Predictors of Progression-Free Survival and Local Tumor Control after Percutaneous Thermal Ablation of Oligometastatic Breast Cancer: Retrospective Study

PurposeTo describe ablation of bone, liver, lung, and soft tissue tumors from oligometastatic breast cancer and to define predictors of local progression and progression-free survival (PFS).Materials and MethodsA total of 33 women (mean age 52 ± 12 years old; range, 28–69 years), underwent 46 thermal ablations of liver (n = 35), lung (n = 7), and bone/soft tissue (n = 4) metastases. Mean tumor diameter was 18 ± 15 mm (range, 6–50 mm). Ablations were performed to eradicate all evident sites of disease (n = 24) or to control growing sites in the setting of other stable or responding sites of disease (n = 22). Patient characteristics, ablation margins, imaging responses, and cases of PFS were assessed. Follow-up imaging was performed using contrast-enhanced computed tomography (CT), magnetic resonance (MR) imaging, or positron-emission tomography/ CT.ResultsMedian PFS was 10 months (95% confidence interval [CI], 6.2 –14.5 months), and time to local progression was 11 months (95% CI, 5–16 months). Eight patients (24%) maintained no evidence of disease during a median follow-up period of 39 months. Ablation margin ≥5 mm was associated with no local tumor progression. Longer PFS was noted in estrogen receptor-positive patients (12 vs 4 months; P = .037) and younger patients (12 vs 4 months; P = .039) treated to eradicate all sites of disease (13 vs 5 months; P = .05). Eighteen patients (55%) developed new metastases during study follow-up.ConclusionsThermal ablation of oligometastatic pulmonary, hepatic, bone, and soft tissue tumors can eliminate local tumor progression if margins are ≥5 mm. Longer PFS was observed in patients who were estrogen receptor-positive and patients who were younger and in whom all sites of disease were eradicated.     

Pleural Effusion after Hepatic Radiofrequency Ablation with Artificial Ascites: Clinical Spectrum and Significance

PurposeTo retrospectively investigate incidence, clinical outcome, and risk factors of iatrogenic pleural effusion in patients with hepatic tumors undergoing radiofrequency (RF) ablation using artificial ascites (AA).Materials and MethodsPatients (N = 163) who underwent RF ablation using AA were classified into pleural effusion and non–pleural effusion groups according to the presence of pleural effusion on immediate follow-up CT and chest radiograph after RF ablation. The pleural effusion group included asymptomatic and symptomatic subgroups. The incidence and subsequent clinical outcomes of patients developing pleural effusion after RF ablation were evaluated.ResultsOverall, 96 patients (58.9%) developed pleural effusion, which resolved in 4.4 d ± 3.1. Hospital length of stay in the pleural effusion group was longer than the non-pleural effusion group (6.5 d ± 2.6 vs 5.7 d ± 2.8, P < .01). The pleural effusion group had longer AA infusion time (P = .01), larger infused AA volume (P < .01), and longer ablation time (P < .01) than the non-pleural effusion group. Eighteen patients (18.8%) developed symptomatic pleural effusion and had a larger infused AA volume than asymptomatic patients with pleural effusion (P < .01). Pleural effusion duration and hospital length stay were also longer in the symptomatic pleural effusion subgroup than in the asymptomatic subgroup (P < .01). Infused AA volume was the only independent prognostic factor of pleural effusion duration in multivariate analysis (P = .038).ConclusionsPleural effusion frequently occurs after RF ablation using AA. Although generally considered negligible, pleural effusion could be a clinical problem and prolong hospitalization. Therefore, operators should be careful not to infuse too much AA when performing RF ablation.     

Safety and Efficacy of Radiofrequency Ablation for Nonfunctioning Benign Thyroid Nodules in Children and Adolescents in 14 Patients over a 10-Year Period

