Microwave Ablation Of Liver Tumors Research Articles

Single-arm prospective study comparing ablation zone volume between time zero and 24h after microwave ablation of liver tumors.

Percutaneous thermal ablation is an effective treatment for primary and metastatic liver tumors and is a recommended local therapy for early-stage hepatocellular carcinoma (HCC). Reported evidence shows an increase in the ablation zone volume over the first 24-h post-liver ablation. This report compares ablation zone volumes immediately at the completion (T = 0) of 26 microwave ablations of liver tumors to 24-h post-procedure (T = 24) volumes. 20 patients, 13 (65%) males, underwent a total of 26 hepatic microwave ablations (MWA) under ultrasound guidance. Contrast-enhanced CT (CECT) or MRI was performed immediately and another CECT 24h post operatively. Evaluation of the ablation zone and comparison of the two post-operative scans were done using BioTrace software. The expansion of ablation zones on post-op CECTs was matched point by point per direction. The distance between each 2 points was measured and grouped by distance. The incidence of each specific distance was then converted into a percentage, first for each case separately, then for all cases altogether. Data were tested by a matched paired one-sided t test. The median lesion diameter was 1.5cm (range 0.5-3.3) with 16 (62%) HCC cases and 9 hepatic metastases (4 neuroendocrine carcinoma, 4 colorectal carcinomas, 1 breast carcinoma, 1 pancreatic cancer). The data show a consistent volume expansion greater than 30% (p = 7.7e-5) 24-h post-ablation, where the median expansion is 57%. Distances between T = 0 and T = 24 equal to 3-7mm occur in over 35% of the cases. The ablation zone expansion at 24-h post-op was not uniform. The final ablation zone is difficult to predict at the time of the procedure. The awareness of the ablation zone expansion is important when treating near-critical structures, managing the heat sink effect, and preserving liver parenchyma.

Effectiveness of integrated prophylactic antibiotics prescription in patients undergoing radiofrequency and microwave ablation of liver tumors: a retrospective cohort study

An institutionalised in-house antibiotic prophylaxis (AP) guideline was developed in May 2019 to standardize AP prescription. This retrospective cohort study evaluated the effectiveness and clinical outcomes of the newly launched AP guideline on patients undergoing radiofrequency (RFA) and microwave (MWA) ablation of the liver from November 2018 to March 2020. Patients without high risk of biliary tree contamination were recommended a single dose of 2g IV cefazolin (or 600mg IV clindamycin in cases of beta-lactam allergy). Univariate analysis was conducted to evaluate the clinical outcomes.
 
 The study included 87 patients who underwent 93 procedures consisting of 18 RFAs and 75 MWAs for liver tumours. Concordance with AP guidelines improved significantly (38.5% vs. 87.0%; p<0.001). There were no ablation-related infections and mortality within 30 days post-ablation, and post-procedural nausea and vomiting were significantly reduced (15.4% vs. 1.9%; p=0.020). No significant difference in post-procedural fever (7.7% vs. 5.6%; p-value=0.693), chest and/or abdominal pain (5.1% vs. 7.4%; p=1.000) were noted.
 
 The newly implemented in-house antibiotic prophylaxis guideline streamlined AP prescribing in patients undergoing RFA and MWA. Additional research is needed to determine the effects on infection and mortality in patients with high-risk factors such as bile duct stents, sphincterotomies, and biliary-enteric anastomoses.

Application and evaluation of hydrodissection in microwave ablation of liver tumours in difficult locations.

