Image-guided tumor ablation: proposal for standardization of terms and reporting criteria

CT versus MR guidance for radiofrequency ablation in patients with colorectal liver metastases: a 10-year follow-up favors MR guidance

OBJECTIVES

To compare the results of CT- vs MR-guided radiofrequency ablation (RFA) of liver metastases (LM) from colorectal cancer after 10 years of follow-up in an observational, retrospective, and multicentric study.

METHODS

A total of 238 patients with 496 LM were treated with RFA either with CT (CT group) or magnetic resonance (MR group) guidance. Every ablated LM was assessed and followed up with diagnostic MRI. Technical success, technique efficacy, predictive factors, recurrence rates, and overall survival were assessed.

RESULTS

The CT group comprised 143 patients and the MR group 77 patients. Eighteen patients underwent ablation with both modalities. Technical success per patient and per lesion was 88% and 93% for CT and 87% and 89.6% for MR, and technique efficacy was 97.1% and 98.6% for CT and 98.7% and 99.3% for MR respectively. Local recurrence following the first ablation (primary patency) occurred in 20.1% (CT) vs 4.6% (MR) (p < 0.001). Residual liver tumor, size of LM, and advanced N and M stage at initial diagnosis were independent predictors for overall survival in both groups. The median overall survival measured from first RFA treatment was 2.6 years. The 1-year, 5-year, and 10-year survival were 85.9%, 25.5%, and 19.1% respectively.

CONCLUSIONS

The MR group had significantly better local control compared to the CT group. There was no significant difference in patient survival between the two groups.

CLINICAL RELEVANCE STATEMENT

MR-guided radiofrequency ablation of colorectal liver metastases is safe and effective, and offers better local control than CT-guided ablation.

KEY POINTS

• Imaging modality for radiofrequency ablation guidance is an independent predictor of local recurrence in colorectal liver metastases. • MR-guided radiofrequency ablation achieved better local control of liver metastases from colorectal cancer than CT-guided. • The number and size of liver metastases are, among others, independent predictors of survival. Radiofrequency ablation with MR guidance improved clinical outcome but does not affect survival.

A review on radiofrequency, laser, and microwave ablations and their thermal monitoring through fiber Bragg gratings

Thermal ablation of tumors aims to apply extreme temperatures inside the target tissue to achieve substantial tumor destruction in a minimally invasive manner. Several techniques are comprised, classified according to the type of energy source. However, the lack of treatment selectivity still needs to be addressed, potentially causing two risks: i) incomplete tumor destruction and recurrence, or conversely, ii) damage of the surrounding healthy tissue. Therefore, the research herein reviewed seeks to develop sensing systems based on fiber Bragg gratings (FBGs) for thermal monitoring inside the lesion during radiofrequency, laser, and microwave ablation. This review shows that, mainly thanks to multiplexing and minimal invasiveness, FBGs provide an optimal sensing solution. Their temperature measurements are the feedback to control the ablation process and allow to investigate different treatments, compare their outcomes, and quantify the impact of factors such as proximity to thermal probe and blood vessels, perfusion, and tissue type.

Drug-Eluting Bead Transarterial Chemoembolization Versus Radiofrequency Ablation as an Initial Treatment of Single Small (≤ 3 cm) Hepatocellular Carcinoma

BACKGROUND

In this study, we aimed to compare the long-term therapeutic outcomes of drug-eluting bead transarterial chemoembolization (DEB-TACE) with those of radiofrequency ablation (RFA) for the initial treatment of a single small (≤ 3 cm) hepatocellular carcinoma (HCC).

METHODS

From January 2010 to December 2021, 259 consecutive patients who underwent DEB-TACE (67 patients) or RFA (192 patients) as a first-line treatment for a single small HCC were enrolled in this retrospective study. The therapeutic outcomes, including cumulative intrahepatic local tumor progression (LTP), progression-free survival (PFS), and long-term overall survival (OS) rates, were compared between the two groups before and after propensity score (PS) matching. Multivariate Cox proportional hazard models were used to evaluate the prognostic factors and differences in OS and PFS between the two groups for all 92 patients after PS matching.

RESULTS

After PS matching, the 1-, 2-, 3-, and 5-year LTP rates were lower in the RFA group than those in the DEB-TACE group (P < 0.001), and the 1-, 2-, 3-, and 5-year PFS rates in the RFA group were higher than those in the DEB-TACE group (P = 0.007). However, the 1-, 2-, 3-, and 5-year OS rates were not significantly different between the RFA and DEB-TACE groups (P = 0.584). Moreover, the OS was not significantly different between the RFA and DEB-TACE groups in the univariate and multivariate analyses, with a hazard ratio (HR) of 0.81. The PFS was significantly higher in the RFA group than that in the DEB-TACE group in the univariate analyses, with a HR of 0.44 (P = 0.009). Multivariate Cox regression analysis showed that albumin (P = 0.019) was an independent prognostic factor for OS. Additionally, the major complication rates were not significantly different between the DEB-TACE and RFA groups (P = 1.000).

CONCLUSION

The LTP and PFS rates of RFA were superior to those of DEB-TACE in the initial treatment of single small HCC after PS matching. However, the OS rates were not significantly different between RFA and DEB-TACE. Therefore, DEB-TACE may be considered an efficient substitute for RFA in some patients with a single small HCC who are ineligible for RFA.

Percutaneous ablative therapies for hepatocellular carcinoma in the caudate lobe of the liver: efficacy and outcome

OBJECTIVE

To assess the efficacy and outcomes of percutaneous ablative therapies for hepatocellular carcinoma (HCC) in the caudate lobe.

METHODS

Patients within Milan criteria, who underwent thermal ablation (RFA/MWA) for HCC were analyzed. Based on the inclusion-criteria, patients were categorized in two groups. Group-1 (caudate-lobe HCC) and Group-2 (non-caudate-lobe HCC). Both the groups were analyzed for technical success (TS), local tumor progression (LTP), disease-free survival (DFS), and overall survival (OS) were compared between both the groups. Predictive factors for LTP, DFS, or OS in the study cohort were analyzed using appropriate statistical analyses.

RESULTS

Twenty-one patients qualified to be in Group-1 while 130 patients fulfilled the criteria for Group-2. TS of 90.5 and 97.7% was seen after the first session of ablation for Group-1 and group-2 respectively, while a TS of 95.2% (Group-1) and 100% (Group-2) was achieved after second session. The right-intercostal-approach was used in 66.7% (n = 14) and the anterior-epigastric-approach was used in 33.3% (n = 7) of patients having caudate-lobe HCC. Procedure-related complications in both the groups were comparable. Although, statistically insignificant, LTP in the Group-1 (19.5%, n = 4) was twice that of non-caudate lobe HCC (8.5%, n = 11). The cumulative DFS rate was better in Group-2 while OS in both groups were comparable. Multivariate analysis showed: tumor size and ablative margin of 5 mm being independent predictors of LTP after percutaneous-ablation of caudate-lobe HCC.

CONCLUSION

Ablative therapies for HCC in caudate lobe is feasible and safe with comparable LTP and OS to non-caudate lobe HCC. Tumor size >2 cm and lack of 5 mm ablative margin are independent predictors of LTP.

ADVANCES IN KNOWLEDGE

1. Percutaneous ablation of caudate lobe HCC is feasible using anterior epigastric approach or right intercostal approach.2. These approaches may allow a safe and effective ablation of caudate lobe HCC with results comparable to non-caudate HCC ablation.

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.

The combination of transcatheter arterial chemoembolisation (TACE) and thermal ablation versus TACE alone for hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma is the sixth most common cancer worldwide. Hepatic resection is regarded as the curative therapy for hepatocellular carcinoma. However, only about 20% of people with hepatocellular carcinoma are candidates for resection, which highlights the importance of effective nonsurgical therapies. Until now, transcatheter arterial chemoembolisation (TACE) is the most common palliative therapy for hepatocellular carcinoma, but its clinical benefits remain unsatisfactory. During recent years, some studies have reported that the combination of TACE plus thermal ablation can confer a more favourable prognosis than TACE alone. However, clear and compelling evidence to prove the beneficial or harmful effects of the combination of TACE and thermal ablation therapy is lacking.

OBJECTIVES

To assess the beneficial and harmful effects of the combination of thermal ablation with TACE versus TACE alone in people with hepatocellular carcinoma.

