Effect of vessel size on creation of hepatic radiofrequency lesions in pigs: assessment of the "heat sink" effect

In vivo noninvasive three-dimensional (3D) assessment of microwave thermal ablation zone using non-contrast-enhanced x-ray CT

PURPOSE

To develop an image processing methodology for noninvasive three-dimensional (3D) quantification of microwave thermal ablation zones in vivo using x-ray computed tomography (CT) imaging without injection of a contrast enhancing material.

METHODS

Six microwave (MW) thermal ablation procedures were performed in three pigs. The ablations were performed with a constant heating duration of 8 min and power level of 30 W. During the procedure images from sixty 1 mm thick slices were acquired every 30 s. At the end of all ablation procedures for each pig, a contrast-enhanced scan was acquired for reference. Special algorithms for addressing challenges stemming from the 3D in vivo setup and processing the acquired images were prepared. The algorithms first rearranged the data to account for the oblique needle orientation and for breathing motion. Then, the gray level variance changes were analyzed, and optical flow analysis was applied to the treated volume in order to obtain the ablation contours and reconstruct the ablation zone in 3D. The analysis also included a special correction algorithm for eliminating artifacts caused by proximal major blood vessels and blood flow. Finally, 3D reference reconstructions from the contrast-enhanced scan were obtained for quantitative comparison.

RESULTS

For four ablations located >3 mm from a large blood vessel, the mean dice similarity coefficient (DSC) and the mean absolute radial discrepancy between the contours obtained from the reference contrast-enhanced images and the contours produced by the algorithm were 0.82 ± 0.03 and 1.92 ± 1.47 mm, respectively. In two cases of ablation adjacent to large blood vessels, the average DSC and discrepancy were: 0.67 ± 0.6 and 2.96 ± 2.15 mm, respectively. The addition of the special correction algorithm utilizing blood vessels mapping improved the mean DSC and the mean absolute discrepancy to 0.85 ± 0.02 and 1.19 ± 1.00 mm, respectively.

CONCLUSIONS

The developed algorithms provide highly accurate detailed contours in vivo (average error < 2.5 mm) and cope well with the challenges listed above. Clinical implementation of the developed methodology could potentially provide real time noninvasive 3D accurate monitoring of MW thermal ablation in-vivo, provided that the radiation dose can be reduced.

Characterization of the ablation zones produced by three commercially available systems from a single vendor for radiofrequency thermoablation in an ex vivo swine liver model

Background

Radiofrequency Ablation (RFA) is rarely performed in veterinary medicine. A rationale exists for its use in selected cases of canine liver tumours. RFA induces ablation zones of variable size and geometry depending on the technique used and on the impedance of the targeted organ.

Objectives

(a) to describe the geometry and reproducibility of the ablation zones produced by three commercially available systems from a single company, using isolated swine liver parenchyma as a model for future veterinary applications in vivo; (b) to study the effects of local saline perfusion into the ablated parenchyma through the electrode tip and of single versus double passage of the electrode on size, geometry and reproducibility of the ablation zones produced.

Methods

Size, and geometry of ablation zones reproduced in six livers with one cooled and perfused (saline) and two cooled and non‐perfused systems, after single or double passage (n = 6/condition), were assessed macroscopically on digitalized images by a blinded operator. Longitudinal and transverse diameters, equivalent diameter, estimated volume and roundness index were measured. Reproducibility was assessed as coefficient of variation.

Results and Conclusions

Ablation zone reproducibility was higher when expressed in terms of ablation zone diameters than estimated volume. Local saline perfusion of the parenchyma through the electrode tip during RFA increased the ablation zone longitudinal diameter. Ablation zone estimated volume increased with saline perfusion only when double passage was performed. These data may provide useful information for those clinicians who intend to include RFA as an additive tool in veterinary interventional radiology.

4D Flow MR Imaging to Improve Microwave Ablation Prediction Models: A Feasibility Study in an In Vivo Porcine Liver

PURPOSE

To characterize the effect of hepatic vessel flow using 4-dimensional (4D) flow magnetic resonance (MR) imaging and correlate their effect on microwave ablation volumes in an in vivo non-cirrhotic porcine liver model.

MATERIALS AND METHODS

Microwave ablation antennas were placed under ultrasound guidance in each liver lobe of swine (n = 3 in each animal) for a total of 9 ablations. Pre- and post-ablation 4D flow MR imaging was acquired to quantify flow changes in the hepatic vasculature. Flow measurements, along with encompassed vessel size and vessel-antenna spacing, were then correlated with final ablation volume from segmented MR images.

RESULTS

The linear regression model demonstrated that the preablation measurement of encompassed hepatic vein size (β = -0.80 ± 0.25, 95% confidence interval [CI] -1.15 to -0.22; P = .02) was significantly correlated to final ablation zone volume. The addition of hepatic vein flow rate found via 4D flow MRI (β = -0.83 ± 0.65, 95% CI -2.50 to 0.84; P = .26), and distance from antenna to hepatic vein (β = 0.26 ± 0.26, 95% CI -0.40 to 0.92; P = .36) improved the model accuracy but not significantly so (multivariate adjusted R² = 0.70 vs univariate (vessel size) adjusted R² = 0.63, P = .24).

CONCLUSIONS

Hepatic vein size in an encompassed ablation zone was found to be significantly correlated with final ablation zone volume. Although the univariate 4D flow MR imaging-acquired measurements alone were not found to be statistically significant, its addition to hepatic vein size improved the accuracy of the ablation volume regression model. Pre-ablation 4D flow MR imaging of the liver may assist in prospectively optimizing thermal ablation treatment.

Toward a clinical real time tissue ablation technology: combining electroporation and electrolysis (E2)

Background

Percutaneous image-guided tissue ablation (IGA) plays a growing role in the clinical management of solid malignancies. Electroporation is used for IGA in several modalities: irreversible electroporation (IRE), and reversible electroporation with chemotoxic drugs, called electrochemotherapy (ECT). It was shown that the combination of electrolysis and electroporation—E2—affords tissue ablation with greater efficiency, that is, lower voltages, lower energy and shorter procedure times than IRE and without the need for chemotoxic additives as in ECT.

Methods

A new E2 waveform was designed that delivers optimal doses of electroporation and electrolysis in a single waveform. A series of experiments were performed in the liver of pigs to evaluate E2 in the context of clinical applications. The goal was to find initial parameter boundaries in terms of electrical field, pulse duration and charge as well as tissue behavior to enable real time tissue ablation of clinically relevant volumes.

Results

Histological results show that a single several hundred millisecond long E2 waveform can ablate large volume of tissue at relatively low voltages while preserving the integrity of large blood vessels and lumen structures in the ablation zone without the use of chemotoxic drugs or paralyzing drugs during anesthesia. This could translate clinically into much shorter treatment times and ease of use compared to other techniques that are currently applied.

RF Ablation Versus Cryoablation for Small Perivascular Hepatocellular Carcinoma: Propensity Score Analyses of Mid-Term Outcomes

PURPOSE

This study aimed to compare radiofrequency (RF) ablation with cryoablation in patients with perivascular hepatocellular carcinoma (HCC) and evaluate the mid-term outcomes of both therapies.

MATERIALS AND METHODS

Between January 2015 and April 2018, 111 patients who underwent percutaneous cryoablation (n = 61) or RF ablation (n = 50) for a single perivascular HCC were included. Perivascular HCC was defined as the presence of contacting peritumoral hepatic vessels that were 3 mm or larger in axial diameter. Local tumor progression (LTP) rates were compared by propensity score matching. Procedure-related complications were also assessed.

RESULTS

The median follow-up was 23 months (range 2-45 months). Twenty-five patients were matched in each group. The cumulative LTP rates at 1 and 3 years were 8.3% and 17.3% in the cryoablation group and 8.7% and 26.1% in the RF ablation group, with no significant difference (p = 0.379). Although there were no significant differences between the two groups, vascular thrombosis (16.0% vs. 9.8%, p = 0.493) and hepatic infarction (12.0% vs. 3.3%, p = 0.137) more frequently occurred in the RF ablation group than in the cryoablation group.