PurposeTo evaluate the efficacy and safety of radiofrequency (RF) ablation for nonfunctioning benign thyroid nodules in children and adolescents.Materials and MethodsFourteen pediatric patients (10 female, 4 male; mean age 15.7 ± 2.3 years, range 12–19 years) with nonfunctioning benign thyroid nodules (mean longest diameter 3.7 ± 1.1 cm, range 2.0–5.6 cm) treated with the use of RF ablation from 2005 to 2015 were evaluated. The inclusion criteria for RF ablation therapy were (i) age <20 years, (ii) benign cytological confirmation by ≥2 separate fine-needle aspiration or core needle biopsies, (iii) pressure symptoms or cosmetic problems caused by thyroid nodules, (iv) absence of any suspicious feature as determined with the use of ultrasound (US), (v) normal serum levels of thyroid hormone and thyrotropin, and (vi) follow-up of >6 months. RF ablation was performed with the use of an RF generator and an 18-gauge internally cooled electrode. RF ablation was performed under local anesthesia without conscious sedation or general anesthesia. Changes in nodules on follow-up US, changes in symptomatic and cosmetic scores, and complications arising during or after RF ablation were evaluated.ResultsMean follow-up period was 36.9 ± 21.7 months (range 6–69 months). At last follow-up visits, mean longest nodule diameter and volume had decreased significantly (3.7 ± 1.1 cm vs 1.4 ± 0.9 cm and 14.6 ± 13.3 mL vs 1.7 ± 4.4 mL; P < 0.001). Both cosmetic and compressive symptoms significantly improved (3.8 ± 0.6 vs 1.4 ± 0.6 and 3.4 ± 1.0 vs 0.1 ± 0.4; P < 0.001). The mean number of ablation sessions was 2.1 ± 1.2 (range 1–5 sessions) and no major complication was encountered during or after RF ablation.ConclusionsRF ablation might be a safe and effective treatment modality for nonfunctioning benign thyroid nodules in children and adolescents.     

Radiofrequency Ablation for the Palliative Treatment of Bone Metastases: Outcomes from the Multicenter OsteoCool Tumor Ablation Post-Market Study (OPuS One Study) in 100 Patients

PurposeTo evaluate the effectiveness of radiofrequency (RF) ablation as measured by change in worst pain score from baseline to 3 mo after RF ablation for the palliative treatment of painful bone metastases.Materials and MethodsOne hundred patients (mean age, 64.6 y) underwent RF ablation for metastatic bone disease and were followed up to 6 mo. Subjects’ pain and quality of life were measured before RF ablation and postoperatively by using the Brief Pain Index and European Quality of Life questionnaires. Opioid agent use and device-, procedure-, and/or therapy-related adverse events (AEs) were collected.ResultsEighty-seven patients were treated for tumors involving the thoracolumbar spine and 13 for tumors located in the pelvis and/or sacrum. All ablations were technically successful, and 97% were followed by cementoplasty. Mean worst pain score decreased from 8.2 ± 1.7 at baseline to 3.5 ± 3.2 at 6 mo (n = 22; P < 0.0001 for all visits). Subjects experienced significant improvement for all visits in average pain (P < .0001), pain interference (P < .0001), and quality of life (P < .003). Four AEs were reported, of which 2 resulted in hospitalization for pneumonia and respiratory failure. All 30 deaths reported during the study were attributed to the underlying malignancy and not related to the study procedure.ConclusionsResults from this study show rapid (within 3 d) and statistically significant pain improvement with sustained long-term relief through 6 mo in patients treated with RF ablation for metastatic bone disease.     

Juxtametallic Bipolar Bone Radiofrequency Ablation: Thermal Monitoring in an Ex-Vivo Model with Specimen MRI and Histopathologic Correlation

PurposeTo measure the ablation zone temperature and nontarget tissue temperature during radiofrequency (RF) ablation in bone containing metal instrumentation versus no metal instrumentation (control group).Materials and MethodsEx vivo experiments were performed on 15 swine vertebrae (control, n = 5; titanium screw, n = 5; stainless steel screw, n = 5). Screws and RF ablation probe were inserted identically under fluoroscopy. During RF ablation (3 W, 5 minutes), temperature was measured 10 mm from RF ablation centerpoint and in muscle contacting the screw. Magnetic resonance (MR) imaging, gross pathologic, and histopathologic analyses were performed on 1 specimen from each group.ResultsAblation zone temperatures at 2.5 and 5 minutes increased by 12.2 °C ± 2.6 °C and 21.5 °C ± 2.1 °C (control); 11.0 °C ± 4.1 °C and 20.0 °C ± 2.9 °C (juxta-titanium screw), and 10.0 °C ± 3.4 °C and 17.2 °C ± 3.5 °C (juxta–stainless steel) screw; differences among groups did not reach significance by analysis of variance (P = .87). Mixed-effects linear regression revealed a statistically significant increase in temperature over time in all 3 groups (4.2 °C/min ± 0.4 °C/min, P < .001). Compared with the control, there was no significant difference in the temperature change over time for titanium (?0.3 °C/min ± 0.5 °C/min, P = .53) or steel groups (?0.4 °C/min ± 0.5 °C/min, P = .38). The mean screw temperature at the final time point did not show a statistically significant change compared with baseline in either the titanium group (?1.2 °C ± 2.3 °C, P = .50) or steel group (2.6 °C ± 2.9 °C, P = .11). MR imaging and pathologic analyses revealed homogeneous ablation without sparing of the peri-hardware zones.ConclusionsAdjacent metallic instrumentation did not affect the rate of or absolute increase in temperature in the ablation zone, did not create peri–metallic ablation inhomogeneities, and did not result in significant nontarget heating of muscle tissue in contact with the metal instrumentation.     

