CT-guided Percutaneous Microwave Ablation Research Articles

CT-guided Percutaneous Microwave Ablation Combined with Local Radiotherapy or Chemotherapy of Malignant Pulmonary Tumors.

The study aimed to investigate the clinical efficacy of CT-guided microwave ablation (MWA) combined with 125I seed implantation or bronchial arterial infusion (BAI) chemotherapy in the treatment of malignant pulmonary tumors. A total of 56 patients who underwent MWA, MWA combined with 125I particle implantation, or MWA combined with BAI chemotherapy for advanced lung cancer or metastatic lung cancer from January 2015 to June 2021 in Guangdong Provincial People's Hospital were enrolled. Among them, 21 patients were treated with MWA (MWA), 18 with MWA combined with 125I seed implantation (MWA+125I), and 17 with MWA combined with BAI chemotherapy (MWA+BAI). The short-term outcomes, complications, Eastern Cooperative Oncology Group (ECOG) performance score (Zubrod-ECOG-WHO, ZPS), survival, and factors related to survival were compared between the three groups. The response rate of the MWA group (9.52%) was significantly lower than that of the MWA+125I group (50.00%) and MWA+BAI chemotherapy group (47.06%), and the differences were statistically significant (p < 0.05). The incidence of complications in the MWA, MWA+125I, and MWA+BAI chemotherapy groups was 47.62%, 55.56%, and 52.94%, respectively, with no significant difference (p > 0.05). Three months after the treatment, the ZPS of the MWA+125I and MWA+BAI chemotherapy groups was significantly lower than before treatment and significantly lower than that of the MWA group in the same period; the differences were statistically significant (p < 0.05). The median survival time of the MWA+125I group was 18 (9.983, 26.017) months and that of the MWA+BAI chemotherapy group was 21 (0.465, 41.535) months, both of which were higher than that of the MWA group [11 (6.686, 15.314) months]; the differences were statistically significant (p < 0.05). Cox regression analysis was performed on the factors related to survival and revealed treatment mode as a protective factor [HR = 0.433, 95% CI = (0.191, 0.984), p = 0.046]. Other factors, such as gender, age, and tumor size, did not independently affect survival. CT-guided MWA combined with 125I seed implantation and MWA combined with BAI chemotherapy are safe and effective for the treatment of advanced lung cancer and metastatic lung cancer, and can control tumor progression and prolong survival time.

Safety and efficacy of CT-guided percutaneous microwave ablation for stage I non-small cell lung cancer in patients with comorbid idiopathic pulmonary fibrosis.

To evaluate the safety and efficacy of microwave ablation (MWA) for stage I non-small cell lung cancer (NSCLC) in patients with idiopathic pulmonary fibrosis (IPF). A retrospective single-center cohort study was conducted in patients with clinical stage I NSCLC who underwent CT-guided MWA from Nov 2016 to Oct 2021. The patients were divided into the IPF group and the non-IPF group. The primary endpoints were 90-day adverse events and hospital length of stay (HLOS). The secondary endpoints included overall survival (OS) and progression-free survival (PFS). A total of 107 patients (27 with IPF and 80 without IPF) were finally included for analysis. No procedure-related acute exacerbation of IPF or death occurred post-MWA. The rates of adverse events were similar between the groups (48.6% vs. 47.7%; p = 0.998). The incidence of grade 3 adverse events in the IPF group was higher than that in the non-IPF group without a significant difference (13.5% vs. 4.6%; p = 0.123). Median HLOS was 5days in both groups without a significant difference (p = 0.078). The 1-year and 3-year OS were 85.2%/51.6% in the IPF group, and 97.5%/86.4% in the non-IPF group. The survival of patients with IPF was significantly poorer than the survival of patients without IPF (p < 0.001). There was no significant difference for PFS (p = 0.271). MWA was feasible in the treatment of stage I NSCLC in patients with IPF. IPF had an adverse effect on the survival of stage I NSCLC treated with MWA. CT-guided microwave ablation is a well-tolerated and effective potential alternative treatment for stage I non-small cell lung cancer in patients with idiopathic pulmonary fibrosis. • Microwave ablation for stage I non-small cell lung cancer was well-tolerated without procedure-related acute exacerbation of idiopathic pulmonary fibrosis and death in patients with idiopathic pulmonary fibrosis. • No differences were observed in the incidence of adverse events between patients with idiopathic pulmonary fibrosis and those without idiopathic pulmonary fibrosis after microwave ablation (48.6% vs. 47.7%; p = 0.998). • The 1-year and 3-year overall survival rates (85.2%/51.6%) in the idiopathic pulmonary fibrosis group were worse than those in the non- idiopathic pulmonary fibrosis group (97.5%/86.4%) (p < 0.001).