CONCLUSION

In patients with perivascular HCC, cryoablation is an effective alternative treatment compared with RF ablation regarding local tumor control and complications.

LEVEL OF EVIDENCE

Level 4 (retrospective case-control study).

Percutaneous cryoablation for the treatment of liver cancer at special sites: an assessment of efficacy and safety

Background

To assess the safety and efficacy of cryoablation (CA) devices for the treatment of liver cancer at special sites in a retrospective study.

Methods

Special site liver cancer was defined as the tumors directly abutting surrounding structures (such as the liver capsule, gallbladder, vessel, diaphragm, intestine, and adrenal gland) with a maximum distance of 1.0 cm between the tumor and these organs. Sixty-six patients (49 men, 17 women; mean age, 60.8 years; age range, 27-82 years) were included. CA procedure was performed to treat 69 tumors under the guidance of computed tomography or ultrasound. Local tumor progression was assessed during the follow-up. A visual analog scale (VAS) evaluated the pain degree. Complications were assessed during and after every procedure.

Results

The number of tumors under the liver capsule and adjacent to the gallbladder, portal or hepatic vein, diaphragm, intestine, and adrenal gland were 29, 5, 8, 14, 7, and 6, respectively. The median follow-up time was 14 months (range, 2-28 months). In the 69 procedures, the technical success rate was 100%. The cumulative local tumor progression rates at 6, 9, 15, and 24 months were 10.2%, 16.5%, 20.9%, and 30.5%, respectively. No cases of serious complications occurred. During operation, the occurrence rates of subcapsular hemorrhage and pneumothorax were 2.9% and 1.4%, respectively. After the operation, the occurrence rate of biloma, capsular injury, subcapsular planting metastasis, and pneumothorax were 1.4%, 18.8%, 1.4%, and 2.8%, respectively. The average score of 66 patients with a VAS was 2.15±0.63 during the operation.

Conclusions

Percutaneous CA is safe and effective for patients with special site liver cancer.

Early and Late Fusion Machine Learning on Multi-Frequency Electrical Impedance Data to Improve Radiofrequency Ablation Monitoring

Radiofrequency ablation (RFA) is a popular modality for tumor treatment. However, inexpensive real-time monitoring of RFA within multiple tissue types is still an ongoing research topic. The objective of this study is to utilize multi-frequency electrical impedance data within real-time RFA depth estimation through data fusion schemes that include non-linear machine learning (ML) models. Multi-frequency tissue complex electrical impedance measurements are used to provide input data to the data fusion schemes. Our results show that the fusion schemes significantly decrease both the spread of residuals and the mean of the residuals for depth estimation. Thus, data fusion can be a significant tool for use in improving the performance of ML-based monitoring for RFA.

Ionomycin-Induced Changes in Membrane Potential Alter Electroporation Outcomes in HL-60 Cells

Previous studies have shown greater fluorophore uptake during electroporation on the anode-facing side of the cell than on the cathode-facing side. Based on these observations, we hypothesized that hyperpolarizing a cell before electroporation would decrease the requisite pulsed electric field intensity for electroporation outcomes, thereby yielding a higher probability of reversible electroporation at lower electric field strengths and a higher probability of irreversible electroporation (IRE) at higher electric field strengths. In this study, we tested this hypothesis by hyperpolarizing HL-60 cells using ionomycin before electroporation. These cells were then electroporated in a solution containing propidium iodide, a membrane integrity indicator. After 20 min, we added trypan blue to identify IRE cells. Our results showed that hyperpolarizing cells before electroporation alters the pulsed electric field intensity thresholds for reversible electroporation and IRE, allowing for greater control and selectivity of electroporation outcomes.

Factors predicting ablation site recurrence following percutaneous microwave ablation of colorectal hepatic metastases

BACKGROUND

Microwave ablation (MWA) is a recognised treatment option for liver metastases. The size of the tumour is a well-established factor that influences the success of MWA. However, the effect of "heat sink" on the success of MWA for hepatic metastases is unclear. The aim of this study was to determine whether heat sink effect is a factor that contributes to ablation site recurrence (ASR).

METHODS

A prospectively maintained database of patients who underwent percutaneous MWA for treatment of colorectal liver metastases was analysed. Imaging and demographic characteristics were compared between metastases that recurred following ablation and those that did not. Proximity to a large hepatic vein was defined as <10 mm.

RESULTS

126 ablations in 87 patients met the inclusion criteria and were studied over a median follow-up period of 28 (12-75) months. ASR was detected in 43 ablations (34%) and was associated with clinical risk score (CRS) ≥2 (OR 2.2 95% CI 1.3-3.3, p = 0.029), metastasis size (OR 0.953 95% CI (0.929-0.978), p < 0.001) and proximity to a large hepatic vein (OR 7.5 95%CI 2.4-22.8, p < 0.001). Proximity to a large hepatic vein was not associated with reduced overall survival (OS) but was associated with liver-specific recurrence (HR 4.7 95%CI 1.7-12.5, p = 0.004).

CONCLUSIONS

In addition to tumour size proximity to large hepatic venous structures is an independent predictor of ASR and liver-specific recurrence following MWA. However, this was not associated with overall survival.

Radiofrequency Ablation and Microwave Ablation in Liver Tumors: An Update

This article provides an overview of radiofrequency ablation (RFA) and microwave ablation (MWA) for treatment of primary liver tumors and hepatic metastasis. Only studies reporting RFA and MWA safety and efficacy on liver were retained. We found 40 clinical studies that satisfied the inclusion criteria. RFA has become an established treatment modality because of its efficacy, reproducibility, low complication rates, and availability. MWA has several advantages over RFA, which may make it more attractive to treat hepatic tumors. According to the literature, the overall survival, local recurrence, complication rates, disease-free survival, and mortality in patients with hepatocellular carcinoma (HCC) treated with RFA vary between 53.2 ± 3.0 months and 66 months, between 59.8% and 63.1%, between 2% and 10.5%, between 22.0 ± 2.6 months and 39 months, and between 0% and 1.2%, respectively. According to the literature, overall survival, local recurrence, complication rates, disease-free survival, and mortality in patients with HCC treated with MWA (compared with RFA) vary between 22 months for focal lesion >3 cm (vs. 21 months) and 50 months for focal lesion ≤3 cm (vs. 27 months), between 5% (vs. 46.6%) and 17.8% (vs. 18.2%), between 2.2% (vs. 0%) and 61.5% (vs. 45.4%), between 14 months (vs. 10.5 months) and 22 months (vs. no data reported), and between 0% (vs. 0%) and 15% (vs. 36%), respectively. According to the literature, the overall survival, local recurrence, complication rates, and mortality in liver metastases patients treated with RFA (vs. MWA) are not statistically different for both the survival times from primary tumor diagnosis and survival times from ablation, between 10% (vs. 6%) and 35.7% (vs. 39.6), between 1.1% (vs. 3.1%) and 24% (vs. 27%), and between 0% (vs. 0%) and 2% (vs. 0.3%). MWA should be considered the technique of choice in selected patients, when the tumor is ≥3 cm in diameter or is close to large vessels, independent of its size. IMPLICATIONS FOR PRACTICE: Although technical features of the radiofrequency ablation (RFA) and microwave ablation (MWA) are similar, the differences arise from the physical phenomenon used to generate heat. RFA has become an established treatment modality because of its efficacy, reproducibility, low complication rates, and availability. MWA has several advantages over RFA, which may make it more attractive than RFA to treat hepatic tumors. The benefits of MWA are an improved convection profile, higher constant intratumoral temperatures, faster ablation times, and the ability to use multiple probes to treat multiple lesions simultaneously. MWA should be considered the technique of choice when the tumor is ≥3 cm in diameter or is close to large vessels, independent of its size.