A Bicentric Propensity Score Matched Study Comparing Percutaneous Computed Tomography–Guided Radiofrequency Ablation to Magnetic Resonance–Guided Focused Ultrasound for the Treatment of Osteoid Osteoma

PurposeTo assess the safety and efficacy of computed tomography–guided radiofrequency (RF) ablation and magnetic resonance–guided focused ultrasound (MRgFUS) in the treatment of osteoid osteoma with a long-term follow-up study.Materials and MethodsDatabase research was performed at 2 different centers with experience in musculoskeletal interventions. Both centers, one performing RF ablation and the other MRgFUS, identified 116 patients who underwent either RF ablation or MRgFUS procedures for the treatment of symptomatic osteoid osteoma and retrospectively evaluated data regarding pain scores using a visual analog scale (VAS). Complications were recorded according to the Cardiovascular and Interventional Radiological Society of Europe classification system. Propensity score matching for multiple variables was performed. Pain scores before and after therapy were compared.ResultsOf 116 patients treated, 61 and 55 underwent RF ablation and MRgFUS, respectively. Before treatment, the mean reported pain in the 2 groups were 9.1 ± 0.88 (RF ablation) and 8.7 ± 0.73 (MRgFUS) VAS units. After treatment, a statistically significant (P < .00001) overall reduction in pain symptomatology was recorded. No statistically significant difference was observed between the mean values of pain after treatment in both groups (P = .256). Over a mean of >2 years of follow-up, 4 cases of relapse (RF ablation, 1; MRgFUS, 3) and 1 complication (RF ablation) were observed. The analysis from propensity score matching that identified a matched cohort of 48 patients showed similar results.ConclusionsThe 2 techniques for the treatment of osteoid osteoma resulted in profound and similar pain relief. The presence of thick cortical bone over the nidus can reduce the effectiveness of MRgFUS.     

Value of 18F-FDG PET/MR Imaging in the Early Evaluation of Treatment Response following Radiofrequency Ablation of Liver Cancer in a Rabbit Model

PurposeTo test the hypothesis that ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography (PET) and magnetic resonance (MR) imaging can detect early residual tumor following radiofrequency (RF) ablation of liver cancer using a VX2 tumor model.Materials and MethodsTwenty-four rabbits with VX2 liver tumors were randomly divided into 3 groups (n = 8/group): Group 1 without RF ablation treatment, Group 2 with complete ablation, and Group 3 with partial ablation. An ¹⁸F-FDG PET/MR imaging scan was obtained within 2 hours after RF ablation. The maximum standardized uptake values (SUV) of the nontreated liver tumor, benign periablational enhancement (BPE), residual tumor, ablated tumor, and adjacent liver parenchyma and mean SUV of the normal liver were measured. The ratios of maximum SUV for these targets to the mean SUV of the normal liver (TNR) were calculated and compared.ResultsThe mean TNR of the nontreated liver tumors in Group 1 was significantly greater than that of the adjacent liver parenchyma (8.68 ± 0.71 vs 1.89 ± 0.26, P < .001). In Group 2, the mean TNR of BPE was significantly greater than that of the adjacent liver parenchyma (2.85 ± 0.20 vs 1.86 ± 0.25, P < .001). In Group 3, the mean TNR of the residual tumor was significantly greater than that of BPE (8.64 ± 0.59 vs 2.78 ± 0.23, P < .001), which was significantly greater than that of completely ablated tumor (2.78 ± 0.23 vs 0.50 ± 0.06, P < .001).Conclusions¹⁸F-FDG PET/MR imaging may serve as a promising imaging tool for the early detection of viable residual tumors due to incomplete tumor ablation.     