Comparison of Microwave and Radiofrequency Ablation for the Treatment of Small- and Medium-Sized Hepatocellular Carcinomas in a Prospective Randomized Trial.

To compare the therapeutic response and clinical outcome of CT-guided percutaneous microwave (MWA) and radiofrequency ablation (RFA) for the treatment of small- and medium-sized HCC. In this prospective trial, 50 patients with HCC were randomly assigned to MWA or RFA treatment. MRI was performed 24 h before and after ablation and subsequently in 3-month intervals. Ablation volumes, ablation durations, adverse events (AE), technique efficacy, technical success, local tumor progression (LTP), disease-free survival (DFS), intrahepatic distant recurrence (IDR), and overall survival (OS) rates were evaluated. The mean ablation volume was 66.5 cm³ for MWA and 29.2 cm³ for RFA (p < 0.01). The mean ablation durations for MWA and RFA were 11.2 ± 4.0 min and 16.3 ± 4.7 min, respectively (p < 0.01). Six mild AEs were documented (p > 0.05). All treatments had a technical success rate and a technique efficacy rate of 100 % (50/50, p = 1.00). LTP within 2 years occurred in 1/25 (4 %) in the MWA group and in 4/25 (16 %) in the RFA group (p = 0.06). IDR within 2 years was 8/25 (32 %) for MWA and 14/25 (56 %) for RFA (p < 0.05). The median DFS was 24.5months and 13.4 months for MWA and RFA, respectively (p = 0.02). The 1-, 2-, 3-year OS rates were 100 %, 80 %, 72 % in the MWA group and 72 %, 64 %, 60 % in the RFA group, respectively (p ≥ 0.14). The clinical outcome after MWA or RFA for HCC treatment was very similar with no significant differences in LTP or OS. However, MWA shows a trend toward better DFS with fewer IDRs than RFA. · MWA allows for larger ablation volumes and a shorter treatment duration compared to RFA in patients with HCC.. · MWA shows a trend toward better disease-free survival and fewer intrahepatic distant recurrences compared to RFA.. · The three-year survival rates show no significant difference between the two methods..

Changes in the pulmonary function of CT-guided microwave ablation for patients with malignant lung tumors.

To investigate the changes in pulmonary function after computed tomography (CT)-guided microwave ablation (MWA) in patients with a malignant lung tumor. From June 2020 to January 2022, 133 patients with a malignant lung tumor who underwent CT-guided percutaneous MWA were included in the study. Pulmonary function tests (PFTs) were performed before (the baseline) and 1 month after the MWA. Vital capacity (VC), forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), FEV1%, maximum mid-expiratory flow (MMEF), and diffusion capacity of the lung for carbon monoxide (DLCO-SB) at 1 month post MWA were compared with that at the baseline. The time of procedure and post-procedure length of hospital stay were also recorded. The mean VC, FVC, FEV1, FEV1%, MMEF, and DLCO-SB at the baseline and 1 month post MWA were 3.23 ± 0.75 and 3.22 ± 0.77 (P = 0.926), 3.20 ± 0.75 and 3.21 ± 0.77 (P = 0.702), 2.35 ± 0.70 and 2.35 ± 0.71 (P = 0.992), 91.97 ± 23.14 and 91.87 ± 23.16 (P = 0.837), 1.83 ± 0.93 and 1.81 ± 0.95 (P = 0.476), and 6.38 ± 1.67 and 6.32 ± 1.62 (P = 0.389), respectively. There was no significant difference in the PFT results before and 1 month post MWA. The mean time of procedure and post-MWA length of hospital stay were 33 min and 2.5 days, respectively. MWA is a lung parenchyma-sparing local treatment, and pulmonary function at 1 month post MWA was not statistically different from the baseline, indicating that MWA may not affect pulmonary function.