To investigate the safety and mid-term outcomes of hydrodissection-assisted microwave ablation (MWA) of hepatocellular carcinoma (HCC) in various difficult locations. A total of 131 HCC patients who underwent ultrasound-guided MWA from March 2017 to March 2019 were included. Following ultrasound examination, patients with tumors at difficult locations were treated with hydrodissection-assisted MWA (hydrodissection group), while those with tumors at conventional locations received MWA (control group). Both groups were compared concerning baseline characteristics, ablation parameters, complete ablation rates, and complication rates. Kaplan-Meier curves analyzed local tumor progression and overall survival, with stratified analysis for different difficult locations (adjacent to gastrointestinal tract, diaphragm, and subcapsular tumors). Additionally, Cox regression analyses were conducted to assess the impact of different difficult locations on these outcomes. Complete ablation rates were similar between the hydrodissection and control groups (91.4% vs. 95.2%, P>0.05). Postoperative complications occurred in three patients, including liver abscess and biliary injury. No significant differences in major or minor complication rates were found between the groups (P>0.05). Local tumor progression was detected in 11 patients (8.4%) at the end of the follow-up period. Neither cumulative local tumor progression rate (P=0.757) nor overall survival rate (P=0.468) differed significantly between the groups. Stratified analysis showed no effect of tumor location difficulty on cumulative local tumor progression or overall survival. Tumor number and size served as independent predictors for overall survival, while minimal ablation margin ≤ 5mm independently predicted local tumor progression. In contrast, the tumor location was not statistically significant. Sensitivity analyses corroborated the robustness of the models. Hydrodissection-assisted MWA for HCC in various difficult locations demonstrated safe and effective, with complete ablation and mid-term outcomes comparable to those for tumors in conventional locations.

Microwave ablation modeling with AMICA antenna: Validation by means a numerical analysis

Background and objectivesPercutaneous microwave thermal ablation is based on electromagnetic waves that generate dielectric heating, and it is widely recognized as one of the mostly used techniques for tumor treatment. The aim of this work is to validate a predictive model capable of providing physicians with guidelines to be used during thermal ablation procedures avoiding collateral damage. MethodsA finite element commercial software, COMSOL Multiphysics, is employed to implement a tuning-parameter approach. Governing equations are written with reference to variable-porosity and Local Thermal Non-Equilibrium (LTNE) equations are employed. The simulations results are compared with available ex-vivo and in-vivo data with the help of regression analysis. For in-vivo data simulations, velocity vector modulus and direction are varied between 0.0007 and 0.0009 m/s and 90–270°, respectively, in order to use this parameter as a tuning one to simulate – and lately optimize with respect to the differences from experimental outcomes - all the possible directions of the blood flow with respect to the antenna, whose insertion angle is not registered in the dataset. ResultsThe model is validated using reference data provided by the manufacturer (AMICA), which is obtained from ex-vivo bovine liver. The model accurately predicts the size and shape of the ablated area, resulting in an overestimation lesser than 10 %. Additionally, predictive data are compared to an in-vivo dataset. The ablated volume is accurately predicted with a mean underestimation of 6 %. The sphericity index is calculated as 0.75 and 0.62 for the predictions and in-vivo data, respectively. ConclusionThis study developed a predictive model for microwave ablation of liver tumors that showed good performance in predicting ablation dimensions and sphericity index for ex-vivo bovine liver and for in-vivo human liver data with the tuning technique. The study emphasizes the necessity for additional development and validation to enhance the accuracy and reliability of in-vivo application.

Combined multiple regional anesthesia for microwave ablation of liver Tumors: Initial experience

ObjectiveThis study aims to assess the feasibility and safety of combined multiple regional anesthesia (CMRA) as a potential strategy to decrease pain and reliance on intravenous analgesics during and after ultrasound-guided microwave ablation (US-guided-MWA) of liver tumors. MethodsA cohort of 75 patients with a total of 99 liver tumors who underwent US-guided-MWA of liver tumors were enrolled. These patients were randomly allocated into three groups: A, B, and C. Prior to the ablation procedure, Group A patients received a combination of hepatic hilar block (HHB), Transversus abdominis plane block (TAPB), and local anesthesia (LA). Patients in Group B were administered HHB in conjunction with LA, while those in Group C received TAPB and LA. Evaluative parameters included the Numerical Rating Scale (NRS) scores, consumption of morphine, incidence of complications, and factors influencing perioperative pain. ResultsAll patients successfully underwent US-guided-MWA. The peak NRS scores for pain during ablation across the three groups were 2.36 ± 1.19, 3.28 ± 1.59, and 4.24 ± 1.42 respectively (P < 0.01), while the count of patients requiring morphine were 4/25, 8/25, and 13/25 respectively (P < 0.01). Postoperative NRS scores for the three groups at 4, 8, 12, 24, and 36-hour intervals demonstrated a pattern of initial increase followed by a decrease, with the order at each interval being: Group A < Group C < Group B. Factors associated with increased pain included larger tumor size, greater number of tumors, and longer procedure and ablation time (P < 0.05). No major complications were recorded across the three groups. ConclusionCMRA offers an effective and safe modality to manage pain during and after US-guided-MWA of liver tumors.