SEARCH METHODS

We performed searches in the Cochrane Hepato-Biliary Group Controlled Trials Register, the Cochrane Central Register of Controlled Trials in the Cochrane Library, MEDLINE, Embase, LILACS, Science Citation Index Expanded, and Conference Proceedings Citation Index-Science. We endeavoured to identify relevant randomised clinical trials also in the China National Knowledge Infrastructure (CNKI) and Wanfang databases. We searched trial registration websites for ongoing studies. We also handsearched grey literature sources. The date of last search was 22 December 2020.

SELECTION CRITERIA

We planned to include all randomised clinical trials comparing the combination of TACE plus thermal ablation versus TACE alone for hepatocellular carcinoma, no matter the language, year of publication, publication status, and reported outcomes.

DATA COLLECTION AND ANALYSIS

We planned to use standard methodological procedures expected by Cochrane. We planned to calculate risk ratios (RRs) with the corresponding 95% confidence intervals (CIs). For time-to-event variables, we planned to use the methods of survival analysis and express the intervention effect as a hazard ratio (HR) with 95% Cl. If the log HR and the variance were not directly reported in reports, we planned to calculate them indirectly, following methods for incorporating summary time-to-event data into meta-analysis. We planned to assess the risk of bias of the included studies using the RoB 2 tool. We planned to assess the certainty of evidence with GRADE and present the evidence in a summary of findings table.

MAIN RESULTS

Out of 2224 records retrieved with the searches, we considered 135 records eligible for full-text screening. We excluded 21 of these records because the interventions used were outside the scope of our review or the studies were not randomised clinical trials. We listed the remaining 114 records, reporting on 114 studies, under studies awaiting classification because we could not be sure that these were randomised clinical trials from the information in the study paper. We could not obtain information on the registration of the study protocol for any of the 114 studies. We could not obtain information on study approval by regional research ethics committees, either from the study authors or through our own searches of trial registries. Corresponding authors did not respond to our enquiries about the design and conduct of the studies, except for one from whom we did not receive a satisfactory response. We also raised awareness of our concerns to editors of the journals that published the 114 studies, and we did not hear back with useful information. Moreover, there seemed to be inappropriate inclusion of trial participants, based on cancer stage and severity of liver disease, who should have obtained other interventions according to guidelines from learned societies. Accordingly, we found no confirmed randomised clinical trials evaluating the combination of TACE plus thermal ablation versus TACE alone for people with hepatocellular carcinoma for inclusion in our review. We identified five ongoing trials, by handsearching in clinical trial websites.

AUTHORS' CONCLUSIONS

We could not find for inclusion any confirmed randomised clinical trials assessing the beneficial or harmful effects of the combination of TACE plus thermal ablation versus TACE alone in people with hepatocellular carcinoma. Therefore, our results did not show or reject the efficiency of the combination of TACE plus thermal ablation versus TACE alone for people with hepatocellular carcinoma. We need trials that compare the beneficial and harmful effects of the combination of TACE plus thermal ablation versus TACE alone in people with hepatocellular carcinoma, not eligible for treatments with curative intent (liver transplantation, ablation surgical resection) and who have sufficient liver reserve, as assessed by the Child Pugh score, and who do not have extrahepatic metastases. Therefore, future trial participants must be classified at Barcelona Clinic Liver Cancer Stage B (intermediate stage) (BCLC-B) or an equivalent, with other staging systems.

CT-monitored minimal ablative margin control in single-session microwave ablation of liver tumors: an effective strategy for local tumor control

OBJECTIVES

To investigate the usefulness of minimal ablative margin (MAM) control by intra-procedural contrast-enhanced CT (CECT) in microwave ablation (MWA) of liver tumors.

METHODS

A total of 334 consecutive liver tumors (240 hepatocellular carcinomas [HCCs] and 94 colorectal liver metastases [CRLMs]) in 172 patients treated with percutaneous MWA were retrospectively included. MAM of each tumor was assessed after expected ablation completion using intra-procedural CECT, allowing within-session additional ablation to any potentially insufficient margin. On immediate post-MWA MRI, complete ablation coverage of tumor and final MAM status were determined. The cumulative local tumor progression (LTP) rate was estimated by using the Kaplan-Meier method. To identify predictors of LTP, Cox regression analysis with a shared frailty model was performed.

RESULTS

Intra-procedural CECT findings prompted additional ablation in 18.9% (63/334) of tumors. Final complete ablation coverage of tumor and sufficient MAM were determined by MRI to be achieved in 99.4% (332/334) and 77.5% (259/334), and their estimated 6-month, 1-year, and 2-year LTP rates were 3.2%, 7.5%, and 12.9%; and 1.0%, 2.1%, and 6.9%, respectively. Insufficient MAM on post-MWA MRI, perivascular tumor location, and tumor size (cm) were independent risk factors for LTP (hazard ratio = 14.4, 6.0, and 1.1, p < 0.001, p = 0.003, and p = 0.011, respectively), while subcapsular location and histology (HCC vs CRLM) were not.

CONCLUSIONS

In MWA of liver tumors, intra-procedural CECT monitoring of minimal ablative margin facilitates identification of potentially suboptimal margins and guides immediate additional intra-session ablation to maximize rates of margin-sufficient ablations, the latter being a highly predictive marker for excellent long-term local tumor control.

KEY POINTS

• In MWA of liver tumors, intra-procedural CECT can identify potentially suboptimal minimal ablative margin, leading to immediate additional ablation in a single treatment session. • Achieving a finally sufficient ablative margin through the MWA with intra-procedural CECT monitoring of minimal ablative margin results in excellent local tumor control.

Missing colorectal liver metastases: the surgical challenge

BACKGROUND

New chemotherapy schemes have allowed for a better radiological response of unresectable colorectal liver metastases, leading to an interesting scenario known as a complete radiological response. The aim of this study was to review the current management of missing liver metastases (MLM) from the liver surgeon's point of view.

METHODS

A systematic search was conducted on all publications of PubMed and Embase between 2003 and 2018. Meta-analysis was performed on MLM resected/unresected. Residual tumor or regrowth and relapse-free survival were used as evaluation indices.

RESULTS

After literature search, 18 original articles were included for analysis. The predictive factors for MLM are type and duration of chemotherapy and size and number of lesions. Magnetic resonance is the most sensitive preoperative technique. Regarding clinical management, liver surgery is deemed the fundamental pillar in the therapeutic strategy of these patients. Meta-analysis due to data heterogeneity was inconclusive.

CONCLUSIONS

Depending on the clinical context, MLM monitoring appears to be a valid therapeutic alternative. Nevertheless, prospective randomized clinical studies are needed.

CT-guided percutaneous radiofrequency ablation of osteoid osteoma: Our experience in 87 patients

Purpose:

To evaluate the technical and clinical success of radiofrequency ablation of osteoid osteoma and analyze the factors responsible for clinical success. We also tried to investigate the role of follow-up computed tomography (CT) imaging.

Materials and Methods:

This is a prospective study approved by the institute's ethics committee involving 87 patients with appendicular osteoid osteoma. CT-guided radio frequency ablation was performed using a bipolar ablation system. Patients were followed up over 15.4 (4–24) months for pain, and clinical success/failure was determined using established criteria. Patients with clinical failure were taken for repeat ablation. Follow-up CT was obtained at 6 months and correlated with clinical success. Procedural scans were later reviewed for technical success in a blinded manner and correlated with clinical success along with other imaging and patient characteristics.

Results:

Mean pre-procedure visual analog scale (VAS) score was 7.0 ± 0.8. Primary success rate after single session was 86.2%(75/87 patients), and overall success rate after one/two sessions was 96.6%(84/87). No major complications were noted. Technical success rate was 89.7%(78/87). All 9 patients who had a suboptimal needle positioning had recurrence where as three patients had recurrence despite technical success. None of the imaging characteristics or history of prior intervention was significantly associated with clinical success. Follow-up CT showed advanced bone healing in 48 lesions, and was confined to the treatment success group. Alternately, minimal/absent bone healing was seen in all (12) patients of primary treatment failure and 27 patients with treatment success.

Conclusions:

CT-guided percutaneous radio frequency ablation is a safe and highly effective treatment for osteoid osteomas even in recurrent and residual cases. Technical success is the most important parameter affecting the outcome. Post radio frequency ablation CT findings have a good positive but a poor negative predictive value in prognostication.

