Finally, advanced computational and planning tools are also discussed.

CONCLUSION

This review lays out the various molecular adaptive mechanisms-the hallmarks of cancer-responsible for therapeutic resistance, on one hand, and how various ablative therapies, including both heating- and freezing-based strategies, overcome many of cancer's defenses, on the other hand, thereby enhancing the potential for curative approaches for various cancers.

Clinical utility of real-time ultrasound-multimodality fusion guidance for percutaneous biopsy of focal liver lesions

OBJECTIVES

To prospectively evaluate the clinical value of real-time ultrasonography (US)-computed tomography (CT)/magnetic resonance imaging (MRI) fusion imaging for percutaneous needle biopsy of focal liver lesions (FLLs), and to compare its biopsy success rate with that of conventional US-guided biopsy in a propensity-score matched group.

METHODS

This study was approved by our Institutional Review Board and informed consent was obtained from all patients enrolled in the prospective study group. Ninety patients referred to the Department of Radiology for percutaneous biopsy of FLLs were enrolled in this study. Tumor visibility, attainment of a safe access route, and technical feasibility were assessed on conventional US first and later on real-time fusion imaging by one of four abdominal radiologists. Thereafter, differences in scores between real-time fusion imaging and conventional US were determined. In addition, overall diagnostic success rates of a real-time fusion imaging-guided biopsy group and a propensity-score matched, conventional US-guided biopsy group, consisting of 100 patients used as historical control, were compared.

RESULTS

With real-time fusion imaging, tumor visibility, attainment of a safe access route, and operator's technical feasibility were significantly improved compared with conventional US (P < .001). In addition, all invisible (n = 13) and not feasible (n = 10) FLLs on conventional US became visible and feasible for percutaneous US-guided biopsy after applying the fusion system. The diagnostic success rate of real-time fusion-guided biopsy was 94.4% (85/90), which was significantly better than that obtained with the conventional US-guided biopsy (94.4% vs. 83%, P < .03), with reduced biopsy procedure times (7.1 ± 3.5 vs. 9.7 ± 2.8, P < .02).

CONCLUSIONS

Real-time US-CT/MR fusion imaging guidance was able to provide clinical value for percutaneous needle biopsy of FLLs by improving the diagnostic success rate of biopsy and by reducing procedure time.

Role of interventional radiology in managing pediatric liver tumors : Part 2: percutaneous interventions

Hepatoblastoma and hepatocellular carcinoma (HCC) are the most common pediatric liver malignancies, with hepatoblastoma occurring more commonly in younger children and HCC occurring more commonly in older children and adolescents. Although surgical resection (including transplant when necessary) and systemic chemotherapy have improved overall survival rate for hepatoblastoma to approximately 80% from 30%, a number of children with this tumor type are not eligible for operative treatment. In contradistinction, pediatric HCC continues to carry a dismal prognosis with an overall 5-year survival rate of 30%. The Paediatric Hepatic International Tumour Trial (PHITT) is an international trial aimed at evaluating both existing and emerging oncologic therapies for primary pediatric liver tumors. Interventional radiology offers a number of minimally invasive procedures that aid in diagnosis and therapy of pediatric liver tumors. For diagnosis, the PHITT biopsy guidelines emphasize and recommend percutaneous image-guided tumor biopsy. Additionally, both percutaneous and endovascular procedures provide therapeutic alternatives that have been, to this point, only minimally utilized in the pediatric population. Specifically, percutaneous ablation offers a number of cytotoxic technologies that can potentially eradicate disease or downstage children with unresectable disease. Percutaneous portal vein embolization is an additional minimally invasive procedure that might be useful to induce remnant liver hypertrophy prior to extended liver resection in the setting of a primary liver tumor. PHITT offers an opportunity to collect data from children treated with these emerging therapeutic options across the world. The purpose of this manuscript is to describe the potential role of minimally invasive percutaneous transhepatic procedures, as well as review the existing data largely stemming from the adult HCC experience.

Thermographic real-time-monitoring of surgical radiofrequency and microwave ablation in a perfused porcine liver model

Radiofrequency ablation (RFA) and microwave ablation (MWA) are currently the dominant modalities to treat unresectable liver tumors. Monitoring the ablation process with b-mode-sonography is often hampered by artefacts. Furthermore, vessels may cause cooling in the adjacent tumor target (heat-sink-effect) with risk of local recurrence. The present study evaluated infrared-thermography to monitor surgical RFA/MWA and detect heat-sink-effects in real-time. RFA and MWA of perfused porcine livers was conducted at peripheral and central-vessel-adjacent locations, and monitored by real-time thermography. Ablation was measured and evaluated by gross pathology. The mean time for ablation was significantly longer in RFA compared with MWA (8 vs. 2 min). Although mean macroscopic ablation diameter was similar (RFA, 3.17 cm; MWA, 3.38 cm), RFA showed a significant heat-sink-effect compared with MWA. The surface temperature during central RFA near vessels was 1/3 lower compared with peripheral RFA (47.11±8.35°C vs. 68.72±12.70°C; P<0.001). There was no significant difference in MWA (50.52±8.35°C vs. 50.18±10.35°C; P=0.74). In conclusion, thermography is suitable to monitor the correct ablation with MWA and RFA. The results of the current study demonstrated a significant heat-sink-effect for RFA, but not MWA near vessels. MWA reaches consistent surface temperatures much faster than RFA. With further in vivo validation, thermography may be useful to ensure appropriate ablation particularly near vulnerable or vascular structures.

