Percutaneous tumor ablation tools: microwave, radiofrequency, or cryoablation--what should you use and why?

Microwave Ablation of the Pig Growth Plate: Proof of Concept for Minimally Invasive Epiphysiodesis

BACKGROUND

Different surgical methods for epiphysiodesis of limb length discrepancy (LLD) have been described. Although these methods are variably effective, they are associated with morbidity (pain and limp) and potential complications. Microwave ablation is a less-invasive opportunity to halt growth by selectively destroying the growth plate via thermal energy to treat LLD in children.

QUESTIONS/PURPOSES

In this proof-of-concept study using an in vivo pig model, we asked: (1) What is the durability of response 2 to 4 months after microwave ablation of the tibial growth plate as measured by length and angulation of the tibia via a CT scan? (2) Was articular cartilage maintained as measured by standard histologic staining for articular cartilage viability?

METHODS

To develop an in vivo protocol for microwave ablation, we placed microwave antennas adjacent to the proximal tibia growth plate in the cadaveric hindlimbs of 18 3-month-old pigs. To determine the suitable time, we varied ablation from 90 to 270 seconds at 65-W power settings. After sectioning the tibia, we visually assessed for discoloration (implying growth plate destruction) that included the central growth plate but did not encroach into the epiphysis in a manner that could disrupt the articular surface. Using this information, we then performed microwave ablation on three live female pigs (3.5 to 4 months old) to evaluate physiologic changes and durability of response. A postprocedure MRI was performed to ensure the intervention led to spatial growth plate alterations similar to that seen in cadavers. This was followed by serial CT, which was used to assess the potential effect on local bone and growth until the animals were euthanized 2 to 4 months after the procedure. We analyzed LLD, angular deformity, and bony deformity using CT scans of both tibias. The visibility of articular cartilage was compared with that of the contralateral tibia via standard histologic staining, and growth rates of the proximal tibial growth plate were compared via fluorochrome labeling.

RESULTS

Eighteen cadaveric specimens showed ablation zones across the growth plate without visual damage to the articular surface. The three live pigs did not exhibit changes in gait or require notable pain medication after the procedure. Each animal demonstrated growth plate destruction, expected limb shortening (0.8, 1.2, and 1.5 cm), and bony cavitation around the growth plate. Slight valgus bone angulation (4º, 5º, and 12º) compared with the control tibia was noted. No qualitatively observable articular cartilage damage was encountered from the histologic comparison with the contralateral tibia for articular cartilage thickness and cellular morphology.

CONCLUSION

A microwave antenna placed into a pig's proximal tibia growth plate can slow the growth of the tibia without apparent pain and alteration of gait and function.

CLINICAL RELEVANCE

Further investigation and refinement of our animal model is ongoing and includes shorter ablation times and comparison of dynamic ablation (moving the antennae during the ablation) as well as static ablation of the tibia from a medial and lateral portal. These refinements and planned comparison with standard mechanical growth arrest in our pig model may lead to a similar approach to ablate growth plates in children with LLD.

Safety and Effectiveness of Track Cauterization for Lung Cryoablation

PURPOSE

To evaluate the safety and effectiveness of track cauterization for lung cryoablation through comparison of postprocedural adverse event (AE) rates.

MATERIALS AND METHODS

Fifty-nine patients who underwent 164 percutaneous lung cryoablation procedures between 2013 and 2018 were included in this retrospective study. The study cohort was subdivided by whether track cauterization was conducted or not at the end of the procedure. The study cohort was also subdivided by the number of probes (1-2 probes vs 3-4 probes). Postablation AE rates were assessed by immediate and delayed (at 1 month or later) AEs, pneumothorax, hemothorax, pleural effusion, and whether intervention was required. Univariate and multivariate logistic regression analyses were used to compare differences in AE rates.

RESULTS

Patients who underwent procedures with track cautery were 2.6 times less likely to exhibit pleural effusion (P = .017). Patients who underwent procedures conducted with a higher number of probes were 3.8 times more likely to receive interventions (P < .001), 1.6 times more likely to experience pneumothorax (P = .037), and 2.1 times more likely to experience pleural effusion (P = .003). History of lung surgery, increased number of probes, size of the probe, and absence of track cautery were noted to be significant predictors of AEs and need for interventions (all P < .05).

CONCLUSIONS

Track cauterization in lung cryoablation was proven to reduce pleural effusion, but no difference in pneumothorax or delayed AEs was noted. The use of fewer probes was associated with a lower rate of AEs.

Lenvatinib radiofrequency ablation sequential therapy offers survival benefits for patients with unresectable hepatocellular carcinoma at intermediate stage and the liver reserve of Child-Pugh A category: A multicenter study

AIM

This study aims to evaluate the efficacy and safety of lenvatinib radiofrequency ablation (RFA) sequential therapy for certain hepatocellular carcinoma (HCC) patients.

METHODS

One hundred and nineteen patients with unresectable HCC in the intermediate stage with Child-Pugh A were retrospectively recruited in a multicenter setting. Those in the lenvatinib RFA sequential therapy group received lenvatinib initially, followed by RFA and the retreatment with lenvatinib. The study compared overall survival (OS), progression-free survival (PFS), tumor response, and adverse events (AEs) between patients undergoing sequential therapy and lenvatinib monotherapy.

RESULTS

After propensity score matching, 25 patients on sequential therapy and 50 on monotherapy were evaluated. Independent factors influencing OS were identified as sequential therapy, modified albumin-bilirubin (mALBI) grade, and relative dose intensity (%) with hazard ratios (HRs) of 0.381 (95% confidence interval [CI], 0.186-0.782), 2.220 (95% CI, 1.410-3.493), and 0.982 (95% CI, 0.966-0.999), respectively. Stratified analysis based on mALBI grades confirmed the independent influence of treatment strategy across all mALBI grades for OS (HR, 0.376; 95% CI, 0.176-0.804). Furthermore, sequential therapy was identified as an independent factor of PFS (HR, 0.382; 95% CI, 0.215-0.678). Sequential therapy significantly outperformed monotherapy on survival benefits (OS: 38.27 vs. 18.96 months for sequential therapy and monotherapy, respectively, p = 0.004; PFS: 13.80 vs. 5.32 months for sequential therapy and monotherapy, respectively, p < 0.001). Sequential therapy was significantly associated with complete response by modified Response Evaluation Criteria in Solid Tumors (odds ratio, 63.089). Ten of 119 patients experienced grade 3 AEs, with no AE beyond grade 3 observed.

CONCLUSION

Lenvatinib RFA sequential therapy might offer favorable tolerability and potential prognostic improvement compared to lenvatinib monotherapy.

Dynamic Changes in the Immune Microenvironment in Tumor-Draining Lymph Nodes of a Lewis Lung Cancer Mouse Model After Microwave Ablation

Purpose

Microwave ablation (MWA) is a minimally invasive technique for treating lung cancer. It can induce immune response; however, its effect on the immune microenvironment in tumor-draining lymph nodes (TdLN) is not well understood. This study aims to identify changes in the immune microenvironment in TdLN following MWA in a Lewis lung cancer (LLC) mouse model.

Methods

LLC mouse model was established and followed by MWA. TdLN were collected at various time points, including pre-MWA and days 1, 2, 4, and 8 post-MWA. Flow cytometry was used to determine the frequencies of CD4+ T cells, CD8+ T cells, regulatory T (Treg) cells, natural killer (NK) cells, dendritic cells (DCs) and other immune cells in the TdLN. Certain cytokines were also detected.

Results

Compared with pre-MWA, the frequency of CD4+ T cells significantly increased from day 1 to day 8 post-MWA. The frequency of CD8+ T cells decreased significantly on days 2 and 4, but no significant changes occurred on days 1 and 8. Significant decreases in the frequencies of Treg cells and Klrg1+ Treg cells were observed from day 1 to day 4. On days 4 and 8, there was a significant increase in the frequency of NK cells. The frequency of resident cDC2 significantly increased on day 4, whereas CD11b+ migratory cDCs increased on day 1. Additionally, on day 4, a notable rise was observed in the frequency of NK cells secreting IFN-γ, while on day 8, there was a significant increase in the frequency of CD8+ T cells secreting both IFN-γ and TNF-α.

Conclusion

MWA of lung cancer can alter the immune microenvironment in the TdLN, triggering immune responses. These changes are particularly evident and intricate within the initial 4 days post-MWA. Treatment combined with MWA within a certain period may significantly enhance anti-tumor immunity.