Evaluation of paravertebral blocks in improving post-procedural pain and decreasing hospital admission after microwave ablation of liver tumors

Although ablations are performed with conscious sedation or general anesthesia, microwave ablations can be painful post procedure. Newer analgesic modalities, including regional blocks, have promoted the proliferation of less invasive anesthesia care for ablative procedures. This study evaluates whether bilateral paravertebral blocks reduce the need for additional analgesics in comparison to unilateral blocks in microwave ablations. In this retrospective study, individuals undergoing microwave ablation who underwent unilateral versus bilateral nerve blocks at a single institution from 2017 to 2019 were compared. Categorical variables were analyzed using Pearson’s chi-squared tests. Comparisons of means were completed using multiple T-tests corrected using the Holm-Sidak method with alpha = 0.05. Regression modeling was used to identify factors related to increased MME (milligram morphine equivalent) usage and post-procedure admission rates. A total of 106 patients undergoing 112 liver MWA procedures were included in this analysis, with patients receiving either a bilateral or unilateral block. Pre-procedural characteristics demonstrated no significant differences in age or gender. Bilateral blocks were associated with decreased usage of gabapentin (14% vs. 0%, p = 0.01) and a lower rate of post-procedure admissions (OR 0.23, p = 0.003). Therefore, when using paravertebral blocks, bilateral blocks are superior to unilateral blocks, as demonstrated by decreased rates of hospital admission and reduced use of systemic neuropathic pain medication. Additionally, reducing post-procedural MME may reduce the rate of admission to the hospital.

Multifunctional high-simulation 3D-printed hydrogel model manufacturing engineering for surgical training.

Advanced bionic organ models with vivid biological structures and wetness and softness are essential for medical-surgical training. Still, there are many challenges in the preparation process, such as matching mechanical properties, good feedback on surgical instruments, reproducibility of specific surgical scenarios, and distinguishability between structural levels. In this paper, we achieved tissuemimicking dual-network (DN) hydrogels with customizable stiffness by adjusting the composition of the hydrogel matrix and the immersion time of the ionic solution to match different biological soft tissues precisely. Combined with advanced threedimensional (3D) printing fabrication techniques, various performance-tunable bionic hydrogel organ models with structural complexity and fidelity, including kidney, liver, pancreas, and vascular tissues, were perfectly fabricated. The simulation and applicability of the model were also simulated for the forced change of the suture needle in the puncture and suture of a single tissue and between different tissues, the cutting of substantive organs by ultrasonic scalpel, the coagulation and hemostasis of blood vessels, the visualization of the internal structure under ultrasound, and the microwave ablation of liver tumors. By constructing advanced biomimetic organ models based on hydrogel with specific and tunable properties, the development of surgical training, medical device testing, and medical education reform will be significantly promoted.

Decreased Length of Stay and Opioid Usage After Liver Cancer Surgery With Enhanced Recovery Pathway Implementation.