Synchronous percutaneous core-needle biopsy and microwave ablation for stage I non-small cell lung cancer in patients with Idiopathic pulmonary fibrosis: initial experience

Purpose This study aimed to retrospectively evaluate the safety and feasibility of computed tomography (CT)-guided synchronous percutaneous core-needle biopsy (CNB) and microwave ablation (MWA) for stage I non-small cell lung cancer (NSCLC) in patients with idiopathic pulmonary fibrosis (IPF). Methods From January 2019 to January 2023, nineteen stage I NSCLC patients with IPF underwent CT-guided synchronous percutaneous CNB and MWA in this study. The technical success rate, complications, local tumor progression (LTP) and overall survival (OS) were observed, and the effect of synchronous percutaneous CNB and MWA were evaluated. Results The technical success rate of synchronous percutaneous CNB and MWA was 100%. With a median follow-up time of 20.36 months, the median OS was 25 months (95% CI: 21.79, 28.20). The six-, twelve- and eighteen-month OS rates were 94.73%, 89.47% and 57.89%, respectively. The six-, twelve- and eighteen-month LTP rates were 0%, 10.52% and 31.57%, respectively. Major complications including pneumothorax, bronchopleural fistula and pneumonia occurred in 26.32% (5/19) patients. None of the patients died during the procedure. Conclusions According to the results of the current study, CT-guided synchronous percutaneous CNB and MWA appears to be a safe and effective for stage I NSCLC in patients with IPF and providing an alternative therapeutic option for local control of pulmonary malignancy in high-risk patients.

First validation of a model-based hepatic percutaneous microwave ablation planning on a clinical dataset

A model-based planning tool, integrated in an imaging system, is envisioned for CT-guided percutaneous microwave ablation. This study aims to evaluate the biophysical model performance, by comparing its prediction retrospectively with the actual ablation ground truth from a clinical dataset in liver. The biophysical model uses a simplified formulation of heat deposition on the applicator and a heat sink related to vasculature to solve the bioheat equation. A performance metric is defined to assess how the planned ablation overlaps the actual ground truth. Results demonstrate superiority of this model prediction compared to manufacturer tabulated data and a significant influence of the vasculature cooling effect. Nevertheless, vasculature shortage due to branches occlusion and applicator misalignment due to registration error between scans affects the thermal prediction. With a more accurate vasculature segmentation, occlusion risk can be estimated, whereas branches can be used as liver landmarks to improve the registration accuracy. Overall, this study emphasizes the benefit of a model-based thermal ablation solution in better planning the ablation procedures. Contrast and registration protocols must be adapted to facilitate its integration into the clinical workflow.

CT-guided percutaneous microwave ablation for pulmonary metastases from colorectal cancer: Prognosis analyses based on the origin of the primary tumor.

Microwave ablation (MWA) is becoming an effective therapy for inoperable pulmonary metastases from colorectal cancer (CRC). However, it is unclear whether the primary tumor location affects survival after MWA. This study aims to investigate the survival outcomes and prognostic factors of MWA based on different primary origins between colon and rectal cancer. Patients who underwent MWA for pulmonary metastases from 2014 to 2021 are reviewed. Differences in survival outcomes between colon and rectal cancer are analyzed with the Kaplan-Meier method and log-rank tests. The prognostic factors between groups are then evaluated by univariable and multivariable Cox regression analyses. A total of 118 patients with 154 pulmonary metastases from CRC are treated in 140 MWA sessions. Rectal cancer has a higher proportion with seventy (59.32%) than colon cancer with forty-eight (40.68%). The average maximum diameter of pulmonary metastases from rectal cancer (1.09 cm) is greater than that of colon cancer (0.89 cm; p = 0.026). The median follow-up is 18.53 months (range 1.10-60.63 months). The disease-free survival (DFS) and overall survival (OS) in colon and rectal cancer groups are 25.97 vs 11.90 months (p = 0.405), and 60.63 vs 53.87 months (p = 0.149), respectively. Multivariate analyses show that only age is an independent prognostic factor in patients with rectal cancer (HR = 3.70, 95% CI: 1.28-10.72, p = 0.023), while none in colon cancer. Primary CRC location has no impact on survival for patients diagnosed with pulmonary metastases after MWA, while a disparate prognostic factor exists between colon and rectal cancer.

Computed tomography-guided percutaneous microwave ablation for renal cell carcinoma: evaluating the performance of nephrometry scores.

