Hepatocellular carcinoma treated with percutaneous radio-frequency ablation: evaluation with follow-up multiphase helical CT

Complications of Percutaneous Radiofrequency Ablation for Hepatocellular Carcinoma

Radiofrequency ablation (RFA) is a potentially curative treatment option for early Hepatocellular carcinoma. The RFA is considered safe with a relatively low incidence of complications ranging from 2%-7.9%. Though most of the complications are self-limiting, sometimes they can be life-threatening. The occurrence of the particular complication depends on various factors like tumour location and morphology, underlying disease and ablation technique. A detailed understanding of potential complications along with the associated risk factors will help to employ strategies to prevent them, identify them early and manage them when they occur. This article demonstrates various radiofrequency ablation-related complications and discusses the risk factors and technical strategies to minimise them and achieve complete ablation of the tumour.

Particle swarm optimization solution for roll-off control in radiofrequency ablation of liver tumors: Optimal search for PID controller tuning

The study investigates the efficacy of a bioinspired Particle Swarm Optimization (PSO) approach for PID controller tuning in Radiofrequency Ablation (RFA) for liver tumors. Ex-vivo experiments were conducted, yielding a 9th order continuous-time transfer function. PSO was applied to optimize PID parameters, achieving outstanding simulation results: 0.605% overshoot, 0.314 seconds rise time, and 2.87 seconds settling time for a unit step input. Statistical analysis of 19 simulations revealed PID gains: Kp (mean: 5.86, variance: 4.22, standard deviation: 2.05), Ki (mean: 9.89, variance: 0.048, standard deviation: 0.22), Kd (mean: 0.57, variance: 0.021, standard deviation: 0.14) and ANOVA analysis for the 19 experiments yielded a p-value ≪ 0.05. The bioinspired PSO-based PID controller demonstrated remarkable potential in mitigating roll-off effects during RFA, reducing the risk of incomplete tumor ablation. These findings have significant implications for improving clinical outcomes in hepatocellular carcinoma management, including reduced recurrence rates and minimized collateral damage. The PSO-based PID tuning strategy offers a practical solution to enhance RFA effectiveness, contributing to the advancement of radiofrequency ablation techniques.

Evaluating treatment response following locoregional therapy for hepatocellular carcinoma: A review of the available serological and radiological tools for assessment

Hepatocellular carcinoma (HCC) is an aggressive primary malignancy of the liver and is the third most common cause of cancer-related global mortality. There has been a steady increase in treatment options for HCC in recent years, including innovations in both curative and non-curative therapies. These advances have brought new challenges and necessary improvements in strategies of disease monitoring, to allow early detection of HCC recurrence. Current serological and radiological strategies for post-treatment monitoring and prognostication and their limitations will be discussed and evaluated in this review.

The Role of Ablative Techniques in the Management of Hepatocellular Carcinoma: Indications and Outcomes

The management of hepatocellular carcinoma (HCC) remains complex and will continue to rely on the multidisciplinary input of hepatologists, surgeons, radiologists, oncologists and radiotherapists. With the appropriate staging of patients and selection of suitable treatments, the outcomes for HCC are improving. Surgical treatments encompassing both liver resection and orthotopic liver transplantation (OLT) are the definitive curative-intent options. However, patient suitability, as well as organ availability, pose essential limitations. Consequently, non-surgical options, such as ablative techniques, play an increasingly important role, especially in small HCCs, where overall and disease-free survival can be comparable to surgical resection. Ablative techniques are globally recommended in recognised classification systems, showing increasingly promising results. Recent technical refinements, as well as the emerging use of robotic assistance, may expand the treatment paradigm to achieve improved oncological results. At present, in very early stage and early stage unresectable disease, percutaneous thermal ablation is considered the treatment of choice. Owing to their different features, various ablative techniques, including radiofrequency ablation, microwave ablation, cryotherapy ablation and irreversible electroporation, have been shown to confer different comparative advantages and applicability. We herein review the role of available ablative techniques in the current complex multidisciplinary management of HCC, with a main focus on the indications and outcomes, and discuss future perspectives.

Predictive Value of Ablative Margin Assessment After Microwave Ablation for Local Tumor Progression in Medium and Large Hepatocellular Carcinoma: Computed Tomography-Computed Tomography Image Fusion Method Versus Side-by-Side Method

OBJECTIVE

This study aimed to explore the feasibility and predictive value for local tumor progression (LTP) of the computed tomography (CT)-CT image fusion method versus side-by-side method to assess ablative margin (AM) in hepatocellular carcinoma ≥3 cm in diameter.

MATERIALS AND METHODS

We selected patients with hepatocellular carcinoma ≥3 cm in diameter who underwent microwave ablation and had complete tumor ablation. We used the CT-CT image fusion method and side-by-side method to assess AM separately and divided the lesions into 3 groups: group I, minimum ablative margin (min-AM) <0 mm (the ablation zone did not fully cover the tumor); group II, 0 mm ≤ min-AM <5 mm; and group III, min-AM ≥5 mm.

RESULTS

A total of 71 patients involving 71 lesions were included. The κ coefficient for the agreement between the CT-CT image fusion method and the side-by-side method in assessing min-AM was 0.14 (P = 0.028). Cumulative LTP rate was significantly different between groups by min-AM from the CT-CT image fusion method (P < 0.05) but not by min-AM from the side-by-side method (P = 0.807). Seventeen of the 20 LTP lesions were located at min-AM on fused CT images, with consistency rate of 85%.

CONCLUSIONS

Compared with the side-by-side method, the CT-CT image fusion method is more accurate in assessing the AM of eccentrically ablated lesions and shows better predictive value for LTP. The min-AM based on CT-CT image fusion assessment is an important influencing factor for LTP.

Indian College of Radiology and Imaging Guidelines on Interventions in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the most common malignancies and a significant cause of cancer-related death. Treatment of HCC depends on the stage of the tumor. As many patients with HCC are not deemed fit for surgical resection or liver transplantation, locoregional therapies play an essential role in the management. Image-guided locoregional treatments include percutaneous ablative therapies and endovascular therapies. The choice of an individual or a combination of therapies is guided by the tumor and patient characteristics. As the outcomes of image-guided locoregional treatments depend on the ability to achieve necrosis of the entire tumor along with a safety margin around it, it is mandatory to follow standard guidelines. In this manuscript, we discuss in detail the various aspects of image-guided locoregional therapies to guide interventional radiologists involved in the care of patients with HCC.

Transcatheter arterial embolization of iatrogenic massive arterioportal fistula in the liver

BACKGROUND

Massive arterioportal fistula (APF) is naturally irreversible and can induce portal hypertension and portal vein thrombosis (PVT), worsening survival outcomes.

PURPOSE

To evaluate the clinical course and details of transarterial embolization (TAE) procedures for massive APF.

MATERIAL AND METHODS

This retrospective single-center observational study evaluated the time until embolization after puncture, imaging, embolization methods, and laboratory data of 10 consecutive patients who were diagnosed with massive APF after puncture and underwent TAE at our hospital from 1 April 2012 to 30 September 2019.

RESULTS

Out of 10 cases, eight demonstrated a simple type and the other two cases a complex network type on the digital subtraction angiography pattern of massive APF. In two simple-type cases for which re-embolization was required, other subsegmental branches were embolized. The two cases showing a complex network type had been embolized via not only the subsegmental branch, but also the extrahepatic and multiple subsegmental branches. Child-Pugh scores were improved in eight of the ten cases. PVT was seen in six cases before embolization, but disappeared after embolization in all cases, despite the fact that three cases had not received anticoagulant therapy. Six cases had digestive varices before embolization, suggesting portal hypertension, and two of the six cases with esophageal varices and one with gastric varices decreased after embolization.