Interventional oncology in children: Where are we now?

Paediatric Interventional Oncology (IO) lags behind adult IO due to a scarcity of specific outcome data. The suboptimal way to evolve this field is relying heavily on adult experiences. The distinct tumour types prevalent in children, such as extracranial germ cell tumours, sarcomas, and neuroblastoma, differ strongly from those found in adults, presenting a completely different biological behaviour. Compounding this challenge, paediatric interventional radiology often employs adapted or off-label techniques, potentially compromising optimal outcomes. This review outlines the present indications for interventional radiology in paediatric cancer, from biopsy to supportive care, including complication management. It emphasises the role of locoregional approaches, and explores the status of common paediatric oncological diseases, highlighting areas where IO has made progress identifying potential opportunities for future advancements in this evolving field.

Changes in liver and kidney function, red blood cell count and hemoglobin levels 1 day after ultrasound-guided percutaneous microwave ablation for uterine fibroids

OBJECTIVE

To investigate the changes in liver and kidney function, red blood cell (RBC) count and hemoglobin (HGB) levels in patients undergoing ultrasound-guided percutaneous microwave ablation (UPMWA) for uterine fibroids on postoperative day 1.

METHODS

The changes in liver and kidney function, RBC count and HGB levels in 181 patients who underwent selective UPMWA in the Second Affiliated Hospital of Shantou University Medical College, China, between August 2017 and January 2023 were retrospectively analyzed.

RESULTS

All patients underwent UPMWA for uterine fibroids; 179 patients had multiple uterine fibroids and 2 patients had single uterine fibroids. The maximum fibroid diameter ranged from 18 to 140 mm, with an average of 68.3 mm. Ultrasound imaging was used to confirm that the blood flow signal within the mass had disappeared in all patients, indicating that the ablation was effective. Within 24 h, compared with before UPMWA, levels of total bilirubin, direct bilirubin, indirect bilirubin and aspartate aminotransferase had significantly increased (p < 0.01), whereas levels of total protein, albumin, globulin, alanine aminotransferase, creatinine and urea had significantly decreased (p < 0.01). Acute kidney injury (AKI) occurred in 1 of the 181 patients. The RBC count and HGB levels decreased significantly after UPMWA (p < 0.01).

CONCLUSION

Ultrasound-guided percutaneous microwave ablation for uterine fibroids can impose a higher detoxification load on the liver and cause thermal damage to and the destruction of RBCs within local circulation, potentially leading to AKI. Protein levels significantly decreased after UPMWA. Therefore, perioperative organ function protection measures and treatment should be actively integrated into clinical practice to improve prognosis and enhance recovery.

Enhancing precision in lung tumor ablation through innovations in CT-guided technique and angle control

BACKGROUND

This retrospective study aimed to evaluate the precision and safety outcomes of image-guided lung percutaneous thermal ablation (LPTA) methods, focusing on radiofrequency ablation (RFA) and microwave ablation (MWA). The study utilized an innovative angle reference guide to facilitate these techniques in the treatment of lung tumors.

METHODS

This study included individuals undergoing LPTA with the assistance of laser angle guide assembly (LAGA) at our hospital between April 2011 and March 2021. We analyzed patient demographics, tumor characteristics, procedure details, and complications. Logistic regressions were employed to assess risk factors associated with complications.

RESULTS

A total of 202 patients underwent ablation for 375 lung tumors across 275 sessions involving 495 ablations. Most procedures used RFA, especially in the right upper lobe, and the majority of ablations were performed in the prone position (49.7%). Target lesions were at a median depth of 39.3 mm from the pleura surface, and remarkably, 91.9% required only a single puncture. Complications occurred in 31.0% of ablations, with pneumothorax being the most prevalent (18.3%), followed by pain (12.5%), sweating (6.5%), fever (5.0%), cough (4.8%), hemothorax (1.6%), hemoptysis (1.2%), pleural effusion (2.0%), skin burn (0.6%), and air emboli (0.2%). The median procedure time was 21 min. Notably, smoking/chronic obstructive pulmonary disease emerged as a significant risk factor for complications.

CONCLUSION

The LAGA-assisted LPTA enhanced safety by improving accuracy and reducing risks. Overall, this investigation contributes to the ongoing efforts to refine and improve the clinical application of these thermal ablation techniques in the treatment of lung tumors.

Perioperative and Survival Outcomes of Patients Treated With Robot-Assisted Partial Nephrectomy and Percutaneous Microwave Ablation for Small Renal Masses: A Single Center Experience

BACKGROUND

Robot assisted partial nephrectomy (RAPN) and microwave ablation (MWA) are 2 of the most advanced techniques for the management of localized small renal masses.

PURPOSE

To compare the perioperative, functional and oncological results of RAPN and MWA.

MATERIALS AND METHODS

Data from 171 consecutive patients undergoing either RAPN or MWA for a localized small renal mass at a single academic center was retrospectively collected. Baseline features included patients' demographics and masses' characteristics. Procedures were compared in terms of perioperative outcomes and renal function variation Progression of a persistent lesion or local recurrence after a complete treatment defined local tumor progression. Descriptive statistics and survival analysis tested the association between predictors and local tumor progression.

RESULTS

Of all, 109 and 62 patients underwent RAPN and MWA. Patients in the MWA group were older (P = .002) had higher Charlson Comorbidity Index (CCI) (P < .001) and higher frequency of preoperative chronic kidney disease (P < .001). MWA led to a shorter postoperative hospitalization time (P < .001) and lower incidence of medical complications (6.5% vs. 22.9%, P = .02) than RAPN. GFR decline was similar between groups both at discharge (P = .39) and at the time of last follow up (P = 1.00). A lower rate of secondary interventions (11.7% vs. 2.8%, P = .037) and a better disease-free survival (83.2% vs. 96.5%, P = .027) were reported after RAPN. Conversely, cancer specific and overall survival were comparable (P > .05). At univariate regression analysis, MWA was associated with local tumor progression (HR 3.46, P = .040).

CONCLUSION

MWA displayed a lower perioperative impact, while functional outcomes were similar after each intervention. RAPN resulted superior in terms of tumor eradication, but no difference was noted regarding cancer specific survival. Thus, MWA represents a valid alternative in frail patients, though less radical than RAPN.

Thermal ablation for hepatic tumors in high-risk locations

Thermal ablative techniques such as radiofrequency and microwave ablation are minimally invasive and cost-effective approaches that are currently being adopted as alternatives to surgical resection for primary and metastatic liver malignancies. However, they are considered to be relatively contraindicated for tumors in high-risk locations due to technical difficulties and a perceived increased risk of perioperative complications. Several techniques, including artificial ascites, non-touch multibipolar ablation, and laparoscopically assisted ablation, can be used to improve the outcomes of ablation for high-risk tumors. This review aims to provide a comprehensive summary of the techniques currently used to improve thermal ablation outcomes for high-risk liver tumors.

Percutaneous Microwave Ablation for Treatment of Retroperitoneal Tumors

Purpose To determine if microwave ablation (MWA) of retroperitoneal tumors can safely provide high rates of local tumor control. Materials and Methods This retrospective study included 19 patients (median age, 65 years [range = 46-78 years]; 13 [68.4%] men and six [31.6%] women) with 29 retroperitoneal tumors treated over 22 MWA procedures. Hydrodissection (0.9% saline with 2% iohexol) was injected in 17 of 22 (77.3%) procedures to protect nontarget anatomy. The primary outcomes evaluated were local tumor progression (LTP) and complication rates. Oncologic outcomes, including overall survival (OS), progression-free survival (PFS), and treatment-free interval (TFI), were examined as secondary outcome measures. Results Median follow-up was 18 months (range = 0.5-113). Hydrodissection was successful in displacing nontarget anatomy in 16 of 17 (94.1%) procedures. The LTP rate was 3.4% (one of 29; 95% CI: 0.1, 17.8) per tumor and 5.3% (one of 19; 95% CI: 0.1, 26.0) per patient. The overall complication rate per patient was 15.8% (three of 19), including two minor complications and one major complication. The OS rate at 1, 2, and 3 years was 81.8%, 81.8%, and 72.7%, respectively, with a median OS estimated at greater than 7 years. There was no evidence of a difference in OS (P = .34) and PFS (P = .56) between patients with renal cell carcinoma (six of 19 [31.6%]) versus other tumors (13 of 19 [68.4%]) and patients treated with no evidence of disease (15 of 22 [68.2%]) versus patients with residual tumors (seven of 22 [31.8%]). Median TFI was 18 months (range = 0.5-108). Conclusion Treatment of retroperitoneal tumors with MWA combined with hydrodissection provided high rates of local control, prolonged systemic therapy-free intervals, and few serious complications. Keywords: Ablation Techniques (ie, Radiofrequency, Thermal, Chemical), Retroperitoneum, Microwave Ablation, Hydrodissection © RSNA, 2024.