Complications of Percutaneous Radiofrequency Ablation of Spinal Osseous Metastases: An 8-Year Single-Center Experience

OBJECTIVE. The purpose of this article was to evaluate the complication rate of percutaneous radiofrequency ablation of spinal osseous metastases. MATERIALS AND METHODS. This retrospective HIPAA-compliant study reviewed complications of radiofrequency ablation combined with vertebral augmentation performed on 266 tumors in 166 consecutive patients for management of vertebral metastases between January 2012 and August 2019. Common Terminology Criteria for Adverse Events (CTCAE) was used to categorize complications as major (grade 3-4) or minor (grade 1-2). Local tumor control rate as well as pain palliation effects evaluated by the Brief Pain Inventory scores determined 1 week, 1 month, 3 months, and 6 months after treatment were documented. Wilcoxon signed rank and Mann-Whitney U tests were used for statistical analysis. RESULTS. Among 266 treated tumors, the total complication rate was 3.0% (8/266), the major complication rate was 0.4% (1/266), and the minor complication rate was 2.6% (7/266). The single major (CTCAE grade 3) periprocedural complication was characterized by lower extremity weakness, difficulty in urination, and lack of erection as a result of spinal cord venous infarct. The seven minor complications included four cases of periprocedural transient radicular pain (CTCAE grade 2) requiring transforaminal steroid injections, one case of delayed secondary vertebral body fracture (CTCAE grade 2) requiring analgesics, and two cases of asymptomatic spinal cord edema on routine follow-up imaging (CTCAE grade 1). The local tumor control rate was 78.9%. There were statistically significant pain palliation effects at all postprocedural time intervals (p < .001 for all). CONCLUSION. Radiofrequency ablation of spinal osseous metastases is safe with a 3.0% rate of complications.

The ameliorating approach of nanorobotics in the novel drug delivery systems: a mechanistic review

Nanoscale robotics have the ability that it can productively transform multiple energy sources into motion and strength which reflects an expeditiously appearing and captivating area for research of robotics. In today's plethora, biomedical nanorobotics played an intricate character with numerous units of robots working at the pathological site in a coordinated manner. The synergistic action of the several nanorobotics has been employed for the fulfilment of the task such as large-scale detoxification, delivery of the large pharmacological/therapeutic efficacious payloads, etc. that is nearly unfeasible or unalterable practically by using single nanorobot. The collective intelligence of the nanorobot is advancing progressively at the nanoscale to reinforce their precision treatment potentially. Conclusively, after obtaining certain consideration regarding the nanorobotics sciences, many professionals are compendiously involving in the emerging highly efficacious therapeutic technology that encourages the scientist or designing of the tissues specific for the site-specific nanorobotic diagnostic devices. As a result, the closed and professional type between the field of Nanotechnology and Medical Sciences will provide another new highly oriented level to the domain of nanorobotics.

The Islanding effect - a special method of percutaneous peritumor ethanol injection for hepatocellular carcinoma: 15-year follow-up outcome

Percutaneous ethanol injection is a well-known ablation therapy for hepatocellular carcinoma and is well-tolerated, inexpensive, and effective with few adverse events. In this study, another type of ethanol injection was introduced in the present study.Sixty two patients with hepatocellular carcinoma received 133 percutaneous peritumor ethanol injection treatments and the 15-year follow-up outcomes were analyzed through a collected database.The technical efficiency was 89.5% (119/133 treatments) after the first percutaneous peritumor ethanol injection procedure. However, after the second repeated percutaneous peritumor ethanol injection procedure, technical efficiency increased to 98.5% (131/133 treatments). The 1 year, 3 years, 5 years, 10 years, and 15 years rates of tumor recurrence were 12.9%, 50.0%, 59.7%, 74.2%, and 74.2%, respectively. Multivariate analysis demonstrated that diabetes, Child-Pugh class B, and tumor size greater than 2 cm were significantly related to tumor recurrence. The 1 year, 3 years, 5 years, 10 years, and 15 years rates of overall survival were 98.4%, 83.6%, 61.3%, 19.4%, and 0%, respectively. Multivariate analysis demonstrated that Child-Pugh class B, tumor size greater than 2 cm, and multiple tumors were significantly related to overall survival.Compared with other ablation methods (including peritumor ethanol injection), percutaneous peritumor ethanol injection can avoid tumor ruptures, reduce tumor proliferation and metastasis, and is suitable for the treatment of small tumors. In addition, when combined with other treatment methods, percutaneous peritumor ethanol injection can form a tumor metastatic isolation zone in advance and improve the comprehensive treatment effect.

Radiofrequency Ablation for Cervical Metastatic Lymph Nodes in Children and Adolescents With Papillary Thyroid Carcinoma: A Preliminary Study

OBJECTIVE

To evaluate the safety and efficacy of radiofrequency ablation (RFA) for metastatic lymph nodes (LNs) in children and adolescents with papillary Thyroid Carcinoma (PTC).

MATERIALS AND METHODS

From December 2014 to March 2018, 10 metastatic LNs(mean volume 0.30 ± 0.38 ml, range 0.06-1.23ml) in 5 children and adolescents (3 females, 2 males; mean age 15.60 ± 2.97 years, range 12-19 years) with PTC treated by RFA were evaluated in this study. The mean number of surgical procedures performed before RFA was 1.2 (range 1-2) and the mean number of treated metastatic LNs per patient was 2 (rang 1-3). RFA was performed with an 18-gauge bipolar RF applicator under local anesthesia. Follow-up consisted of US and serum thyroglobulin (Tg) level at 1, 3, 6, 12 months and every 12 months thereafter.

RESULTS

All the patients were well tolerant to RFA procedure and no procedure-related complications occurred. During a mean follow-up time of 52.00 ± 21.44 months, the initial volume of LNs was 0.30 ± 0.38 ml, which significantly decreased to 0.01 ± 0.03 ml (P = 0.005) with a mean VRR of 99.28 ± 2.27%. A total of 9 metastatic LNs (90.00%) completely disappeared. After RFA, 2 patients developed newly metastases. One patient had additional RFA. The other one with multiple LN metastases underwent total thyroidectomy with central neck dissection.

CONCLUSION

As a less invasive and effective technique, RFA may provide another alternative to the existing therapeutic modalities for cervical metastatic LNs in children and adolescents with PTC.

Pre-operative Assessment of Ablation Margins for Variable Blood Perfusion Metrics in a Magnetic Resonance Imaging Based Complex Breast Tumour Anatomy: Simulation Paradigms in Thermal Therapies

BACKGROUND AND OBJECTIVES

Image-guided medical interventions facilitates precise visualization at treatment site. The conformal prediction for sparing healthy tissue fringes precisely in the vicinity of irregular tumour anatomy remains clinically challenging. Pre-clinical image-based computational modelling is imperative as it helps in enhancement of treatment quality, augmenting clinical-decision making, while planning, targeting, controlling, monitoring and assessing treatment response with an effective risk assessment before the onset of treatment in clinical settings. In this study, the influence of heat deposition rate (SAR), exposure duration, and variable blood perfusion metrics for a patient-specific breast tumour is quantified considering the tumour margins thereby suggesting need of geometrically accurate models.

METHODS

A three-dimensional realistic model mimicking dimensions of a female breast, comprising ~1.7 cm irregular tumour, was generated from patient specific two-dimensional DICOM format MRI images through image segmentation tools MIMICS 19.0® and 3-Matic 11.0® which is finally exported to COMSOL Multiphysics 5.2® as a volumetric mesh for finite element analysis. The Pennes bioheat transfer model and Arrhenius thermal damage model of cell-death are integrated to simulate a coupled biophysics problem. A comparative blood perfusion analysis is done to evaluate the response of tumour during heating considering thermal damage extent, including the tumour margins while sparing critical adjoining healthy tissues.

RESULTS

The evaluated thermal damage zones for 1 mm, 2 mm and 3 mm fringe heating region (beyond tumour boundary) reveals 0.09%, 0.21% and 0.34% thermal damage to the healthy tissue (which is <1%) and thus successful necrosis of the tumour. The iterative computational experiments suggests treatment margins < 5 mm are sufficient enough as heating beyond 3 mm fringe layer leads to higher damage surrounding the tumour approximately 1.5 times the tumour volume. Further, the heat-dosage requirements are 22% more for highly perfused tumour as compared to moderately perfused tumour with an approximate double time to ablate the whole tumour volume.

CONCLUSIONS

Depending on the blood perfusion characteristics of a tumour, it is a trade-off between heat-dosage (SAR) and exposure/treatment duration to get desired thermal damage including the irregular tumour boundaries while taking into account, the margin of healthy tissue. The suggested patient-specific integrated multiphysics-model based on MRI-Images may be implemented for pre-treatment planning based on the tumour blood perfusion to evaluate the thermal ablation zone dimensions clinically and thereby avoiding the damage of off-target tissues. Thus, risks involving underestimation or overestimation of thermal coagulation zones may be minimised while preserving the surrounding normal breast parenchyma.