CONCLUSION

TAE for massive APF contributed to the improvement of hepatic reserve, the disappearance of PVT, and the improvement of portal hypertension; however, embolization of multiple branches may still be required in some cases.

Complications after Thermal Ablation of Hepatocellular Carcinoma and Liver Metastases: Imaging Findings

Tumour ablation is a strategy of treatment of hepatic tumours in patients with small hepatocellular carcinoma (HCC) (<3 cm) or in patients unfit for surgical resection. Moreover, tumor ablation can be used as an adjuvant therapy or may be used in association with resection in case of patients with poor functional liver disease. These types of treatment usually could be performed percutaneously under image guidance. The most clinically verified and used ablation modalities are Radiofrequency Ablation (RFA) and microwave ablation (MWA). However, despite both of them are considered minimally invasive techniques, they could be related to post-procedural complications. The International Working Group on Image-Guided Tumor and the Society of Interventional Radiology (SIR) identified major and minor post-ablative complications. Major complications, as vascular complications, occur in 2.2% to 3.1% of cases and include all the high risk pathological conditions which could increase the level of care or result in hospital admission or substantially prolonged hospital stay (SIR classifications C−E). Minor complications, as biliary complications, occur in 5% to 8.9% and include self-limiting conditions that are considered to be of low risk for the patient’s outcome. The purpose of this review is to summarise the main pathological ultrasound (US) and Computed Tomography (CT) findings, that may arise after ablative treatment. To simplify the analysis, the pathological pictures are divided according to the site of damage into vascular, biliary and extrahepatic complications.

A Review of Imaging Methods to Assess Ultrasound-Mediated Ablation

Ultrasound ablation techniques are minimally invasive alternatives to surgical resection and have rapidly increased in use. The response of tissue to HIFU ablation differs based on the relative contributions of thermal and mechanical effects, which can be varied to achieve optimal ablation parameters for a given tissue type and location. In tumor ablation, similar to surgical resection, it is desirable to include a safety margin of ablated tissue around the entirety of the tumor. A factor in optimizing ablative techniques is minimizing the recurrence rate, which can be due to incomplete ablation of the target tissue. Further, combining focal ablation with immunotherapy is likely to be key for effective treatment of metastatic cancer, and therefore characterizing the impact of ablation on the tumor microenvironment will be important. Thus, visualization and quantification of the extent of ablation is an integral component of ablative procedures. The aim of this review article is to describe the radiological findings after ultrasound ablation across multiple imaging modalities. This review presents readers with a general overview of the current and emerging imaging methods to assess the efficacy of ultrasound ablative treatments.

Early Assessment of Response to Radiofrequency Ablation With CT Perfusion Imaging in Rabbit VX2 Liver Tumor Model

Objectives

To discriminate viable tumors from benign periablational enhancement (BPE) in early stage after radiofrequency ablation (RFA) is a major confounding problem. The goal of this study is to evaluate quantitative assessment and diagnostic value of CT perfusion between viable tumors and BPE after RFA in the rabbit liver VX2 tumor model, with pathological results as the standard.

Methods

Twenty-eight VX2 liver tumors were treated with RFA, on days 1, 3, 7, and 14, seven rabbits were randomly chosen for CT perfusion and performed pathology examinations immediately. The perfusion parameters along with the profile of time-density curves (TDCs) and pseudo-color images of the parameters were observed in both BPE and viable tumors, then compared with the pathology results. The perfusion parameters included blood flow (BF), blood volume (BV), time to peak (TTP), permeability (P), arterial liver perfusion (ALP), portal venous perfusion (PVP) and hepatic perfusion index (HPI).

Results

A total of 26/28 rabbits successfully underwent CT perfusion, while 6/26 lesions were confirmed to be viable tumors. The TDCs of BPE were mainly speed-up platform curves (15/26), while the viable tumors showed mainly speed-up speed-down (3/6) and speed-up platform (2/6) curves. The PVP values were significantly higher, and the HPI values were significantly lower for BPE at all time points than viable tumors (P < 0.05). Both of PVP value and HPI value have high efficiency for the differential diagnosis of the viable tumors and BPE at each time point. These characteristics of CT perfusion parameters were consistent with pathological changes.

Conclusions

The TDCs, PVP and HPI have the potential to indicate BPE and viable tumors effectively early after RFA treatment, the results were highly consistent with pathology. CT perfusion has advantages with great efficacy in monitoring the therapeutic effect early after RFA treatment.

Characteristic changes of the ablation zone on contrast-enhanced computed tomography after radiofrequency ablation of hepatic metastases

Purpose:

Size and density measurements of the ablation zones on contrast-enhanced computed tomography (CT) after radiofrequency ablation (RFA) of hepatic metastases of primary breast or colorectal cancer were acquired over time.

Materials and Methods:

Twenty-five liver metastases [colorectal cancer (CRC): n = 16; mean size: 19.6 ± 8.5 mm; breast cancer (BC): n = 9; 27.9 ± 13.6 mm] in 15 patients (CRC: n = 11; age: 65.4 ± 6.5 years; BC: n = 4; 62.0 ± 13.8 years) treated by RFA were included in this retrospective study. All patients had undergone postinterventional serial follow-up using multidetector CT (MDCT) (1 day/1/4/7/10/14/18/23/>24 months) without evidence of local tumor recurrence during the follow-up. The ablation zones were evaluated using a commercial software tool (Syngo CT Oncology) in order to determine volumetric, RECIST-, WHO- and density changes over the course of time. Results were compared by applying repeated measures analysis of variance and displayed graphically.

Results:

The RF ablation zones demonstrated significant shrinkage (P ≤ 0.05) over the first 7 months (volume, RECIST, WHO) of the follow-up. Follow-up after 7 months did not show any significant changes in size (P > 0.05) (mean volume (ml): 55.2/34.7/26.3/16.5/12.7/10.0/8.9/8.1/7.5; RECIST (mm): 58.7/49.3/43.7/37.8/34.2/31.3/29.1/27.3/24.8; WHO (mm²): 2458.3/1769.3/1341.8/1027.1/870.1/720.2/649.0/570.4/511.3). Mean density values decreased significantly between 1 day (58.9 HU) and 1 month (47.5 HU) after the procedure.

Conclusion:

Typical changes in size and density values of RF-induced, recurrence-free ablation zones after RFA of hepatic metastases of colorectal and breast cancer were acquired, showing a significant decrease in density of the ablation zone within the first month and significant shrinkage within the first 7 months after RFA.

Prognostic Value of the Preoperative Lymphocyte-C-Reactive Protein Ratio in Hepatocellular Carcinoma Patients Treated with Curative Intent: A Large-Scale Multicentre Study

Purpose

This study aimed to evaluate the prognostic value of the lymphocyte-C-reactive protein ratio (LCR) score, a novel inflammation-based score based on lymphocytes and C-reactive protein, in hepatocellular carcinoma (HCC) patients treated with curative intent.

Patients and Methods

A total of 1158 HCC patients undergoing surgical resection or radiofrequency ablation with curative intent were recruited from 3 different centres and divided into a primary cohort (n=716) and a validation cohort (n=442). Univariate and multivariate analyses were performed to identify variables associated with overall survival (OS). The discriminatory accuracy of seven inflammation-based scores was compared by using the concordance index (C-index).

Results

The LCR score differentiated HCC patients into two groups with distinct prognoses (1-, 3-, and 5-year OS rates and median OS: 92.9%, 81.9%, 73.3% and 99.2 months and 79.8%, 56.6%, 49.7% and 69.1 months; P<0.001). Multivariate analysis showed that LCR score, AFP, ALBI score, tumour size, and TNM stage were independently associated with OS. When patients were stratified according to different disease states, the LCR score could still differentiate HCC patients into two groups with distinct prognoses (all P<0.005). The LCR score demonstrated a markedly superior C-index of 0.621 compared with the other inflammation-based scores (0.503–0.590). These findings were supported by the validation cohort.