The Value of Local Therapies in Advanced Adrenocortical Carcinoma

International guidelines recommend local therapies (LTs) such as local thermal ablation (LTA; radiofrequency, microwave, cryoablation), transarterial (chemo)embolisation (TA(C)E), and transarterial radioembolisation (TARE) as therapeutic options for advanced adrenocortical carcinoma (ACC). However, the evidence for these recommendations is scarce. We retrospectively analysed patients receiving LTs for advanced ACC. Time to progression of the treated lesion (tTTP) was the primary endpoint. The secondary endpoints were best objective response, overall progression-free survival, overall survival, adverse events, and the establishment of predictive factors by multivariate Cox analyses. A total of 132 tumoural lesions in 66 patients were treated with LTA (n = 84), TA(C)E (n = 40), and TARE (n = 8). Complete response was achieved in 27 lesions (20.5%; all of them achieved by LTA), partial response in 27 (20.5%), and stable disease in 38 (28.8%). For the LTA group, the median tTTP was not reached, whereas it was reached 8.3 months after TA(C)E and 8.2 months after TARE (p < 0.001). The median time interval from primary diagnosis to LT was >47 months. Fewer than four prior therapies and mitotane plasma levels of >14 mg/L positively influenced the tTTP. In summary, this is one of the largest studies on LTs in advanced ACC, and it demonstrates a very high local disease control rate. Thus, it clearly supports the guideline recommendations for LTs in these patients.

Risk assessment of pneumothorax in colorectal lung metastases treated by percutaneous thermal ablation: a multicenter retrospective cohort study

PURPOSE

To evaluate the risk of pneumothorax in the percutaneous image-guided thermal ablation (IGTA) treatment of colorectal lung metastases (CRLM).

METHODS

Data regarding patients with CRLM treated with IGTA from five medical institutions in China from 2016 to 2023 were reviewed retrospectively. Pneumothorax and non-pneumothorax were compared using the Student's t -test, χ 2 test and Fisher's exact test. Univariate logistic regression analysis was conducted to identify potential risk factors, followed by multivariate logistic regression analysis to evaluate the predictors of pneumothorax. Interactions between variables were examined and used for model construction. Receiver operating characteristic curves and nomograms were generated to assess the performance of the model.

RESULTS

A total of 254 patients with 376 CRLM underwent 299 ablation sessions. The incidence of pneumothorax was 45.5%. The adjusted multivariate logistic regression model, incorporating interaction terms, revealed that tumour number [odds ratio (OR)=8.34 (95% CI: 1.37-50.64)], puncture depth [OR=0.53 (95% CI: 0.31-0.91)], pre-procedure radiotherapy [OR=3.66 (95% CI: 1.17-11.40)], peribronchial tumour [OR=2.32 (95% CI: 1.04-5.15)], and emphysema [OR=56.83 (95% CI: 8.42-383.57)] were significant predictive factors of pneumothorax (all P <0.05). The generated nomogram model demonstrated a significant prediction performance, with an area under the receiver operating characteristic curve of 0.800 (95% CI: 0.751-0.850).

CONCLUSIONS

Pre-procedure radiotherapy, tumour number, peribronchial tumour, and emphysema were identified as risk factors for pneumothorax in the treatment of CRLM using percutaneous IGTA. Puncture depth was found to be a protective factor against pneumothorax.

Treatment strategies for malignant pulmonary nodule: beyond lobectomy. Point-counterpoint

PURPOSE OF REVIEW

Technological advancement in low-dose computed tomography resulted in an increased incidental discovery of early-stage lung cancer and multifocal ground glass opacity. The demand for parenchyma-preserving treatment strategies is greater now than ever. Pulmonary ablative therapy is a groundbreaking technique to offer local ablative treatment in a lung-sparing manner. It has become a promising technique in lung cancer management with its diverse applicability. In this article, we will review the current development of ablative therapy in lung and look into the future of this innovative technique.

RECENT FINDINGS

Current literature suggests that ablative therapy offers comparable local disease control to other local therapies and stereotactic body radiation therapy (SBRT), with a low risk of complications. In particular, bronchoscopic microwave ablation (BMWA) has considerably fewer pleural-based complications due to the avoidance of pleural puncture. BMWA can be considered in the multidisciplinary treatment pathway as it allows re-ablation and allows SBRT after BMWA.

SUMMARY

With the benefits which ablative therapy offers and its ability to incorporate into the multidisciplinary management pathway, we foresee ablative therapy, especially BMWA gaining significance in lung cancer treatment. Future directions on developing novel automated navigation platforms and the latest form of ablative energy would further enhance clinical outcomes for our patients.

Thermal ablation of hepatocellular carcinoma

Percutaneous treatment of hepatocellular carcinoma (HCC) by means of thermal ablation (TA) has been introduced in clinical guidelines as a potentially curative treatment for the early stages of the disease since the early 2000s. Due to its safety profile and cost-effectiveness, TA can be offered as a first-line treatment for patients with HCC smaller than 3 cm. Thermal ablative techniques are in fact widely available at many centres worldwide and include radiofrequency (RF) and microwave (MW) ablation, with the latter increasingly applied in clinical practice in the last decade. Pre-clinical studies highlighted, as potential advantages of MW-based ablation, the ability to achieve higher temperatures (>100°C) and larger ablation zones in shorter times, with less susceptibility to blood flow-induced heat sink effects. Despite these advantages, there is no evidence of superior overall survival in patients treated with MW as compared to those treated with RF ablation. Local control has been proven to be superior to MW ablation with a similar complication rate. It is expected that further improvement of TA results in the treatment of HCC will result from the refinement of guidance and monitoring tools and the careful assessment of ablation margins. Thermal ablative treatments may also be performed on nodules larger than 3 cm by applying multiple devices or combining percutaneous and intra-arterial approaches. The role of novel immunotherapy regimens in combination with ablation is also currently under evaluation in clinical trials, with several potential benefits. In this review, indications, technical principles, results, and future prospects of TA for the treatment of HCC will be examined.

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.

Sclerotherapy, cryoablation, and surgical fixation of an intraosseous tibial venous malformation

Intraosseous vascular malformations are rare vascular anomalies that present unique treatment challenges due to structural instability, embolization and sclerotherapy resistance, and tendency to recur. Patients may have clinical manifestations including pain, functional impairment, increased fracture risk, and decreased quality of life. Image-guided ablation techniques are emerging interventional treatment options for soft tissue tumors and complicated vascular anomalies. Percutaneous image-guided cryoablation offers a potential alternative as an isolated or adjunct therapy for intraosseous vascular malformations.

Potential biomarkers for predicting immune response and outcomes in lung cancer patients undergoing thermal ablation

Thermal ablation is a promising alternative treatment for lung cancer. It disintegrates cancer cells and releases antigens, followed by the remodeling of local tumor immune microenvironment and the activation of anti-tumor immune responses, enhancing the overall effectiveness of the treatment. Biomarkers can offer insights into the patient's immune response and outcomes, such as local tumor control, recurrence, overall survival, and progression-free survival. Identifying and validating such biomarkers can significantly impact clinical decision-making, leading to personalized treatment strategies and improved patient outcomes. This review provides a comprehensive overview of the current state of research on potential biomarkers for predicting immune response and outcomes in lung cancer patients undergoing thermal ablation, including their potential role in lung cancer management, and the challenges and future directions.