Transcatheter CT Hepatic Arteriography Compared with Conventional CT Fluoroscopy Guidance in Percutaneous Thermal Ablation to Treat Colorectal Liver Metastases: A Single-Center Comparative Analysis of 2 Historical Cohorts

PurposeTo evaluate safety and efficacy of CT hepatic arteriography compared with conventional CT fluoroscopy guidance in percutaneous radiofrequency (RF) and microwave (MW) ablation to treat colorectal liver metastases (CRLM).Materials and MethodsThis single-center comparative, retrospective study analyzed data of 108 patients treated with 156 percutaneous ablation procedures (42 CT fluoroscopy guidance [25 RF ablation, 17 MW ablation]; 114 CT hepatic arteriography guidance [18 RF ablation, 96 MW ablation]) for 260 CRLM between January 2009 and May 2019. Local tumor progression-free survival (LTPFS) was assessed using univariate and multivariate Cox proportional hazard regression analyses. LTPFS and overall survival (OS) were estimated using the Kaplan-Meier method.ResultsThere were no complications related to the transarterial catheter procedure. CT hepatic arteriography proved superior to CT fluoroscopy regarding 2-year LTPFS (18/202 [8.9%] vs 19/58 [32.8%]; P < .001, respectively). CT hepatic arteriography versus CT fluoroscopy (hazard ratio = 0.28; 95% confidence interval, 0.15–0.54; P < .001) and MW ablation versus RF ablation (hazard ratio = 0.52; 95% confidence interval, 0.24–1.12; P = .094) were positive predictors for longer LTPFS. Multivariate analysis revealed that CT hepatic arteriography versus CT fluoroscopy (hazard ratio = 0.41; 95% confidence interval, 0.19–0.90; P = .025) was associated with a significantly superior LTPFS. OS was similar between the 2 cohorts (P = .3).ConclusionsWhile adding procedure time and marginal patient burden, transcatheter CT hepatic arteriography–guided ablation was associated with increased local disease control and superior LTPFS compared with conventional CT fluoroscopy. CT hepatic arteriography represents a safe and valid alternative to CT fluoroscopy, as it reduces the number of repeat ablations required without adding risk or detrimental effect on survival.     

Endovascular Venous Stenosis and Thrombosis Large Animal Model: Angiographic,Histological, and Biomechanical Characterizations

PurposeTo characterize an ovine endovascular radiofrequency (RF) ablation-based venous stenosis and thrombosis model for studying venous biomechanics and response to intervention.Materials and MethodsUnilateral short-segment (n = 2) or long-segment (n = 6) iliac vein stenoses were created in 8 adult sheep using an endovenous RF ablation technique. Angiographic assessment was performed at baseline, immediately after venous stenosis creation, and after 2-week (n = 6) or 3-month (n = 2) survival. Stenosed iliac veins and the contralateral healthy controls were harvested for histological and biomechanical assessment.ResultsAt follow-up, the short-segment RF ablation group showed stable stenosis without occlusion. The long-segment group showed complete venous occlusion/thrombosis with the formation of collateral veins. Stenosed veins showed significant wall thickening (0.28 vs 0.16 mm, P = .0175) and confluent collagen deposition compared with the healthy controls. Subacute nonadherent thrombi were apparent at 2 weeks, which were replaced by fibrous luminal obliteration with channels of recanalization at 3 months. Stenosed veins demonstrated increased longitudinal stiffness (448.5 ± 5.4 vs 314.6 ± 1.5 kPa, P < .0001) and decreased circumferential stiffness (140.8 ± 2.6 vs 246.0 ± 1.6 kPa, P < .0001) compared with the healthy controls.ConclusionEndovenous RF ablation is a reliable technique for creating venous stenosis and thrombosis in a large animal model with histological and biomechanical attributes similar to those seen in humans. This platform can facilitate understanding of venous biomechanics and testing of venous-specific devices and interventions.     

Combination of Microwave Ablation and Percutaneous Osteoplasty for Treatment of Painful Extraspinal Bone Metastasis