Conclusion

The preoperative LCR score is a novel, stable, and clinically feasible prognostic marker for patients with HCC, independent of liver function, tumour characteristics, and treatment allocation and is superior to other inflammation-based scores in terms of its prognostic ability.

Imaging after percutaneous thermal and non-thermal ablation of hepatic tumour: normal appearances, progression and complications

The increasing number of liver tumours treated by percutaneous ablation leads all radiologists to be confronted with the difficult interpretation of post-ablation imaging. Radiofrequency and microwave techniques are most commonly used. Recently, irreversible electroporation treatments that do not induce coagulation necrosis but cellular apoptose and respect the collagen architecture of bile ducts and vessels have been introduced and lead to specific post-ablation features and evolution. Ablations cause 'normal' changes in ablation and periablation zones. It is necessary to know these post-ablation features to avoid the misinterpretation of recurrence or complication that would lead to unnecessary treatments. Another challenge for the radiologist is to detect as early as possible the residual unablated tumour or the disease progression (local progression and tumour seeding) that will require a new treatment. Finally, the complications, frequent or rarer, should be recognised to be managed adequately. The purpose of this article is therefore to describe the large spectrum of normal and pathological aspects related to the treatment of hepatic tumour by percutaneous thermal ablation and irreversible electroporation ablation.

SN, Kulkarni SS, Shetty NS, Gupta A, Gupta S. Indian Society of Vascular and Interventional Radiology Expert Consensus Statements for Ablation in Hepatocellular Carcinoma: Part II

Locoregional therapies play an important role in the management of hepatocellular carcinoma (HCC). Percutaneous ablation is one of the most commonly employed nonsurgical methods for treating very early and early HCC. For small HCC, ablation is potentially curative and competes with surgical resection. The widespread availability and the spectrum of ablative techniques mandate uniform approach among interventional radiologists. Thus, it is desirable to have a consensus regarding various aspects of the liver ablation. This article represents a consensus document of the experts from the Indian Society of Vascular and Interventional Radiology involved in the care of patients with HCC. The statements are presented in two parts.

Radiofrequency ablation using internally cooled wet electrodes in bipolar mode for the treatment of recurrent hepatocellular carcinoma after locoregional treatment: A randomized prospective comparative study

Objective

This study aimed to compare the efficacy between bipolar radiofrequency ablation (RFA), using twin internally cooled wet (TICW) electrodes, and switching monopolar RFA, using separable clustered (SC) electrodes, in the treatment of recurrent hepatocellular carcinoma (HCC) after locoregional treatment.

Materials and methods

In this single-center, two-arm, parallel-group, randomized controlled study, we performed a 1:1 random allocation on eligible patients with recurrent HCC after locoregional treatment, to receive TICW-RFA or SC-RFA. The primary endpoint was the minimum diameter of the ablation zone per unit ablation time. Secondary endpoints included other technical parameters, complication rate, technical success and technique efficacy, and clinical outcomes.

Results

Enrolled patients were randomly assigned to the TICW-RFA group (n = 40) or SC-RFA group (n = 37). The two groups did not show significant differences in the primary endpoint, the minimum diameter of the ablation zone per unit ablation time was 2.71 ± 0.98 mm/min and 2.61 ± 0.96 mm/min in the TICW-RFA and SC-RFA groups, respectively (p = 0.577). Total RF energy delivery (11.75 ± 9.04 kcal vs. 22.61 ± 12.98 kcal, p < 0.001) and energy delivery per unit time (0.81 ± 0.49 kcal/min vs. 1.45 ± 0.42 kcal/min, p < 0.001) of the TICW-RFA group were less than those of the SC-RFA group. No procedure-related death or major complications occurred. Technical success was achieved in all patients in both groups, and technique efficacy rates were 100% (46/46) in the TICW-RFA group and 95.0% (38/40) in the SC-RFA group (p = 0.213). The 1-year and 2-year cumulative LTP rates were 11.8% and 24.2%, respectively, in the TICW-RFA group, and 8.6% and 18.1%, respectively, in the SC-RFA group (p = 0.661).

Conclusion

In this single-center randomized controlled study from a Korean tertiary referral hospital, TICW-RFA demonstrated similar therapeutic efficacy and safety profile for recurrent HCC after locoregional treatment compared with SC-RFA.

Trial registration

ClinicalTrials.gov (NCT03806218)

Follow-up of percutaneous microwave (MW) ablation of hepatic lesion: predictive value of CT at 24-h compared with CT at 1 month

To retrospectively assess the predictive value of the CT performed at 24 h, compared with the CT performed at 1 month, in the evaluation of the technical success of microwave (MW) ablation of hepatic lesions. In a single center, 50 patients with HCC underwent percutaneous MW ablation between November 2016 and March 2019. Each patient underwent a contrast-enhanced CT exam at 24 h and at 1 month after the procedure. For each patient, was assessed the presence or absence of residual disease, the appearance of a new lesion, complications, and the involvement of the hepatic capsule, both at 24-h and at 1 month. Overall correlation between residual disease, appearance of a new nodule and complications was also assessed. A total of 50 hepatic lesions were treated with US-guided MW ablation. Patients' mean age was 70.9 years (range 28-87 years). Mean nodule diameter was 17.6 mm (range 7-35 mm). Contingency tables and the χ² test showed a strong association when looking at capsule involvement (accuracy: 100%), residual disease (accuracy: 90%; p-value 0.003), and the appearance of a new HCC nodule (accuracy: 88%; p-value 0.007); regarding complications, the accuracy was 78% (p-value 0.014). Optimal correlation was reached in 62% of cases, moderate correlation in 26%, minimum correlation in 10% of cases; no cases of zero correlation were recorded. CT at 24 h and 1 month showed comparable efficacy in evaluating residual disease after MW thermal ablation of liver lesions. However, further studies are needed to assess which factors may cause false-negative results at the 24-h CT.

Iatrogenic Arterioportal Fistula Caused by Radiofrequency Ablation of Hepatocellular Carcinoma: Clinical Course and Treatment Outcomes

PURPOSE

To analyze the clinical course and treatment outcomes of patients with iatrogenic arterioportal fistula (APF) caused by radiofrequency (RF) ablation of hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

Among the 1,620 hepatocellular carcinoma patients treated by RF ablation between January 2012 and August 2017, 99 who developed APF after RF ablation were included in this retrospective study. Depending on the extent of portal vein enhancement on arterial phase images, APF was classified as massive or nonmassive. The patients' clinical course was investigated and statistically evaluated by univariable and multivariable analyses.

RESULTS

Thrombocytopenia (odds ratio [OR] = 3.939; 95% confidence interval [CI], 1.141-13.598) was the only risk factor for developing massive APF. Eleven patients underwent embolotherapy (technical success rate, 90.9%) and no patients experienced serious adverse events within 30 days of the procedure. Patients with massive APF (66.7%) had a significantly higher chance of a Child-Pugh score increase than did the patients with nonmassive APF (13.6%) (P < .001). Massive APF had a significantly lower chance of natural regression than did nonmassive APF (P < .001). Child-Pugh B (OR = 17.739; 95% confidence interval, 2.361-133.279) and massive APF without treatment (OR = 11.061; 95% confidence interval, 1.257-97.341) were independent risk factors for liver failure that led to death of liver transplant within 1 year after RF ablation.

CONCLUSIONS

Massive APF caused by RF ablation is mostly irreversible and significantly worsens patients' outcomes, but may be effectively treated with embolotherapy.