The purpose of the current study is to evaluate the performance of RENAL and mRENAL scores, in the prediction of oncological outcomes in patients treated with microwave ablation (MWA) for (T1) renal cell carcinomas (RCC). Institutional database retrospective research identified 76 patients with a biopsy-proven solitary T1a (84%) or T1b (16%) RCC; all patients underwent CT-guided MWA ablation. Tumor complexity was reviewed by calculating RENAL and mRENAL scores. The majority of the lesions were exophytic (82.9%), with > 7mm nearness to the collecting system (53.9%), located posteriorly (73.6%), and lower to polar lines (61.8%). Mean RENAL and mRENAL scores were 5.7 (SD = 1.9) and 6.1 (SD = 2.1) respectively. Progression rates were significantly higher with greater tumor size (> 4cm), with < 4mm nearness to the collecting system, for tumors crossing a polar line and with the anterior location. None of the above was associated with complications. RENAL and mRENAL scores were significantly higher in patients with incomplete ablation. The ROC analysis showed the significant prognostic ability of both RENAL and mRENAL scores for progression. In both scores, the optimal cut-off point was 6.5. Univariate Cox regression analysis for progression showed a hazard ratio of 7.73 for the RENAL score and 7.48 for the mRENAL score. The results of the present study show that the risk of progression was higher in patients with RENAL and mRENAL score of > 6.5, in T1b tumors, close to the collective system (< 4mm), crossing polar lines and anterior location. CT-guided percutaneous MWA is a safe and effective technique for the treatment of T1a renal cell carcinomas.Different morphometric parameters of RCC tumors includingRENAL and mRENAL score > 6.5, size, proximity to the collecting system, and crossing of polar linesimpact the efficacy of MWA and progressionsurvival rates. • The risk of progression is higher in patients with RENAL and mRENAL score > 6.5, in T1b tumors, close to the collective system (< 4mm), crossing polar lines and anterior location. • The significant prognostic ability of the mRENAL score for progression was higher than the respective of the RENAL score. • Complications were not associated with any of the above factors.

Early enlarging cavitation after percutaneous microwave ablation of primary lung cancer

Purpose This retrospective study assessed the incidence rate, risk factors, and clinical course of early enlarging cavitation after percutaneous microwave ablation (MWA) of primary lung cancer (PLC). Methods This study included 557 lesions of 514 patients with PLC who underwent CT-guided percutaneous MWA between 1 January 2018 and 31 December 2021. Of these patients, 29 developed early enlarging cavitation and were enrolled in the cavity group, and 173 were randomly enrolled in the control group. Early enlarging cavitation of the lung was defined as the development of a cavity ≥30 mm within 7 days after MWA. Results Overall, 31 (5.57%, 31/557 tumors) early enlarging cavitations occurred at an average of 5.83 ± 1.55 d after MWA. The risk factors were lesion contact with a large vessel (diameter ≥3 mm), lesion contact with the bronchus (diameter ≥2 mm), and a large ablated parenchymal volume. The cavity group had a higher incidence rate of delayed hydropneumothorax (12.9%) and bronchopleural fistula (9.68%) than the control group, resulting in a longer hospitalization (9.09 ± 5.26 days). Until Dec 31, 2022, 27 cavities disappeared after a mean of 217.88 ± 78.57 d (range, 111–510 d), two persisted, and two were lost to follow-up. Conclusions Early enlarging cavitation occurred in 5.57% PLC cases that underwent MWA, causing serve complications and longer hospitalization. The risk factors were ablated lesion contact with large vessels and bronchi, as well as a larger ablated parenchymal volume.

Percutaneous CT-Guided Microwave Ablation Combined with Pedicle Screw Fixation Followed by Vertebroplasty (MASFVA): Initial Experience of a Minimally Invasive Treatment of Vertebral Metastases with Extension to the Vertebral Pedicle.

(1) Background: The aim of this study was to retrospectively evaluate the safety and efficacy of a combined CT-guided percutaneous microwave ablation (MWA) and pedicle screw fixation followed by vertebroplasty (MASFVA) for the treatment and stabilization of painful vertebral metastases with vertebral pedicle involvement. (2) Methods: from January 2013 to January 2017 11 patients with 16 vertebral metastatic lesions (7 men and 5 women; mean age, 65 ± 11 years) with vertebral metastases underwent CT-guided microwave ablation and screw fixation followed by vertebroplasty (MASFVA). Technical success, complication rate, pain evaluation using a visual analogue scale (VAS), Oswestry Disability Index (ODI) and local tumor control were examined. (3) Results: Technical success rate was 100%. No procedure-related major complications occurred. VAS score decreased from 6.8 ± 0.7 to 0.6 ± 0.6. ODI score decreased from 3.1 ± 0.7 to 1.2 ± 0.4. All patients could walk independently without neurological complication after one week from the procedure. No new bone fractures or local disease recurrence occurred during a median follow-up of 12 months. (4) Conclusions: Our results suggest that MWA and percutaneous pedicle screw fixation followed by vertebroplasty for the treatment of painful vertebral metastases is a safe and effective procedure for painful vertebral metastases with vertebral pedicle involvement, allowing pain relief and local tumor control.