Enhanced recovery after surgery (ERAS) pathways are associated with better postoperative recovery; however, evidence is lacking in liver cancer surgery. This study aimed to evaluate the impact of an ERAS pathway in US veterans undergoing liver cancer surgery. We initiated an ERAS pathway for liver cancer surgery with preoperative, intraoperative, and postoperative interventions, which included a novel regional anesthesia technique, erector spinae plane block, for multimodal analgesia management. A retrospective quality improvement study was conducted with patients undergoing elective open hepatectomy or microwave ablation of liver tumors before and after ERAS pathway implementation. With 24 patients in the post-ERAS group and 23 patients in the pre-ERAS group, we found a significant decreased length of stay in the ERAS group (4.1 days ± 3.9) compared with traditional care (8.6 days ± 7.1, P = .01) and decreased perioperative opioid consumption including intraoperative opioids (post-ERAS 49.8 mg ± 28.5 vs pre-ERAS 98 mg ± 42.3, P = 4.1E-5), postoperative opioids (post-ERAS 65.3 mg ± 59.9 vs pre-ERAS 175.7 mg ± 210.6, P = .018), and patient-controlled analgesia requirements (post-ERAS 0% vs pre-ERAS 50%, P < .001). The implementation of ERAS for liver cancer surgery in our veteran population translates into decreased length of stay and perioperative opioid consumption. Although this study is limited as a quality improvement project implemented at one institution with a small sample size, our results are clinically and statistically significant and sufficient to warrant further investigation into the efficacy of ERAS as the surgical needs of the US veteran population increase.

Virtual Treatment Zone From Cone Beam CT Commonly Alters Treatment Plan and Identifies Tumor at Risk for Under-Treatment in US or US Fusion-Guided Microwave Ablation of Liver Tumors.

Tumor ablation is included in several major cancer therapy guidelines. One technical challenge of percutaneous ablation is targeting and verification of complete treatment, which is prone to operator variabilities and human imperfections and are directly related to successful outcomes, risk for residual unablated tumor and local progression. The use of "Prediction Ablation Volume Software" may help the operating Interventional Radiologist to better plan, deliver, and verify before the ablation, via virtual treatment zones fused to target tumor. Fused and superimposed images provide 3-dimensional information from different timepoints, just when that information is most useful. The aim of this study is to evaluate the technical success and efficacy of an ablation treatment flowchart provided by a cone beam computed tomography (CBCT) "Prediction Ablation Volume Software." This is a single-center retrospective study. From April 2021 to January 2022, 29 nonconsecutive evaluable patients with 32 lesions underwent liver ablation with Prediction Ablation Volume Software. Each patient was discussed in a multidisciplinary tumor board and underwent an enhanced computed tomography or magnetic resonance imaging approximately 1 month before the procedure, as well as ∼1 month after. Technical success was defined as treatment of the tumor according to the protocol, covered completely by the Prediction Ablation Volume. Technical efficacy was defined as assessment of complete ablation of the target tumor at imaging follow up (∼1 month). Technical success, technical efficacy, and procedural factors were studied. Technical success was achieved in 30 of 32 liver lesions (94%), measuring 20 mm mean maximum diameter. The antenna was repositioned in 16 of 30 (53%) evaluable target lesions. Residual tumor was detected at 1 month imaging follow up in only 4 of 30 (13%) of the treated lesion. Technical efficacy was of 87% in this retrospective description of our process. The implementation of a CBCT Prediction Ablation Volume Software and flowchart for the treatment of liver malignancies altered the procedure, and demonstrated high technical success and efficacy. Such tools are potentially useful for procedural prediction and verification of ablation.

Concordance of Intra-operative Ultrasound with Pre-operative MRI for Microwave Ablation of Liver Tumors

Concordance of Intra-operative Ultrasound with Pre-operative MRI for Microwave Ablation of Liver Tumors

Three Year Single Center Experience with Systematic CT-guided Stereotactic Microwave Ablation for Liver Tumors

Three Year Single Center Experience with Systematic CT-guided Stereotactic Microwave Ablation for Liver Tumors

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

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

Feasibility and efficacy of superconducting open-configuration magnetic resonance-guided microwave ablation of malignant liver tumors with real-time imaging sequences.