Imaging findings during and after percutaneous cryoablation of hepatic tumors

OBJECTIVE

Imaging plays a key role in the assessment of patients before, during, and after percutaneous cryoablation of hepatic tumors. Intra-procedural and early post-procedure imaging with CT and MRI is vital to the assessment of technical success including adequacy of ablation zone coverage. Recognition of the normal expected post-procedure findings of hepatic cryoablation such as ice ball formation, hydrodissection, and the normal appearance of the ablation zone is crucial to be able to differentiate from complications including vascular, biliary, or non-target organ injury. Delayed imaging is essential for determination of clinical effectiveness and detection of unexpected findings such as residual unablated tumor and local tumor progression. The purpose of this article is to review the spectrum of expected and unexpected imaging findings that may occur during or after percutaneous cryoablation of hepatic tumors.

CONCLUSION

Differentiating expected from unexpected findings during and after hepatic cryoablation helps radiologists identify residual or recurrent tumor and detect procedure-related complications.

Percutaneous Laser Ablation of Unifocal Papillary Thyroid Microcarcinoma: Utility of Conventional Ultrasound and Contrast-Enhanced Ultrasound in Assessing Local Therapeutic Response

PURPOSE

To investigate the use of conventional ultrasound and contrast-enhanced ultrasound (CEUS) in assessing local therapeutic response of percutaneous laser ablation (PLA) for papillary thyroid microcarcinoma (PTMC).

METHODS

Sixty-four patients with 64 PTMCs who were referred to our hospital from November 2013 to July 2016 were treated with PLA. The extent of ablation was assessed by CEUS at 10-20 min and 7 days after PLA. The size and volume of the ablation zone were evaluated on conventional ultrasound at 1 h, 1, 3, 6 and 12 months, and every half-year thereafter, and recurrences were also recorded. Ultrasound-guided fine needle aspiration biopsy (FNAB) of the ablated area was performed at 1, 6 and 12 months after PLA.

RESULTS

Two incomplete ablations were detected by CEUS, and a second ablation was performed. The mean largest diameter and volume of the ablated area on CEUS at 10-20 min and 7 days after PLA were significantly larger than those of pre-treatment on conventional ultrasound (p < 0.05, for both). At the last follow-up, the mean largest diameter was reduced from 4.6 ± 1.5 to 0.6 ± 1.3 mm (p < 0.0.5), and the average volume was 41.0 ± 40.4 mm³, which decreased to 1.8 ± 6.7 mm³ (p < 0.0.5). A cervical metastatic lymph node was detected on ultrasound and confirmed by ultrasound-guided FNAB at 30 months after PLA.

CONCLUSIONS

CEUS could play a crucial role in assessing the completeness of PLA for treating PTMC, and conventional ultrasound can not only guide the FNAB process but also is important in the follow-up of PTMC after PLA.

Imaging evaluation of sorafenib for treatment of advanced hepatocellular carcinoma

Sorafenib, which is a novel targeted agent, plays an important role in treating advanced hepatocellular carcinoma (HCC) through its antiangiogenic and antiproliferative effects. However, conventional morphology-based radiographic evaluation systems may underestimate the efficacy of sorafenib in HCC due to a lack of apparent tumor shrinkage or altered tumor morphology in many cases. This calls for the development of more accurate imaging methods for evaluating sorafenib. The introduction of tumor burden measurements based on viability and other evolving imaging approaches for assessing therapeutic effects are promising for overcoming some of the limitations of the morphology-based criteria. In this review, we summarize various imaging methods that are used to assess treatment responses of advanced HCC to sorafenib. Imaging markers predictive of prognosis in advanced HCC after treatment with sorafenib are also included and discussed.

Comparison of Chronologic Change in the Size and Contrast-Enhancement of Ablation Zones on CT Images after Irreversible Electroporation and Radiofrequency Ablation

Objective

To compare short-, mid-, and long-term follow-up ablation zone volume alterations as well as imaging features on contrast-enhanced computed tomography (CT) after irreversible electroporation (IRE) of primary and secondary liver tumors with findings subsequent to radiofrequency ablation (RFA).

Materials and Methods

Volume assessment of 39 ablation zones (19 RFA, 20 IRE) after intervention was performed at four time intervals (day 0 [t1; n = 39], day 1-7 [t2; n = 25], day 8-55 [t3; n = 28], after day 55 [t4; n = 23]) on dual-phase CT. Analysis of peripheral rim enhancement was conducted. Lesion's volume decrease relative to the volume at t1 was calculated and statistically analyzed with respect to patient's sex, age, ablation modality (IRE/RFA), and history of platinum-based chemotherapy (PCT).

Results

No influence of patient's sex or age on ablation volume was detected. The decrease in ablation zones' volume was significantly larger (p < 0.05 for all time intervals) after IRE (arterial phase, 7.5%; venous phase, 9.7% of initial volume) compared to RFA (arterial phase, 39.6%; venous phase, 45.3% of initial volume). After RFA, significantly smaller decreases in the ablation volumes, in general, were detected in patients treated with PCT in their history (p = 0.004), which was not detected after IRE (p = 0.288). In the arterial phase, peripheral rim enhancement was frequently detected after both IRE and RFA. In the venous phase, rim-enhancement was depicted significantly more often following IRE at t1 and t2 (pt1 = 0.003, pt2 < 0.001).

Conclusion

As per our analysis, ablation zone volume decreased significantly in a more rapid and more profound manner after IRE. Lesion's remodeling after RFA but not IRE seems to be influenced by PCT, possibly due to the type of cell death induced by the different ablation modalities.

Fusion imaging with contrast-enhanced ultrasonography for evaluating the early therapeutic efficacy of radiofrequency ablation for small hypervascular hepatocellular carcinomas with iso-echoic or unclear margins on conventional ultrasonography

PURPOSE

We evaluated the efficacy of fusion imaging combining contrast-enhanced ultrasonography (CEUS) images and arterial phase contrast-enhanced CT (CECT) or hepatobiliary phase magnetic resonance imaging with gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (EOB-MRI) images for the early evaluation of the effectiveness of radiofrequency ablation (RFA) for small hypervascular hepatocellular carcinoma (HCC) with iso-echoic or unclear margins on conventional US.

METHODS

Forty HCCs (22 iso-echoic and 18 unclear margin lesions) with mean diameters of 13.7 mm were treated using RFA under the guidance of fusion imaging with CEUS. The adequacy of RFA was evaluated using fusion imaging with CEUS 1 day after RFA. CECT or EOB-MRI was performed 1 month after RFA. We reviewed the images obtained using both modalities.

RESULTS

When the 1-month CECT or EOB-MRI scans were used as the reference standard, the sensitivity, specificity, and accuracy of the 1-day fusion imaging for the diagnosis of the adequate ablation of these HCCs were 97, 100, and 98%, respectively; the kappa value for the agreement between the findings using the two modalities was 0.655.

CONCLUSION

Fusion imaging with CEUS appears to be a useful method for the early evaluation of the efficacy of RFA for the treatment of HCCs with iso-echoic or unclear margins on conventional US.

Ablative safety margin depicted by fusion imaging with post-treatment contrast-enhanced ultrasound and pre-treatment CECT/CEMRI after radiofrequency ablation for liver cancers

OBJECTIVE

To evaluate the value of fusion imaging with post-treatment contrast-enhanced ultrasound (CEUS) and pre-treatment contrast-enhanced CT/MRI (CECT/CEMRI) in evaluating ablative safety margin after percutaneous ultrasound (US)-guided radiofrequency ablation (RFA) for liver cancers.