PurposeTo evaluate the efficacy and safety of microwave (MW) ablation combined with percutaneous osteoplasty (POP) on painful extraspinal bone metastases.Materials and MethodsIn this retrospective study, 50 adult patients with 56 extraspinal bone metastasis lesions, who suffered from refractory moderate to severe pain, were treated with MW ablation and POP. Changes in quality of life were evaluated based on the Visual Analog Scale (VAS), daily morphine consumption, and the Oswestry Disability Index (ODI) before and immediately after the procedure and during follow-up times.ResultsTechnical success was achieved in all patients. Mean preoperative VAS score and morphine dose were 7.0 ± 2.6 (range, 3–10) and 66.7 ± 33.2 mg (range, 10–120 mg), respectively. Mean postoperative VAS scores and daily morphine doses were as follows: 1 day, 3.5 ± 2.1 and 36.1 ± 25.8 mg (P < .05); 1 week, 1.5 ± 1.7 and 12.2 ± 14.8 mg (P < .001); 1 month, 0.9 ± 1.4 and 5.7 ± 10.0 mg (P < .001); and 3 months, 0.6 ± 1.2 and 4.7 ± 8.4 mg (P < .001). A significant decrease in the ODI score was also observed (P < .05). Periprocedural death was not observed. A pathologic fracture occurred in 1 (2%) patient with femoral metastasis, and local infection was observed in 2 (4%) patients. Minor cement leakage occurred in 4 (8%) patients with no symptomatic or intra-articular extravasation. No local tumor progression occurred in patients with imaging follow-up.ConclusionsMW ablation combined with POP is an effective and safe treatment for painful extraspinal bone metastases, which can significantly relieve pain and improve quality of life.     

MR Imaging–Based In Vivo Macrophage Imaging to Monitor Immune Response after Radiofrequency Ablation of the Liver

PurposeTo establish molecular magnetic resonance (MR) imaging instruments for in vivo characterization of the immune response to hepatic radiofrequency (RF) ablation using cell-specific immunoprobes.Materials and MethodsSeventy-two C57BL/6 wild-type mice underwent standardized hepatic RF ablation (70 °C for 5 minutes) to generate a coagulation area measuring 6–7 mm in diameter. CD68⁺ macrophage periablational infiltration was characterized with immunohistochemistry 24 hours, 72 hours, 7 days, and 14 days after ablation (n = 24). Twenty-one mice were subjected to a dose-escalation study with either 10, 15, 30, or 60 mg/kg of rhodamine-labeled superparamagnetic iron oxide nanoparticles (SPIONs) or 2.4, 1.2, or 0.6 mg/kg of gadolinium-160 (¹⁶⁰Gd)-labeled CD68 antibody for assessment of the optimal in vivo dose of contrast agent. MR imaging experiments included 9 mice, each receiving 10-mg/kg SPIONs to visualize phagocytes using T2¹-weighted imaging in a horizontal-bore 9.4-T MR imaging scanner, ¹⁶⁰Gd-CD68 for T1-weighted MR imaging of macrophages, or 0.1-mmol/kg intravenous gadoterate (control group). Radiological-pathological correlation included Prussian blue staining, rhodamine immunofluorescence, imaging mass cytometry, and immunohistochemistry.ResultsRF ablation–induced periablational infiltration (206.92 μm ± 12.2) of CD68⁺ macrophages peaked at 7 days after ablation (P < .01) compared with the untreated lobe. T2¹-weighted MR imaging with SPION contrast demonstrated curvilinear T2¹ signal in the transitional zone (TZ) (186 μm ± 16.9), corresponsing to Iron Prussian blue staining. T1-weighted MR imaging with ¹⁶⁰Gd-CD68 antibody showed curvilinear signal in the TZ (164 μm ± 3.6) corresponding to imaging mass cytometry.ConclusionsBoth SPION-enhanced T2¹-weighted and ¹⁶⁰Gd-enhanced T1-weighted MR imaging allow for in vivo monitoring of macrophages after RF ablation, demonstrating the feasibility of this model to investigate local immune responses.     

Liver Tumor Ablation Procedure Duration and Estimated Patient Radiation Dose: Comparing Positron Emission Tomography/CT and CT Guidance