Real-time monitoring radiofrequency ablation using tree-based ensemble learning models

BACKGROUND

Radiofrequency ablation is a minimally-invasive treatment method that aims to destroy undesired tissue by exposing it to alternating current in the 100 kHz-800 kHz frequency range and heating it until it is destroyed via coagulative necrosis. Ablation treatment is gaining momentum especially in cancer research, where the undesired tissue is a malignant tumor. While ablating the tumor with an electrode or catheter is an easy task, real-time monitoring the ablation process is a must in order to maintain the reliability of the treatment. Common methods for this monitoring task have proven to be accurate, however, they are all time-consuming or require expensive equipment, which makes the clinical ablation process more cumbersome and expensive due to the time-dependent nature of the clinical procedure.

METHODS

A machine learning (ML) approach is presented that aims to reduce the monitoring time while keeping the accuracy of the conventional methods. Two different hardware setups are used to perform the ablation and collect impedance data at the same time and different ML algorithms are tested to predict the ablation depth in 3 dimensions, based on the collected data.

RESULTS

Both the random forest and adaptive boosting (adaboost) models had over 98% R² on the data collected with the embedded system-based hardware instrumentation setup, outperforming Neural Network-based models.

CONCLUSIONS

It is shown that an optimal pair of hardware setup and ML algorithm (Adaboost) is able to control the ablation by estimating the lesion depth within a test average of 0.3mm while keeping the estimation time within 10ms on a ×86-64 workstation.

Similar complication rates for irreversible electroporation and thermal ablation in patients with hepatocellular tumors

Background To compare the frequency of adverse events of thermal microwave (MWA) and radiofrequency ablation (RFA) with non-thermal irreversible electroporation (IRE) in percutaneous ablation of hepatocellular carcinoma (HCC). Patients and methods We retrospectively analyzed 117 MWA/RFA and 47 IRE procedures (one tumor treated per procedure; 144 men and 20 women; median age, 66 years) regarding adverse events, duration of hospital and intensive care unit (ICU) stays and occurrence of a post-ablation syndrome. Complications were classified according to the Clavien & Dindo classification system. Results 70.1% of the RFA/MWA and 63.8% of the IRE procedures were performed without complications. Grade I and II complications (any deviation from the normal postinterventional course, e.g., analgesics) occurred in 26.5% (31/117) of MWA/RFA and 34.0% (16/47) of IRE procedures. Grade III and IV (major) complications occurred in 2.6% (3/117) of MWA/RFA and 2.1% (1/47) of IRE procedures. There was no significant difference in the frequency of complications (p = 0.864), duration of hospital and ICU stay and the occurrence of a post-ablation syndrome between the two groups. Conclusions Our results suggest that thermal (MWA and RFA) and non-thermal IRE ablation of malignant liver tumors have comparable complication rates despite the higher number of punctures and the lack of track cauterization in IRE.

Shrinkage of hepatocellular carcinoma after radiofrequency ablation following transcatheter arterial chemoembolization: Analysis of contributing factors

Objective

This study was conducted to investigate tumor shrinkage and influencing factors in patients with hepatocellular carcinoma (HCC) from radiofrequency (RF) ablation following transcatheter arterial chemoembolization (TACE).

Methods

A total of 222 patients underwent combined sequential treatment of TACE and RF ablation for HCC at our institution between 2008 and 2014. Of those, 86 patients (men, 68; women, 18) who achieved compact iodized oil tagging and complete ablation were included for this retrospective study. We measured three-dimensional tumor diameters and calculated tumor volumes on pre-treatment CT/MRI and follow-up CT scans performed post-TACE, post-ablation, and 1 month post-treatment, respectively. To compare periodically generated tumor diameters and volumes, repeated measures analysis of variance (ANOVA) was applied. Multiple linear regression analysis was performed to identify factors impacting tumor shrinkage after RF ablation.

Results

Diameters and volumes of HCCs declined significantly in the immediate aftermath of RF ablation (i.e., between post-TACE and post-ablation CT scans) (p < 0.001, for both). Mean reduction rates in tumor diameter and volume immediately after RF ablation were 18.2 ± 9.1% and 44.4 ± 14.6%, respectively. Of note, tumors of left hepatic lobe and in subphrenic or perivascular locations showed lower rates of post-ablative volume reduction than those in counterpart locations (p = 0.002, 0.046, 0.024, respectively). Tumor size and liver function did not influence tumor shrinkage after RF ablation.

Conclusion

In patients with HCC, significant tumor shrinkage occurs immediately after RF ablation. The degree of shrinkage in response to ablative treatment seems to vary by tumor location.

Can we ablate liver lesions close to large portal and hepatic veins with MR-guided HIFU? An experimental study in a porcine model

OBJECTIVES

Invasive treatment of tumors adjacent to large hepatic vessels is a continuous clinical challenge. The primary aim of this study was to examine the feasibility of ablating liver tissue adjacent to large hepatic and portal veins with magnetic resonance imaging-guided high-intensity focused ultrasound (MRgHIFU). The secondary aim was to compare sonication data for ablations performed adjacent to hepatic veins (HV) versus portal veins (PV).

MATERIALS AND METHODS

MRgHIFU ablations were performed in six male land swine under general anesthesia. Ablation cells of either 4 or 8 mm diameter were planned in clusters (two/animal) adjacent either to HV (n = 6) or to PV (n = 6), with diameter ≥ 5 mm. Ablations were made using 200 W and 1.2 MHz. Post-procedure evaluation was made on contrast-enhanced MRI (T1w CE-MRI), histopathology, and ablation data from the HIFU system.

RESULTS

A total of 153 ablations in 81 cells and 12 clusters were performed. There were visible lesions with non-perfused volumes in all animals on T1w CE-MRI images. Histopathology showed hemorrhage and necrosis in all 12 clusters, with a median shortest distance to vessel wall of 0.4 mm (range 0-2.7 mm). Edema and endothelial swelling were observed without vessel wall rupture. In 8-mm ablations (n = 125), heat sink was detected more often for HV (43%) than for PV (19%; p = 0.04).

CONCLUSIONS

Ablations yielding coagulative necrosis of liver tissue can be performed adjacent to large hepatic vessels while keeping the vessel walls intact. This indicates that perivascular tumor ablation in the liver is feasible using MRgHIFU.

KEY POINTS

• High-intensity focused ultrasound ablation is a non-invasive treatment modality that can be used for treatment of liver tumors. • This study shows that ablations of liver tissue can be performed adjacent to large hepatic vessels in an experimental setting. • Liver tumors close to large vessels can potentially be treated using this modality.

Percutaneous ablation for perivascular hepatocellular carcinoma: Refining the current status based on emerging evidence and future perspectives

Various therapeutic modalities including radiofrequency ablation, cryoablation, microwave ablation, and irreversible electroporation have attracted attention as energy sources for effective locoregional treatment of hepatocellular carcinoma (HCC); these are accepted non-surgical treatments that provide excellent local tumor control and favorable survival. However, in contrast to surgery, tumor location is a crucial factor in the outcomes of locoregional treatment because such treatment is mainly performed using a percutaneous approach for minimal invasiveness; accordingly, it has a limited range of ablation volume. When the index tumor is near large blood vessels, the blood flow drags thermal energy away from the targeted tissue, resulting in reduced ablation volume through a so-called “heat-sink effect”. This modifies the size and shape of the ablation zone considerably. In addition, serious complications including infarction or aggressive tumor recurrence can be observed during follow-up after ablation for perivascular tumors by mechanical or thermal damage. Therefore, perivascular locations of HCC adjacent to large intrahepatic vessels can affect post-treatment outcomes. In this review, we primarily focus on physical properties of perivascular tumor location, characteristics of perivascular HCC, potential complications, and clinical outcomes after various locoregional treatments; moreover, we discuss the current status and future perspectives regarding percutaneous ablation for perivascular HCC.