Percutaneous cryoablation in early stage hepatocellular carcinoma: analysis of local tumor progression factors

PURPOSE

We aimed to evaluate the effectiveness and safety of percutaneous cryoablation (PC) for early or very early stage hepatocellular carcinoma (HCC) and assess the risk factors for local tumor progression (LTP) after PC.

METHODS

A total of 45 treatment-naïve patients treated with PC for early or very early stage HCCs were included in this retrospective study. The safety of PC was assessed by evaluating procedure-related complications and comparing hepatic function before and after the procedure. The effectiveness was assessed by evaluating technical success, LTP rates, and disease progression (DP) rates. Prognostic factors associated with LTP after PC were also analyzed.

RESULTS

Technical success and complete response were achieved in all patients (100%) by 1 month after PC. During a mean of 28.1±15.6 months of follow-up, the incidences of LTP and DP were 11.1% and 37.8%, respectively. The LTP-free and DP-free survival rates were 93.3% and 84.4% at 1 year and 88.9% and 62.2% at 2 years, respectively. Hepatic function was normalized within 3 months after PC. There were no major complications and only one minor complication of small hematoma. On univariate and multivariate analysis, minimal ablative margin <5 mm was the only significant risk factor associated with LTP.

CONCLUSION

PC is a safe and effective therapy for patients with early or very early stage HCC. Minimal ablative margin <5 mm was a significant prognostic factor for LTP.

Palliative Radiofrequency Ablation Accelerates the Residual Tumor Progression Through Increasing Tumor-Infiltrating MDSCs and Reducing T-Cell-Mediated Anti-Tumor Immune Responses in Animal Model

Previous studies showed that radiofrequency ablation (RFA) has a favorable treatment efficacy for hepatocellular carcinoma (HCC) or colorectal liver metastases (CRLMs). Palliative RFA (pRFA) resulting from larger HCC or multiple CRLMs further accelerated the progression of potential residual tumor, yet its mechanism was still unknown. This study investigated the influence of myeloid-derived suppressor cells (MDSCs) on T-cell immune responses and tumor recurrence after pRFA. CT26 tumor models were used. The percentage of MDSCs in peripheral blood was analyzed by flow cytometry after pRFA. The level of Th1 and Th2 cytokines were measured by ELISA through different treatments (n = 4/group). The tumor-infiltrating MDSCs, dendritic cells, and intracellular cytokines level were analyzed by IHC staining after different treatments. The functional CD8⁺ T cells were confirmed by the co-localization immunofluorescence staining. The long-term outcomes were also evaluated through CT26 and 4T1 tumor models. The results showed that tumor models treated with pRFA displayed significant increases in the percentage of MDSCs of peripheral blood and tumor infiltration. The expression level of TGF-β and IL-6 after pRFA was higher than that before pRFA by ELISA and IHC staining. After depleting MDSCs by combining with Abs, the pRFA + Abs group achieved a higher level of Th1 cytokines and greatly enhanced the percentage of tumor-infiltrating functional CD8⁺ T cells when compared with pRFA alone. The depletion of MDSCs through combination with Abs also resulted in tumor regression. In conclusion, pRFA accelerates the residual tumor progression through increasing tumor-infiltrating MDSCs and reducing T-cell-mediated anti-tumor immune responses, which could provide a potential approach for delaying tumor recurrence caused by pRFA.

Treating thyroid nodules by radiofrequency: is the delivered energy correlated with the volume reduction rate? A pilot study

OBJECTIVE

Radiofrequency ablation (RFA) was proven as effective in reducing thyroid nodules' volume. However, whether technical procedure aspects could influence the volume reduction rate (VRR) has not been clarified. This retrospective pilot study aimed to analyze the correlation of RFA power, duration, and energy with VRR.

METHODS

During the period from June to December 2018 two primary-care centers treated benign thyroid nodules of adult outpatients according to the same RFA procedure. Technical parameters to be investigated were the following: median power (P_median), effective time of treatment (T_eff), energy calculated as P_median × T_eff (E_calc), and energy delivered per mL as Kcal × 4184 × nodule's volume (E_del). Continuous variables were analyzed by the Mann-Whitney test. Data of 1-year posttreatment follow-up were collected on December 2019 and the correlation of the above parameters with VRR was analyzed by linear regression.

RESULTS

Forty-one nodules were included and their 1-year VRR was 66.6%. RFA was performed with a P_median of 55 W, T_eff 10.24 min, E_calc 31,380 J, and E_del 1473 J/mL. E_del was significantly correlated with VRR (p = 0.014) while P_median, T_eff, and E_calc not. A strong correlation of E_del with VRR was found in nodules <10 mL (p = 0.001) while no significant correlation was observed in nodules >10 mL.

CONCLUSIONS

This study showed that the energy delivered with RFA is the only technical parameter significantly correlated with the VRR of thyroid nodules.

US-guided Microwave Ablation of Low-Risk Papillary Thyroid Microcarcinoma: Longer-Term Results of a Prospective Study

BACKGROUND

Papillary thyroid microcarcinoma (PTMC) has become a main cause of the extremely high incidence of thyroid carcinoma. This study aimed to evaluate the longer-term effectiveness of ultrasound (US)-guided microwave ablation (MWA) for treatment of low-risk PTMC with a large population.

METHODS

This prospective study was approved by ethics committee of our institution. MWA was performed under US-guidance for 119 unifocal PTMC patients without clinically cervical or distant metastasis. The target ablation zone exceeded the tumor edge judged by contrast-enhanced US to avoid marginal residue and recurrence. US and thyroid function evaluation were followed at 1, 3, 6, and 12 months after treatment and every 6 to 12 months thereafter. Any adverse event associated with MWA was evaluated.

RESULTS

The follow-up duration after MWA was 37.2 ± 20.9 months (range 12-101 months). Tumor volume decreased significantly from 1.87 ± 1.03 mL immediately after MWA to 0.01 ± 0.04 mL at the final evaluation (P < 0.001), with a mean volume reduction ratio of 99.4 ± 2.2% and 107 cases (93.9%) got complete remission. A patient was detected with cervical lymph node metastasis at 26-month follow-up and underwent 1 additional MWA treatment successfully. No distant metastasis was observed. All the acquired histological pathology results confirmed the absence of residual or recurrent tumor cells after MWA. No delayed complications associated with MWA were encountered for all patients.

CONCLUSIONS

Percutaneous MWA is technically feasible for complete PTMC destruction and showed well longer-term effectiveness; thus, it seems to be an effective nonsurgical therapy to complement the current recommendation for selected low-risk PTMC patients.

Radiofrequency ablation of functioning and non-functioning thyroid nodules: a single institution 12-month survey

PURPOSE

Radiofrequency (RF) treatment has played an increasing role in the management of benign thyroid nodules in recent years. The aim of this retrospective study was to evaluate the efficacy of RF treatment on volume reduction in functioning and non-functioning thyroid nodules.

PATIENTS AND METHODS

We reviewed the medical records of patients who had thyroid nodule RF ablation at our department between August 2017 and May 2018. Patients underwent a periodical follow-up with ultrasound examinations and thyroid function tests at 1, 3, 6 and 12 months from RF. Complications were assessed using the reporting standards of Interventional societies.

RESULTS

43 patients were submitted to thyroid nodule RF ablation treatment. Patients were subdivided into two groups, those with functioning (17 patients) or non-functioning nodules. At baseline (i.e. pre-RF treatment), the two groups of patients were superimposable for gender, age, BMI, nodule volume and maximum nodule diameter. The volume reduction of all 43 nodules was 69.1 ± 17.3% (range 26.0-94.5%) with no difference between functioning and non-functioning lesions (72.9 ± 18.1% vs 66.7 ± 16.7%, p = 0.254). A total energy delivered per nodule was 16.5 ± 6.8 kJ, with no difference between functioning and non-functioning lesions (14.5 ± 7.2 kJ vs. 18.2 ± 6.3 kJ, p = 0.083, respectively). No major complications were observed.

CONCLUSIONS

Radiofrequency ablation is a clinically effective and safe outpatient treatment in patients with benign nodules. In particular, we showed that a single treatment is effective in restoring euthyroidism in patients with autonomously functioning thyroid nodules.

Clinical application of contrast-enhanced ultrasound after percutaneous renal tumor ablation

OBJECTIVE

To evaluate the effectiveness of contrast-enhanced ultrasound (CEUS) in detecting incomplete ablation and local recurrence of renal tumors after percutaneous radiofrequency ablation (RFA).