PurposeTo compare procedure duration and patient radiation dose in positron emission tomography/computed tomography (PET/CT) and CT-guided liver tumor ablation procedures.Materials and MethodsIn this retrospective, case-control study, 275 patients underwent 368 image-guided ablation procedures to treat 537 tumors. Radiologists used PET/CT guidance for 117 procedures and CT guidance for 251 procedures. PET/CT-guided procedures were performed by one radiologist (C: P.B.S.). All 3 radiologists (A: J.G.S., B: a radiologist who is not an author on this article, and C: P.B.S.) performed CT-guided procedures. Potential confounders included patient demographics, clinical and tumor characteristics, and procedural variables.ResultsThe mean duration and estimated patient radiation dose of PET/CT-guided procedures performed by radiologist C were 21.5 ± 4.9 minutes longer and 0.7 ± 2.8 mSv higher than CT-guided procedures performed by all radiologists in an unadjusted comparison. Adjusting for confounding, mean duration and estimated dose of PET/CT-guided procedures performed by radiologist C were 28.3 ± 3.8 minutes longer (P < .0001) and 6.2 ± 2.9 mSv higher (P = .03) than CT-guided procedures performed by the same radiologist. Comparing CT-guided procedures performed by all 3 radiologists, adjusted mean durations and estimated patient doses of procedures by the least experienced radiologist, radiologist A, and the second most experienced radiologist, radiologist B, were 24.2 ± 5.1 (P < .0001) and 18.1 ± 8.9 (P = .04) minutes longer and 13.1 ± 3.7 (P < .001) and 14.5 ± 6.4 (P = .02) mSv higher, respectively, than procedures performed by the most experienced radiologist, radiologist C.ConclusionsPET/CT-guided liver ablations had a slightly longer duration with slightly higher estimated patient radiation dose than similar CT-guided liver ablations. Procedure duration and patient dose do not appear to be major impediments to the emerging field of PET/CT-guided tumor ablation.     

CT Densitometry and Morphology of Radiofrequency-Ablated Stage IA Non–Small Cell Lung Cancer: Results from the American College of Surgeons Oncology Group Z4033 (Alliance) Trial

PurposeTo evaluate tumor and ablation zone morphology and densitometry related to tumor recurrence in participants with Stage IA non–small cell lung cancer undergoing radiofrequency ablation in a prospective, multicenter trial.Materials and MethodsForty-five participants (median 76 years old; 25 women; 20 men) from 16 sites were followed for 2 years (December 2006 to November 2010) with computed tomography (CT) densitometry. Imaging findings before and after ablation were recorded, including maximum CT attenuation (in Hounsfield units) at precontrast and 45-, 90-, 180-, and 300-s postcontrast.ResultsEvery 1-cm increase in the largest axial diameter of the ablation zone at 3-months’ follow-up compared to the index tumor reduced the odds of 2-year recurrence by 52% (P = .02). A 1-cm difference performed the best (sensitivity, 0.56; specificity, 0.93; positive likelihood ratio of 8). CT densitometry precontrast and at 45 seconds showed significantly different enhancement patterns in a comparison among pretreated lung cancer (delta = +61.2 HU), tumor recurrence (delta = +57 HU), and treated tumor/ablation zone (delta [change in attenuation] = +16.9 HU), (P < .0001). Densitometry from 45 to 300 s was also different among pretreated tumor (delta = −6.8 HU), recurrence (delta = −11.2 HU), and treated tumor (delta = +12.1 HU; P = .01). Untreated and residual tumor demonstrated washout, whereas treated tumor demonstrated increased attenuation.ConclusionsAn ablation zone ≥1 cm larger than the initial tumor, based on 3-month follow-up imaging, is recommended to decrease odds of recurrence. CT densitometry can delineate tumor versus treatment zones.     

CT-Guided Percutaneous Cryoablation in Patients with Lung Nodules Mainly Composed of Ground-Glass Opacities

PurposeTo assess the safety and efficacy of cryoablation in patients with lung nodules mainly composed of ground-glass opacities (GGOs).Materials and MethodsIn this retrospective study, 50 patients (mean age, 65.0 years ± 12.3; 28 women) with a diagnosis of lung GGO nodules who underwent cryoablation were included (from June 2016 to June 2021). The local recurrence rate, incidence of regional metastases to lymph nodes, incidence of distant metastases, adverse events, and lung function condition were analyzed.ResultsFollow-up computed tomography (CT) was performed at a mean of 33 months (range, 3–60 months) after the cryoablation procedure. Outcomes were only evaluated in 30 patients. A total of 20 patients were excluded. Of these 20 patients, 10 patients had no cancer detected by histopathological analysis and a diagnosis was made using CT or positron emission tomography (PET)-CT, The other 10 patients had nodules with a diameter of <10 mm and a consolidation-to-tumor ratio of >0.25; thus, histopathological analysis was not performed because of the small nodule size, and patients were diagnosed using CT or PET-CT. The local recurrence rate was 0% (0 of 30). Evidence of regional metastases of lymph nodes was not found in any patients (0%; 0 of 30), and the incidence of distant metastases was 0% (0 of 30). No major adverse events were noted. Lung function recovered to normal within 1 month after cryoablation in all patients.ConclusionsCryoablation may serve as a safe and feasible option for the treatment of lung nodules mainly composed of GGOs.     