To evaluate the safety and effectiveness of open superconducting magnetic resonance (MR)-guided microwave ablation of liver tumors and explore feasibility of real-time imaging sequence-guided needle insertion technique. Medical records of December 2019-May 2021 of microwave ablations of liver tumors under MR guidance in XX University Cancer Center were reviewed. Real-time imaging-guided puncture technique refers to real-time insertion and adjusting the position of a microwave applicator under a fast imaging sequence. The safety and efficacy of the procedure among the enrolled patients were assessed. Twenty-six patients underwent 27 procedures, with 30 lesions ablated (long diameter: 1.51 ± 0.81 cm, short diameter: 1.30 ± 0.61 cm). There were 20 cases of primary liver cancer and 10 of liver metastases. All lesions were identified by MR imaging (MRI), and all procedures were successfully performed using the finger positioning method for puncture sites. Five patients underwent real-time guided needle insertion techniques. Further, the microwave applicators reached the target position at once, and the entire insertion process was completed within 3 min. The completion rate of the real-time guided needle insertion technology was 100%, and 25 (92.6%) patients had minor complications. No severe complications were observed, and the technical success rate of 30 MRI-guided lesions was 100%. Finally, the complete ablation rate of the MRI-guided ablation after the first procedure was 93.1%. Open MR-guided microwave ablation is safe and effective in treating liver tumors. Furthermore, real-time imaging sequence-guided puncture technique under MRI is feasible and efficient.

Comparison of deep and moderate neuromuscular blockade in microwave ablation of liver tumours: a randomized-controlled clinical trial

Microwave ablation (MWA) is gaining popularity for the treatment of small primary hepatocellular carcinoma and metastatic lesions especially if patients are not candidates for surgical resection. Deep neuromuscular blockade (DMB) is perceived to improve surgical working conditions compared to moderate neuromuscular blockade (MMB) but no studies have examined the same benefits in MWA of liver tumours. This study aimed to compare the clinical outcomes of DMB and MMB in MWA of liver tumours in terms of liver excursion, performance scores by the interventional radiologists and patients, requirements of additional muscle relaxants and complications. 50 patients were recruited and 45 patients (22 in MMB group, 23 in DMB group) completed the study. The mean liver excursion for the MMB group (1.42 ± 1.83 mm) was significantly higher than the DMB group (0.26 ± 0.38 mm) (p = 0.001). The mean Leiden-Surgical Rating Scale (L-SRS) rated by the two interventional radiologists were 4.5 ± 0.59 and 3.6 ± 0.85 for the DMB and MMB groups, respectively (p = 0.01). There was also statistically significant difference on patient satisfaction scores (0–10: Extremely Dissatisfied–Extremely Satisfied) between DMB (8.74 ± 1.1) and MMB (7.86 ± 1.25) groups (p = 0.01). 5 patients from MMB group and none from DMB group required bolus relaxant during the MWA procedure. Adverse events were also noted to be more severe in the MMB group. In conclusion, DMB significantly reduced liver excursion and movement leading to improved accuracy, safety and success in ablating liver tumour.

Abstract No. 521 Use of electromagnetic tracking navigation software and its effect on percutaneous microwave ablation of liver tumors