The efficacy of computed tomography-guided percutaneous microwave ablation in patients with osteoid osteoma according to nidus location in long bones: A single-centre initial experience

This study aims to assess the efficacy of microwave ablation (MWA) treatment in painful extra-articular osteoid osteoma (OO) in long bones in a consecutive series of patients and to compare the technical and clinical success in terms of pain scores according to their location. A total of 23 patients who were diagnosed with OO in long bones and treated with MWA between January 1, 2016, and June 1, 2020 were enrolled in this study. Medical data and images were reviewed for age, gender, size of the nidus and duration of pain. Patients were then categorized into three groups according to the location of nidus (pertrochanteric, metaphyseal or diaphyseal). Operation length and technical and clinical success rates were compared. Technical success was achieved in 100% of patients. Primary clinical success following MWA was 82.6%. The most common location was the pertrochanteric region (34.8%). In comparing the pain scores with the locations of the lesions, no statistically significant difference was found between the first-day (p = 0.504) and first-week (p = 0.648). However, significant difference was present between the first month (p = 0.016), third month (p &lt; 0.001) and sixth month (p = 0.001). The statistically significant differences between the sites were due to the difference between the pertrochanteric and diaphyseal lesions. CT-guided percutaneous MWA is safe and effective in the treatment of OO located in long bones without any recurrence. However, management of pertrochanteric OOs requires specific expertise and follow up. Further studies are expected in the future to assess the long-term efficacy and safety of MWA for the treatment of OO, especially for cases in pertrochanteric locations of the femur, which have an increased risk of local recurrence.

Robotic laser position versus freehand in CT-guided percutaneous microwave ablation for single hepatocellular carcinoma (diameter < 3 cm): a preliminary study

Purpose To compare the accuracy and safety of robotic laser position (RLP) versus freehand for antenna CT-guided microwave ablation (MWA) of single hepatocellular carcinoma (HCC) (diameter < 3 cm). Materials and methods This retrospective study was conducted between May 2020 and June 2021. A total of 40 patients with early HCC who underwent CT-guided MWA were divided into two groups: a freehand group (n = 20) and a RLP group (n = 20). Based on in-plane and out-of-plane data, the actual puncture point error (APPE), number of repositioning procedures, and operative duration were compared using the Mann–Whitney U test. Ablation-related complications were compared using the Chi-squared test. Results The mean diameter of HCC patients who received MWA was 2.4 ± 0.5 cm. For in-plane APPE, APPE was comparable between the two groups (p = 0.299). However, for the out-of-plane position, the APPE in the freehand group was higher than that in the RLP group (p = 0.027). The number of repositioning procedures was 0 (range, 0–0) for RLP-guided procedures and 3 (range, 2–5) for freehand procedures, showing a statistically significant difference between the two groups (p < 0.001). The mean operative duration for freehand procedures was 39 min, compared with 26 min for RLP-guided procedures, showing a significant difference (p = 0.013). No deaths or major complications were directly related to MWA. Minor complications in the freehand group were comparable with those in the RLP group (p = 0.313). Conclusion RLP guidance significantly reduces the number of antenna repositioning procedures in MWA and improves puncture accuracy for target HCC out-of-plane. In addition, the operative duration of robotic guidance was shorter than that of freehand guidance.

A prospective trial of CT-guided percutaneous microwave ablation for lung tumors.