Contrast-Enhanced Ultrasound of the Liver: Optimizing Technique and Clinical Applications

OBJECTIVE

The purpose of this article is to review the general principles, technique, and clinical applications of contrast-enhanced ultrasound of the liver.

CONCLUSION

Proper technique and optimization of contrast-enhanced ultrasound require a balance between maintaining the integrity of the microbubble contrast agent and preserving the ultrasound signal. Established and emerging applications in the liver include diagnosis of focal lesions, aiding ultrasound-guided intervention, monitoring of therapy, and aiding surgical management.

Efficacy and safety of ultrasound-guided implantation of fiducial markers in the liver for stereotactic body radiation therapy

Objective

Stereotactic body radiation therapy (SBRT) for the treatment of a malignancy in the liver requires the perilesional implantation of fiducial markers for lesion detection. The purpose of this study is to evaluate the efficacy and safety of ultrasound (US) -guided marker implantation for SBRT.

Methods

We retrospectively reviewed 299, US–guided, intrahepatic fiducial markers implanted in 101 patients between November 2013 and September 2014. SBRT-planning CT images were analyzed to determine the technical success of the implantation, the mean distance between the tumor margin and the marker, with the ideal location of fiducials defined as the distance between a marker and a tumor less than 3 cm and the distance between markers greater than 2 cm according to the tumor conspicuity seen on gray-scale US and the artifact obscuring tumor margins. We also evaluated procedure-related major and minor complications.

Results

Technical success was achieved in 291 (97.3%) fiducial marker implantations. The mean distance between the tumor and the marker was 3.1 cm (S.D., 2.1 cm; range, 0–9.5 cm). Of 101 patients, 72 lesions (71.3%, 2.2 ± 1.0 cm; range, 0–3.0 cm) had fiducial markers located in an ideal location. The ideal location of fiducials was more common in visible lesions than in poorly conspicuous lesions (90.2% vs. 52.0%, P < 0.001). Seventeen markers (5.8%) developed beam-hardening artifacts obscuring the tumor margins. There were no major complications, although 12 patients (11.9%) developed minor complications.

Conclusions

US-guided implantation of fiducial markers in the liver is an effective and safe procedure with only rare complications.

Post-Procedure Evaluation of Microwave Ablations of Hepatocellular Carcinomas Using Electrode Displacement Elastography

Microwave ablation has been used clinically as an alternative to surgical resection. However, lack of real-time imaging to assess treated regions may compromise treatment outcomes. We previously introduced electrode displacement elastography (EDE) for strain imaging and verified its feasibility in vivo on porcine animal models. In this study, we evaluated EDE on 44 patients diagnosed with hepatocellular carcinoma, treated using microwave ablation. The ablated region was identified on EDE images for 40 of the 44 patients. Ablation areas averaged 13.38 ± 4.99 cm² on EDE, compared with 7.61 ± 3.21 cm² on B-mode imaging. Contrast and contrast-to-noise ratios obtained with EDE were 232% and 98%, respectively, significantly higher than values measured on B-mode images (p < 0.001). This study indicates that EDE is feasible in patients and provides improved visualization of the ablation zone compared with B-mode ultrasound.

Application of imaging fusion combining contrast-enhanced ultrasound and magnetic resonance imaging in detection of hepatic cellular carcinomas undetectable by conventional ultrasound

BACKGROUND AND AIM

The aim of this study is to explore the value of volume navigation image fusion-assisted contrast-enhanced ultrasound (CEUS) in detection for radiofrequency ablation guidance of hepatocellular carcinomas (HCCs), which were undetectable on conventional ultrasound.

METHODS

From May 2012 to May 2014, 41 patients with 49 HCCs were included in this study. All lesions were detected by dynamic magnetic resonance imaging (MRI) and planned for radiofrequency ablation but were undetectable on conventional ultrasound. After a bolus injection of 2.4 ml SonoVue® (Bracco, Italy), LOGIQ E9 ultrasound system with volume navigation system (version R1.0.5, GE Healthcare, Milwaukee, WI, USA) was used to fuse CEUS and MRI images. The fusion time, fusion success rate, lesion enhancement pattern, and detection rate were analyzed.