Computed Tomography‒Guided Microwave Ablation Combined with Osteoplasty for the Treatment of Bone Metastases: A Multicenter Clinical Study

PurposeTo evaluate the efficacy and safety of combined microwave ablation (MWA) and osteoplasty as a palliative therapy for painful bone metastases.Materials and MethodsAs an extension of a previous limited single-center study, a retrospective review was conducted for 147 patients (77 male, 70 female) with painful bone metastases who underwent MWA combined with osteoplasty. In total, 102 (69.4%), 41 (27.9%), and 4 (2.7%) patients had spinal metastases, extraspinal metastases, and both, respectively. Treatment efficacy was determined by comparing visual analog scale (VAS) scores, daily morphine equivalent opioid consumption, and Oswestry disability index (ODI) scores before treatment and during the follow-up period (mean follow-up, 9.8 months; range 3–16).ResultsThe mean VAS score significantly declined from 6.4 ± 2.3 before treatment to 3.2 ± 2.1, 1.9 ± 1.6, 1.8 ± 1.6, 1.8 ± 1.6, and 1.9 ± 1.6 at 24 hours, 1 week, 4 weeks, 12 weeks, and 24 weeks after treatment, respectively (P < .01). Furthermore, the mean daily morphine equivalent opioid consumption was significantly reduced from 81.5 ± 32.8 mg before treatment to 40.0 ± 20.6, 32.4 ± 10.2, 26.4 ± 10.0, 21.5 ± 8.3, and 19.3 ± 7.4 mg. The mean ODI score also declined after treatment (P < .0001). Major complications occurred in 4 of 147 patients, with 1 pathologic fracture, 1 nerve injury, and 2 mild skin infections. Minor cement leakages were observed at 69 sites (32.8%).ConclusionsMWA combined with osteoplasty is an effective and safe treatment for painful bone metastases.     

Diffusion-Weighted MR Imaging of Primary and Secondary Lung Cancer: Predictive Value for Response to Transpulmonary Chemoembolization and Transarterial Chemoperfusion

PurposeTo examine predictive value of apparent diffusion coefficient (ADC) in diffusion-weighted imaging (DWI) for response of patients with primary and secondary lung neoplasms undergoing transpulmonary chemoembolization (TPCE) and transarterial chemoperfusion (TACP) treatment.Materials and MethodsThirty-one patients (mean age ± SD 64 ± 12.4 y) with 42 lung target lesions (13 primary and 29 secondary) underwent DWI and subsequent ADC analysis on a 1.5T MR imaging scanner before and 30.3 days ± 6.4 after first session of TPCE or TACP. After 3.1 treatment sessions ± 1.4 performed in 2- to 4-week intervals, morphologic response was analyzed by comparing tumor diameter and volume before and after treatment on unenhanced T1-weighted MR images. On a per-lesion basis, response was classified according to Response Evaluation Criteria In Solid Tumors.ResultsThreshold ADC increase of 20.7% indicated volume response with 88% sensitivity and 78% specificity (area under the curve [AUC] = 0.84). Differences between ADC changes in volume response groups were significant (P = .002). AUC for volume response predicted by ADC before treatment was 0.77. Median ADC before treatment and mean ADC change were 1.09 × 10⁻³ mm²/second and 0.36 × 10⁻³ mm²/second ± 0.23, 1.45 × 10⁻³ mm²/second and 0.14 × 10⁻³ mm²/second ± 0.16, and 1.30 × 10⁻³ mm²/second and 0.06 × 10⁻³ mm²/second ± 0.19 in partial response, stable disease, and progressive disease groups. In primary lung cancer lesions, strong negative correlation of ADC change with change in diameter (ρ = −.87, P < .001) and volume (ρ = −.66, P = .016) was found. In metastases, respective correlation coefficients were ρ = −.18 (P = .356) and ρ = −.35 (P = .061).ConclusionsADC quantification shows considerable diagnostic value for predicting response and monitoring TPCE and TACP treatment of patients with primary and secondary lung neoplasms.     