Electromagnetic tracking (ET) navigation software has been previously shown to reduce radiation dose, number of CT scans, and needle manipulations in biopsy patients. The purpose of our study is to evaluate the safety and efficacy of ET navigation software in patients undergoing microwave ablation of liver tumors. A single-center, retrospective review of all microwave ablations of liver tumors less than or equal to 3 cm in diameter from January 1, 2017 through June 30, 2109 was performed. Variables recorded include patient demographics, type of tumor, number of tumors ablated in a single session, number of CT scans (NCT), radiation dose (RD), tumor location, ± preablation iodized oil stain of target lesion (IOS), response rate (using mRECIST criteria), adverse events, procedure time (PT), and anesthesia time (AT). In total, 266 tumors were ablated in 196 patients, over 231 sessions; median age of patients is 66 years old, with 74.1% male. 90 tumors were ablated using ET and 156 were ablated without ET. The median RD for the ET patients was 656 mGycm, compared to 683 mGycm in the non-ET group (P = 0.05). Median NCT in the ET group was 5 and 6 in the non-ET group (P <0.01). ET patients with IOS tumors had lower RD and NCT compared to non-ET patients with IOS (P = 0.02, P <0.01 respectively) and non-ET patients without IOS in their tumors (P = 0.09, P = 0.01 respectively). For difficult to navigate dome lesions (tumors in segments 7 and 8 based Couinaud classification), ET patients had lower RD and NCT compared to non-ET patients (P = 0.1, P <0.01 respectively). PT between the ET and non-ET dome lesion groups was not significantly different in patients undergoing ablation of a single tumor (53 minutes versus 50 minutes, P = 0.27); similar findings were also noted for AT (2 hours and 7 minutes versus 2 hours and 3 minutes, P = 0.67). Complete response rate at 3 months was 98.2% in the ET group and 92.1% in the non-ET group (P = 0.04). ET can potentially reduce RD and NCT in microwave ablation patients, including in tumors with IOS or a dome lesion. PT and AT were comparable between the two groups. Additionally, ET may improve complete response rate at 3 months post procedure.Tabled 1nMedian RD (mGycm)Median NCTET906565Non-ET1566836P = 0.05P <0.01ET + stain356425ET (no stain)55656.56Non-ET + stain926577Non-ET (no stain)646976ET + stain/non-ET + stainP = 0.02P <0.01ET + stain/non-ET (no stain)P = 0.09P = 0.01ET + dome277396ET + non-dome60591.355Non-ET + dome588388Non-ET + non-dome98605.56ET + dome/non-ET + domeP = 0.1P <0.01 Open table in a new tab

4:21 PM Abstract No. 41 Unilateral thoracic paravertebral regional anesthesia reduces intraprocedure opioid administration for microwave ablation of liver tumors

4:21 PM Abstract No. 41 Unilateral thoracic paravertebral regional anesthesia reduces intraprocedure opioid administration for microwave ablation of liver tumors

Safety margin assessment after microwave ablation of liver tumors: inter- and intrareader variability.

BackgroundThe aim of the study was to evaluate the inter- and intrareader variability of the safety margin assessment after microwave ablation of liver tumors using post-procedure computed tomography (CT) images as well as to determine the sensitivity and specificity of identification remnant tumor tissue.Patients and methodsA retrospective analysis of 58 patients who underwent microwave ablation (MWA) of primary or secondary liver malignancies (46 hepatocellular carcinoma, 9 metastases of a colorectal cancer and 3 metastases of pancreatic cancer) between September 2017 and June 2019 was conducted. Three readers estimated the minimal safety margin in millimeters using side-by-side comparison of the 1-day pre-ablation CT and 1-day post-ablation CT and judged whether ablation was complete or incomplete. One reader estimated the safety margin again after 6 weeks. Magnetic resonance imaging (MRI) after 6 weeks was the gold standard.ResultsThe intraclass correlation coefficient (ICC) for estimation of the minimal safety margin of all three readers was 0.357 (95%-confidence interval 0.194–0.522). The ICC for repeated assessment (reader 1) was 0.774 (95%-confidence interval 0.645–0.860). Sensitivity and specificity of the detection of complete tumor ablation, defined as no remnant tumor tissue in 6 weeks follow-up MRI, were 93%/82%/82% and 33%/17%/83%, respectively.ConclusionsIn clinical practice, the safety margin after liver tumor ablation is often assessed using side-by-side comparison of CT images. In the study, we were able to show, that this technique has a poor reliability (ICC 0.357). From our point of view, this proves the necessity of new technical procedures for the assessment of the safety distance.

Complications from percutaneous microwave ablation of liver tumours: a pictorial review.