BackgroundPercutaneous ablation is an alternative treatment for lung cancer in non-operable patients. This is a prospective clinical trial for percutaneous microwave ablation (pMWA) of biopsy-proven lung cancer to demonstrate safety and efficacy.MethodsA prospective trial from 6-1-2016 to 1-1-2019 enrolled patients with biopsy-proven primary or metastatic lung cancer <3 cm in size and 1 cm away from the pleura for pMWA with the Emprint Ablation System with Thermosphere Technology for Phase I analysis, (Clinicaltrials.gov; #NCT0267302). Patients were followed for 1 year with PET/CT and PET/MR to determine patterns of recurrence and efficacy of ablation.ResultsAfter 12 patients consented for biopsy, 6 patients underwent treatment of 7 lesions, 3/6 women, median age of 67 (IQR, 65–70) years, body mass index (BMI): 27.8 (IQR, 21.4–32.1) kg/m2, lesion distance to pleura 24.4 (IQR, 13–38) mm, lesion size of 10.7 (IQR, 6–14) mm, and ablation duration time 5.9 (IQR, 3–10) minutes. pMWA were completed at 75 W. Twelve adverse events were reported (1 Grade 3, 3 Grade 2, and 8 Grade 1 events) with Grade 4 or 5 events. Mean % change after ablation in forced expiratory volume in one second (FEV1) was −2% and diffusion capacity for carbon monoxide (DLCO) was −1%. After 2–3 months, the lesions would decrease in size, rim thickness, fluorodeoxyglucose (FDG) activity, and T2 signal. FDG activity after 6 months was below blood pool in all cases. The ablation zones stabilized by 6–12 months. One patient expired during the study from pneumonia unrelated to ablation without local recurrence. Of the seven ablations during the 1 year follow-up, there was local tumor recurrence at 271 days following ablation at the apex of the ablation zone, subsequently successfully treated with percutaneous cryoablation (Cryo).ConclusionspMWA appears to be a safe and effective mechanism for treatment of primary and secondary tumors of the lung, with possible preservation of pulmonary function.

Factors Associated with Pulmonary Function Changes in Patients Undergoing Microwave Ablation for Pulmonary Ground-Glass Nodules.

Purpose: Microwave ablation has become an alternative treatment for pulmonary ground-glass nodules (GGN) and is widely accepted by clinicians. However, its effect on lung function remains unknown. Therefore, this retrospective study aimed to explore pulmonary function changes and associated risk factors in patients undergoing computed tomography (CT)-guided microwave ablation (MWA) for treating pulmonary GGN. Materials and Methods: Thirty-five patients diagnosed with pulmonary GGN on thin-layer chest CT and enhanced CT were examined. Patients unable or unwilling to undergo thoracoscopic surgery underwent CT-guided simultaneous percutaneous core needle biopsy and MWA. Pulmonary function tests (PFT) were performed before ablation and 3 days and 6 months post-ablation. Forced expiratory volume in one second (FEV1), FEV1%, forced vital capacity (FVC), maximal voluntary ventilation (MVV), and peak expiratory flow (PEF) values pre- and post-MWA were analysed. Linear regression analysis was used to examine the correlation between ablation volume and changes in PFT findings 3 days post-ablation. Associations between patient characteristics, rates of postoperative complications, and PFT findings were analysed. Results: Forty-eight lesions were completely ablated and examined intraoperatively. There were significant differences in pre- and post-operative PFT findings on day 3 but not at 6 months. The mean ablation volume after 3 days of 11.4 ± 6.3 cm3 was positively correlated with changes in FEV1, MVV, and PEF values. Patients’ age (mean, 59.4 ± 13.0 years) positively correlated with changes in PEF values. The rates of change in FVC and MVV values were significantly higher with multiple pulmonary nodules than with isolated pulmonary nodule. PFT findings were similar between patients who experienced or did not experience complications (eg, pneumothorax and pleural effusion). Conclusions: Pulmonary function could be impaired shortly after MWA. PFT findings may correlate with age, ablation volume, and number of ablated lesions. In most patients, pulmonary function returned to the preoperative state after 6 months.

Technical and safety performance of CT-guided percutaneous microwave ablation for lung tumors: an ablate and resect study.

BackgroundPercutaneous image-guided thermal ablation has an increasing role in the treatment of primary and metastatic lung tumors. Achieving acceptable clinical outcomes requires better tools for pre-procedure prediction of ablation zone size and shape.MethodsThis was a prospective, non-randomized, single-arm, multicenter study conducted by Medtronic (ClinicalTrials.gov ID: NCT02323854). Subjects scheduled for resection of metastatic or primary lung nodules underwent preoperative percutaneous microwave ablation. Ablation zones as measured via CT imaging following ablation immediately and before resection surgically versus predicted ablation zones as prescribed by the investigational system software were compared. This CT scan occurred after the ablation was finished but the antenna still in position. Time (minutes) from antenna placement to removal was 23.7±13.1 (n=14); median: 21.0 (range, 6.0 to 48.0). The definition of the secondary endpoint of complete ablation was 100% non-viable tumor cells based on nicotinamide adenine dinucleotide hydrogen (NADH) staining. Safety endpoints were type, incidence, and severity of adverse events.ResultsFifteen patients (mean age 58.9 years; 67% male; 33% female) were enrolled in the study, 33.3% (5/15) with previous thoracic surgery, 73% (11/15) with metastasis, and 27% (4/15) with primary lung tumors. All underwent percutaneous microwave ablation followed by surgical resection the same day. Complete ablation was detected in 54.4% (6/11), incomplete ablation in 36.4% (4/11), and delayed necrosis in 9.1% (1/11). There were no device-related adverse events. Ablation zone volume was overestimated in all patients.ConclusionsHistological complete ablation was observed in 55% of subjects. CT scanning less than an hour after ablation and tissue shrinkage may account for the smaller zone of ablation observed compared to predicted by the investigational system software.