RESULTS

Image fusions were conducted successfully in 49 HCCs, the technical success rate was 100%. The average fusion time was (9.2 ± 2.1) min (6-12 min). The mean diameter of HCCs was 25.2 ± 5.3 mm (mean ± SD), and mean depth was 41.8 ± 17.2 mm. The detection rate of HCCs using CEUS/MRI imaging fusion (95.9%, 47/49) was significantly higher than CEUS (42.9%, 21/49) (P < 0.05). For small HCCs (diameter, 1-2 cm), the detection rate using imaging fusion (96.9%, 32/33) was also significantly higher than CEUS (18.2%, 6/33) (P < 0.01). All HCCs displayed a rapid wash-in pattern in the arterial phase of CEUS.

CONCLUSIONS

Imaging fusion combining CEUS and MRI is a promising technique to improve the detection, precise localization, and accurate diagnosis of undetectable HCCs on conventional ultrasound, especially small and atypical HCCs.

Novel Imaging Diagnosis for Hepatocellular Carcinoma: Consensus from the 5th Asia-Pacific Primary Liver Cancer Expert Meeting (APPLE 2014)

Current novel imaging techniques in the diagnosis of hepatocellular carcinoma (HCC), with the latest evidence in this field, was discussed at the Asia-Pacific Primary Liver Cancer Expert (APPLE) meeting held in Taipei, Taiwan, in July 2014. Based on their expertise in a specific area of research, the novel imaging group comprised 12 participants from Japan, South Korea, Taiwan, and China and it included 10 abdominal radiologists, one hepatologist, and one pathologist. The expert participants discussed topics related to HCC imaging that were divided into four categories: (i) detection method, (ii) diagnostic method, (iii) evaluation method, and (iv) functional method. Consensus was reached on 10 statements; specific comments on each statement were provided to explain the rationale for the voting results and to suggest future research directions.

Radiofrequency ablation for hepatocellular carcinoma: utility of conventional ultrasound and contrast-enhanced ultrasound in guiding and assessing early therapeutic response and short-term follow-up results

The purpose of this study was to assess the efficacy of conventional ultrasound (US) and contrast-enhanced ultrasound (CEUS) in guiding and assessing early therapeutic response to radiofrequency (RF) ablation for hepatocellular carcinomas (HCCs; up to 3 lesions, each ≤3 cm in diameter) and to report the short-term follow-up results. Between September 2011 and January 2013, 63 patients with 78 HCCs (≤3 cm) underwent conventional US- and CEUS-guided percutaneous RF ablation. CEUS was repeated after 20-30 min to assess therapeutic response, and local efficacy was further confirmed by contrast-enhanced magnetic resonance imaging (MRI) 1 mo after tumor ablation. Patients were followed periodically to look for local tumor or disease progression. Survival probability was estimated with the Kaplan-Meier method. Complete ablation was achieved for 76 (97.4%) of 78 HCCs in one (n = 73) or two (n = 3) sessions. No major complications were observed in any patient. The overall concordance in assessment of therapeutic efficacy of RF ablation between CEUS and MRI was 97.4% (76/78 tumors). The concordance test gave a value of κ = 0.74 (p < 0.001), indicating that CEUS had a high diagnostic agreement with MRI. During a mean follow-up of 20 mo, the local tumor progression rate was 5.3% (4/76 tumors). The 1-, 1.5- and 2-y cumulative survival rates were 98.4%, 96.1% and 92.6%, respectively. Although CEUS has some intrinsic limitations, the combined use of conventional US and CEUS provides a safe and efficient tool to guide RF ablation for HCCs 3 cm or smaller, with encouraging results in terms of survival rate and minimal complications. Moreover, the immediate post-procedural CEUS can be a reliable alternative to contrast-enhanced MRI for assessing the early therapeutic response to RF ablation.

Recent Advances in Tumor Ablation for Hepatocellular Carcinoma

Image-guided tumor ablation for early stage hepatocellular carcinoma (HCC) is an accepted non-surgical treatment that provides excellent local tumor control and favorable survival benefit. This review summarizes the recent advances in tumor ablation for HCC. Diagnostic imaging and molecular biology of HCC has recently undergone marked improvements. Second-generation ultrasonography (US) contrast agents, new computed tomography (CT) techniques, and liver-specific contrast agents for magnetic resonance imaging (MRI) have enabled the early detection of smaller and inconspicuous HCC lesions. Various imaging-guidance tools that incorporate imaging-fusion between real-time US and CT/MRI, that are now common for percutaneous tumor ablation, have increased operator confidence in the accurate targeting of technically difficult tumors. In addition to radiofrequency ablation (RFA), various therapeutic modalities including microwave ablation, irreversible electroporation, and high-intensity focused ultrasound ablation have attracted attention as alternative energy sources for effective locoregional treatment of HCC. In addition, combined treatment with RFA and chemoembolization or molecular agents may be able to overcome the limitation of advanced or large tumors. Finally, understanding of the biological mechanisms and advances in therapy associated with tumor ablation will be important for successful tumor control. All these advances in tumor ablation for HCC will result in significant improvement in the prognosis of HCC patients. In this review, we primarily focus on recent advances in molecular tumor biology, diagnosis, imaging-guidance tools, and therapeutic modalities, and refer to the current status and future perspectives for tumor ablation for HCC.