Percutaneous microwave ablation of liver tumours is a well-established technique that has been proven to be effective in the curative and palliative treatment of small volume primary and secondary liver tumours. Microwave ablation is designed to achieve larger areas of necrosis compared to radiofrequency ablation and has a good safety profile among liver tumour treatments. Mortality is unreported and major complications are rare. Knowledge of potential complications is essential for interventional radiologists performing liver ablation in order to reduce patient morbidity. The aim of this review is to illustrate major complications post microwave ablation in a pictorial format as well as a discussion on how best to avoid these complications.

Abstract No. 511 Tumor FDG avidity before and immediately following PET/CT-guided microwave ablation of liver tumors allows visualization and quantification of tumor tissue contraction

To measure liver tumor tissue contraction effects resulting from microwave ablation (MWA) using intraprocedural 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) images obtained before and after MWA. This HIPAA-compliant, retrospective study included 36 patients (16 women, 20 men; 37-85 years old, mean age 63) who underwent PET/CT-guided MWA of 42 FDG-avid liver tumors from May 2013 to February 2018. In three of the patients undergoing MWA, three additional FDG-avid tumors were not ablated (unablated tumors were considered for separate surgical or radiation therapy). The mean preprocedure FDG dose was 8.1mCi (range 4.9-12.0mCi). The pre- and post-ablation PET/CT images were obtained with a mean FDG uptake time of 101min and 176min, respectively. PET/CT images were reviewed by two readers reading by consensus. Mean tumor-to-normal-liver standardized uptake value ratio (SUVratio), mean tumor diameter (average of short and long axis), and automated tumor metabolic volume were measured for each tumor on both the pre and post-ablation PET images. Presence of central tumor necrosis on PET/CT images prior to ablation was documented. A two-tailed paired t-test was used to analyze differences in these metrics before and after ablation. Comparing intraprocedural pre and post ablation PET images, the mean SUVratio (tumor-to-normal-liver) increased from 4.9 to 7.1, or 44% (p < 0.001). The mean tumor diameter decreased from 22.5mm to 16.4mm, or 27% (p < 0.001). The mean tumor volume decreased from 10.5 cm3 to 5.9 cm3, or 44% (p < 0.001). For the three centrally necrotic tumors, the mean tumor diameter decrease was only 11% (p < 0.05) and the mean tumor volume decrease (20%) was not significant (p = 0.13). No significant changes in mean tumor diameter (p = 0.42) and mean tumor volume (p = 0.65) were seen in the three unablated tumors. Intraprocedural PET images of FDG-avid liver tumors allow visualization and quantification of the tissue contraction effects of microwave ablation during FDG PET/CT-guided procedures. The ability to visualize the contracted tumor may be relevant when intraprocedural PET/CT imaging techniques are used to assess the ablation margin.

Computer-assisted needle trajectory planning and mathematical modeling for liver tumor thermal ablation: A review.

Radiofrequency ablation (RFA) and microwave ablation (MWA) have become an important means for treating liver tumors. RFA and MWA are a minimally invasive therapy which involves an ablation applicator or needle (i.e., radiofrequency electrode or microwave antenna) inserted percutaneously into a tumor under the guidance of medical imaging, so as to destroy the tumor in situ by heating-induced coagulation necrosis. Treatment planning, particularly needle trajectory planning, is crucial to RFA and MWA. In clinical procedures, however, needle trajectory planning still relies on the personal experience of clinicians. Manual needle trajectory planning is tedious and may cause inter-operator difference. Therefore, computer-assisted needle trajectory planning techniques are of clinical value and have been extensively explored. However, a literature review that focuses on computer-assisted needle trajectory planning for liver tumor RFA and MWA has not been reported. In this paper, we conducted an extensive review on computer-assisted needle trajectory planning for RFA and MWA of liver tumors. Fundamentals of needle trajectory planning are summarized. Algorithms for single-needle and multi-needle trajectory planning are analyzed. Shortcomings of current computer-assisted needle trajectory planning algorithms are discussed and future developments are suggested.