Reduction of microwave ablation needle related metallic artifacts using virtual monoenergetic images from dual-layer detector spectral CT in a rabbit model with VX2 tumor

The purpose of the study was to investigate the application of virtual monoenergetic images (VMIs) in reducing metal artifacts in rabbit VX2 liver cancer models treated with microwave ablation (MWA) therapy. A total of 31 VX2 liver cancer models that accepted CT-guided percutaneous microwave ablation were analyzed. Conventional images (CIs) with the most severe metallic artifacts and their corresponding energy levels from 40 to 200 keV with 10 keV increment of VMIs were reconstructed for further analysis. Objective image analysis was assessed by recording the attenuation (HU) and standard deviation of the most severe hyper/hypodense artifacts as well as artifact-impaired liver parenchyma tissue. Two radiologists visually evaluated the extent of artifact reduction, assessed data obtained by a diagnostic evaluation of liver tissues, and appraised the appearance of new artifacts according to the grade score. Statistical analysis was performed to compare the difference between CIs and each energy level of VMIs. For subjective assessment, reductions in hyperdense and hypodense artifacts were observed at 170–200 keV and 160–200 keV, respectively. The outcomes of the diagnostic evaluation of adjacent liver tissue were statistically higher at 140–200 keV for VMIs than for CIs. In terms of objective evaluation results, VMIs at 90–200 keV reduced the corrected attenuation of hyperdense and of artifact-impaired liver parenchyma compared with CIs (P < 0.001). When VMIs at 80–200 keV decreased the hypodense artifacts (P < 0.001). Therefore, we concluded that VMIs at 170–200 keV can obviously decrease the microwave ablation needle-related metal artifacts objectively and subjectively in rabbit VX2 liver cancer models.

Abstract No. 157 Computed tomography–guided percutaneous microwave ablation as bridging therapy for patients with hepatocellular carcinoma awaiting liver transplant: a single-center experience

Our objective was to determine the pathologic response of computed tomography (CT)–guided percutaneous microwave ablation as bridging therapy for patients with hepatocellular carcinoma awaiting liver transplant. A single-center retrospective analysis was conducted of 78 patients (M:F = 67:13) with mean age of 58.9 years ± 14 months (SD) with 78 hepatocellular carcinoma within Milan criteria that were treated with percutaneous MWA as bridging therapy and subsequent orthotopic liver transplant between August 2014 and September 2018. The pathology reports of the explanted livers were reviewed to assess for residual disease. Residual disease was categorized as complete or incomplete necrosis. Patient demographics, tumor/procedural characteristics, and laboratory values were evaluated. Survival from time of ablation and time of transplant were recorded and compared between cohorts using log rank tests. Median time to liver transplant post-MWA was 10.9 months (7.4 - 14.1 months) (IQR). The mean tumor size was 2.45 cm ± .76 cm (SD), (range = 0.9-4.6 cm). The median survival from ablation was 56.7 (IQR = 72.2—42.9 months), and the median survival from transplant was 44.7 months (IQR = 59.0—32.6 months). Complete necrosis in 61% of cases. There was no significant difference in survival for patients with complete (P = 0.40) versus incomplete necrosis (P = 0.71). There was no significant difference in survival from orthotopic liver transplant between patients with macroscopically (P = 0.37) or microscopically (P = 0.68) evident disease. CT-guided percutaneous microwave ablation is effective in achieving complete necrosis for patients with hepatocellular carcinoma who are awaiting orthotopic liver transplant.