METHODS

31 patients were included for RFA treatment and underwent CEUS examination after RFA, ablation zone and contrast distribution in the ablation area were observed, CEUS images were compared with enhanced CT/MRI images to determine the residual tumors and local recurrence of renal tumors.

RESULTS

The average maximum diameters of the tumor and the ablation zone after the first RFA were 32.3 ± 14.7 mm and 35.9 ± 12.2 mm, respectively. A higher rate of complete tumor ablation was achieved if the ablation zone was larger than the primary tumor (p = 0.026). Within 1 month after RFA, contrast-enhanced CT/MRI examinations demonstrated incomplete ablation in 9 of 31 patients (29.0%), while CEUS revealed incomplete ablation in 8 of 31 patients (25.8%). The sensitivity, specificity, positive predictive value and negative predictive value of CEUS in evaluating complete ablation of renal tumors were 88.9%, 100%, 100%, 95.7%, respectively. During the follow-up period, local recurrence was reported in 2 (7.4%) of the 27 patients with complete tumor ablation. Tumor recurrence signs in the two patients were identified by both CEUS and contrast-enhanced CT/MRI. Therefore, both the sensitivity and specificity of CEUS for the evaluation of tumor recurrence were 100%.

CONCLUSION

After percutaneous RFA of renal tumors, the effectiveness of CEUS in the follow-up assessment of residual and recurrent tumors is basically the same as that of contrast-enhanced CT/MRI.

ADVANCES IN KNOWLEDGE

In this study, we evaluated the effectiveness of CEUS in the follow-up assessment of residual and recurrent tumors after RFA is basically the same as that of contrast-enhanced CT/MRI. Combining multiple follow-up methods may improve the detection rate of residual or recurrent tumors.

Long-Term Efficacy of a Single Session of RFA for Benign Thyroid Nodules: A Longitudinal 5-Year Observational Study

CONTEXT

Radiofrequency ablation (RFA) of benign thyroid nodules has been gaining consensus. However, no solid information on its long-term efficacy is available.

OBJECTIVE

To analyze the long-term results of single-session RFA.

DESIGN

Retrospective longitudinal observational study.

SETTING

Primary care center.

PATIENTS OR OTHER PARTICIPANTS

Adult outpatients who underwent a single-session RFA and posttreatment follow-up of least 3 years.

INTERVENTION

Ultrasound-guided RFA was performed after local anesthesia by "moving-shot" technique. RFA was performed with a median power of 55W and a median time of 14 minutes with an internally cooled 18-gauge electrode with an active 10-mm tip.

MAIN OUTCOME MEASURES

Objective (trend of nodule volume) and subjective (compressive and cosmetic concerns) response to RFA were evaluated. Continuous variables were analyzed by the Wilcoxon and ANOVA test and their correlations by using the Spearman test. Categorical variables were compared by Pearson χ2 test.

RESULTS

Two hundred and fifteen patients were included. An early significant reduction of nodule volume was found at 1 year, lasting up to 5 years. A 67% nodule shrinkage was observed at the end of the observation period. The best response was recorded in nodules below 10 mL (79% reduction early and 81% at 5 years). Patients' symptoms were significantly reduced.

CONCLUSIONS

This study, by demonstrating a durable shrinkage of benign thyroid nodules treated by RFA with an improvement of subjective symptoms, establishes the reliability of RFA as alternative to surgery in the management of thyroid nodules, thus representing a remarkable novelty for clinical practice.

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.

Local treatment of oligometastatic disease: current role

The presence of distant metastases has long been a predictor of poor outcome in solid cancer. However, in an oncologic situation called oligometastatic disease (OMD), multiple studies have revealed a survival benefit with aggressive treatment of these metastases. Besides surgery and radiation therapy, local thermal therapies have developed into a treatment option for OMD. Most studies concerning local therapy of OMD are available for colorectal cancer, which is therefore the focus of this article. Furthermore, this review gives a basic overview of the most popular ablation techniques for treatment of OMD.

Image-Guided Thyroid Ablation: Proposal for Standardization of Terminology and Reporting Criteria

Background: Image-guided tumor ablation is commonly performed in clinical practice. Trying to standardize terminology and data collection to enable a more reliable comparison among the different studies, in 2003, a document entitled "Image-Guided Tumor Ablation: Proposal for Standardization of Terms and Reporting Criteria" was published by the International Working Group on Image-Guided Tumor Ablation. Since then, ablations have evolved significantly, with the development of new technology and techniques and applications. This has included benign thyroid nodules, and their ablation has become increasingly accessible, not only among radiologists but also among other specialists involved in thyroid care, including endocrinologists and surgeons. This has resulted in further inhomogeneity in how data are presented and reported among different studies, resulting in a need for standardization to homogenize language and data reporting on the topic. Summary: In February 2018 in Milano, Italy, a meeting involving specialists concerned with minimally invasive treatments of thyroid lesions was organized, and the Italian Working Group on Minimally Invasive Treatments of the Thyroid was founded with the aim of establishing a collaborative network among all clinicians working in this field. The first work of this group is to present a proposal for standardization of terminology and reporting criteria on image-guided ablations to treat benign thyroid nodules. Conclusion: This proposal was drafted with the goal of providing guidance for standardized reporting of results in studies regarding image-guided thyroid ablations. We encourage adoption of this terminology worldwide, anticipating that this will facilitate improved communication and understanding within the field and stimulate further discussion on the topic over the next years.

Combination of radiofrequency ablation and transcatheter arterial chemoembolization to treat hepatocellular carcinoma: measurement of distance from needle tip to nodule for assessment of local tumor progression

OBJECTIVE

This study was performed to determine the relationship between the minimum distance from the radiofrequency ablation (RFA) needle tip to the tumor and local tumor progression (LTP) of hepatocellular carcinoma (HCC) nodules and identify prognostic factors for LTP.

METHODS

We reviewed 197 patients (197 nodules) who underwent RFA after transcatheter arterial chemoembolization for HCC from January 2010 to January 2015. Three-dimensional registration of images was used to calculate the minimum distance from the tip to the tumor. We then divided the minimum distance into two groups: <2 and ≥2 mm. Contrast-enhanced computed tomography was performed after treatment. The LTP rate was calculated 1 and 3 years after RFA. We performed multivariate analysis to identify independent prognostic factors for LTP.

RESULTS

The cumulative 1-year LTP rates in the <2- and ≥2-mm groups were 82.7% and 4.3%, respectively, and the cumulative 3-year LTP rates in the two groups were 94.8% and 10.8%, respectively. The minimum distance from the needle tip to the tumor was an independent prognostic factor for LTP.

CONCLUSIONS

A minimum distance of 2 mm from the needle tip to the tumor should be completely ablated along with the tumor.

Effects of thermal ablation on Treg/Th17 in hepatocellular carcinoma of mice

The study was aimed to explore the possible function of thermal ablation treatment on T helper 17 (Th17) cells and regulatory T (Treg) cells in transplantation of hepatocellular carcinoma in mice. In total, 60 male C57BL/6 mice were divided into control group, model group, and treat group. Flow cytometry was used to detect the frequency of Th17 and Treg cells in peripheral blood. The levels of interleukin (IL)-17, IL-23, IL-10, and transforming growth factor beta (TGF-β) in serum were detected by enzyme-linked immunosorbent assay (ELISA).The levels of IL-17, RORγt, Foxp3, and TGF-β mRNA in tumor tissues were detected by real-time fluorescence quantitative PCR (qRT-PCR). Compared with the model group, tumor size was significantly decreased after thermal ablation treatment. After treatment, the frequency of Th17 cells in peripheral blood was significantly decreased, while the frequency of Treg cells was profoundly increased ( P < 0.05). The levels of IL-17 and IL-23 were significantly downregulated, while IL-10 and TGF-β levels were upregulated ( P < 0.05). IL-17 and RORγt mRNA levels in tumor tissues were significantly decreased ( P < 0.05), and Foxp3 and TGF-β mRNA levels were significantly increased ( P < 0.05). Thermal ablation treatment plays a positive role in the treatment of hepatoma in mice through affecting the imbalance of Th17/Treg cells.