SHORT-TERM OUTCOMES OF PERCUTANEOUS RADIOFREQUENCY AND MICROWAVE ABLATION IN THE TREATMENT OF SMALL RENAL MASSES

Although the gold standard in the management of kidney tumors is surgical treatment, thermal ablation methods are a viable therapeutic option for patients with small (<4 cm) renal masses who are poor surgical candidates. The aim of this study was to compare the technical success, primary efficacy and complication rate of percutaneous radiofrequency and microwave ablation in the treatment of small renal masses. A retrospective analysis of consecutive patients with small renal masses treated with radiofrequency or microwave ablation between December 2017 and January 2022 was conducted. Response to the ablative therapy was assessed on contrast-enhanced computed tomography examination after 3 months. Ablations of 44 kidney lesions were performed in 43 patients. Sixteen lesions were treated with radiofrequency and 28 with microwave ablation. Both methods were associated with high technical success (100%). Primary efficacy rates of radiofrequency and microwave ablation were 81.3% and 89.3%, respectively. Ablation-related complications were noted only in the patients treated with microwave ablation (18.5%), all of them being low grade (Clavien-Dindo 1 and 2). Radiofrequency and microwave ablation exhibited comparable efficacy in the treatment of small renal masses. Microwave ablation was associated with a comparatively higher number of complications.

Introduction to interventional oncology: A COG Diagnostic Imaging Committee/SPR Oncology Committee White Paper

Interventional radiology (IR) is a valuable resource when caring for pediatric solid tumor patients. As minimally invasive, image-guided procedures become more relied upon to answer challenging diagnostic questions and provide alternative therapeutic options, IR is poised to become a contributing member of the multidisciplinary oncology team. Improved imaging techniques allow for better visualization during biopsy procedures, transarterial locoregional treatments have the potential to deliver targeted cytotoxic therapy while limiting systemic side effects, and percutaneous thermal ablation can be used to treat chemo-resistant tumors of various solid organs. Additionally, interventional radiologists are able to perform routine, supportive procedures for oncology patients that include central venous access placement, lumbar punctures, and enteric feeding tube placements with high levels of technical success and excellent safety profiles.

Combining energy-based focal ablation and immune checkpoint inhibitors: preclinical research and clinical trials

Energy-based focal therapy (FT) uses targeted, minimally invasive procedures to destroy tumors while preserving normal tissue and function. There is strong emerging interest in understanding how systemic immunity against the tumor can occur with cancer immunotherapy, most notably immune checkpoint inhibitors (ICI). The motivation for combining FT and ICI in cancer management relies on the synergy between the two different therapies: FT complements ICI by reducing tumor burden, increasing objective response rate, and reducing side effects of ICI; ICI supplements FT by reducing local recurrence, controlling distal metastases, and providing long-term protection. This combinatorial strategy has shown promising results in preclinical study (since 2004) and the clinical trials (since 2011). Understanding the synergy calls for understanding the physics and biology behind the two different therapies with distinctive mechanisms of action. In this review, we introduce different types of energy-based FT by covering the biophysics of tissue-energy interaction and present the immunomodulatory properties of FT. We discuss the basis of cancer immunotherapy with the emphasis on ICI. We examine the approaches researchers have been using and the results from both preclinical models and clinical trials from our exhaustive literature research. Finally, the challenges of the combinatory strategy and opportunities of future research is discussed extensively.

Ablation of pulmonary neoplasms: review of literature and future perspectives

Thermal ablation is a minimally invasive technology used to treat many types of tumors, including lung cancer. Specifically, lung ablation has been increasingly performed for unsurgical fit patients with both early-stage primi-tive lung cancer and pulmonary metastases. Image-guided available techniques include radiofrequency ablation, microwave ablation, cryoablation, laser ablation and irreversible electroporation. Aim of this review is to illustrate the major thermal ablation modalities, their indications and contraindications, complications, outcomes and notably the possible future challenges.

Laparoscopic microwave ablation versus percutaneous microwave ablation of hepatic malignancies: Efficacy and recurrence-free survival outcomes in patients

BACKGROUND

Hepatic thermal ablation has been found to be effective and equivalent to resection in certain liver histologies. Of the 16,000 annual liver ablations performed in the United States, only 13% (2,080 ablations) are performed laparoscopically. The laparoscopic technique remains underused even with the benefits of improved staging and better access to tumors. The purpose of this study is to compare laparoscopic microwave ablation versus percutaneous microwave ablation in terms of efficacy and recurrence-free survival outcomes in patients with hepatic malignancies.

METHODS

A comparative analysis was performed on 275 patients (289 ablation procedures) who underwent laparoscopic microwave ablation or percutaneous microwave ablation between February 2011 and May 2021. Ablation success was confirmed postprocedure and recurrence was monitored at follow-up via contrast-enhanced computed tomography/magnetic resonance imaging and/or computed tomography/positron emission tomography.

RESULTS

The groups were similar for sex, age, body mass index, location of tumor, size of tumor, and number of tumors. Ablation success was 100% in both groups. Local recurrence was significant (5%: laparoscopic microwave ablation vs 22%: percutaneous microwave ablation, P = .002) and same-lobe recurrence (21%: laparoscopic microwave ablation vs 24%: percutaneous microwave ablation) was lower in the laparoscopic microwave ablation group. Median recurrence-free survival was 15.8 months for the laparoscopic microwave ablation group and 5.6 months for the percutaneous microwave ablation group (P = .0002). Overall, 90-day complications were lower in the laparoscopic microwave ablation group (11%) compared with the percutaneous microwave ablation group (21%) (P = .11).

CONCLUSION

Laparoscopic surgical ablation is a critical surgical skill that must be taught in fellowship. Laparoscopic microwave ablation leads to better tumor specific outcomes and oncologic outcomes demonstrating clinical efficacy in the treatment of hepatic malignancies compared with percutaneous microwave ablation.

Ultrasound-guided thermal ablation for papillary thyroid microcarcinoma: A systematic review

OBJECTIVE

Thyroidectomy is the first-line treatment for papillary thyroid microcarcinoma (PTMC), but often involves aggressive overtreatment. Thermal ablation (TA) has been gradually used for the treatment of recurrent PTMC. However, it is not recommended for the treatment of primary PTMC according to the Korean and Italian guidelines. Therefore, this systematic review aimed to analyse the indications, efficacy, and safety of TA in the treatment of PTMC.

DESIGN

Systematic review.

PATIENTS AND MEASUREMENTS

A search strategy was developed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. A total of 27 articles were included in this study until January 2022.

RESULTS

According to current guidelines and studies, we divided the indications of TA for PTMC into six primary and three secondary indications. Laser ablation (LA) has the advantages of a small needle, accurate output energy and precision ablation, and it is safe to important organs around the lesion. The patients recover quickly after radiofrequency ablation (RFA), with no major complications, recurrence, or lymph node metastasis. The volume reduction rate after RFA was the highest, followed by microwave ablation and LA, and the improvement in patient quality of life after TA was significantly better than after thyroidectomy.

CONCLUSIONS

TA is an effective alternative method for surgery in the treatment of low-risk PTMC and has the advantages of being minimally invasive, economical, having less bleeding and having a high postoperative quality of life.

Ablation for Benign Liver Tumors: Current Concepts and Limitations

Percutaneous ablation under imaging guidance is a curative treatment that can induce complete tumor necrosis with advantages of minimal invasiveness and a low risk of complications. Thermal ablation, which includes radiofrequency ablation and microwave ablation, is a representative technique that has sufficient antitumor effects in cases of hepatocellular carcinoma with ≤3 lesions measuring ≤3 cm and preserved liver function. The short- and long-term outcomes of patients are comparable with those achieved with surgical resection. Despite their nonmalignant nature, some benign liver tumors require treatment for symptoms caused by the presence of the tumor and/or continuous enlargement. Ablation may be the treatment of choice because it has lower burden on patients than surgical treatment. This review describes the recent concepts, progress, and limitations of ablation-based treatment for benign liver tumors.

Role of the Interventional Radiologist in the Treatment of Desmoid Tumors

Desmoid tumors are locally aggressive soft tissue tumors with variable clinical presentation. As is the case with most relatively rare tumors, a multidisciplinary team approach is required to best manage these patients. Surgical resection, systemic therapy, and radiation therapy have classically been mainstays of treatment for desmoid tumors; however, a more conservative “wait-and-see” approach has been adopted given their high recurrence rates and significant morbidity associated with the aforementioned therapies. Given the challenges of classical treatment methods, interventional radiologists have begun to play a significant role in minimally invasive interventions for desmoid tumors. Herein, the authors review imaging characteristics of desmoid tumors, current management recommendations, and minimally invasive therapeutic intervention options.