Hydrodissection of the Retrohepatic Space: A Technique to Physically Separate a Liver Tumour from the Inferior Vena Cava and the Ostia of the Hepatic Veins

OBJECTIVE

To report a technique of percutaneous retrohepatic hydrodissection, highlighting its potential to physically separate liver tumours from the inferior vena cava (IVC) and the ostia of the hepatic veins (HV).

MATERIALS AND METHODS

Between December 2017 and April 2018, hydrodissection of the retrohepatic IVC was performed in 5 patients (5 females; mean age 64.5 years) undergoing percutaneous ablation of 5 liver metastases (mean size: 3.6 cm) located adjacent to the IVC. Number of hydrodissection needles, volume of hydrodissection, separation of tumour/liver parenchyma from IVC/HV post-hydrodissection; technical success of ablation; and complications were tabulated.

RESULTS

Two to three 22G spinal needles were required per case for adequate dissection. Mean volume to obtain sufficient hydrodissection was 410 ml on average. Physical separation of the IVC and tumour/hepatic parenchyma was successful in all cases, by 9 mm on average (range 5-12 mm). It also leaded to physical separation of the ostia of the right and middle HV in all cases. There was no early or delayed complication, notably no venous thrombosis in the post-operative period. All lesions but one were completely ablated after one session at 3-month follow-up. The patient with residual tumour was successfully retreated.

CONCLUSION

Retrohepatic hydrodissection is a feasible technique to separate a tumour from the IVC and/or ostia of the HV. This could potentially limit the heat-sink effect/reduce the risk of thrombosis. Larger follow-up studies are required to assess efficacy on a long-term basis.

Physiologic and histopathologic effects of targeted lung denervation in an animal model

Parasympathetic efferent innervation of the lung is the primary source of lung acetylcholine. Inhaled long-acting anticholinergics improve lung function and symptoms in patients with chronic obstructive pulmonary disease. Targeted lung denervation (TLD), a bronchoscopic procedure intended to disrupt pulmonary parasympathetic inputs, is an experimental treatment for chronic obstructive pulmonary disease. The physiologic and histologic effects of TLD have not previously been assessed. Eleven sheep and two dogs underwent circumferential ablation of the main bronchi with simultaneous balloon surface cooling using a lung denervation system (Nuvaira, Inc., Minneapolis, MN). Changes in pulmonary air flow resistance were monitored before and following TLD. Four animals were assessed for the presence or abolishment of the sensory axon-mediated Hering-Breuer reflex before and following TLD. Six sheep were histologically evaluated 30 days post-TLD for the extent of lung denervation (axonal staining) and effect on peribronchial structures near the treatment site. No adverse clinical effects were seen in any treated animals. TLD produced a ~30% reduction in pulmonary resistance and abolished the sensory-mediated Hering-Breuer reflex. Axonal staining was consistently decreased 60% at 30 days after TLD. All treated airways exhibited 100% epithelial integrity. Damage to other peribronchial structures was minimal. Tissue 1 cm proximal and distal to the treatment was normal, and the esophagus and periesophageal vagus nerve branches were unaffected. TLD treatment effectively denervates the lung while protecting the bronchial epithelium and minimizing effects on peribronchial structures.

NEW & NOTEWORTHY The feasibility of targeted lung denervation, a new minimally invasive therapy for obstructive lung disease, has been demonstrated in humans with preliminary clinical studies demonstrating improvement in symptoms, pulmonary function, and exercise capacity in patients with chronic obstructive pulmonary disease. This preclinical animal study demonstrates the ability of targeted lung denervation to disrupt vagal inputs to the lung and details its physiologic and histopathologic effects.

Tumor Location Influences Oncologic Outcomes of Hepatocellular Carcinoma Patients Undergoing Radiofrequency Ablation

Radiofrequency ablation (RFA) is recommended as a first-line therapy for small hepatocellular carcinoma (HCC). Tumor location is a potential factor influencing the procedure of RFA. To compare oncologic outcomes of RFA for different tumor locations, this retrospective study enrolled 194 patients with small HCC who had undertaken RFA. The HCC nodules were classified as peri-hepatic-vein (pHV) or non-pHV, peri-portal-vein (pPV) or non-pPV, and subcapsular or non-subcapsular HCC. The regional recurrence-free survival (rRFS), overall survival (OS), recurrence-free survival (recurrence in any location, RFS) and distant recurrence-free survival (dRFS) were compared. Operation failures were recorded in five pPV HCC patients, which was more frequent than in non-pPV HCC patients (p = 0.041). The 1-, 3-, and 5-year rRFS was 68.7%, 53.7%, and 53.7% for pHV patients and 85.1%, 76.1%, and 71.9% for non-pHV patients, respectively (p = 0.012). After propensity score matching, the 1-, 3-, and 5-year rRFS was still worse than that of non-pHV patients (p = 0.013). The OS, RFS, and dRFS were not significantly different between groups.

CONCLUSIONS

A pHV location was a risk factor for the regional recurrence after RFA in small HCC patients. The tumor location may not influence OS, RFS, and dRFS. Additionally, a pPV location was a potential high-risk factor for incomplete ablation.

Percutaneous cryoablation for perivascular hepatocellular carcinoma: Therapeutic efficacy and vascular complications

OBJECTIVES

To evaluate the therapeutic efficacy of and vascular complications associated with percutaneous cryoablation for the treatment of perivascular HCC.

METHODS

Between August 2015 and September 2017, 58 consecutive patients (48 men, 10 women; mean age, 61.1 years; age range, 44-84 years) who underwent percutaneous cryoablation were included. All patients had a single perivascular HCC (mean size, 1.3 cm; Barcelona clinic liver cancer-stage 0 or A) that was in contact with hepatic vessels, ≥ 3 mm or larger in axial diameter. Local tumour progression (LTP) was estimated by the Kaplan-Meier method. In addition, several procedure-related vascular complications were evaluated immediately after treatment and during follow-up CT: peritumoral vessel thrombosis; infarction; aggressive intrasegmental recurrence (AIR) (the simultaneous development of ≥ 3 nodular or infiltrative tumours). The follow-up CT was performed in all patients 1 month after the procedure, and every 3 months thereafter.

RESULTS

The median follow-up period was 22 months (range, 3-29 months). The technical success rate of cryoablation was 96.6% (56/58). The 1- and 2-year cumulative LTP rates were 3.6% and 14.6%, respectively. Although peritumoral vessel thrombosis occurred in 6.9% of cases (4/58), no cases of hepatic infarction were observed and AIR did not develop during follow-up. Half of the thombi in the peritumoral vessels immediately after cryoablation disappeared on follow-up CT images.

CONCLUSION

Cryoablation could be an effective tool for the treatment of perivascular HCC with a very low risk of vascular complications.

KEY POINTS

• Cryoablation allowed a high technical success rate for perivascular HCC. • Only 6.9% developed peritumoral vessel thrombosis without major vascular complications like infarction. • Two-year cumulative LTP rate was 14.6%, without aggressive tumour recurrence on follow-up.

Radiofrequency ablation vs. surgery for perivascular hepatocellular carcinoma: Propensity score analyses of long-term outcomes

BACKGROUND & AIMS

The therapeutic outcomes of surgical resection (SR) or radiofrequency ablation (RFA) for perivascular hepatocellular carcinoma (HCC) have not been compared. The aim of this study was to compare SR with RFA as first-line treatment in patients with perivascular HCC and to evaluate the long-term outcomes of both therapies.

METHODS

This retrospective study was approved by the institutional review board. The requirement for informed consent was waived. Between January 2006 and December 2010, a total of 283 consecutive patients with small perivascular HCCs (≤3 cm, Barcelona Clinic Liver Cancer stage 0 or A) underwent SR (n = 182) or RFA (n = 101) as a first-line treatment. The progression-free survival (PFS) and overall survival (OS) rates were compared by propensity score matching. Subgroup analysis of these outcomes was conducted according to the type of hepatic vessels.