Complications of Percutaneous Bone Tumor Cryoablation: A 10-year Experience

Background Percutaneous cryoablation has been shown to be effective in the management of painful bone tumors. However, knowledge of the complication rate and risk factors for complication is currently lacking. Purpose To report the complication rate and associated risk factors for bone tumor cryoablation. Materials and Methods This retrospective study reviewed complications in 239 consecutive patients (131 men and 108 women; median age, 64 years; age range, 6-86 years) who underwent cryoablation of 320 primary or metastatic bone tumors between January 2008 and November 2017. Common Terminology Criteria for Adverse Events was used to categorize complications as major (grade 3-4) or minor (grade 1-2). Multivariable analysis was performed for variables with P values less than .20, including age, tumor location, adjacent critical structures, number of cryoprobes, and Eastern Cooperative Oncology Group performance status (ECOG-PS). Results Among the 320 tumors, the total complication rate was 9.1% (29 of 320; 95% confidence interval [CI]: 6%, 12.2%). The major complication rate was 2.5% (eight of 320; 95% CI: 0.8%, 4.2%), with secondary fracture the most frequent complication (1.2% [four of 320]; mean delay, 71 days); cryoablation site infection, tumor seeding, bleeding, and severe hypotension were each observed in 0.3% (one of 320) of procedures. Minor complications included postprocedural pain (2.2% [seven of 320]), peripheral neuropathy (0.9% [three of 320]), and temporary paresthesia (0.9% [three of 320]). For all complications, associated risk factors included ECOG-PS greater than 2 (odds ratio [OR], 3.1 [95% CI: 3, 7.6]; P = .01), long-bone cryoablation (OR, 17.8 [95% CI: 2.3, 136.3]; P = .01), and use of more than three cryoprobes (OR, 2.5 [95% CI: 1.0, 6.0]; P = .04); for major complications, associated risk factors included age greater than 70 years (OR, 7.1 [95% CI: 1.6, 31.7]; P = .01) and use of more than three cryoprobes (OR, 23.6 [95% CI: 2.8, 199.0]; P = .01). Conclusion Bone tumor cryoablation is safe, with a 2.5% rate of major complications, most commonly secondary fracture (1.2%). Major complications are associated with age greater than 70 years and use of more than three cryoprobes. © RSNA, 2019 Online supplemental material is available for this article. See also the editorial by Jennings in this issue.

Different effects of oxycodone and remifentanil in patients undergoing ultrasound-guided percutaneous radiofrequency ablation of hepatic cancer: a randomized trial

Background

Percutaneous radiofrequency ablation (RFA) is a recently introduced alternative technique for the treatment of hepatic cancer. Anesthesia is required for RFA of hepatic cancer to achieve patient comfort and immobilization during this painful procedure. The purpose of this study was to investigate the analgesic efficacy and evaluate the safety of a single intravenous injection of oxycodone hydrochloride for this procedure.

Patients and methods

A total of 120 American Society of Anesthesiologists class I–II grade patients for elective ultrasound-guided percutaneous RFA were enrolled in this randomized controlled trial. Patients were randomized (1:1) to receive either a single intravenous injection of oxycodone (group O) or continuous infusion of remifentanil (group R). Both groups received the continuous infusion of dexmedetomidine for sedation. Visual analog scale (VAS), rescue analgesic, and side effects were checked during the periprocedural period. In addition, patient and oncologist satisfaction on a scale of 1–5 were determined.

Results

VAS score in group O was significantly lower than in group R at 1, 2, and 3 hours after RFA, and patients in group O required analgesics significantly later and less doses in the first 24 hours after RFA. The occurrence of unwanted body movements was significantly lower in group O. We found no complications including allergic reaction, excessive sedation, and chest wall rigidity in all patients. The patient satisfaction score was significantly higher in group O than that in group R.

Conclusion

Ultrasound-guided percutaneous RFA for hepatic cancer can be completed both with continuous infusion of remifentanil or a single intravenous injection of oxycodone. However, oxycodone hydrochloride provides better patient experience with higher satisfactory score and less unwanted body movements, relieves post-procedural pain better, and is not associated with an increase in adverse effects.

Nanomaterials as photothermal therapeutic agents

Curing cancer has been one of the greatest conundrums in the modern medical field. To reduce side-effects associated with the traditional cancer therapy such as radiotherapy and chemotherapy, photothermal therapy (PTT) has been recognized as one of the most promising treatments for cancer over recent years. PTT relies on ablation agents such as nanomaterials with a photothermal effect, for converting light into heat. In this way, elevated temperature could kill cancer cells while avoiding significant side effects on normal cells. This theory works because normal cells have a higher heat tolerance than cancer cells. Thus, nanomaterials with photothermal effects have attracted enormous attention due to their selectivity and non-invasive attributes. This review article summarizes the current status of employing nanomaterials with photothermal effects for anti-cancer treatment. Mechanisms of the photothermal effect and various factors affecting photothermal performance will be discussed. Efficient and selective PTT is believed to play an increasingly prominent role in cancer treatment. Moreover, merging PTT with other methods of cancer therapies is also discussed as a future trend.

Percutaneous Irreversible Electroporation (IRE) of Hepatic Malignancy: A Bi-institutional Analysis of Safety and Outcomes

Aim

Irreversible electroporation (IRE) is a non-thermal ablative option in patients unsuitable for standard thermal ablation, due to its potential to preserve collagenous structures (vessels and ducts) and a reduced susceptibility to heat sink effects. In this series from two large tertiary referral hepatobiliary centres, we aim to assess the safety/outcomes of hepatic IRE.

Materials and Methods

Bi-institutional retrospective, longitudinal follow-up series of IRE for primary hepatic malignancy; [hepatocellular carcinoma (n = 20), cholangiocarcinoma (n = 3)] and secondary metastatic disease; colorectal (n = 28), neuroendocrine (n = 1), pancreatic (n = 1), breast (n = 1), gastrointestinal stromal tumour (GIST, n = 1) and malignant thymoma (n = 1). Outcome measures included procedural safety/effectiveness, time to progression and time to death.

Results

Between 2013 and 2017, 52 patients underwent percutaneous IRE of 59 liver tumours in 53 sessions. All tumours were deemed unsuitable for thermal ablation. Cases were performed using ultrasound (US) or computed tomography (CT) guidance. A complete ablation was achieved in n = 44, (75%) of cases with an overall complication rate of 17% (n = 9). Of the complete ablation group, median time to progression was 8 months. At 12 months, 44% were progression-free (95% CI 30–66%). The data suggest that larger lesion size (> 2 cm) is associated with shorter time to progression and there is highly significant difference with faster time to progression in mCRC compared with HCC. Median survival time was 38 months.

Conclusion

This bi-institutional review is the largest UK series of IRE and suggests this ablative technology can be a useful tool, but appears to mainly induce local tumour control rather than cure with HCC having better outcomes than mCRC.

Intravoxel Incoherent Motion Diffusion-weighted MR Imaging for Early Evaluation of the Effect of Radiofrequency Ablation in Rabbit Liver VX2 Tumors

RATIONALE AND OBJECTIVES

This study aims to investigate the value of intravoxel incoherent motion (IVIM)-derived parameters for early evaluation of the efficiency of radiofrequency ablation (RFA) treatment for rabbit liver VX2 tumor.

MATERIALS AND METHODS

Eighteen rabbit liver VX2 tumor models were constructed, and computed tomography-guided RFA was performed. One day before and 7 days after RFA, 18 models underwent magnetic resonance imaging, including contrast-enhanced imaging and IVIM diffusion-weighted imaging with 16 b-factors (0-1000 s/mm²). Post-RFA liver tumors were segmented into viable tumor, inflammatory reaction, and ablation necrotic regions according to gross and histopathologic examinations. Parameters derived from IVIM were calculated. One-way analysis of variance and least significant difference test were used for comparisons among the three regions. The diagnostic performance of parameters was evaluated using receiver operating characteristic (ROC) analysis.

RESULTS

ADC_total, D, and f values were significantly lower in viable tumor than in inflammatory reaction regions (all P < .05), but D* showed no significant difference between the two regions. ADC_total values of viable tumor regions were significantly lower than that of ablation necrotic regions (P = .007), but D* values of necrotic regions were significantly lower than that of viable tumor regions (P = .045). In ROC analysis, ADC showed the highest area under the ROC curve for differentiating inflammatory reaction from viable tumor region.

CONCLUSIONS

ADC_total, D, and f were valuable discriminating markers for differentiation between regions of viable tumor and inflammatory reaction in post-RFA tumor, especially ADC_total outperformed the other two parameters with higher diagnostic performance.