A meta-analysis and systematic review of the comparison of laparoscopic ablation to percutaneous ablation for hepatic malignancies

BACKGROUND

The optimal access for thermal ablation of the liver has not been evaluated in the literature for the laparoscopic versus percutaneous techniques. The aim of this manuscript was to determine the optimal ablation technique and patient selection for hepatic malignancies by comparing the efficacy and recurrence-free survival of laparoscopic and percutaneous thermal ablation.

METHODS

A detailed literature search was made in PubMed, Web of Science, Google scholar, and EMBASE for related research publications. The data were extracted and assessed by two reviewers independently. Analysis of pooled data was performed, and Odds Ratio (OR) or Hazard Ratio (HR) with corresponding confidence intervals (CIs) was calculated and summarized respectively.

RESULTS

A total of 10 articles were included with 1916 ablation patients. Laparoscopic ablation success (Median 100%) was found to be higher than percutaneous ablation success (median 89.4%) (p = ns). There was a higher percentage of both local and non-local hepatic recurrence in the patients treated with percutaneous ablation versus laparoscopic ablation. Meta-analysis indicated no difference in the adjusted hazard rate of recurrence by procedure type (p = 0.94). Laparoscopic ablation had a higher percentage of complications compared to percutaneous ablation (median lap 14.5% vs. perc 3.3%).

CONCLUSIONS

While laparoscopic and percutaneous ablation are both effective interventions for hepatic malignancies, laparoscopic ablation was found to have improved ablation success and less local and non-local hepatic recurrence compared to percutaneous ablation.

Management of renal cell carcinoma in transplant kidney: a systematic review and meta-analysis

INTRODUCTION

After transplantation, approximately 10% of renal cell carcinomas are detected in graft kidneys. These tumors (gRCC) present surgeons with the difficulty of finding a treatment that guarantees both oncological clearance and maintenance of function. We conducted a systematic review and an individual patient data meta-analysis on the oncology, safety and functional outcomes of the available treatments for gRCC.

EVIDENCE ACQUISITION

A systematic search was performed across MEDLINE, EMBASE, and Web of Science including any study reporting perioperative, functional and survival outcomes for patients undergoing graft nephrectomy (GN), partial nephrectomy (PN) or thermal ablation (TA) for gRCC. Quade's ANCOVA, Spearman Rho and Pearson χ², Kaplan-Meier, Log-rank and Standard Cox regression and other tests were used to compare treatments. Studies' quality was evaluated using a modified version of Newcastle Ottawa Scale.

EVIDENCE SYNTHESIS

A number of 29 studies (357 patients) were included. No differences between TA and PN were found in terms of safety, functional and oncological outcomes for T1a gRCCs. When applied to pT1b gRCC, PN showed no difference in complications, progression or cancer-specific deaths compared to smaller lesions; PN validity for pT2 gRCCs should be considered unverified due to lack of sufficient evidence. The efficacy and safety of PN or TA for multiple gRCC remain controversial. In case of non-functioning, large (T≥2), complicated or metastatic gRCCs, GN appears to be the most reasonable choice. Quality of evidence ranged from very low to moderate. Studies with large cohorts and longer follow-up are still needed to clarify oncological and functional differences.

CONCLUSIONS

PN and TA might be offered as a nephron-sparing treatment in patients with T1a gRCC. There is no significant difference between these options and GN in terms of oncological outcomes and complications. PN and TA offer similar functional outcomes and graft preservation. PN for T1b gRCC seems feasible and safe, but its validity should be considered unverified.

Percutaneous image-guided thermal ablation of lung cancer: What is the evidence?

Thermal ablation techniques have now been used for more than twenty years in the treatment of primary lung tumours, predominantly non-small cell lung cancer (NSCLC). Although primarily used for the treatment of early-stage disease in non-surgical patients, thermal ablation is now also being used in selected patients with oligometastatic and oligoprogressive disease. This review discusses the techniques available for thermal ablation, the evidence for use of thermal ablation in primary lung tumours in early- and advanced-stage disease and compares thermal ablation to alternative treatment strategies.

Semi-automatic artifact quantification in thermal ablation probe and algorithms for the evaluation of metal artifact reduction

OBJECTIVES

To compare metal artifacts and evaluation of metal artifact reduction algorithms during probe positioning in computed tomography (CT)-guided microwave ablation (MWA), cryoablation (CRYO), and radiofrequency ablation (RFA).

MATERIALS AND METHODS

Using CT guidance, individual MWA, CRYO, and RFA ablation probes were placed into the livers of 15 pigs. CT imaging was then performed to determine the probe's position within the test subject's liver. Filtered back projection (B30f) and iterative reconstructions (I30-1) were both used with and without dedicated iterative metal artifact reduction (iMAR) to generate images from the initial data sets. Semi-automatic segmentation-based quantitative evaluation was conducted to estimate artifact percentage within the liver, while qualitative evaluation of metal artifact extent and overall image quality was performed by two observers using a 5-point Likert scale: 1-none, 2-mild, 3-moderate, 4-severe, 5-non-diagnostic.

RESULTS

Among MWA, RFA, and CRYO, compared with non-iMAR in B30f reconstruction, the largest extent of artifact volume percentages were observed for CRYO (11.5-17.9%), followed by MWA (4.7-6.6%) and lastly in RFA (5.5-6.2%). iMAR significantly reduces metal artifacts for CRYO and MWA quantitatively (p = 0.0020; p = 0.0036, respectively) and qualitatively (p = 0.0001, p = 0.0005), but not for RFA. No significant reduction in metal artifact percentage was seen after applying iterative reconstructions (p > 0.05). Noise, contrast-to-noise-ratio, or overall image quality did not differ between probe types, irrespective of the application of iterative reconstruction and iMAR.

CONCLUSION

A dedicated metal artifact algorithm may decrease metal artifacts and improves image quality significantly for MWA and CRYO probes. Their application alongside with dedicated metal artifact algorithm should be considered during CT-guided positioning.

An endoluminal cylindrical sectored-ring ultrasound phased-array applicator for minimally-invasive therapeutic ultrasound

BACKGROUND

The size of catheter-based ultrasound devices for delivering ultrasound energy to deep-seated tumors is constrained by the access pathway which limits their therapeutic capabilities.

PURPOSE

To devise and investigate a deployable applicator suitable for minimally-invasive delivery of therapeutic ultrasound, consisting of a 2D cylindrical sectored-ring ultrasound phased array, integrated within an expandable paraboloid-shaped balloon-based reflector. The balloon can be collapsed for compact delivery and expanded close to the target position to mimic a larger-diameter concentric-ring sector-vortex array for enhanced dynamic control of focal depth and volume.

METHODS

Acoustic and biothermal simulations were employed in 3D generalized homogeneous and patient-specific heterogeneous models, for three-phased array transducers with 32, 64, and 128 elements, composed of sectored 4, 8, and 16 tubular ring transducers, respectively. The applicator performance was characterized as a function of array configuration, focal depth, phasing modes, and balloon reflector geometry. A 16-element proof-of-concept phased array applicator assembly, consisting of four tubular transducers each divided into four sectors, was fabricated, and characterized with hydrophone measurements along and across the axis, and ablations in ex vivo tissue.

RESULTS

Simulation results indicated that transducer arrays (1.5 MHz, 9 mm OD × 20 mm long), balloon sizes (41-50 mm expanded diameter, 20-60 mm focal depth), phasing mode (0-4) and sonication duration (30 s) can produce spatially localized acoustic intensity focal patterns (focal length: 3-22 mm, focal width: 0.7-8.7 mm) and ablative thermal lesions (width: 2.7-16 mm, length: 6-46 mm) in pancreatic tissue across a 10-90 mm focal depth range. Patient-specific studies indicated that 0.1, 0.46, and 1.2 cm³ volume of tumor can be ablated in the body of the pancreas for 120 s sonications using a single axial focus (Mode 0), or four, and eight simultaneous foci in a toroidal pattern (Mode 2 and 4, respectively). Hydrophone measurements demonstrated good agreement with simulation. Experiments in which chicken meat was thermally ablated indicated that volumetric ablation can be produced using single or multiple foci.

CONCLUSIONS

The results of this study demonstrated the feasibility of a novel compact ultrasound applicator design capable of focusing, deep penetration, electronic steering, and volumetric thermal ablation. The proposed applicator can be used for compact endoluminal or laparoscopic delivery of localized ultrasound energy to deep-seated targets.