The status of contemporary image-guided modalities in oncologic surgery

OBJECTIVE

To review the current trends in optical imaging to guide oncologic surgery.

BACKGROUND

Surgical resection remains the cornerstone of therapy for patients with early stage solid malignancies and more than half of all patients with cancer undergo surgery each year. The technical ability of the surgeon to obtain clear surgical margins at the initial resection remains crucial to improve overall survival and long-term morbidity. Current resection techniques are largely based on subjective and subtle changes associated with tissue distortion by invasive cancer. As a result, positive surgical margins occur in a significant portion of tumor resections, which is directly correlated with a poor outcome.

METHODS

A comprehensive review of studies evaluating optical imaging techniques is performed.

RESULTS

A variety of cancer imaging techniques have been adapted or developed for intraoperative surgical guidance that have been shown to improve functional and oncologic outcomes in randomized clinical trials. There are also a large number of novel, cancer-specific contrast agents that are in early stage clinical trials and preclinical development that demonstrate significant promise to improve real-time detection of subclinical cancer in the operative setting.

CONCLUSIONS

There has been an explosion of intraoperative imaging techniques that will become more widespread in the next decade.

Prognostic factors for survival after transarterial chemoembolization combined with microwave ablation for hepatocellular carcinoma

AIM: To analyze prognostic factors for survival after transarterial chemoembolization (TACE) combined with microwave ablation (MWA) for hepatocellular carcinoma (HCC).

METHODS: Clinical data of 86 patients who underwent TACE combined with MWA between January 2006 and December 2013 were retrospectively analyzed in this study. Survival curves were detected using log-rank test. Univariate analysis was performed using log-rank test with respect to 13 prognostic factors affecting survival. All statistically significant prognostic factors identified by univariate analysis were entered into a Cox proportion hazards regression model to identify independent predictors of survival. P values were two-sided and P < 0.05 was considered statistically significant.

RESULTS: Median follow-up time was 47.6 mo, and median survival time of enrolled patients was 21.5 mo. The 1-, 2-, 3- and 5-year overall survival rates were 72.1%, 44.1%, 31.4% and 13.9%, respectively. Tumor size(χ² = 14.999, P = 0.000), Barcelona Clinic Liver Cancer (BCLC) stage (χ² = 29.765, P = 0.000), Child-Pugh class (χ² = 51.820, P = 0.000), portal vein tumor thrombus (PVTT) (χ² = 43.086, P = 0.000), arterio-venous fistula (χ² = 29.791, P = 0.000), MWA therapy times (χ² = 12.920, P = 0.002), Eastern Cooperative Oncology Group (ECOG) score (χ² = 28.660, P = 0.000) and targeted drug usage (χ² = 10.901, P = 0.001) were found to be significantly associated with overall survival by univariate analysis. Multivariate analysis identified that tumor size (95%CI: 1.608-4.962, P = 0.000), BCLC stage (95%CI: 1.016-2.208, P = 0.020), PVTT (95%CI: 2.062-9.068, P = 0.000), MWA therapy times (95%CI: 0.402-0.745, P = 0.000), ECOG score (95%CI: 1.012-3.053, P = 0.045) and targeted drug usage (95%CI: 1.335-3.143, P = 0.001) were independent prognostic factors associated with overall survival.

CONCLUSION: Superior performance status, MWA treatment and targeted drug were favorable factors, and large HCC, PVTT and advanced BCLC stage were risk factors for survival after TACE-MWA for HCC.

Combination guidance of contrast-enhanced US and fusion imaging in radiofrequency ablation for hepatocellular carcinoma with poor conspicuity on contrast-enhanced US/fusion imaging

PURPOSE

The purpose of this study was to evaluate the usefulness of the combination guidance of contrast-enhanced US (CEUS) and fusion imaging in radiofrequency ablation (RFA) for hepatocellular carcinoma (HCC) with poor conspicuity on B-mode US and CEUS/fusion imaging.

MATERIALS AND METHODS

We conducted a retrospective cohort study, which included 356 patients with 556 HCCs that were inconspicuous on B-mode US. A total of 192 patients with 344 HCCs, 123 patients with 155 HCCs, and 37 patients with 57 HCCs underwent RFA under CEUS guidance, fusion imaging guidance, and the combination of CEUS and fusion imaging guidance.