Understanding the nuances of microwave ablation for more accurate post-treatment assessment

Microwave ablation (MWA) is a relatively new thermal modality for minimally invasive procedures compared with radiofrequency ablation. Although MWA and radiofrequency ablation are thermal modalities, their underlying physics and principles greatly differ. Consequently, it is imperative that clinicians be aware of how these differences impact realized ablation volumes to consistently ensure technical success and better patient outcomes. This paper will review the nuances specific to MWA technology (i.e., tissue properties, perfusion/heat sink effect, ablation assessment, imaging accuracy and tissue contraction) that are often overlooked based on familiarity with conventional thermal modalities to guide more accurate assessment of post-treatment MWA volumes.

A DNA nanorobot functions as a cancer therapeutic in response to a molecular trigger in vivo

Nanoscale robots have potential as intelligent drug delivery systems that respond to molecular triggers. Using DNA origami we constructed an autonomous DNA robot programmed to transport payloads and present them specifically in tumors. Our nanorobot is functionalized on the outside with a DNA aptamer that binds nucleolin, a protein specifically expressed on tumor-associated endothelial cells, and the blood coagulation protease thrombin within its inner cavity. The nucleolin-targeting aptamer serves both as a targeting domain and as a molecular trigger for the mechanical opening of the DNA nanorobot. The thrombin inside is thus exposed and activates coagulation at the tumor site. Using tumor-bearing mouse models, we demonstrate that intravenously injected DNA nanorobots deliver thrombin specifically to tumor-associated blood vessels and induce intravascular thrombosis, resulting in tumor necrosis and inhibition of tumor growth. The nanorobot proved safe and immunologically inert in mice and Bama miniature pigs. Our data show that DNA nanorobots represent a promising strategy for precise drug delivery in cancer therapy.

Endogenous Catalytic Generation of O2 Bubbles for In Situ Ultrasound-Guided High Intensity Focused Ultrasound Ablation

High intensity focused ultrasound (HIFU) surgery generally suffers from poor precision and low efficiency in clinical application, especially for cancer therapy. Herein, a multiscale hybrid catalytic nanoreactor (catalase@MONs, abbreviated as C@M) has been developed as a tumor-sensitive contrast and synergistic agent (C&SA) for ultrasound-guided HIFU cancer surgery, by integrating dendritic-structured mesoporous organosilica nanoparticles (MONs) and catalase immobilized in the large open pore channels of MONs. Such a hybrid nanoreactor exhibited sensitive catalytic activity toward H₂O₂, facilitating the continuous O₂ gas generation in a relatively mild manner even if incubated with 10 μM H₂O₂, which finally led to enhanced ablation in the tissue-mimicking PAA gel model after HIFU exposure mainly resulting from intensified cavitation effect. The C@M nanoparticles could be accumulated within the H₂O₂-enriched tumor region through enhanced permeability and retention effect, enabling durable contrast enhancement of ultrasound imaging, and highly efficient tumor ablation under relatively low power of HIFU exposure in vivo. Very different from the traditional perfluorocarbon-based C&SA, such an on-demand catalytic nanoreactor could realize the accurate positioning of tumor without HIFU prestimulation and efficient HIFU ablation with a much safer power output, which is highly desired in clinical HIFU application.

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.

Local tumour progression after percutaneous ablation of colorectal liver metastases according to RAS mutation status

BACKGROUND

Percutaneous ablation is a common treatment for colorectal liver metastasis (CLM). However, the effect of rat sarcoma viral oncogene homologue (RAS) mutation on outcome after ablation of CLMs is unclear.

METHODS

Patients who underwent image-guided percutaneous ablation of CLMs from 2004 to 2015 and had known RAS mutation status were analysed. Patients were evaluated for local tumour progression as observed on imaging of CLMs treated with ablation. Multivariable Cox regression analysis was performed to determine factors associated with local tumour progression-free survival.

RESULTS

The study included 92 patients who underwent ablation of 137 CLMs. Thirty-six patients (39 per cent) had mutant RAS. Rates of local tumour progression were 14 per cent (8 of 56) for patients with wild-type RAS and 39 per cent (14 of 36) for patients with mutant RAS (P = 0·007). The actuarial 3-year local tumour progression-free survival rate after percutaneous ablation was worse in patients with mutant RAS than in those with wild-type RAS (35 versus 71 per cent respectively; P = 0·001). In multivariable analysis, negative predictors of local tumour progression-free survival were a minimum ablation margin of less than 5 mm (hazard ratio (HR) 2·48, 95 per cent c.i. 1·31 to 4·72; P = 0·006) and mutant RAS (HR 3·01, 1·60 to 5·77; P = 0·001).

CONCLUSION

Mutant RAS is associated with an earlier and higher rate of local tumour progression in patients undergoing ablation of CLMs.

Embryonic origin of primary colon cancer predicts survival in patients undergoing ablation for colorectal liver metastases

BACKGROUND

In patients with primary colorectal cancer (CRC) or unresectable metastatic CRC, midgut embryonic origin is associated with worse prognosis. The impact of embryonic origin on survival after ablation of colorectal liver metastases (CLM) is unclear.

METHODS

We identified 74 patients with CLM who underwent percutaneous ablation during 2004-2015. Survival and recurrence after ablation of CLM from midgut origin (n = 18) and hindgut origin (n = 56) were analyzed. Prognostic value of embryonic origin was evaluated.

RESULTS

Recurrence-free survival (RFS) and overall survival (OS) after percutaneous ablation were worse in patients from midgut origin (3-year RFS: 5.6% vs. 24%, P = 0.004; 3-year OS: 25% vs. 70%, P 0.001). In multivariable analysis, factors associated with worse OS were midgut origin (hazard ratio [HR] 4.87, 95% CI 2.14-10.9, P 0.001), multiple CLM (HR 2.35, 95% CI 1.02-5.39, P = 0.044), and RAS mutation (HR 2.78, 95% CI 1.25-6.36, P = 0.013). At a median follow-up of 25 months, 56 patients (76%) had developed recurrence, 16 (89%) with midgut origin and 40 (71%) with hindgut origin (P = 0.133). Recurrent disease was treated with local therapy in 20 patients (36%), 2 (13%) with midgut origin and 18 (45%) with hindgut origin (P = 0.022).

CONCLUSION

Compared to CLM from hindgut origin tumors, CLM from midgut origin tumors were associated with worse survival after ablation, which was partly attributable to the fact that patients with hindgut origin were more frequently candidates for local therapy at recurrence.

Follow-up after focal therapy in renal masses: an international multidisciplinary Delphi consensus project

PURPOSE

To establish consensus on follow-up (FU) after focal therapy (FT) in renal masses. To formulate recommendations to aid in clinical practice and research.

METHODS

Key topics and questions for consensus were identified from a systematic literature research. A Web-based questionnaire was distributed among participants selected based on their contribution to the literature and/or known expertise. Three rounds according to the Delphi method were performed online. Final discussion was conducted during the "8th International Symposium on Focal Therapy and Imaging in Prostate and Kidney Cancer" among an international multidisciplinary expert panel.

RESULTS

Sixty-two participants completed all three rounds of the online questionnaire. The panel recommended a minimum follow-up of 5 years, preferably extended to 10 years. The first FU was recommended at 3 months, with at least two imaging studies in the first year. Imaging was recommended biannually during the second year and annually thereafter. The panel recommended FU by means of CT scan with slice thickness ≤3 mm (at least three phases with excretory phase if suspicion of collecting system involvement) or mpMRI. Annual checkup for pulmonary metastasis by CT thorax was advised. Outside study protocols, biopsy during follow-up should only be performed in case of suspicion of residual/persistent disease or radiological recurrence.

CONCLUSIONS

The consensus led to clear FU recommendations after FT of renal masses supported by a multidisciplinary expert panel. In spite of the low level of evidence, these recommendations can guide clinicians and create uniformity in the follow-up practice and for clinical research purposes.

Pyogenic liver abscess: current status and predictive factors for recurrence and mortality of first episodes

BACKGROUND

In times of modern surgery, transplantation and percutaneous techniques, pyogenic liver abscess (PLA) has essentially become a problem of biliary or iatrogenic origin. In the current scenario, diagnostic approach, clinical behavior and therapeutic outcomes have not been profoundly studied. This study analyzes the clinical and microbiological features, diagnostic methods, therapeutic management and predictive factors for recurrence and mortality of first episodes of PLA.

METHODS

A retrospective single-center study was conducted including 142 patients admitted to the Hospital Italiano de Buenos Aires, between 2005 and 2015 with first episodes of PLA.