The efficacy and safety of thermal ablation for patients with lung malignancy: a meta-analysis of 12 studies in China

BACKGROUND

Thermal ablation has been increasingly used in the treatment of lung cancer in recent years. This meta-analysis aims to investigate the therapeutic effect and safety of thermal ablation plus chemotherapy as compared with chemotherapy alone in treating patients with lung malignancy in China based on current evidence.

METHODS

Databases including PubMed, Web of Science, Embase and the Cochrane Library were searched for clinical reports. Additional literature search was also performed by searching the reference list of included studies and latest reviews. Raw data including objective response rate, disease control rate, progression-free survival, overall survival and the incidence of major complication were extracted and pooled.

RESULTS

A total of 12 studies in China including 1282 patients with lung malignancy were included in this meta-analysis. The number of studies that reported data of objective response rate, disease control rate, progression-free survival, overall survival and major complication was 8, 7, 7, 6 and 7, respectively. The combination therapy of thermal ablation plus chemotherapy showed a significantly better efficacy in improving objective response rate (odds ratio = 2.73; P < 0.001) and disease control rate (odds ratio = 2.43; P < 0.001) as compared with chemotherapy alone. Thermal ablation was also a significant protective factor for progression-free survival (hazard ratio = 0.43; P < 0.001) and overall survival (hazard ratio = 0.49; P < 0.001). Besides, thermal ablation did not increase the risk of major complication (odds ratio = 0.75; P = 0.252).

CONCLUSION

The present meta-analysis based on these studies in China suggested that thermal ablation is a promising technique to provide better disease response and survival outcomes for patients with lung malignancy. Thermal ablation is worth further promotion in treating lung malignancy and application in clinical practice.

Image-guided percutaneous ablation for lung malignancies

Image-guided percutaneous lung ablation has proven to be an alternative and effective strategy in the treatment of lung cancer and other lung malignancies. Radiofrequency ablation, microwave ablation, and cryoablation are widely used ablation modalities in clinical practice that can be performed along or combined with other treatment modalities. In this context, this article will review the application of different ablation strategies in lung malignancies.

Cryoablation for the Treatment of Kidney Cancer: Comparison With Other Treatment Modalities and Review of Current Treatment

With cancer among the leading causes of death worldwide and kidney cancer among the more common cancers in the United States, it has become increasingly important to ensure that first-line treatments remain validated and supported in recent literature. Surgical intervention has long remained the gold standard for intervention but with newer techniques and technology on the horizon, there must be a constant review of other options that may provide improved outcomes and reduction of associated risks. Ablative techniques have gained traction and are becoming a valuable intervention for multiple different types of cancers, kidney cancer included. Cryoablation, a newer ablative technique taking advantage of extreme cold to freeze and destroy abnormal tissue, provides a promising option for treatment. Currently, no review article, to our knowledge, compares all the different treatment options for kidney cancer. Additionally, while some literature has addressed cryoablation in comparison to other methods of management, there has not been an extensive review to combine our current understanding of these comparisons. In this review article, we provide an overview of each of the commonly used treatments for kidney cancer and summarize the current literature regarding the advantages and disadvantages of each intervention. Finally, we seek to compare cryoablation, a newer option for treatment, to each of the approaches with the goal of evaluating the best methods for management and determining cryoablation's role alongside these current interventions.

Assessing long-term locoregional control of spinal osseous metastases after microwave ablation

Osseous metastases to the spine result in significant pain and decreased quality of life. The purpose of this study was to evaluate the long-term efficacy of microwave ablation (MWA) for the treatment of spinal metastases regarding pain reduction and local control of disease progression. In this single center retrospective study, patients with osseous metastases to the spine undergoing MWA with vertebroplasty from 2013 to 2020 were included. Locoregional control of metabolic activity at the treated level was assessed using PET/CT scan both pre- and post-procedure. Pain reduction was measured using change in visual analog scale (VAS) pain score. Forty-eight spinal levels were treated with MWA in 28 patients (57 % male, mean age 68 ± 9 years). Median ablation time, energy, and temperature were 4 min and 13 s, 3.6 kJ, and 80 °C, respectively. Median pre-procedure maximum standard uptake value (SUVmax) was significantly reduced following ablation, from 4.55 (IQR 3.65-6.1) to 0 (IQR 0-1.8; p < 0.001), over an average of 29 ± 14.1 month follow up period. Pre-procedure VAS pain score was reduced from median (IQR) of 8 (6.5-9) to 1(1-2), 2(1-3) and 1(0.5-3) at 24 h, four weeks, and six months post-procedure, respectively (all p < 0.001 with respect to pre-procedure scores). In conclusion, this study supports microwave ablation as an effective technique for pain palliation and long-term locoregional tumor control of oligometastatic spinal disease as assessed by metabolic response.

Effects of microwave ablation on serum Golgi protein 73 in patients with primary liver cancer

BACKGROUND

Microwave ablation (MWA) is an effective treatment option for patients with primary liver cancer. However, it has been reported that the MWA procedure induces a hepatic inflammatory response and injury, which may negatively affect the efficacy of MWA. As such, the discovery of reliable markers to monitor the patient’s response to MWA is needed. Golgi protein 73 (GP73) has been shown to be associated with chronic liver disease. To date, the potential value of serum GP73 in the dynamic monitoring during MWA of liver cancer remains unclear.

AIM

To examine the effects of MWA on the serum levels of GP73 in patients with primary liver cancer.

METHODS

A total of 150 primary liver cancer patients with a single small lesion (≤ 3 cm in diameter) were retrospectively enrolled spanning the period between January 2016 and October 2018. All of the patients received MWA for the treatment of primary liver cancer. Serum GP73, alpha-fetoprotein (AFP), and widely used liver biochemical indicators [serum albumin, total bilirubin (TBIL), alanine aminotransferase (ALT), and aspartate aminotransferase (AST)] were compared before MWA and at different time points, including 1, 2, and 4 wk following the ablation procedure.

RESULTS

Complete tumor ablation was achieved in 95.33% of the patients at 1 mo after MWA. The 1-, 2-, and 3-year disease-free survival rates were 74.67%, 59.33%, and 54.00%, respectively. The serum AFP levels were significantly decreased at 1, 2, and 4 wk after MWA; they returned to the normal range at 12 wk after MWA; and they remained stable thereafter during follow-up in those cases without recurrence. In contrast, the serum GP73 levels were significantly increased at 1 and 2 wk after MWA. The serum GP73 levels reached the peak at 2 wk after MWA, started to decline after hepatoprotective treatment with glycyrrhizin and reduced glutathione, and returned to the pretreatment levels at 12 and 24 wk after MWA. Notably, the changes of serum GP73 in response to MWA were similar to those of TBIL, ALT, and AST.

CONCLUSION

Serum GP73 is markedly increased in response to MWA of liver cancer. Thus, serum GP73 holds potential as a marker to monitor MWA-induced inflammatory liver injury in need of amelioration.

Advanced CT techniques for hepatic microwave ablation zone monitoring and follow-up

PURPOSE

To evaluate utility of advanced CT techniques including HighlY constrained back-projection and dual-energy CT for intra- and post-procedure hepatic microwave ablation zone monitoring.

METHODS

8 hepatic microwave ablations were performed in 4 adult swine (5 min/65 W). Low-dose routine CECT and dual-energy CT images were obtained every 1 min during ablation. Images were reconstructed ± HYPR. Image quality and dose metrics were collected. 21 MWA were performed in 4 adult swine. Immediate post-procedure CECT was performed in the arterial, portal venous, and delayed phases using both routine and DECT imaging with full-dose weight-based IV contrast dosing. An additional 16 MWA were subsequently performed in 2 adult swine. Immediate post-procedure CT was performed with half-dose IV contrast using routine and DECT. 12 patients (10 M/2F, mean age 62.4 yrs) with 14 hepatic tumors (4 HCC, 10 metastatic lesions) treated with MWA were prospectively imaged with DECT 1 month post-procedure. 120 kV equivalent images were compared to DECT [51 keV, iodine material density]. Image quality and dose metrics were collected.