RESULTS

The average number of treatment sessions was 1.1 (range: 1-2) in the CEUS guidance group, 1.1 (range: 1-2) in the fusion imaging guidance group, and 1.1 (range: 1-3) in the combination of CEUS and fusion imaging guidance group. Treatment analysis did not reveal significantly more RFA treatment sessions in the combination guidance group than in the other groups (p = 0.97, Student's t test). During the follow-up period (1.1-85.3 months, mean ± SD, 43.2 ± 59.5), the 3-year local tumor progression rates were 4.9, 7.2, and 5.9% in the CEUS guidance group, the fusion imaging guidance group, and the combination guidance group, respectively (p = 0.84, log-rank test).

CONCLUSION

In spite of selection bias, session frequency and local tumor progression were not different under the combination guidance with CEUS and fusion imaging in RFA. The combination of fusion imaging and CEUS guidance in RFA therapy is an effective treatment for HCC with poor conspicuity on B-mode US and CEUS/fusion imaging.

Ultrasound fusion imaging of hepatocellular carcinoma: a review of current evidence

With advances in technology, imaging techniques that entail fusion of sonography and CT or MRI have been introduced in clinical practice. Ultrasound fusion imaging provides CT or MRI cross-sectional multiplanar images that correspond to the sonographic images, and fusion imaging of B-mode sonography and CT or MRI can be displayed simultaneously and in real time according to the angle of the transducer. Ultrasound fusion imaging helps us understand the three-dimensional relationship between the liver vasculature and tumors, and can detect small liver tumors with poor conspicuity. This fusion imaging is attracting the attention of operators who perform radiofrequency ablation (RFA) for the treatment of hepatic malignancies because this real-time, multimodality comparison can increase monitoring and targeting confidence during the procedure. When RFA with fusion imaging was performed on small hepatocellular carcinomas (HCCs) with poor conspicuity, it was reported that the rates of technical success and local tumor progression were 94.4-100% and 0-8.3%. However, there have been no studies comparing fusion imaging guidance and contrast-enhanced sonography, CT or MRI guidance in ablation. Fusion imaging-guided RFA has proved to be effective for HCCs that are poorly defined on not only conventional B-mode sonography but also contrast-enhanced sonography. In addition, fusion imaging could be useful to assess the treatment response of RFA because of three-dimensional information. Here, we give an overview of the current status of ultrasound fusion imaging for clinical application in the liver.

Fusion imaging of real-time ultrasonography with CT or MRI for hepatic intervention

With the technical development of ultrasonography (US), electromagnetic tracking-based fusion imaging of real-time US and computed tomography/magnetic resonance (CT/MR) images has been used for percutaneous hepatic intervention such as biopsy and radiofrequency ablation (RFA). Because of the fusion imaging technique, the fused CT or MR images show the same plane and move synchronously while performing real-time US. With this information, fusion imaging can enhance lesion detectability and reduce the false positive detection of focal hepatic lesions with poor sonographic conspicuity. Three-dimensional US can also be fused with realtime US for the percutaneous RFA of liver tumors requiring overlapping ablation. When fusion imaging is not sufficient for identifying small focal hepatic lesions, contrast-enhanced US can be added to fusion imaging.

The value of artificial pleural effusion for percutaneous microwave ablation of liver tumour in the hepatic dome: a retrospective case-control study

PURPOSE

The aim of this study was to evaluate the feasibility, safety, and efficiency of percutaneous microwave ablation (MWA) with artificial pleural effusion for liver tumours located in the hepatic dome.

MATERIALS AND METHODS

A total of 112 sessions of artificial pleural effusion performed on 102 liver tumour patients were summarised and analysed at our hospital. Among them, 31 hepatocellular carcinoma patients treated by percutaneous MWA were selected as the artificial pleural effusion group. The control group without artificial pleural effusion was matched with tumour size, tumour location and the histological grades of differentiation. The primary technique effectiveness rate, local tumour progression rate and tumour-free survival rate were compared.

RESULTS

Artificial pleural effusion was achieved successfully in 110 of 112 sessions (98.2%), which helped to improve the visibility in 98.8% (82/83) and acquire safe puncture path in 96.3% (26/27). There were no statistical differences between the artificial pleural effusion group and the control group in the primary technique effectiveness rate (p = 1.000), the 1-, 2-, and 3-year local tumour progression rates (p = 0.669), and the 1-, 2-, and 3-year tumour-free survival rates (p = 0.979).

CONCLUSIONS

Percutaneous MWA with artificial pleural effusion could be a feasible, safe, and effective technique for liver tumours located in the hepatic dome.