RESULTS

Prevailing identifiable causes were biliary diseases (47.9%) followed by non-biliary percutaneous procedures (NBIPLA, 15.5%). Seventeen patients (12%) were liver recipients. Eleven patients (7.8%) died and 18 patients (13.7%) had recurrence in the first year of follow up. The isolation of multiresistant organisms (p = 0.041) and a history of cholangitis (p < 0.001) were independent risk factors for recurrence. Mortality was associated with serum bilirubin >5 mg/dL (p = 0.022) and bilateral involvement (p = 0.014) in the multivariate analysis.

CONCLUSION

NBPLA and PLA after transplantation may be increasing among the population of PLA in referral centers. History of cholangitis is a strong predictor for recurrence. Mortality is associated to hiperbilirrubinemia and anatomical distribution of the lesions.

Efficacy and Safety of Ultrasound-Guided Radiofrequency Ablation for Treating Low-Risk Papillary Thyroid Microcarcinoma: A Prospective Study

BACKGROUND

Papillary thyroid microcarcinoma (PTMC) has a high incidence and a good prognosis. Surgical operation for all PTMC might be an overtreatment. The objective of this study was to evaluate the efficacy and safety of ultrasound (US)-guided radiofrequency ablation (RFA) for treating low-risk PTMC.

METHODS

Ninety-eight PTMC in 92 patients were included in this study. US and contrast-enhanced ultrasound (CEUS) examinations were performed before ablation. RFA was performed using the moving-shot technique. The ablation area exceeded the tumor edge to prevent marginal residue and recurrence. Patients were followed at 1, 3, 6, and 12 months and every six months thereafter. US and CEUS examinations were used to evaluate the ablation area. At three months after ablation, US-guided core-needle biopsy (CNB) was performed in the center, at the edge of the ablation area, and in the surrounding thyroid parenchyma to exclude recurrence.

RESULTS

The mean tumor volume was 118.8 ± 106.9 mm³. The mean volume reduction ratio (VRR) was 0.47 ± 0.27, 0.19 ± 0.16, 0.08 ± 0.11, 0.04 ± 0.10, and 0 at 1, 3, 6, 12, and 18 months after RFA, respectively. Significant differences in the VRR were found between every two follow-up times before six months (p < 0.01), and no significant differences in the VRR were found between six months and after 12 months (p = 0.42). Of all the nodules, 10 (41.7%) resolved in six months, and 23 (95.8%) resolved in 12 months. No residual or recurrent tumor tissue was detected in RFA area or in residual thyroid tissue during follow-up. No suspicious metastatic lymph nodes were detected. The histological pathology results of US-guided CNB confirmed the absence of residual or recurrent tumor. No major complications were encountered.

CONCLUSIONS

RFA can effectively eliminate low-risk PTMC with a very small complication rate. RFA may be an alternative strategy for the treatment of PTMC.

Image-guided thermal ablation of benign thyroid nodules

Benign thyroid nodules are a common disease in the general population. Most often, they are completely asymptomatic and discovered occasionally during routine ultrasound examinations, and do not require any treatment. When thyroid nodules become symptomatic, surgical excision is still considered standard treatment. In the last few years, several experiences in the treatment of benign thyroid nodules through image-guided percutaneous thermal ablation have been reported with encouraging results, so that currently, these treatments are often proposed as first-choice options for patients with symptomatic benign thyroid nodules. In this paper, we discuss the present literature on the topic, focusing on different techniques available for image-guided percutaneous ablation, particularly radiofrequency (RFA), laser (LA), microwave (MWA), and high-intensity-focus ultrasound (HIFU). Little evidence about the efficacy of MWA and HIFU is now available. According to the literature, good results have been obtained with RFA and LA. Regarding RFA, volume reduction after ablative treatment has been found to range from 47 to 84 % at 3-6 months, and from 62 to 93 % at 1 year; LA also seems to be effective in achieving shrinkage of thyroid nodules, with volume reduction from 37 to 81 % at 3-6 months, and from 13 to 82 % at 1-year follow-up. Moreover, applications of advanced image-guidance modality, such as contrast-enhanced ultrasound and virtual navigation with fusion imaging, are discussed.

Minimal vascular flows cause strong heat sink effects in hepatic radiofrequency ablation ex vivo

BACKGROUND

The present paper aims to assess the lower threshold of vascular flow rate on the heat sink effect in bipolar radiofrequency ablation (RFA) ex vivo.

METHODS

Glass tubes (vessels) of 3.4 mm inner diameter were introduced in parallel to bipolar RFA applicators into porcine liver ex vivo. Vessels were perfused with flow rates of 0 to 1,500 ml/min. RFA (30 W power, 15 kJ energy input) was carried out at room temperature and 37°C. Heat sink effects were assessed in RFA cross sections by the decrease in ablation radius, area and by a high-resolution sector planimetry.

RESULTS

Flow rates of 1 ml/min already caused a significant cooling effect (P ≤ 0.001). The heat sink effect reached a maximum at 10 ml/min (18.4 mm/s) and remained stable for flow rates up to 1,500 ml/min.

CONCLUSIONS

Minimal vascular flows of ≥1 ml/min cause a significant heat sink effect in hepatic RFA ex vivo. A lower limit for volumetric flow rate was not found. The maximum of the heat sink effect was reached at a flow rate of 10 ml/min and remained stable for flow rates up to 1,500 ml/min. Hepatic inflow occlusion should be considered in RFA close to hepatic vessels.

Radiofrequency ablation vs. hepatic resection for resectable colorectal liver metastases

The treatments of resectable colorectal liver metastases (CRLM) are controversial. This study aimed to evaluate the relative efficacy and safety of hepatic resection (HR) and radiofrequency ablation (RFA) for treating resectable CRLM. Between January 2004 and May 2010, the enrolled patients were given hepatic resection (HR group; n=32) or percutaneous RFA (RFA group; n=21) as a first-line treatment for CRLM. All the tumors had a maximum diameter of 3.5 cm and all patients had five or less tumors. The patient background, tumor characteristics, cumulative survival rate and recurrence-free survival rate were assessed in both groups. There were significantly more patients with comorbidities in the RFA group than those in the HR group (17 in RFA group vs. 10 in HR group; P<0.000). The mean maximum tumor diameter in the HR group and RFA group was 2.25±0.68 and 1.89±0.62 cm (P=0.054), and the mean number of tumors was 2.28±1.05 and 2.38±1.12 (P=0.744), respectively. The 1-, 3- and 5-year cumulative survival rates in the HR group were 87.5%, 53.1% and 31.3%, respectively, and those in the RFA group were 85.7%, 38.1% and 14.2%, respectively with the differences being not significant between the two groups (P=0.062). The 1-, 3- and 5-year recurrence-free survival rates in the HR group were 90.6%, 56.3% and 28.1%, respectively, and those in the RFA group were 76.1%, 23.8% and 4.8%, respectively, with the differences being significant between the two groups (P=0.036). In conclusion, as HR has greater efficacy than RFA in the treatment of resectable CRLM, we recommend it as the first option for this malignancy.

Titanium wire implants with nanotube arrays: A study model for localized cancer treatment

Adverse complications associated with systemic administration of anti-cancer drugs are a major problem in cancer therapy in current clinical practice. To increase effectiveness and reduce side effects, localized drug delivery to tumour sites requiring therapy is essential. Direct delivery of potent anti-cancer drugs locally to the cancer site based on nanotechnology has been recognised as a promising alternative approach. Previously, we reported the design and fabrication of nano-engineered 3D titanium wire based implants with titania (TiO2) nanotube arrays (Ti-TNTs) for applications such as bone integration by using in-vitro culture systems. The aim of present study is to demonstrate the feasibility of using such Ti-TNTs loaded with anti-cancer agent for localized cancer therapy using pre-clinical cancer models and to test local drug delivery efficiency and anti-tumour efficacy within the tumour environment. TNF-related apoptosis-inducing ligand (TRAIL) which has proven anti-cancer properties was selected as the model drug for therapeutic delivery by Ti-TNTs. Our in-vitro 2D and 3D cell culture studies demonstrated a significant decrease in breast cancer cell viability upon incubation with TRAIL loaded Ti-TNT implants (TRAIL-TNTs). Subcutaneous tumour xenografts were established to test TRAIL-TNTs implant performance in the tumour environment by monitoring the changes in tumour burden over a selected time course. TRAIL-TNTs showed a significant regression in tumour burden within the first three days of implant insertion at the tumour site. Based on current experimental findings these Ti-TNTs wire implants have shown promising capacity to load and deliver anti-cancer agents maintaining their efficacy for cancer treatment.