RESULTS

The median follow-up was 7.8 years. Matching yielded 62 pairs of patients. In the two matched groups, the PFS rates at 5 and 10 years were 58.0% and 17.8%, respectively, in the SR group, and 25.4% and 14.1%, respectively, in the RFA group (p <0.001). The corresponding OS rates at 5 and 10 years were 93.5% and 91.9% in the SR group and 82.3% and 74.1% in the RFA group, respectively (p <0.001). In contrast to those in patients with perivenous HCCs, subgroup analysis indicated that extrahepatic recurrence and OS were significantly different according to the treatment modality in patients with periportal HCCs (p = 0.004 and p <0.001, respectively).

CONCLUSIONS

In patients with small perivascular HCCs, SR provided better long-term tumor control and OS than RFA, particularly for periportal tumors.

LAY SUMMARY

Surgical resection and radiofrequency ablation are both treatment options for perivascular hepatocellular carcinoma. We compared outcomes in patients treated with either method. Surgical resection provided better long-term tumor control and overall survival than radiofrequency ablation for patients with a small perivascular hepatocellular carcinoma (≤3 cm) as a first-line treatment, particularly for periportal tumors. The location of the tumor and the type of peritumoral hepatic vessels need to be considered when choosing between surgical resection and radiofrequency ablation for small HCCs.

Effect of Microbubble-Enhanced Ultrasound on Radiofrequency Ablation of Rabbit Liver

Microbubble-enhanced ultrasound (MEUS) can non-invasively disrupt and block liver blood perfusion. It may potentially overcome the heat sink effect during a thermal ablation and consequently enhance radiofrequency ablation (RFA) of the liver. We propose a new strategy combining RFA with MEUS. For ultrasound treatment, an 831-kHz air-backed focused transducer directed 400-cycle bursts at 4.3 MPa to the liver at a 9-Hz rate. The treatment was nucleated by a lipids microbubble forming MEUS. Eighteen surgically exposed rabbit livers were treated using MEUS combined with RFA; the other 32 livers were treated using MEUS (n = 14) or RFA (n = 18) alone and served as the controls. Contrast ultrasound imaging confirmed that MEUS treatment significantly reduced liver blood perfusion by cutting contrast peak intensities in half (44.7%-54.1%) without severe liver function damage. The ablated liver volume treated using MEUS combined with RFA was 2.8 times greater than that treated using RFA alone. In conclusion, RFA of the liver can be safely and greatly enhanced by combination with MEUS pre-treatment.

Post Locoregional Therapy Treatment Imaging in Hepatocellular Carcinoma Patients: A Literature-based Review

Imaging plays a crucial role in the diagnosis of hepatocellular carcinoma (HCC) as well as in determining treatment efficacy, or complications, following therapy. Unlike other cancers, HCC is most commonly treated by locoregional therapies (LRTs) such as thermal ablation, transarterial chemoembolization, and transarterial radioembolization. These treatments can lead to changes on imaging that make determination of residual/recurrent disease difficult. This literature-based review discusses the expected postimaging findings following LRT.

Safety and Efficacy of Percutaneous Thermal Ablation of Juxta-Cardiac Hepatic Tumours

INTRODUCTION

To evaluate the safety and efficacy of percutaneous thermal ablation of liver tumours in a juxta-cardiac (JC) location.

MATERIALS AND METHODS

From January 2010 to December 2014, out of 274 cases of hepatic ablation, 33 consecutive patients who received thermal ablation (radiofrequency or microwave) to left hepatic lobe tumours were included in this study. Patients were divided into two groups: JC or non-juxta-cardiac (NJC) (tumour margin ≤ 10 mm or > 10 mm from the cardiac border, respectively). Imaging follow-up was performed at 6-week and 3-monthly intervals. Technical success, 30-day complications and local tumour control/recurrence were recorded. Statistical analysis was performed with t test and Fisher's test. Univariate and multivariate survival analyses were performed using Cox regression.

RESULTS

Patients comprised of 23 men and 10 women (mean age 67.0 years). Mean tumour size was 2.2 ± 0.9 cm (28 hepatocellular carcinoma and 5 metastases). Mean follow-up time was 21.2 months (range 2-72 months). There were no differences between the JC and NJC groups in the rates of complete ablation (86.7 vs 83.3% P = 1.0), tumour recurrence (20.0 vs 22.2%, P = 0.95) or complication rates (6.7 vs 11.1% P = 1.0). Metastatic lesions were associated with a higher rate of recurrent disease (hazard ratio 3.86, 95% CI 1.0-14.8%, P = 0.05).

DISCUSSION

Percutaneous thermal ablation of JC tumours has similar rates of local tumour control and safety profile when compared to tumours in a NJC location. Tumours in a JC location should not be considered a contraindication for thermal ablation.

Utility of endoscopic ultrasound and endoscopy in diagnosis and management of hepatocellular carcinoma and its complications: What does endoscopic ultrasonography offer above and beyond conventional cross-sectional imaging?

Hepatocellular carcinoma constitutes over 90% of the primary liver tumors, the rest being cholangiocarcinoma. It has an insidious presentation, which is responsible for the delayed presentation. Hence, the management strategy relies on screening to diagnose it an early stage for curative resection and/or treatment with local ablative techniques or chemotherapy. However, even with different screening programs, more than 60% of tumors are still detected at an advanced stage, leading to an unchanged mortality rate, thereby implying a room for improvement in the screening and diagnostic process. In the last few years, there has been evolution of utility of endoscopy, specifically endoscopic ultrasonography along with Fine needle aspiration, for this purpose, which we comprehensively review in this article.

Percutaneous radiofrequency ablation in the treatment of pulmonary malignancies: efficacy, safety and predictive factors

Purpose

The purpose of this study was to evaluate the efficacy, safety and predictive factors of RFA of primary and secondary lung malignancies.

Patients and Methods

79 patients with 129 primary and secondary lung malignancies were enrolled in a retrospective study. We treated 74 pulmonary metastases of colorectal cancer, 13 malignant melanoma lesions, 13 renal cancer metastases, 5 primary lung malignancies and 24 tumors of other different entities. All patients were considered to be unsuitable candidates for surgery, radiotherapy or chemotherapy. The primary endpoint was local tumor control, secondary endpoints were overall survival, safety and predictive factors, e.g. distance to pleura, vessels and bronchi.

Results

The median tumor size was 1.2 cm (0.5–3.0 cm). After a median follow-up of 14 months (3–81 months), the LTC was 85.3 %. There were 34 lesions (26.4%) with complete remission, 48 (37.2 %) partial remission, 28 (21.7%) stable disease and 19 lesions (14.7%) with progressive disease. We evaluated an OS of 27 months. Pneumothorax in 19 cases (14.7%) and pleural effusion in 2 cases (1.6 %) were the leading complications (CTCAE, 5 grade III adverse events). The only significant influence regarding the outcome after RFA was the initial tumor size (p = 0.01). Distance to vessel, bronchi, and pleura showed no significant effect (p = 0.81; p = 0.82; p = 0.80).

Radiofrequency Ablation Combined With Transarterial Chemoembolization for Specially Located Small Hepatocellular Carcinoma

OBJECTIVE

To investigate the safety and efficacy of radiofrequency ablation combined with transarterial chemoembolization in patients with specially located small hepatocellular carcinoma.

MATERIALS AND METHODS

Between March 2014 and March 2017, a total of 26 patients with 26 lesions (10 perivascular, 6 subdiaphragmatic, 5 subcapsular, 5 perivascular, and subdiaphragmatic location; mean diameter 2.12 (0.62) cm), who received radiofrequency ablation-transarterial chemoembolization treatment, were retrospectively analyzed. Local tumor response was assessed by computed tomography/magnetic resonance imaging 1 month after the procedure. Tumor-free survival was also assessed according to the modified Response Evaluation Criteria in Solid Tumors. Complications were evaluated according to the National Cancer Institute's Common Terminology Criteria for Adverse Events (version 4.0).