Therapeutic response assessment of RFA for HCC: Contrast-enhanced US, CT and MRI

Radiofrequency ablation (RFA) is commonly applied for the treatment of hepatocellular carcinoma (HCC) because of the facile procedure, and the safety and effectiveness for the treatment of this type of tumor. On the other hand, it is believed that HCC cells should spread predominantly through the blood flow of the portal vein, which could lead to the formation of intrahepatic micrometastases. Therefore, monitoring tumor response after the treatment is quite important and accurate assessment of treatment response is critical to obtain the most favorable outcome after the RFA. Indeed, several reports suggested that even small HCCs of ≤ 3 cm in diameter might carry intrahepatic micrometastases and/or microvascular invasion. From this point of view, for preventing local recurrences, RFA should be performed ablating a main tumor as well as its surrounding non-tumorous liver tissue where micrometastases and microvascular invasion might exist. Recent advancement of imaging modalities such as contrast-enhanced ultrasonic, computed tomography, and magnetic resonance imaging are playing an important role on assessing the therapeutic effects of RFA. The local recurrence rate tends to be low in HCC patients who were proven to have adequate ablation margin after RFA; namely, not only disappearance of vascular enhancement of main tumor, but also an adequate ablation margin. Therefore, contrast enhancement gives important findings for the diagnosis of recurrent HCCs on each imaging. However, hyperemia of non-tumorous liver surrounding the ablated lesion, which could be attributed to an inflammation after RFA, may well obscure the findings of local recurrence of HCCs after RFA. Therefore, we need to carefully address to these imaging findings given the fact that diagnostic difficulties of local recurrence of HCC. Here, we give an overview of the current status of the imaging assessment of HCC response to RFA.

Radiofrequency ablation of very-early-stage hepatocellular carcinoma inconspicuous on fusion imaging with B-mode US: value of fusion imaging with contrast-enhanced US

Background/Aims

To determine the value of fusion imaging with contrast-enhanced ultrasonography (CEUS) and computed tomography (CT)/magnetic resonance (MR) images for percutaneous radiofrequency ablation (RFA) of very-early-stage hepatocellular carcinomas (HCCs) that are inconspicuous on fusion imaging with B-mode ultrasound (US) and CT/MR images.

Methods

This retrospective study was approved by our institutional review board and the requirement for informed consent was waived. Fusion imaging with CEUS using Sonazoid contrast agent and CT/MR imaging was performed on HCCs (<2 cm) that were inconspicuous on fusion imaging with B-mode US. We evaluated the number of cases that became conspicuous on fusion imaging with CEUS. Percutaneous RFA was performed under the guidance of fusion imaging with CEUS. Technical success and major complication rates were assessed.

Results

In total, 30 patients with 30 HCCs (mean, 1.2 cm; range, 0.6-1.7 cm) were included, among which 25 (83.3%) became conspicuous on fusion imaging with CEUS at the time of the planning US and/or RFA procedure. Of those 25 HCCs, RFA was considered feasible for 23 (92.0%), which were thus treated. The technical success and major complication rates were 91.3% (21/23) and 4.3% (1/23), respectively.

Conclusions

Fusion imaging with CEUS and CT/MR imaging is highly effective for percutaneous RFA of very-early-stage HCCs inconspicuous on fusion imaging with B-mode US and CT/MR imaging.

Multimodality imaging to assess immediate response to irreversible electroporation in a rat liver tumor model

PURPOSE

To compare changes on ultrasonographic (US), computed tomographic (CT), and magnetic resonance (MR) images after irreversible electroporation (IRE) ablation of liver and tumor tissues in a rodent hepatoma model.

MATERIALS AND METHODS

Studies received approval from the institutional animal care and use committee. Forty-eight rats were used, and N1-S1 tumors were implanted in 24. Rats were divided into groups and allocated for studies with each modality. Imaging was performed in normal liver tissues and tumors before and after IRE. MR imaging was performed in one group before and after IRE after hepatic vessel ligation. US images were graded to determine echogenicity changes, CT attenuation was measured (in Hounsfield units), and MR imaging signal-to-noise ratio (SNR) was measured before and after IRE. Student t test was used to compare attenuation and SNR measurements before and after IRE (P < .05 indicated a significant difference).

RESULTS

IRE ablation produced greater alterations to echogenicity in normal tissues than in tumors. Attenuation in ablated liver tissues was reduced compared with that in control tissues (P < .001), while small attenuation differences between ablated (42.11 HU ± 2.11) and control (45.14 HU ± 2.64) tumors trended toward significance (P = .052). SNR in ablated normal tissues was significantly altered after IRE (T1-weighted images: pre-IRE, 145.95 ± 24.32; post-IRE, 97.80 ± 18.03; P = .004; T2-weighted images, pre-IRE, 47.37 ± 18.31; post-IRE, 90.88 ± 37.15; P = .023). In tumors, SNR differences before and after IRE were not significant. No post-IRE signal changes were observed after hepatic vessel ligation.

CONCLUSION

IRE induces rapid changes on gray-scale US, unenhanced CT, and MR images. These changes are readily visible and may assist a performing physician to delineate ablation zones from the unablated surrounding parenchyma.