RESULTS

Gas created during MWA led to high CNR in all intraprocedural CT datasets. Optimal CNRs were noted at 4 min with CNR 6.7, 15.5,15.9, and 21.5 on LD-CECT, LD-CECT + HYPR, DECT, and DECT + HYPR, respectively (p < 0.001). Image quality scores at 4 min were 1.8, 2.8, 2.4, and 3, respectively (p < 0.001). Mean radiation dose (CTDIvol) was eightfold higher for the DECT series. For swine, post-procedural DECT images (IMD/51 keV) showed improved CNR compared to routine CT at all time points with full and with reduced dose contrast (CNR 4.6, 3.2, and 1.5, respectively, at half-contrast dose, p < 0.001). For human subjects, the 51 keV and IMD images showed higher CNRs (5.8, 4.8 vs 4.0, p < 0.001) and SNRs (3.7, 5.9 vs 2.8). Ablation zone sharpness was improved with DECT (routine 3.0 ± 0.7, DECT 3.5 ± 0.5). Diagnostic confidence was higher with DECT (routine 2.3 ± 0.9, DECT 2.6 ± 0.8). Mean DLP for DECT was 905.7 ± 606 mGy-cm, CTDIvol 37.5 ± 21.2 mGy, and effective dose 13.6 ± 9.1 mSv, slightly higher than conventional CT series.

CONCLUSION

Advanced CT techniques can improve CT image quality in peri-procedural hepatic microwave ablation zone evaluation.

Precision Imaging Guidance in the Era of Precision Oncology: An Update of Imaging Tools for Interventional Procedures

Interventional oncology (IO) procedures have become extremely popular in interventional radiology (IR) and play an essential role in the diagnosis, treatment, and supportive care of oncologic patients through new and safe procedures. IR procedures can be divided into two main groups: vascular and non-vascular. Vascular approaches are mainly based on embolization and concomitant injection of chemotherapeutics directly into the tumor-feeding vessels. Percutaneous approaches are a type of non-vascular procedures and include percutaneous image-guided biopsies and different ablation techniques with radiofrequency, microwaves, cryoablation, and focused ultrasound. The use of these techniques requires precise imaging pretreatment planning and guidance that can be provided through different imaging techniques: ultrasound, computed tomography, cone-beam computed tomography, and magnetic resonance. These imaging modalities can be used alone or in combination, thanks to fusion imaging, to further improve the confidence of the operators and the efficacy and safety of the procedures. This article aims is to provide an overview of the available IO procedures based on clinical imaging guidance to develop a targeted and optimal approach to cancer patients.

Interventional Radiology in the Management of Metastases and Bone Tumors

Interventional Radiology (IR) has experienced an exponential growth in recent years. Technological advances of the last decades have made it possible to use new treatments on a larger scale, with good results in terms of safety and effectiveness. In musculoskeletal field, painful bone metastases are the most common target of IR palliative treatments; however, in selected cases of bone metastases, IR may play a curative role, also in combination with other techniques (surgery, radiation and oncology therapies, etc.). Primary malignant bone tumors are extremely rare compared with secondary bone lesions: osteosarcoma, Ewing sarcoma, and chondrosarcoma are the most common; however, the role of interventional radiology in this fiels is marginal. In this review, the main techniques used in interventional radiology were examined, and advantages and limitations illustrated. Techniques of ablation (Radiofrequency, Microwaves, Cryoablation as also magnetic resonance imaging-guided high-intensity focused ultrasound), embolization, and Cementoplasty will be described. The techniques of ablation work by destruction of pathological tissue by thermal energy (by an increase of temperature up to 90 °C with the exception of the Cryoablation that works by freezing the tissue up to -40 °C). Embolization creates an ischemic necrosis by the occlusion of the arterial vessels that feed the tumor. Finally, cementoplasty has the aim of strengthening bone segment weakened by the growth of pathological tissue through the injection of cement. The results of the treatments performed so far were also assessed and presented focused the attention on the management of bone metastasis.

Image-Guided Percutaneous Ablation for Primary and Metastatic Tumors

Image-guided percutaneous ablation methods have been further developed during the recent two decades and have transformed the minimally invasive and precision features of treatment options targeting primary and metastatic tumors. They work by percutaneously introducing applicators to precisely destroy a tumor and offer much lower risks than conventional methods. There are usually shorter recovery periods, less bleeding, and more preservation of organ parenchyma, expanding the treatment options of patients with cancer who may not be eligible for resection. Image-guided ablation techniques are currently utilized for the treatment of primary and metastatic tumors in various organs including the liver, pancreas, kidneys, thyroid and parathyroid, prostate, lung, bone, and soft tissue. This article provides a brief review of the various imaging modalities and available ablation techniques and discusses their applications and associated complications in various organs.

A Technical Guide to Palliative Ablation of Recurrent Cancers in the Deep Spaces of the Suprahyoid Neck

Treatment options for patients with recurrent head and neck cancer, whether locoregional recurrence of previously treated head and neck cancer or secondary primary malignancy, are limited. Percutaneous ablation is a minimally invasive procedure that can be used with palliative intent in the head and neck to achieve symptomatic relief and local tumor control, potentially fulfilling treatment gaps of current standard of care options. Image guidance is key when navigating the deep spaces of the neck with special attention paid to critical structures within the carotid sheath. This review article provides an overview and highlights the important nuances of performing percutaneous ablations in the head and neck. It covers general principles, ablative modalities, image guidance, procedural technique, expected outcomes, and possible complications.

Percutaneous ablation of renal tumors versus surgical ablation and partial nephrectomy: Medicare trends and reimbursement cost comparison from 2010 to 2018

PURPOSE

The purpose of this study is to analyze trends in Medicare volume and reimbursement for percutaneous and surgical ablation as well as laparoscopic and open partial nephrectomy for treatment of small renal tumors from 2010 to 2018.

METHODS

Claims from the Medicare Part B Physician/Supplier Procedure Summary from 2010 to 2018 were extracted using CPT codes for percutaneous and surgical renal ablation and surgical and laparoscopic partial nephrectomy. Facility reimbursement and relative value units (RVUs) were obtained using the Centers for Medicare & Medicaid Services physician fee schedule look-up tool.

RESULTS

Volume of percutaneous ablation increased from 2539 to 4571 procedures (80.0%). Specifically, percutaneous cryoablation became the dominant technique, increasing from 1434 to 2981 procedures (107.9%). Overall, volume of partial nephrectomy also increased by 40.4%, driven by an increase in laparoscopic partial nephrectomy from 3227 to 7770 procedures (140.8%) with a decrease in open partial nephrectomy from 3489 to 1661 (- 52.4%). Volume of surgical ablations also decreased 72.7% from 1260 to 344 procedures. In 2018, reimbursement was $358.56 for percutaneous radiofrequency ablation, $481.32 for percutaneous cryoablation, $1216.43 for surgical radiofrequency ablation, $1269.35 for surgical cryoablation, $1381.67 for open partial nephrectomy, and $1552.66 for laparoscopic partial nephrectomy.

CONCLUSION

There has been a trend toward minimally invasive techniques for treatment of small renal tumors among Medicare patients. Laparoscopic partial nephrectomy has become the dominant treatment. In the setting of evidence showing comparable outcomes with surgery as well as lower costs to insurers, the volume of percutaneous ablation has also markedly increased.

Microwave versus radiofrequency ablation for the treatment of liver malignancies: a randomized controlled phase 2 trial

Microwave (MWA) and radiofrequency ablation (RFA) are main ablative techniques for hepatocellular carcinoma (HCC) and colorectal liver metastasis (MT). This randomized phase 2 clinical trial compares the effectiveness of MWA and RFA as well as morphology of corresponding ablation zones. HCC and MT patients with 1.5–4 cm tumors, suitable for ablation, were randomized into MWA or RFA Groups. The primary endpoint was short-to-long diameter ratio of ablation zone (SLR). Primary technical success (TS) and a cumulative local tumor progression (LTP) after a median 2-year follow-up were compared. Between June 2015 and April 2020, 82 patients were randomly assigned (41 patients per group). For the per-protocol analysis, five patients were excluded. MWA created larger ablation zones than RFA (p = 0.036) although without differences in SLR (0.5 for both groups, p = 0.229). The TS was achieved in 98% (46/47) and 90% (45/50) (p = 0.108), and LTP was observed in 21% (10/47) vs. 12% (6/50) (OR 1.9 [95% CI 0.66–5.3], p = 0.238) of tumors in MWA vs. RFA Group, respectively. Major complications were found in 5 cases (11%) vs. 2 cases (4%), without statistical significance. MWA and RFA show similar SLR, effectiveness and safety in liver tumors between 1.5 and 4 cm.