Risk prediction of pleural effusion in lung malignancy patients treated with CT-guided percutaneous microwave ablation: a nomogram and artificial neural network model

Objectives To develop an effective nomogram and artificial neural network (ANN) model for predicting pleural effusion after percutaneous microwave ablation (MWA) in lung malignancy (LM) patients. Methods LM patients treated with MWA were randomly allocated to either the training cohort or the validation cohort (7:3). The predictors of pleural effusion identified by univariable and multivariable analyses in the training cohort were used to develop a nomogram and ANN model. The C-statistic was used to evaluate the predictive accuracy in both the training and validation cohorts. Results A total of 496 patients (training cohort: n = 357; validation cohort: n = 139) were enrolled in this study. The predictors selected into the nomogram for pleural effusion included the maximum power (hazard ratio [HR], 1.060; 95% confidence interval [CI], 1.022–1.100, p = 0.002), the number of pleural punctures (HR, 2.280; 95% CI, 1.103–4.722; p = 0.026) and the minimum distance from needle to pleura (HR, 0.840; 95% CI, 0.775–0.899; p < 0.001). The C-statistic showed good predictive performance in both cohorts, with a C-statistic of 0.866 (95% CI, 0.787–0.945) internally and 0.782 (95% CI, 0.644–0.920) externally (training cohort and validation cohort, respectively). The optimal cutoff value for the risk of pleural effusion was 0.16. Conclusions Maximum power, number of pleural punctures and minimum distance from needle to pleura were predictors of pleural effusion after MWA in LM patients. The nomogram and ANN model could effectively predict the risk of pleural effusion after MWA. Patients showing a high risk (>0.16) on the nomogram should be monitored for pleural effusion.

Survival prediction for non-small cell lung cancer patients treated with CT-guided microwave ablation: development of a prognostic nomogram

Objectives To explore the outcomes of CT-guided percutaneous microwave ablation (MWA) in non-small cell lung cancer (NSCLC) patients, and then develop an effective nomogram to predict the survival. Methods NSCLC patients treated with MWA were randomly allocated to either the training cohort or the validation cohort (3:1). The primary outcome measurement was overall survival (OS), whose predictors were identified by univariate and multivariate analyses in the training cohort. Then, a predictive nomogram was developed to predict the OS, with the predictive accuracy evaluated by C-statistic and receiver operating characteristic in both the training and validation cohorts. Results A total of 234 patients (training cohort: n = 176; validation cohort: n = 58) and 271 tumors with a median OS of 17.0 ± 12.2 months were included. The predictors selected into the nomogram included tumor diameter (hazard ratio [HR], 2.12; 95% confidence interval [CI], 1.37-3.30; p < 0.001), extrapulmonary metastases (HR, 1.77; 95% CI, 1.06–2.95; p = 0.030), tumor stage (HR, 1.38; 95% CI, 1.07–1.79; p = 0.013), tumor type (HR, 2.00; 95% CI, 1.48–2.72; p < 0.001) and post-MWA TKIs (HR, 0.55; 95% CI, 0.34–0.89; p < 0.001), based on the results of univariate and multivariate analyses. The C-statistic showed good predictive performance, with a C-statistic of 0.838 (95% CI, 0.779–0.897) internally and 0.808 (95% CI, 0.695–0.920) externally (training cohort and validation cohort, respectively). Conclusions The nomogram was effective in predicting the OS in NSCLC patients treated with MWA, and could be applied to identify patients who may benefit most from MWA and be helpful for clinical decision making.

Efficacy and safety of CT-guided microwave ablation for stage T1a renal cell carcinoma in patients with a solitary kidney

Objective To retrospectively evaluate early clinical outcomes of percutaneous microwave ablation (MWA) for stage T1a renal cell carcinomas (RCCs) in solitary kidney patients. Materials and methods 15 solitary kidney patients with 16 stage T1a N0M0 biopsy-proved RCCs underwent CT-guided percutaneous microwave ablation between October 2016 and July 2020. The patients were followed up with contrast-enhanced computed tomography or magnetic resonance imaging at 1, 3, and 6 months and every 6 months thereafter. Serum creatinine levels of each patient pre MWA, 1 day after MWA and the most recent record were collected. Technical effectiveness, local recurrence, survival rates and complications were accessed. Results Complete ablation was achieved in all 16 tumors (100%) including 13 clear cell carcinomas and 3 papillary carcinomas. Within the follow-up time (median: 24 months) no tumor recurrence or major complication was detected. No significant change in serum creatinine level was noted. The cancer-specific survival rate was 100% (15 of 15), and 1-, 2-, and 3-year overall survival rates were 100%, 93.3%, and 93.3%, respectively. Conclusion Percutaneous MWA is an effective and safe treatment option for stage T1a RCCs in solitary kidney patients; it can achieve high complete ablation rate in selected lesions of appropriate size and location.