METHODS

34 consecutive patients with 47 liver lesions who had undergone RFA were included. Fusion imaging with post-treatment CEUS and pre-treatment CECT/CEMRI was carried out to evaluate local treatment response and ablative safety margin within 1-3 days after RFA. The minimal ablative safety margins of the ablation zones were recorded. The complete response (CR) rate was calculated with reference to CECT/CEMRI results 1 month after RFA. The local tumour progression (LTP) was also recorded.

RESULTS

Of the 47 ablation zones, 47 (100%) were clearly depicted with CEUS-CECT/CEMRI fusion imaging, 36 (76.6%) with US-CECT/CEMRI fusion imaging and 21 (44.7%) with conventional US (both p < 0.001). The minimal ablative safety margins were great than or equal to 5 mm in 28 ablation zones, between 0 and 5 mm in 15, and less than 0 mm in 4. For the four lesions without enough ablative safety margin, three were referred to follow-up because CEUS showed larger ablation zones than pre-treatment lesions and the remaining lesion was subject to additional RFA 5 days after the first RFA. The CR rate was 95.7% (45/47) with reference to CECT/CEMRI results 1 month after RFA. During 2 to 34 months follow-up, LTP was found in two (4.4%) of 45 lesions with CR. Insufficient ablative safety margin was more commonly found in those lesions with LTP than those without LTP (1/4 vs 1/43, p < 0.001).

CONCLUSION

Fusion imaging with post-treatment CEUS and pre-treatment CECT/CEMRI can depict the ablative safety margin accurately after RFA. Inadequate ablative safety margin is associated with LTP. Depiction of ablative safety margin by fusion imaging after ablation might be considered as a routine procedure to assess the treatment response of RFA. Advances in knowledge: Fusion imaging with post-treatment CEUS and pre-treatment CECT/CEMRI is an effective method to evaluate the ablative safety margin early after RFA. Therefore, it should be recommended to be used as a routine procedure after RFA for liver cancers.

A Comparative Study of Ablation Boundary Sharpness After Percutaneous Radiofrequency, Cryo-, Microwave, and Irreversible Electroporation Ablation in Normal Swine Liver and Kidneys

PURPOSE

To compare ablation boundary sharpness after percutaneous radiofrequency ablation (RFA), cryoablation (CA), microwave ablation (MWA) and irreversible electroporation (IRE) ablation in normal swine liver and kidney.

MATERIALS AND METHODS

Percutaneous CT-guided RFA (n = 5), CA (n = 5), MWA (n = 5) and IRE (n = 5) were performed in the liver and kidney of four Yorkshire pigs. Parameters were chosen to produce ablations 2-3 cm in diameter with a single ablation probe. Contrast-enhanced CT imaging was performed 24 h after ablation, and animals were killed. Treated organs were removed and processed for histologic analysis with hematoxylin and eosin, and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL). Three readers independently analyzed CT, H&E and TUNEL stained images of the ablation boundary to delineate regions of (1) viable cells, (2) complete necrosis or (3) mixture of viable and necrotic cells which was defined as the transition zone (TZ). The width of TZ was compared across the techniques and organs.

RESULTS

Ablations appeared as non-contrast-enhancing regions on CT with sharp transition to enhancing normal tissue. On TUNEL stained slides, the mean width (μm) of the TZ after MWA was 319 ± 157 in liver and 267 ± 95 in kidney, which was significantly lower than RFA (811 ± 477 and 938 ± 429); CA (452 ± 222 and 700 ± 563); and IRE (1319 ± 682 and 1570 ± 962) (all p < 0.01). No significant differences were observed between the organs.

CONCLUSION

Under similar conditions, the width of the TZ at the ablation boundary varies significantly between different ablation techniques.

Rate of local tumor progression following radiofrequency ablation of pathologically early hepatocellular carcinoma

AIM

To evaluate whether pathologically early hepatocellular carcinoma (HCC) exhibited local tumor progression after radiofrequency ablation (RFA) less often than typical HCC.

METHODS

Fifty pathologically early HCCs [tumor diameter (mm): mean, 15.8; range, 10-23; follow-up days after RFA: median, 1213; range, 216-2137] and 187 typical HCCs [tumor diameter (mm): mean, 15.6; range, 6-30; follow-up days after RFA: median, 1116; range, 190-2328] were enrolled in this retrospective study. The presence of stromal invasion (namely, tumor cell invasion into the intratumoral portal tracts) was considered to be the most important pathologic finding for the diagnosis of early HCCs. Typical HCC was defined as the presence of a hyper-vascular lesion accompanied by delayed washout using contrast-enhanced computed tomography or contrast-enhanced magnetic resonance imaging. Follow-up examinations were performed at 3-mo intervals to monitor for signs of local tumor progression. The local tumor progression rates of pathologically early HCCs and typical HCCs were then determined using the Kaplan-Meier method.

RESULTS

During the follow-up period for the 50 pathologically early HCCs, 49 (98%) of the nodules did not exhibit local tumor progression. However, 1 nodule (2%) was associated with a local tumor progression found 636 d after RFA. For the 187 typical HCCs, 46 (24.6%) of the nodules exhibited local recurrence after RFA. The follow-up period until the local tumor progression of typical HCC was a median of 605 d, ranging from 181 to 1741 d. Among the cases with typical HCCs, local tumor progression had occurred in 7.0% (7/187), 16.0% (30/187), 21.9% (41/187) and 24.6% (46/187) of the cases at 1, 2, 3 and 4 years, respectively. Pathologically early HCC was statistically associated with a lower rate of local tumor progression, compared with typical HCC, when evaluated using a log-rank test (P = 0.002).

CONCLUSION

The rate of local tumor progression for pathologically early HCCs after RFA was significantly lower than that for typical HCCs.

Comparison of elastography, contrast-enhanced ultrasonography, and computed tomography for assessment of lesion margin after radiofrequency ablation in livers of healthy dogs

OBJECTIVE To assess by use of various diagnostic imaging modalities acute changes in livers of healthy dogs after radiofrequency ablation (RFA) and determine the capability of each imaging modality to monitor ablation lesion changes.

ANIMALS 6 healthy Beagles.

PROCEDURES 12 ablation lesions were created in the liver of the dogs (2 lesions/dog). Ablation lesions were evaluated by use of conventional ultrasonography, strain elastography, and contrast-enhanced ultrasonography immediately after (time 0), 30 to 60 minutes after, and 3 days after RFA, and by use of CT 30 minutes and 3 days after RFA. Three dogs were euthanized shortly after RFA, and the other 3 dogs were euthanized on day 3. Lesion size measured by each imaging modality was compared with necropsy findings.

RESULTS Immediately after RFA, clear margins were more visible with elastography and contrast-enhanced ultrasonography than with conventional ultrasonography, which had acoustic shadowing. On triphasic contrast CT, the ablation zone, which indicated necrosis and hemorrhage, was not enhanced and could be measured. Marked enhancement of the periablation rim was observed during the venous phase and was identified as granulation tissue. Size of the ablation area measured on enhanced CT images was strongly correlated with actual lesion size.

CONCLUSIONS AND CLINICAL RELEVANCE For dogs of this study, CT was the most reliable method for lesion size determination. Although ultrasonographic imaging measurements underestimated lesion size, all modalities could be used to provide additional real-time guidance for RFA procedures of the liver as well as for other RFA procedures.

CT Perfusion for Early Response Evaluation of Radiofrequency Ablation of Focal Liver Lesions: First Experience

PURPOSE

To investigate the value of perfusion CT (P-CT) for early assessment of treatment response in patients undergoing radiofrequency ablation (RFA) of focal liver lesions.