RESULTS

Complete response was achieved in all patients 1 month after the procedure. During a median follow-up duration of 16.76 months (95% confidence interval: 7.78-25.73 months), local tumor recurrence occurred in 2 patients and new intrahepatic lesions developed in 7 patients. The 1-, 2-, and 3-year cumulative local tumor progression rates were 3.84%, 7.69%, and 7.69%, respectively. The median tumor-free survival duration was 21.96 months (95% confidence interval: 17.58-26.34 months). The 1-, 2-, and 3-year tumor-free survival rates were 67.4%, 46.1%, and 39.3%, respectively.

CONCLUSION

The radiofrequency ablation-transarterial chemoembolization combination therapy appears to be safe and effective and might be a treatment option for specially located small hepatocellular carcinoma lesions that have a risk of incomplete ablation or major complications.

131I-Labeled Copper Sulfide-Loaded Microspheres to Treat Hepatic Tumors via Hepatic Artery Embolization

Purpose: Transcatheter hepatic artery embolization therapy is a minimally invasive alternative for treating inoperable liver cancer but recurrence is frequent. Multifunctional agents, however, offer an opportunity for tumor eradication. In this study, we were aim to synthesized poly (lactic-co-glycolic acid) (PLGA) microspheres encapsulating hollow CuS nanoparticles (HCuSNPs) and paclitaxel (PTX) that were then labeled with radioiodine-131 (¹³¹I) to produce ¹³¹I-HCuSNPs-MS-PTX. This compound combines the multi-theranostic properties of chemotherapy, radiotherapy and photothermal therapy. In addition, it can also be imaged with single photon emission computed tomography (SPECT) imaging and photoacoustic imaging. Methods: We investigated the value of therapeutic and imaging of ¹³¹I-HCuSNPs-MS-PTX in rats bearing Walker-256 tumor transplanted in the liver. After the intra-arterial (IA) injection of ¹³¹I-HCuSNPs-MS-PTX, ¹⁸F-Fluorodeoxyglucose (¹⁸F-FDG) micro-positron emission tomography/computed tomography (micro-PET/CT) imaging was used to monitor the therapeutic effect. PET/CT findings were verified by immunohistochemical analysis. SPECT/CT and photoacoustic imaging were performed to demonstrate the distribution of ¹³¹I-HCuSNPs-MS-PTX in vivo. Results: We found that embolization therapy in combination with chemotherapy, radiotherapy and photothermal therapy offered by ¹³¹I-HCuSNPs-MS-PTX completely ablated the transplanted hepatic tumors at a relatively low dose. In comparison, embolization monotherapy or combination with one or two other therapies had less effective anti-tumor efficacy. The combination of SPECT/CT and photoacoustic imaging effectively confirmed microsphere delivery to the targeted tumors in vivo and guided the near-infrared laser irradiation. Conclusion: Our study suggests that there is a clinical theranostic potential for imaging-guided arterial embolization with ¹³¹I-HCuSNPs-MS-PTX for the treatment of liver tumors.

Hepatocellular carcinoma treatment: ablation and arterial embolization

Percutaneous and endovascular techniques take an important role in the therapeutic management of patients with hepatocarcinoma. Different techniques of percutaneous ablation, especially indicated in tumors up to 2cm diameter offer, at least, similar results to surgical resection. Taking advantage of double hepatic vascularization and exclusive tumor nutrition by the artery, several endovascular techniques of treating the tumor have been developed. Intra-arterial administration of embolizing particles, alone or charged with drug (chemoembolization), will produce ischemia and consequent necrosis with excellent results in selected patients. Certain types of particles may exclusively be carriers of a therapeutic agent when they incorporate a radioisotope that facilitates the direct intratumoral selective irradiation (radioembolization). This technique has demonstrated its efficacy in lesions not susceptible to be treated with other methods and should be considered, together with ablation and chemoembolization, in the therapeutic algorithms of hepatocarcinoma.

MoS2 nanosheets encapsulated in sodium alginate microcapsules as microwave embolization agents for large orthotopic transplantation tumor therapy

In recent years, it is prevalent to treat various kinds of the tumors through microwave ablation method. However, it is still very difficult to ablate large tumors by the traditional microwave ablation therapy. In this work, an effective microwave embolization agent designed by encapsulating molybdenum sulfide nanosheets in the sodium alginate microcapsules, denoted as MSMCs, was prepared for the effective therapy of large tumor. The toxicity evaluation showed that MSMC had a good biocompatibility in vitro. The in vitro and in vivo experiments demonstrated that the MSMC was an excellent embolic and microwave susceptible agent that could be used for dual-enhanced microwave ablation therapy. As such, the MSMC showed excellent tumor therapeutic effect with 5 times larger ablation zone observed by magnetic resonance (MR) imaging than the microwave alone after 3 days treating. Besides, the tumor is nearly completely ablated and can not be recurrent due to the persistent hyperthermia. Moreover, MSMCs have a good biocompatibility and can be degraded and cleared from the body. It is believed that the MSMC is demonstrated to be a promising multifunctional theranostic agent used for treating the larger tumor via the synergistic therapy of enhanced microwave ablation and transcatheter arterial embolization (TAE).

Optical flow and image segmentation analysis for noninvasive precise mapping of microwave thermal ablation in X-ray CT scans - ex vivo study

PURPOSE

To develop image processing algorithms for noninvasive mapping of microwave thermal ablation using X-ray CT.

METHODS

Ten specimens of bovine liver were subjected to microwave ablation (20-80 W, 8 min) while scanned by X-ray CT at 5 s intervals. Specimens were cut and manually traced by two observers. Two algorithms were developed and implemented to map the ablation zone. The first algorithm utilises images segmentation of Hounsfield units changes (ISHU). The second algorithm utilises radial optical flow (ROF). Algorithm sensitivity to spatiotemporal under-sampling was assessed by decreasing the acquisition rate and reducing the number of acquired projections used for image reconstruction in order to evaluate the feasibility of implementing radiation reduction techniques.

RESULTS

The average radial discrepancy between the ISHU and ROF contours and the manual tracing were 1.04±0.74 and 1.16±0.79mm, respectively. When diluting the input data, the ISHU algorithm retained its accuracy, ranging from 1.04 to 1.79mm. By contrast, the ROF algorithm performance became inconsistent at low acquisition rates. Both algorithms were not sensitive to projections reduction, (ISHU: 1.24±0.83mm, ROF: 1.53±1.15mm, for reduction by eight fold). Ablations near large blood vessels affected the ROF algorithm performance (1.83±1.30mm; p < 0.01), whereas ISHU performance remained the same.

CONCLUSION

The two suggested noninvasive ablation mapping algorithms can provide highly accurate contouring of the ablation zone at low scan rates. The ISHU algorithm may be more suitable for clinical practice as it appears more robust when radiation dose reduction strategies are employed and when the ablation zone is near large blood vessels.

Iodized Oil Transarterial Chemoembolization and Radiofrequency Ablation for Small Periportal Hepatocellular Carcinoma: Comparison with Nonperiportal Hepatocellular Carcinoma

PURPOSE

This study aims to evaluate the treatment outcomes of iodized oil transarterial chemoembolization (TACE) and subsequent radiofrequency ablation (RFA) for small (≤3 cm) periportal hepatocellular carcinoma (HCC) compared with nonperiportal HCC.

METHODS

Twenty-three patients [periportal group (PG); mean age, 59.8 years; 22 men, 1 woman] with periportal HCC (in contact with the portal vein >3 mm in diameter) and 279 patients [nonperiportal group (NPG); mean age, 59.1 years; 234 men, 45 women] with nonperiportal HCC were treated between March 2010 and January 2014. All cases were contraindicated for ultrasound-guided RFA or resection. Mean tumor size was 1.2 cm in each group. The baseline characteristics were not different between the groups, except for alpha-fetoprotein level (41.0 ng/dL in NPG vs. 8.8 ng/dL in PG, p = 0.001). Local tumor progression (LTP), disease-free survival (DFS), overall survival (OS), intrasegmental recurrence, and complications were analyzed using the Kaplan-Meier method and Fisher's exact test.