Fusion imaging-guided radiofrequency ablation for hepatocellular carcinomas not visible on conventional ultrasound

OBJECTIVE

The objective of our study was to assess whether fusion imaging of conventional ultrasound and liver CT or MR images can improve the conspicuity of lesions and feasibility of percutaneous radiofrequency ablation (RFA) for the treatment of hepatocellular carcinomas (HCCs) not visible on ultrasound. Whether peritumoral anatomic landmarks can be used for the placement of an electrode in HCCs not visible on ultrasound even after image fusion was also evaluated.

MATERIALS AND METHODS

Planning ultrasound for percutaneous RFA was performed using conventional ultrasound first and then using fusion imaging later during the same session. The visibility of HCCs and feasibility of RFA on conventional ultrasound and on fusion imaging were assessed. We evaluated how many HCCs initially not visible on conventional ultrasound could be visualized and ablated after applying the fusion imaging technique. One hundred twenty HCCs not visible on conventional ultrasound in 96 patients were included.

RESULTS

When fusion imaging was applied, 38 of the 120 (31.7%) HCCs that were initially not visible could be seen and RFA was feasible. Among the remaining 82 HCCs still not visible after image fusion, 26 (31.7%) were ablated under the guidance of fusion imaging the technique based on peritumoral anatomic landmarks. Overall, 64 of 120 (53.3%) HCCs (59.4%, 57 of 96 patients) not visible on conventional ultrasound could be ablated under the guidance of the fusion imaging technique.

CONCLUSION

Fusion imaging can improve the conspicuity of HCCs and the feasibility of percutaneous RFA of HCCs not visible on conventional ultrasound. Peritumoral anatomic landmarks can be used for electrode placement in HCCs that are still not visible even after image fusion.

Relationship between postoperative imaging findings and therapeutic effect in patients with unresectable hepatocellular carcinoma after ultrasound-guided percutaneous radiofrequency ablation

AIM: To investigate the relationship between postoperative imaging findings and therapeutic effect in patients with unresectable hepatocellular carcinoma after ultrasound-guided percutaneous radiofrequency ablation (PRFA).

METHODS: Thirty-six patients with unresectable hepatocellular carcinoma who undersent ultrasound-guided percutaneous radiofrequency ablation were selected. The levels of alanine aminotransferase (ALT), aspartate aminotrans-ferase (AST), total bilirubin (TBIL), albumin (ALB), and alpha fetal protein (AFP) as well as imaging findings were retrospectively analyzed (1 day before, 7, 14 and 28 d after PRFA).

RESULTS: The levels of ALT and AST were significantly higher on day 7 after PRFA than on day 1 before PRFA (102.21 U/L ± 53.41 U/L vs 55.34 U/L ± 36.57 U/L, 90.58 U/L ± 37.22 U/L vs 65.77 U/L ± 40.29 U/L), and they decreased to preoperative levels on day 14. Patients with an AFP level decreased by ≥ 50% on day 28 showed complete ablation of the tumors on magnetic resonance imaging (MRI) and high echo area with liquefaction and no blood flow in the center of the lesions on ultrasound. Patients with elevated AFP values showed incomplete ablation of the tumors on MRI and incomplete high echo area with blood flow on ultrasound. The effective rate of PRFA was higher than 60% when the levels of AFP were used as evaluation criterion. The 3-year survival rate was 68%. The median survival time was 38.09 mo.

CONCLUSION: The imaging findings can well reflect the changes of serum markers and recurrence in patients with unresectable hepatocellular carcinoma after ultrasound-guided percutaneous radiofrequency ablation. Imaging examinations can be used as an effective approach for the detection of recurrence of hepatocellular carcinoma.

Mechanisms of cryoablation: clinical consequences on malignant tumors

While the destructive actions of a cryoablative freeze cycle are long recognized, more recent evidence has revealed a complex set of molecular responses that provides a path for optimization. The importance of optimization relates to the observation that the cryosurgical treatment of tumors yields success only equivalent to alternative therapies. This is also true of all existing therapies of cancer, which while applied with curative intent; provide only disease suppression for periods ranging from months to years. Recent research has led to an important new understanding of the nature of cancer, which has implications for primary therapies, including cryosurgical treatment. We now recognize that a cancer is a highly organized tissue dependent on other supporting cells for its establishment, growth and invasion. Further, cancer stem cells are now recognized as an origin of disease and prove resistant to many treatment modalities. Growth is dependent on endothelial cells essential to blood vessel formation, fibroblasts production of growth factors, and protective functions of cells of the immune system. This review discusses the biology of cancer, which has profound implications for the diverse therapies of the disease, including cryosurgery. We also describe the cryosurgical treatment of diverse cancers, citing results, types of adjunctive therapy intended to improve clinical outcomes, and comment briefly on other energy-based ablative therapies. With an expanded view of tumor complexity we identify those elements key to effective cryoablation and strategies designed to optimize cancer cell mortality with a consideration of the now recognized hallmarks of cancer.