METHODS AND MATERIALS

20 consecutive patients (14 men; mean age 64 ± 14) undergoing P-CT within 24 h after RFA of liver metastases (n = 10) or HCC (n = 10) were retrospectively included. Two readers determined arterial liver perfusion (ALP, mL/min/100 mL), portal liver perfusion (PLP, mL/min/100 mL), and hepatic perfusion index (HPI, %) in all post-RFA lesions by placing a volume of interest in the necrotic central (CZ), the transition (TZ), and the surrounding parenchymal (PZ) zone. Patients were classified into complete responders (no residual tumor) and incomplete responders (residual/progressive tumor) using imaging follow-up with contrast-enhanced CT or MRI after a mean of 57 ± 30 days. Prediction of treatment response was evaluated using the area under the curve (AUC) from receiver operating characteristic analysis.

RESULTS

Mean ALP/PLP/HPI of both readers were 4.8/15.4/61.2 for the CZ, 9.9/16.8/66.3 for the TZ and 20.7/29.0/61.8 for the PZ. Interreader agreement of HPI was fair for the CZ (intraclass coefficient 0.713), good for the TZ (0.813), and excellent for the PZ (0.920). For both readers, there were significant differences in HPI of the CZ and TZ between responders and nonresponders (both, P < 0.05). HPI of the TZ showed the highest AUC (0.911) for prediction of residual tumor, suggesting a cut-off value of 76 %.

CONCLUSION

Increased HPI of the transition zone assessed with P-CT after RFA might serve as an early quantitative biomarker for residual tumor in patients with focal liver lesions.

Hepatocellular carcinoma ≤ 4 cm treated with radiofrequency ablation with or without percutaneous ethanol injection

BACKGROUND

To compare the survival of Chinese cirrhotic patients with hepatocellular carcinoma (HCC) ≤ 4 cm who underwent radiofrequency ablation (RFA) alone or a combination of RFA with percutaneous ethanol injection (PEI).

MATERIAL AND METHODS

Retrospective analysis was performed for 681 cases with HCC ≤ 4 cm who were treated with RFA alone or RFA combined with PEI (RFA + PEI) between 2004 and 2011.

RESULTS

As a result, 180 patients in each group were selected after propensity score matching (PSM). Higher overall survival (OS) and recurrence-free survival (RFS) rates were achieved by RFA + PEI compared with RFA alone (P = 0.019 and 0.009, respectively). The 1-, 3-, and 5-year cumulative OS rates were 78.0, 44.4, and 30.1% for patients in RFA group and 88.2, 58.0, and 41.1% for patients in RFA + PEI group, respectively. Besides, the 1-, 3-, and 5-year cumulative RFS rates were 77.0, 43.8, and 29.2% in RFA group, and 87.9, 57.6, and 38.4% in RFA + PEI group, respectively. The local recurrence, complete ablation and five-year mortality showed no distinct differences between RFA and RFA + PEI groups in three subgroups classified with tumor size. Moreover, Cox regression multivariate analysis results showed that sex and treatment approach were significantly related to OS, whereas sex, status of HBsAg, local recurrence, and number of tumor nodule were related to RFS.

CONCLUSION

Therefore, the combination of RFA and PEI yielded better OS and RFS rates than RFA alone for Chinese patients with HCC ≤ 4 cm.

Contrast-enhanced ultrasonography used for post-treatment responses evaluation of radiofrequency ablations for hepatocellular carcinoma: a meta-analysis

OBJECTIVE

This meta-analysis aims to analyze the usefulness of contrast-enhanced ultrasonography (CEUS) for post-treatment responses evaluation of radiofrequency ablation (RFA) for hepatocellular carcinoma (HCC) management.

METHODS

Literature retrieval in three databases PubMed, Embase and Cochrane Library was conducted up to September 2015, with pre-defined criteria. The technical success rate, local tumour recurrence and local tumour progression were the measurement indexes. Cochran's Q test and I(2) were used for heterogeneity detection. Subgroup analyses were performed for complete ablation rate stratified by study designs, contrast agents and post-operative testing time points. Statistical analyses were conducted using Stata(®) 12.0 software (Stata Corporation, College Station, TX).

RESULTS

12 studies consisting of 772 patients were included in this study. The CEUS-evaluated success rate of RFA for HCCs was 91%. The proportion of ablative margin <5 mm was 53%. The local tumour recurrence rate and local tumour progression rate were 4% and 8%, respectively. Subgroup analysis indicated that the CEUS-assessed technical success rate with Sonazoid™ (Daiichi-Sankyo, Tokyo, Japan) as the contrast agent was higher (95%) than those with other agents [SH U 508A (Schering AG, Berlin, Germany) 86%; SonoVue (Bracco SpA, Milan, Italy) 87%]. The success rate assessed within 24 h (94%) after treatment was higher than longer time (1-3 days 86%; 1 month 91%).

CONCLUSION

The meta-analysis showed that the CEUS-evaluated success rate of RFA for HCCs was 91%. The local tumour recurrence rate and local tumour progression rate were 4% and 8%, respectively.

ADVANCES IN KNOWLEDGE

Using meta-analysis, the study provided more reliable assessment of usefulness of CEUS, which could provide guidelines for HCC treatment.

Imaging Features of Radiofrequency Ablation with Heat-Deployed Liposomal Doxorubicin in Hepatic Tumors

INTRODUCTION

The imaging features of unresectable hepatic malignancies in patients who underwent radiofrequency ablation (RFA) in combination with lyso-thermosensitive liposomal doxorubicin (LTLD) were determined.

MATERIALS AND METHODS

A phase I dose escalation study combining RFA with LTLD was performed with peri- and post- procedural CT and MRI. Imaging features were analyzed and measured in terms of ablative zone size and surrounding penumbra size. The dynamic imaging appearance was described qualitatively immediately following the procedure and at 1-month follow-up. The control group receiving liver RFA without LTLD was compared to the study group in terms of imaging features and post-ablative zone size dynamics at follow-up.

RESULTS

Post-treatment scans of hepatic lesions treated with RFA and LTLD have distinctive imaging characteristics when compared to those treated with RFA alone. The addition of LTLD resulted in a regular or smooth enhancing rim on T1W MRI which often correlated with increased attenuation on CT. The LTLD-treated ablation zones were stable or enlarged at follow-up four weeks later in 69% of study subjects as opposed to conventional RFA where the ablation zone underwent involution compared to imaging acquired immediately after the procedure.

CONCLUSION

The imaging features following RFA with LTLD were different from those after standard RFA and can mimic residual or recurrent tumor. Knowledge of the subtle findings between the two groups can help avoid misinterpretation and proper identification of treatment failure in this setting. Increased size of the LTLD-treated ablation zone after RFA suggests the ongoing drug-induced biological effects.

Usefulness of contrast enhanced ultrasound in monitoring therapeutic response after hepatocellular carcinoma treatment

In the last years, the development in the oncology field has been huge and rapid. In particular, the evaluation of response to anti-tumour treatments has been being object of intense research, producing significant changes. Response assessment after therapy in solid neoplasias has always used radiological imaging techniques, with tumour size reduction representing a presumed therapeutic efficacy. However, with the introduction of anti-angiogenetic drugs the evaluation of tumour size has become unsuitable because some tumours, under treatment, show only tumour perfusion changes rather than lesion shrinkage. Between different imaging techniques with contrast-enhancement, contrast-enhanced ultrasound (CEUS) and, in particular, dynamic CEUS have arisen as a promising and non-invasive device for monitoring cancer treatments. Moreover, the introduction of perfusion software has even more refined the technique since it is able to provide quantitative parameters related to blood flow and blood volume that can be associated with tumour response and clinical outcome such as the progression free survival and the overall survival. Here, we give an overview of the current status of CEUS in monitoring hepatocellular carcinoma response to different kind of treatments.

Optimal imaging surveillance schedules after liver-directed therapy for hepatocellular carcinoma

PURPOSE

To optimize surveillance schedules for the detection of recurrent hepatocellular carcinoma (HCC) after liver-directed therapy.