Direction of Tissue Contraction after Microwave Ablation: A Comparative Experimental Study in Ex Vivo Bovine Liver

Objective

This study aimed to investigate the direction of tissue contraction after microwave ablation in ex vivo bovine liver models.

Materials and Methods

Ablation procedures were conducted in a total of 90 sites in ex vivo bovine liver models, including the surface (n = 60) and parenchyma (n = 30), to examine the direction of contraction of the tissue in the peripheral and central regions from the microwave antenna. Three commercially available 2.45-GHz microwave systems (Emprint, Neuwave, and Surblate) were used. For surface ablation, the lengths of two overlapped square markers were measured after 2.5- and 5-minutes ablations (n = 10 ablations for each system for each ablation time). For parenchyma ablation, seven predetermined distances between the markers were measured on the cutting plane after 5- and 10-minutes ablations (n = 5 ablations for each system for each ablation time). The contraction in the radial and longitudinal directions and the sphericity index (SI) of the ablation zones were compared between the three systems using analysis of variance.

Results

In the surface ablation experiment, the mean longitudinal contraction ratio and SI from a 5-minutes ablation using the Emprint, Neuwave, and Surblate systems were 28.92% and 1.04, 20.10% and 0.53, and 24.90% and 0.45, respectively (p < 0.001). A positive correlation between longitudinal contraction and SI was noted, and a similar radial contraction was observed. In the parenchyma ablation experiment, the mean longitudinal contraction ratio and SI from a 10-minutes ablation using the three pieces of equipment were 38.60% and 1.06, 32.45% and 0.61, and 28.50% and 0.50, respectively (p < 0.001). There was a significant difference in the longitudinal contraction properties, whereas there was no significant difference in the radial contraction properties.

Conclusion

The degree of longitudinal contraction showed significant differences depending on the microwave ablation equipment, which may affect the SI of the ablation zone.

Percutaneous Image-Guided Ablation of Lung Tumors

Tumors of the lung, including primary cancer and metastases, are notoriously common and difficult to treat. Although surgical resection of lung lesions is often indicated, many conditions disqualify patients from being surgical candidates. Percutaneous image-guided lung ablation is a relatively new set of techniques that offers a promising treatment option for a variety of lung tumors. Although there have been no clinical trials to definitively compare its efficacy to those of traditional treatments, lung ablation is widely practiced and generally accepted to be safe and effective. Especially encouraging results have recently emerged for cryoablation, one of the newer ablative techniques. This article reviews the indications, techniques, contraindications, and complications of percutaneous image-guided ablation of lung tumors with special attention to cryoablation and its recent developments in protocol optimization.

Image-guided locoregional non-intravascular interventional treatments for hepatocellular carcinoma: Current status

Hepatocellular carcinoma (HCC) is one of the most deadly and frequent cancers worldwide, although great advancement in the treatment of this malignancy have been made within the past few decades. It continues to be a major health issue due to an increasing incidence and a poor prognosis. The majority of patients have their HCC diagnosed at an intermediate or advanced stage in theUSA or China. Curative therapy such as surgical resection or liver transplantation is not considered anoption of treatment at these stages.

Transarterial chemoembolization (TACE), the most widely used locoregional therapeutic approach, used to be the mainstay of treatment for cases with unresectable cancer entities. However, for those patients with hypovascular tumors or impaired liver function reserve, TACE is a suboptimal treatment option. For example, embolization does not result in complete coverage of a hypovascular tumor, and may rather promotes postoperative tumor recurrence, or leave residual tumor, in these TACE-resistance patients. In addition, TACE carries a higher risk of hepatic decompensation in patients with poor liver function or reserve.

Non-vascular interventional locoregional therapies for HCC include radiofrequency ablation (RFA), microwave ablation (MWA), high-intensity focused ultrasound (HIFU), laser-induced thermotherapy (LITT), cryosurgical ablation (CSA), irreversible Electroporation (IRE), percutaneous ethanol injection (PEI), and brachytherapy. Recent advancements in these techniques have significantly improved the treatment efficacy of HCC and expanded the population of patients who qualify for treatment. This review embraces the current status of imaging-guided locoregional non-intravascular interventional treatments for HCCs, with a primary focus on the clinical evaluation and assessment of the efficacy of combined therapies using these interventional techniques.

Use of percutaneous microwave ablation in the treatment of retroperitoneal neoplasia in three dogs

CASE DESCRIPTION

3 dogs with retroperitoneal masses (2 renal and 1 located near the diaphragm) were treated by percutaneous microwave ablation (MWA).

CLINICAL FINDINGS

Dogs between 11 and 13 years of age weighing between 13.7 and 43.8 kg had either a renal mass (n = 2) or a mass located in the caudodorsal aspect of the retroperitoneal space near the right side of the diaphragm (1). Cytology revealed that one of the renal masses and the mass located near the diaphragm were malignant neoplasias. Findings on cytologic evaluation of a sample of the other renal mass was nondiagnostic. Maximum mass diameters ranged between 1.4 and 2.5 cm.

TREATMENT AND OUTCOME

All dogs were treated by percutaneous MWA. Probes were directed into tumors by use of ultrasound and CT guidance, and microwave energy was applied to each mass. Findings on imaging of each mass following MWA was consistent with successful treatment. No intraprocedural or major postprocedural complications occurred, and all dogs were discharged from the hospital within 3 days of treatment. Two dogs died at 3 and 21 months after MWA with no known local recurrence; 1 dog was still alive 64 months after treatment.

CLINICAL RELEVANCE

Although the indications for MWA in the treatment of neoplasia in companion animals are limited, the outcomes of dogs in the present report provided preliminary evidence that percutaneous MWA can be safely used to effectively treat retroperitoneal neoplasia. This procedure was successfully performed with image guidance in all 3 dogs.

Cryoablation in Locoregional Management of Complex Unresectable Chest Neoplasms

RATIONALE AND OBJECTIVES

The aim of our retrospective study was to assess the safety and feasibility of cryoablation in high-risk patients with complex chest neoplastic lesions.

MATERIALS AND METHODS

Twenty patients with complex chest malignancies, both primary and secondary, located in the mediastinum, lung, and chest wall, underwent percutaneous CT-guided cryoablation treatments. Procedural success as well as complications were evaluated.

RESULTS

A total of 24 neoplastic lesions were treated (mean diameter: 27 mm; range: 7-54 mm). Technical success was obtained in all patients, without major complications or intraprocedural death. A pneumothorax not requiring a drainage tube placement was registered in 50% of patients, while 3/24 patients had a grade 3 pneumothorax requiring a chest tube placement.

CONCLUSION

Percutaneous CT-guided cryoablation seems a safe and feasible treatment for complex thoracic lesions.

Current trends and perspectives in interventional radiology for gastrointestinal cancers

Gastrointestinal (GI) cancers often require a multidisciplinary approach involving surgeons, endoscopists, oncologists, and interventional radiologists to diagnose and treat primitive cancers, metastases, and related complications. In this context, interventional radiology (IR) represents a useful minimally-invasive tool allowing to reach lesions that are not easily approachable with other techniques. In the last years, through the development of new devices, IR has become increasingly relevant in the context of a more comprehensive management of the oncologic patient. Arterial embolization, ablative techniques, and gene therapy represent useful and innovative IR tools in GI cancer treatment. Moreover, IR can be useful for the management of GI cancer-related complications, such as bleeding, abscesses, GI obstructions, and neurological pain. The aim of this study is to show the principal IR techniques for the diagnosis and treatment of GI cancers and related complications, as well as to describe the future perspectives of IR in this oncologic field.

Current Management of Oligometastatic Lung Cancer and Future Perspectives: Results of Thermal Ablation as a Local Ablative Therapy

A growing body of evidence shows improved overall survival and progression-free survival after thermal ablation in non-small cell lung carcinoma (NSCLC) patients with a limited number of metastases, combined with chemotherapy or tyrosine kinase inhibitors or after local recurrence. Radiofrequency ablation and microwave ablation are the most evaluated modalities, and target tumor size <3 cm (and preferably <2 cm) is a key factor of technical success and efficacy. Although thermal ablation offers some advantages over surgery and radiotherapy in terms of repeatability, safety, and quality of life, optimal management of these patients requires a multidisciplinary approach, and further randomized controlled trials are required to help refine patient selection criteria. In this article, we present a comprehensive review of available thermal ablation modalities and recent results supporting their use in oligometastatic and oligoprogressive NSCLC disease along with their potential future implications in the emerging field of immunotherapy.