Fusion imaging-guided percutaneous biopsy of focal hepatic lesions with poor conspicuity on conventional sonography

OBJECTIVES

The purpose of this study was to evaluate the effectiveness of real-time fusion imaging (sonography combined with computed tomography or magnetic resonance imaging) for percutaneous sonographically guided biopsy of focal hepatic lesions with poor sonographic conspicuity.

METHODS

This study was conducted as a retrospective analysis of a prospective database and was approved by the Institutional Review Board. Patients who had target lesions with poor conspicuity on B-mode sonography for percutaneous biopsy were enrolled in the study. Lesion conspicuity was assessed by conventional B-mode sonography first and then by fusion imaging later in the same session. We compared lesion conspicuity and detection rates between B-mode sonography and fusion imaging and evaluated how many cases of initially invisible lesions on B-mode sonography became visible on fusion imaging. The technical success rate was evaluated on the basis of the final diagnoses, which were established by pathologic examination of the biopsy specimens as well as follow-up clinical and radiologic examinations.

RESULTS

A total of 22 patients were enrolled in the study. On fusion imaging, lesion conspicuity was increased in 63.6% of focal hepatic lesions (14 of 22). Moreover, 66.7% of lesions (6 of 9) that were invisible on B-mode sonography became visible on fusion imaging. The true-positive detection rate was significantly different between B-mode sonography and fusion imaging (9 of 22 versus 19 of 22; P = .0044). Percutaneous biopsy was performed for all lesions, including 3 target lesions that were invisible even on fusion imaging. The technical success rate was 95.5% (21 of 22).

CONCLUSIONS

Fusion imaging is effective for percutaneous biopsy of focal hepatic lesions with poor sonographic conspicuity.

Contrast-enhanced ultrasound in the preoperative, intraoperative and postoperative assessment of liver lesions

The use of contrast agents (CA) with liver ultrasound (US) has gained recently an established role for the diagnosis of various hepatic diseases due to their safety, high versatility and low costs (contrast-enhanced ultrasound: CEUS). The purpose of this review is to provide a state-of-the-art summary of the available evidence for their use in the characterization of focal liver lesions. A published work search was conducted for all preclinical and clinical studies involving CA on hepatic US imaging. CEUS increases the sensitivity for lesion detection and the specificity to differentiate between benign and malignant diseases due to the enhanced visualization of the tumor microcirculation. Results achieved seem at least equivalent to those of spiral computed tomography or magnetic resonance imaging. The association of CA with intraoperative ultrasound has changed the surgical approach in 25% of patients and guarantees complete ablations by a single session in most of them. CEUS provides detailed information about tumor vasculature, improves the preoperative characterization and therefore the therapeutic strategy, and can evaluate the intraoperative completeness of the ablation.

CT with hepatic arterioportography as a pretreatment examination for hepatocellular carcinoma patients: a randomized controlled trial

OBJECTIVES

The combination of computed tomography with hepatic arteriography and arterial portography (CTHA/CTAP) can detect additional hepatocellular carcinoma (HCC) nodules undetected by conventional dynamic CT.

METHODS

In this single-center, randomized, open-label, controlled trial, we randomly assigned 280 patients who were diagnosed as having HCC by conventional dynamic CT, and eligible for radiofrequency ablation (RFA), to undergo CTHA/CTAP before treatment, or to the control group. Newly detected HCC nodules by CTHA/CTAP were intended to be ablated completely. The primary end point was recurrence-free survival and the key secondary end point was overall survival. The analysis was conducted on an intention-to-treat basis. Those with nonablated nodules were treated as for recurrence.

RESULTS

A total of 75 nodules were newly diagnosed as HCC by CTHA/CTAP in 45 patients. Three patients (one in the CTHA/CTAP group and two in the control group) who refused treatment were excluded from all analyses. The cumulative recurrence-free survival rates at 1, 2, and 3 years were 60.1, 29.0, and 18.9% in the CTHA/CTAP group and 52.2, 29.7, and 23.1% in the control group, respectively (P=0.66 by log-rank test; hazard ratio, 0.94 for CTHA/CTAP vs. control; 95% confidence interval (CI), 0.73-1.22). The cumulative overall survival rates at 3 and 5 years were 79.7 and 56.4% in the CTHA/CTAP group and 86.8 and 60.1% in the control group, respectively (P=0.50; hazard ratio, 1.15, 95% CI, 0.77-1.71).

CONCLUSIONS

CTHA/CTAP may detect recurrent lesions earlier. However, CTHA/CTAP before RFA did not improve cumulative recurrence-free survival or overall survival.