MATERIALS AND METHODS

New methods have emerged that allow quantitative analysis and optimization of surveillance schedules for diseases with substantial rates of recurrence such as HCC. These methods were applied to 1,766 consecutive chemoembolization, radioembolization, and radiofrequency ablation procedures performed on 910 patients between 2006 and 2011. Computed tomography or magnetic resonance imaging performed just before repeat therapy was set as the time of "recurrence," which included residual and locally recurrent tumor as well as new liver tumors. Time-to-recurrence distribution was estimated by Kaplan-Meier method. Average diagnostic delay (time between recurrence and detection) was calculated for each proposed surveillance schedule using the time-to-recurrence distribution. An optimized surveillance schedule could then be derived to minimize the average diagnostic delay.

RESULTS

Recurrence is 6.5 times more likely in the first year after treatment than in the second. Therefore, screening should be much more frequent in the first year. For eight time points in the first 2 years of follow-up, the optimal schedule is 2, 4, 6, 8, 11, 14, 18, and 24 months. This schedule reduces diagnostic delay compared with published schedules and is cost-effective.

CONCLUSIONS

The calculated optimal surveillance schedules include shorter-interval follow-up when there is a higher probability of recurrence and longer-interval follow-up when there is a lower probability. Cost can be optimized for a specified acceptable diagnostic delay or diagnostic delay can be optimized within a specified acceptable cost.

Various complications of percutaneous radiofrequency ablation for hepatic tumors: radiologic findings and technical tips

Radiofrequency ablation is a safe and effective treatment for primary and secondary liver malignancies and has a low complication rate; however, there are various radiofrequency ablation-related complications which can occur from the thorax to the pelvis. Although most of these complications are usually minor and self-limited, they may become fatal if diagnosis and treatment are delayed. It is important for radiologists performing radiofrequency ablation to have a perspective regarding the possible radiofrequency ablation-related complications and their risk factors as well as the radiologic findings for their timely detection and increase of the treatment efficacy, and thereby encouraging the use of the radiofrequency ablation technique. This article illustrates the various imaging features of common and rare radiofrequency ablation-related complications as well as offers technical tips in order to avoid these complications.

Tumour-related neoangiogenesis: functional dynamic perfusion computed tomography for diagnosis and treatment efficacy assessment in hepatocellular carcinoma

BACKGROUND

Aim of the study was to determine the value of perfusion computed tomography in the quantitative assessment of tumour-related neoangiogenesis for the diagnosis and treatment of hepatocellular carcinoma lesions.

METHODS

Overall, 47 consecutive patients with cirrhotic liver disease, with a high risk of hepatocellular carcinoma, and undergoing standard surveillance (six-month intervals) were eligible for inclusion in this prospective study; based on Barcelona Clinic Liver Cancer guidelines, 27 patients were enrolled. Perfusion computed tomography was performed in 29 biopsy-proven hepatocellular carcinoma lesions before and after treatment with transarterial chemoembolization or radiofrequency ablation. The dynamic study was performed with a 256-slice multidetector-computed tomography scanner; the following parameters were measured: hepatic perfusion, arterial perfusion, blood volume, hepatic perfusion index, and time-to-peak in all patients.

RESULTS

Hepatocellular carcinoma lesions had the following median perfusion values: perfusion 46.3mL/min/100g; blood volume 20.4mL/100mg; arterial perfusion 42.9mL/min; hepatic perfusion index 92.5%; time to peak 18.7s. Significantly lower perfusion values were obtained in correctly treated lesions or surrounding parenchyma than in viable hepatocellular carcinoma tissue.

CONCLUSIONS

In hepatocellular carcinoma, perfusion computed tomography could contribute to a non-invasive quantification of tumour blood supply related to the formation of new arterial structures, and enable the assessment of therapeutic response.

Quantitative evaluation of CT-perfusion map as indicator of tumor response to transarterial chemoembolization and radiofrequency ablation in HCC patients

PURPOSE

To assess if radiofrequency ablation (RFA) and transarterial chemoembolization (TACE) may influence the evaluation of perfusion parameters obtained with CT-perfusion (CT-p) in HCC treated patients.

MATERIALS AND METHODS

Thirty-three consecutive cirrhotic patients with biopsy-proven diagnosis of HCC lesions and candidates to TACE or RFA were included. The CT-p study of hepatic parenchyma and of treated lesions was performed about 1 month after treatment on 16 multidetector CT after injection of 50mL of non ionic contrast agent (350mg I/mL) at a flow rate of 6mL/s acquiring 40 dynamic scans. A dedicated perfusion software which generated a quantitative map of arterial and portal perfusion by means of colour scale was employed.The following perfusion parameters were assessed before and after RFA or TACE treatment: hepatic perfusion (HP), arterial perfusion (AP), blood volume (BV), time to peak (TTP), hepatic perfusion index (HPI).

RESULTS

A complete treatment was obtained in 16 cases and incomplete treatment in the 17 remaining cases. The perfusion data of completely treated lesions were: HP 10.2±6.3; AP 10.4±7; BV 4.05±4.8; TTP 38.9±4.2; HPI 9.9±9.2, whereas in partially treated lesions were: HP 43.2±15.1mL/s/100g; AP 38.7±8.8mL/min; BV 20.7±9.5mL/100mg; TTP 24±3.7s; HPI 61.7±7.5%. In adjacent cirrhotic parenchyma, the parameters of all evaluated patients were: HP 13.2±4; AP 12.3±3.4; BV 11.8±2.8; TTP 43.9±2.9; and HPI 17.1±9.8. A significant difference (P<0.001) was found for all parameters between residual viable tumor tissue (P<0.001) compared to successfully treated lesion due to the presence of residual arterial vascular structure in viable portion of treated HCC.

CONCLUSION

According to our results, CT-p evaluation is not influenced by TACE or RFA treatments, thus representing a feasible technique that allows a reproducible quantitative evaluation of treatment response in HCC patients.

Irreversible electroporation ablation of malignant hepatic tumors: subacute and follow-up CT appearance of ablation zones

PURPOSE

To describe findings on contrast-enhanced computed tomography (CT) images of malignant hepatic tumors 24-72 hours after percutaneous ablation by irreversible electroporation (IRE) and at midterm follow-up.

MATERIALS AND METHODS

Retrospective analysis of 52 malignant liver tumors-30 primary hepatic tumors and 22 hepatic metastases-in 34 patients (28 men and 6 women, mean age 64 y) treated by IRE ablation was performed. Ablation zones were evaluated by two examiners in a consensus reading by means of a dual-phase CT scan (consisting of a hepatic arterial and portal venous phase) performed 24-72 hours after IRE ablation and at follow-up.

RESULTS

During the portal venous phase, ablation zones either were homogeneously hypoattenuating (n = 36) or contained heterogeneously isoattenuating or hyperattenuating (n = 16) foci, or both, in a hypoattenuating area. Of 52 lesions, 38 included gas pockets. Peripheral contrast enhancement of the ablation defect was evident in 23 tumors during the arterial phase and in 36 tumors during the portal venous phase. Four tumors showed intralesional abscesses after the intervention. At follow-up (mean, 4.7 mo), the mean volume of the ablation defects was reduced to 29% of their initial value.

CONCLUSIONS

Because normal findings on contrast-enhanced CT images after IRE ablation may be very similar to the typical characteristics of potential complications following ablation, such as liver abscesses, CT scans must be carefully analyzed to distinguish normal results after intervention from complications requiring further treatment.

Radiofrequency ablation of liver VX2 tumor: experimental results with MR diffusion-weighted imaging at 3.0T

PURPOSE

To evaluate the value of DWI in detecting the lesions of pre- and post-radiofrequency ablation (RFA) of the rabbit liver VX2 tumors.