RESULTS

TACE and RFA were successfully performed in all patients. Mean follow-up period of PG and NPG was 33.8 and 42.8 months, respectively. LTP (p = 0.701), DFS (p = 0.718), and OS (p = 0.359) were not different between the two groups. Intrasegmental recurrence occurred in two patients (one in each group), and its incidence was not different (p = 0.212). Complications requiring further treatment occurred in 1/23 (4.3%) in PG and 5/279 (1.8%) in NPG. No procedure-related mortality occurred.

CONCLUSIONS

Iodized oil TACE and subsequent RFA are effective alternative treatments for small periportal HCC (≤3 cm) when percutaneous ultrasound- or CT-guided RFA or resection is not feasible.

A new mild hyperthermia device to treat vascular involvement in cancer surgery

Surgical margin status in cancer surgery represents an important oncologic parameter affecting overall prognosis. The risk of disease recurrence is minimized and survival often prolonged if margin-negative resection can be accomplished during cancer surgery. Unfortunately, negative margins are not always surgically achievable due to tumor invasion into adjacent tissues or involvement of critical vasculature. Herein, we present a novel intra-operative device created to facilitate a uniform and mild heating profile to cause hyperthermic destruction of vessel-encasing tumors while safeguarding the encased vessel. We use pancreatic ductal adenocarcinoma as an in vitro and an in vivo cancer model for these studies as it is a representative model of a tumor that commonly involves major mesenteric vessels. In vitro data suggests that mild hyperthermia (41-46 °C for ten minutes) is an optimal thermal dose to induce high levels of cancer cell death, alter cancer cell's proteomic profiles and eliminate cancer stem cells while preserving non-malignant cells. In vivo and in silico data supports the well-known phenomena of a vascular heat sink effect that causes high temperature differentials through tissues undergoing hyperthermia, however temperatures can be predicted and used as a tool for the surgeon to adjust thermal doses delivered for various tumor margins.

[Image-guided tumor ablation]

INTRODUCTION

Ablatives techniques for destroying in situ a tumoral process aim tissular necrosis by the application of several physical principles.

MATERIAL AND METHODS

We searched MEDLINE^®, Embase^®, using (MeSH) words; from January 2005 through May 2017, and we looked for all the studies. Investigators graded the strength of evidence in terms of methodology, language and relevance.

RESULTS

Forty-seven articles were analyzed. We described ablative techniques and sorted them in thermal and non-thermal therapies according to the used physical principle and their frequency of use in the urological pathology.

CONCLUSION

Percutaneous ablative therapies are mini-invasive techniques, which have an important role in tumors focal treatment. This article is a review of the ablative therapies and describes their physical principles, their equipment and their recent technological modifications, which have been developed to improve the clinical success of these techniques.

Loco-regional treatment of HCC: current status

Hepatocellular carcinoma (HCC) represents one of the few cancers for which locoregional treatments are recognised as being able to cure and/or prolong survival and are included in international guidelines. This is due to the unique nature of HCC, in most cases occurring in patients with underlying virus- or alcohol-related cirrhosis. The treatment choice in patients with HCC is therefore driven not only by tumour staging, as in the great majority of cancers, but also by careful evaluation of liver function and physical status. Another specific feature of HCC is that it is the only tumour that can be cured by organ transplantation, with the aim of treating both the cancer and underlying liver disease. These characteristics configure a complex scenario and prompt the need for close cooperation among interventional oncologists, surgeons, hepatologists, and anaesthesiologists. In patients with limited hepatic disease, preserved hepatic function and good performance status, categorised as very early and early-stage HCC according to the Barcelona Clinic Liver Cancer (BCLC) classification, image-guided tumour ablation is included among the curative treatments. More than half of patients with HCC are, however, diagnosed late, despite the widespread implementation of surveillance programmes, when curative treatments cannot be applied. For patients presenting with multinodular HCC and relatively preserved liver function, absence of cancer-related symptoms, and no evidence of vascular invasion or extrahepatic spread transcatheter arterial chemoembolisation (TACE) is the current standard of care. Although anti-tumour activity and promising survival results has been reported in cohorts of patients with advanced HCC treated with radio-embolisation, systemic treatment with the multi-kinase inhibitor, sorafenib, is still recommended for patients at this stage. In this article, current treatment strategies for HCC according to tumour stage are discussed, underlining the latest advances in the literature and technical developments.

Ultrasound-guided percutaneous microwave ablation assisted by three-dimensional visualization operative treatment planning system and percutaneous transhepatic cholangial drainage with intraductal chilled saline perfusion for larger hepatic hilum hepatocellular (D ≥ 3 cm): preliminary results

To assess the clinical efficiency of ultrasound-guided percutaneous microwave ablation (US-PMWA) assisted by three-dimensional (3D) visualization operative treatment planning system and percutaneous transhepatic cholangial drainage with intraductal chilled saline perfusion (PTCD-ICSP) for larger hepatic hilum hepatocellular carcinoma (HH-HCC) (D ≥ 3 cm). The combination therapy was performed in 14 patients from Sep 2011 to May 2017. The major outcomes for assessment were biliary duct complications, local tumor recurrence, distant recurrence and overall survival rates. Median follow-up period was 26 months. The series of 3D visualization operative treatment planning, PTCD-ICSP and US-PMWA were successfully performed and complete ablation was achieved in all cases. The mean session for one tumor was 1.0 ± 0.4. The mean ablation time for per tumor was 1805 ± 567s. The saline volume used for the PTCD-ICSP was 250-450 ml per session. The 1-, 2-, and 3-year local tumor recurrence rates were 7.1%, 14.3%, and 35.7%, the 1-, 2-, and 3-year distant recurrence rates were 0%, 14.3%, and 28.6%, and 1-, 2-, and 3-year overall survival rates were 100%, 92.9%, and 71.4%, respectively. No severe complications related to ablation occurred.

Conclusions

US-PMWA assisted by 3D visualization operative treatment planning system and PTCD-ICSP appears to be a safe, effective and innovative technique for management for larger HH-HCCs, which improved the prognosis.

Long-term survival of hepatocellular carcinoma after percutaneous radiofrequency ablation guided by ultrasound

Background

The risk factors for recurrence and death after radiofrequency ablation (RFA) for hepatocellular carcinoma (HCC) remain poorly known. This study was aimed to study the 10-year overall survival (OS) of HCC treated by ultrasound (US)-guided RFA and the risk factors for recurrence and death.

Methods

Between June 2005 and June 2016, 1000 patients with HCC treated by US-guided RFA at 4 hospitals in China; among them, 525 patients met the criteria for radical ablation and 410 had high AFP levels before RFA treatment. Clinical and biochemical factors were tested for association with recurrence and survival. Patients were divided into the recurrence (n = 348) and no recurrence groups (n = 62).

Results

The 5- and 10-year survival rates were 66 and 35%, respectively. Tumor size (HR = 1.36, 95% CI 1.12–1.65), albumin levels (HR = 0.76, 95% CI 0.65–0.91), prothrombin time (HR = 2.18, 95% CI 1.54–3.10), and α-fetoprotein levels (HR = 1.13, 95% CI 1.00–1.26) were independently associated with mortality after RFA for HCC. Tumor size (HR = 1.27, 95% CI: 1.15–1.40), HBV-DNA (HR = 7.70, 95% CI 3.57–16.63), AFP levels before treatment (HR = 2.172, 95% CI 1.256–3.756, P = 0.006), and AFP response (HR = 4.722, 95% CI 1.053–21.184, P = 0.0427) were independently associated with the risk of recurrence of HCC after RFA. The median survival of the patients with and without recurrence after RFA was 54 (95% CI 45–58) and 62 (95% CI 48–80) months, respectively (log-rank, P = 0.04).