MATERIALS AND METHODS

Twenty-two New Zealand White rabbits were tested. The protocol was approved by the Committee on the Ethics of Animal Experiments. Twenty separate tumor fragments were implanted into the livers of 20 rabbits, the liver was exposed by performing midline laparotomy. 3.0T MR DWI (b = 0, 200, 400, 600, 800,1000 s/mm2) were performed 14-21 days after tumor implantation (mean, 17 days) in the 18 tumor-bearing animals. Then RFA was performed in the 18 tumor-bearing animals and in the two healthy animals. 3.0T MR DWI was performed 7-10 days after RFA (mean, 8 days). Pathology exam was performed immediately after the completion of post- RFA MR imaging. Analyzing the features of MRI and ADC values in the pre- and post- RFA lesions of the VX2 tumors, and histopathologic results were compared with imaging findings.

RESULTS

The difference of ADC value between viable tumor and normal liver parenchyma was significant (P<.001). After RFA, when b = 200, 400, 600, 800, 1000 s/mm2, the differences of ADC values of viable tumor, granulation tissue, necrosis, normal liver parenchyma were significant (P<.001). At the time the animals were sacrificed after RFA and MR imaging, histopathologic results of local viable tumors were found in 9 (50%) of the 18 treated tumors. Macroscopic viable tumors were found at the RFA sites in 3 (17%), all 3 macroscopic viable tumors were visualized at the periphery of the RFA areas.

CONCLUSIONS

3.0T MR DWI can be used to follow up the progress of the RFA lesion, it is useful in detecting different tissues after RFA, and it is valuable in the further clinical research.

Radiofrequency ablation for colorectal liver metastases

The management of hepatic metastases from colorectal cancer (HMCRC) is multimodal including chemotherapy, surgical resection, radiation therapy, and focused destruction technologies. Radiofrequency ablation (RFA) is the most commonly used focused destruction technology. It represents a therapeutic option that may be potentially curative in cases where surgical excision is contra-indicated. It also increases the number of candidates for surgical resection among patients whose liver metastases were initially deemed unresectable. This article explains the techniques, indications, and results of radiofrequency ablation in the treatment of hepatic colorectal metastases.

Imaging features following transarterial chemoembolization and radiofrequency ablation of hepatocellular carcinoma

Transarterial chemoembolization and radiofrequency ablation are currently the most widely used modalities in the minimally invasive treatment of unresectable hepatocellular carcinoma. This article briefly summarizes the minimally invasive therapeutic options in the management of hepatocellular carcinoma focusing on transarterial chemoembolization and radiofrequency ablation and describes normal post-treatment imaging appearances. Imaging features of post-treatment local tumor recurrence as well as procedure-related complications following these interventions have also been described.

MDCT findings after hepatic chemoembolization with DC-beads: what the radiologist needs to know

Transcatheter arterial chemoembolization with drug-eluting beads (TACE-DC-beads) is a new local treatment for primary or metastatic liver tumors. Despite technical efforts to achieve highly selective embolization of the tumor-supplying vessels, small, or large insults to the non-tumorous parenchyma are inevitably induced by the embolic materials or procedure itself. Parenchymal changes following TACE-DC-beads include bile duct injuries (bile duct dilatation, periportal edema, and bilomas), obliteration of intrahepatic portal vein branches, hypodense ill-defined areas, and perilesional parenchymal enhancement. The radiologist must be familiar with the changes induced by this treatment in order to distinguish therapeutic effect and collateral findings from complications and residual or recurrent tumor.

Surveillance of HCC Patients after Liver RFA: Role of MRI with Hepatospecific Contrast versus Three-Phase CT Scan-Experience of High Volume Oncologic Institute

Purpose. To compare the diagnostic accuracy of hepatospecific contrast-enhanced MRI versus triple-phase CT scan after radiofrequency ablation (RFA) in hepatocellular carcinoma (HCC) patients. Methods. Thirty-four consecutive HCC patients (42 hepatic nodules) were treated with percutaneous RFA and underwent MR and CT scans. All patients were enrolled in a research protocol that included CT with iodized contrast medium injection and MR with hepatospecific contrast medium injection. All patients were restaged within four weeks and at 3 months from ablation. The images were reviewed by four different radiologists to evaluate tumor necrosis, residual or recurrence disease, and evidence of new foci. Results. Thirty-two nodules were necrotic after treatment; 10 showed residual disease. Six new HCCs were identified. At first month followup CT has identified 34 necrotic lesions and 8 residual diseases; no new foci were recognized. At MRI instead, 32 complete necrotic lesions were identified, 10 lesions showed residual disease, and 2 new HCCs were found. At three months, CT demonstrated 33 completely necrotic lesions, 9 residual diseases, and 2 new HCCs. MR showed 31 complete necrotic lesions, 11 cases of residual disease, and 6 new HCCs. Conclusions. Hepatospecific contrast-enhanced MRI is more effective than multiphase CT in assessment of HCC treated with RFA.

Iodine quantification with dual-energy CT: phantom study and preliminary experience with VX2 residual tumour in rabbits after radiofrequency ablation

OBJECTIVE

The purpose of our study was to validate iodine quantification in a phantom study with dual-source dual-energy CT (DECT) and to apply this technique to differentiate benign periablational reactive tissue from residual tumour in VX2 carcinoma in rabbits after radiofrequency ablation (RFA).

METHODS

We applied iodine quantification with DECT in a phantom and in VX2 carcinoma in rabbits after incomplete RFA to differentiate benign periablational reactive tissue from residual tumour and evaluated its efficacy in demonstrating response to therapeutic RFA. A series of tubes containing solutions of varying iodine concentration were scanned with DECT. The iodine concentration was calculated and compared with known true iodine concentration. Triple-phase contrast-enhanced DECT data on 24 rabbits with VX2 carcinoma were then assessed at Day 3 (n=6), 1 week (n=6), 2 weeks (n=6) and 3 weeks (n=6) after incomplete RFA independently by 2 readers. Dual-energy postprocessing was used to produce iodine-only images. Regions of interest were positioned on the iodine image over the lesion and, as a reference, over the aorta, to record iodine concentration in the lesion and in the aorta. The pathological specimens were sectioned in the same plane as DECT imaging, and the lesion iodine concentration and lesion-to-aorta iodine ratio of residual tumour and benign periablational reactive tissue were assessed.

RESULTS

There was excellent correlation between calculated and true iodine concentration (r=0.999, p<0.0001) in the phantom study. The lesion iodine concentration and lesion-to-aorta iodine ratio in residual tumour were significantly higher than in benign periablational reactive tissue in the 2-week group during the arterial phase (AP) (p<0.01) and in the 3-week group during both the AP (p<0.05) and the portal venous phase (p<0.05). There was no significant difference between them with respect to the lesion iodine concentration or lesion-to-aorta iodine ratio in the 3-day and 1-week groups.

CONCLUSION

Iodine quantification with DECT is accurate in a phantom study and can be used to differentiate benign periablational reactive tissue from residual tumour in VX2 carcinoma in rabbits after RFA.

ADVANCES IN KNOWLEDGE

Iodine quantification with DECT may help in differentiating benign periablational reactive tissue from residual tumour in VX2 carcinoma in rabbits after RFA.

Liposomal doxorubicin plus radiofrequency ablation for complete necrosis of a hepatocellular carcinoma

Radiofrequency ablation (rfa) is a standard treatment for small, unresectable hepatocellular carcinomas (hccs). However, rfa for larger tumours is less successful, and intravenous lyso-thermosensitive liposomal doxorubicin during rfa is one technique postulated to potentially address that limitation. This drug-plus-device combination therapy was used to completely treat a hcc in a patient who underwent liver transplantation 79 days later.