Conclusions

Tumor size, albumin, prothrombin time, and α-fetoprotein levels were independently associated with mortality after US-guided RFA for HCC, while tumor size and HBV-DNA were independently associated with recurrence. Patients with recurrence had a poorer survival compared with those without.

Protective and Heat Retention Effects of Thermo-sensitive Basement Membrane Extract (Matrigel) in Hepatic Radiofrequency Ablation in an Experimental Animal Study

PURPOSE

To evaluate the protective effect of using thermo-sensitive basement membrane extract (Matrigel) for hydrodissection to minimize thermal injury to nearby structures and to evaluate its heat sink effect on the ablation zone in radiofrequency ablation (RFA) of the liver.

MATERIALS AND METHODS

First, the viscosity profile and heat sink effect of Matrigel were assessed during RFA in vitro and ex vivo. Fresh pig liver tissue was used, and the temperature changes in Matrigel and in 5% dextrose in water (D5W) during RFA were recorded. Then, the size of the ablation zone in the peripheral liver after RFA was measured. Second, in an in vivo study, 45 Sprague-Dawley rats were divided into three groups of 15 rats each (Matrigel, D5W and control). In the experimental groups, artificial ascites with 10 ml of Matrigel or D5W were injected using ultrasound guidance prior to RFA. The frequency of thermal injury to the nearby organs was compared among the three groups, with assessments of several locations: near the diaphragm, the abdominal wall and the gastrointestinal (GI) tract. Finally, the biological degradation of Matrigel by ultrasound was evaluated over 60 days.

RESULTS

First, Matrigel produced a greater heat retention (less heat sink) effect than D5W during ex vivo ablation (63 ± 9 vs. 26 ± 6 °C at 1 min on the surface of the liver, P < 0.001). Hepatic ablation zone volume did not differ between the two groups. Second, thermal injury to the nearby structures was found in 14 of 15 cases (93.3%) in the control group, 8 of 15 cases (53.3%) in the D5W group, and 1 of 15 cases (6.7%) in the Matrigel group. Significant differences in the thermal injury rates for nearby structures were detected among the three groups (P < 0.001). The most significant difference in the thermal injury rate was found in locations near the GI tract (P = 0.003). Finally, Matrigel that was injected in vivo was gradually degraded during the following 60 days.

CONCLUSIONS

Using thermo-sensitive Matrigel as a hydrodissection material might help reduce the frequency of collateral thermal injury to nearby structures, especially in locations close to the GI tract, compared to conventional D5W. Additionally, Matrigel did not increase the heat sink effect on the ablation zone during ablation and was degraded over time in vivo.

Decision Making: Thermal Ablation Options for Small Renal Masses

Renal cell carcinoma is a relatively common tumor, with an estimated 63,000 new cases being diagnosed in the United States in 2016. Surgery, be it with partial or total nephrectomy, is considered the mainstay of treatment for many patients. However, those patients with small renal masses, typically less than 3 to 4 cm in size who are deemed unsuitable for surgery, may be suitable for percutaneous thermal ablation. We review the various treatment modalities, including radiofrequency ablation, microwave ablation, and cryoablation; discuss the advantages and disadvantages of each method; and review the latest data concerning the performance of the various ablative modalities compared with each other, and compared with surgery.

Potential Mechanisms of Vascular Thrombosis after Microwave Ablation in an in Vivo Liver

PURPOSE

To evaluate potential biologic and thermal mechanisms of the observed differences in thrombosis rates between hepatic vessels during microwave (MW) ablation procedures.

MATERIALS AND METHODS

MW ablation antennae were placed in single liver lobes of 2 in vivo porcine liver models (n = 3 in each animal; N = 6 total) in the proximity of a large (> 5 mm) portal vein (PV) and hepatic veins (HVs). Each ablation was performed with 100 W for 5 minutes. Conventional ultrasound imaging and intravascular temperature probes were used to evaluate vessel patency and temperature changes during the ablation procedure. Vascular endothelium was harvested 1 hour after ablation and used to characterize genes and proteins associated with thrombosis in PVs and HVs.

RESULTS

Targeted PVs within the MW ablation zone exhibited thrombosis at a significantly higher rate than HVs (54.5% vs 0.0%; P = .0046). There was a negligible change in intravascular temperature in PVs and HVs during the ablation procedure (0.2°C ± 0.4 vs 0.6°C ± 0.9; P = .46). PVs exhibited significantly higher gene expression than HVs in terms of fold differences in thrombomodulin (2.9 ± 2.0; P = .0001), von Willebrand factor (vWF; 7.6 ± 1.5; P = .0001), endothelial protein C receptor (3.50 ± 0.49; P = .0011), and plasminogen activator inhibitor (1.46 ± 0.05; P = .0014). Western blot analysis showed significantly higher expression of vWF (2.32 ± 0.92; P = .031) in PVs compared with HVs.

CONCLUSIONS

Large PVs exhibit thrombosis more frequently than HVs during MW ablation procedures. Biologic differences in thrombogenicity, rather than heat transfer, between PVs and HVs may contribute to their different rates of thrombosis.

Adverse effects of irreversible electroporation of malignant liver tumors under CT fluoroscopic guidance: a single-center experience

PURPOSE

We aimed to describe the frequency of adverse events after computed tomography (CT) fluoroscopy-guided irreversible electroporation (IRE) of malignant hepatic tumors and their risk factors.

METHODS

We retrospectively analyzed 85 IRE ablation procedures of 114 malignant liver tumors (52 primary and 62 secondary) not suitable for resection or thermal ablation in 56 patients (42 men and 14 women; median age, 61 years) with regard to mortality and treatment-related complications. Complications were evaluated according to the standardized grading system of the Society of Interventional Radiology. Factors influencing the occurrence of major and minor complications were investigated.

RESULTS

No IRE-related death occurred. Major complications occurred in 7.1% of IRE procedures (6/85), while minor complications occurred in 18.8% (16/85). The most frequent major complication was postablative abscess (4.7%, 4/85) which affected patients with bilioenteric anastomosis significantly more often than patients without this condition (43% vs. 1.3%, P = 0.010). Bilioenteric anastomosis was additionally identified as a risk factor for major complications in general (P = 0.002). Minor complications mainly consisted of hemorrhage and portal vein branch thrombosis.

CONCLUSION

The current study suggests that CT fluoroscopy-guided IRE ablation of malignant liver tumors may be a relatively low-risk procedure. However, patients with bilioenteric anastomosis seem to have an increased risk of postablative abscess formation.

Advantage of sorafenib combined with radiofrequency ablation for treatment of hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) is a leading cause of death worldwide. Among the surgical and nonsurgical treatments available, radiofrequency ablation (RFA) and sorafenib have been shown to have efficacy. There is little evidence whether combination of these therapies would have additional benefits.

METHODS

In a mouse model of HCC, effects of sorafenib were determined by tumor size, RFA-induced necrosis area (triphenyltetrazolium chloride staining), microvascular density (MVD; 4',6-diamidino-2-phenylindole and anti-CD31 antibody staining), and tumor perfusion (magnetic resonance imaging).

RESULTS

The RFA-induced necrosis area was 80.98 ± 9.14 and 69.49 ± 7.46 mm2 in mice administered 80 and 40 mg/kg sorafenib, respectively, but only 57.29 ± 3.39 mm2 in controls. Sorafenib also reduced tumor volume and enhanced RFA-induced tumor destruction in a dose-dependent manner, and reduced both MVD and tumor perfusion.

CONCLUSIONS

The results of our study suggest a potential role for combining RFA with sorafenib for treatment of HCC. Sorafenib could enhance RFA efficiency, possibly through its angiogenesis suppressive effects.