Accuracy of a CT-Ultrasound Fusion Imaging Guidance System Used for Hepatic Percutaneous Procedures

PurposeTo evaluate the accuracy of a fusion imaging guidance system using ultrasound (US) and computerized tomography (CT) as a real-time imaging modality for the positioning of a 22-gauge needle in the liver.Materials and MethodsThe spatial coordinates of 23 spinal needles placed at the border of hepatic tumors before radiofrequency thermal ablation were determined in 23 patients. Needles were inserted up to the border of the tumor with the use of CT-US fusion imaging. A control CT scan was carried out to compare real (x, y, z) and virtual (x′, y′, z′) coordinates of the tip of the needle (D for distal) and of a point on the needle located 3 cm proximally to the tip (P for proximal).ResultsThe mean Euclidian distances were 8.5 ± 4.7 mm and 10.5 ± 5.3 mm for D and P, respectively. The absolute value of mean differences of the 3 coordinates (|x′ − x|, |y′ − y|, and |z′ − z|) were 4.06 ± 0.9, 4.21 ± 0.84, and 4.89 ± 0.89 mm for D and 3.96 ± 0.60, 4.41 ± 0.86, and 7.66 ± 1.27 mm for P. X = |x′ − x| and Y = |y′ − y| coordinates were <7 mm with a probability close to 1. Z = |z′ − z| coordinate was not considered to be larger nor smaller than 7 mm (probability >7 mm close to 50%).ConclusionsPositioning errors with the use of US-CT fusion imaging used in this study are not negligible for the insertion of a 22-gauge needle in the liver. Physicians must be aware of such possible errors to adapt the treatment when used for thermal ablation.     

Immunofluorescence Assay of Ablated Colorectal Liver Metastases: The Frozen Section of Image-Guided Tumor Ablation?

PurposeTo validate an immunofluorescence assay (IFA) detecting residual viable tumor (VT) as intraprocedural thermal ablation (TA) zone assessment and demonstrate its prognostic value for local tumor progression (LTP) after colorectal liver metastasis (CLM) TA.Materials and MethodsThis prospective study, approved by the institutional review board, included 99 patients with 155 CLMs ablated between November 2009 and January 2019. Tissue samples from the ablation zone (AZ) center and minimal margin underwent immunofluorescent microscopic examination interrogating cellular morphology and mitochondrial viability (IFA) within 30 minutes after ablation. The same tissue samples were subsequently evaluated with standard morphologic and immunohistochemical methods. The sensitivity, specificity, and overall accuracy of IFA versus standard morphologic and immunohistochemical examination were calculated. The LTP-free survival rates were evaluated for the 12-month follow-up period.ResultsOf the 311 tissue samples stained, 304 (98%) were deemed evaluable. Of these specimens, 27% (81/304) were considered positive for the presence of VT. The accuracy of IFA was 94% (286/304). The sensitivity and specificity were 100% (63/63) and 93% (223/241), respectively. The 18 false-positive IFA assessments corresponded to samples that included viable cholangiocytes. The 12-month LTP-free survival was 59% versus 78% for IFA positive versus negative for VT AZs, respectively (P < .001). There was no difference in LTP between margin positive only and central AZ–positive tumors (25% vs 31%, P = 1).ConclusionsThe IFA assessment of the AZ can be completed intraprocedurally and serve as a valid real-time biomarker of complete tumor eradication or detect residual VT after TA. This method could improve tumor control by TA.     

Phantom and Animal Study of a Robot-Assisted,CT-Guided Targeting System using Image-Only Navigation for Stereotactic Needle Insertion without Positional Sensors

PurposeTo evaluate the feasibility and accuracy of a robotic system to integrate and map computed tomography (CT) and robotic coordinates, followed by automatic trajectory execution by a robotic arm. The system was hypothesized to achieve a targeting error of <5 mm without significant influence from variations in angulation or depth.Materials and MethodsAn experimental study was conducted using a robotic system (Automated Needle Targeting device for CT [ANT-C]) for needle insertions into a phantom model on both moving patient table and moving gantry CT scanners. Eight spherical markers were registered as targets for 90 insertions at different trajectories. After a single ANT-C registration, the closed-loop software targeted multiple markers via the insertion of robotically aligned 18-gauge needles. Accuracy (distance from the needle tip to the target) was assessed by postinsertion CT scans. Similar procedures were repeated to guide 10 needle insertions into a porcine lung. A regression analysis was performed to test the effect of needle angulation and insertion depth on the accuracy of insertion.ResultsIn the phantom model, all needle insertions (median trajectory depth, 64.8 mm; range, 46.1–153 mm) were successfully performed in single attempts. The overall accuracy was 1.36 mm ± 0.53, which did not differ between the 2 types of CT scanners (1.39 mm ± 0.54 [moving patient table CT] vs 1.33 mm ± 0.52 [moving gantry CT]; P = .54) and was not significantly affected by the needle angulation and insertion depth. The accuracy for the porcine model was 9.09 mm ± 4.21.ConclusionsRobot-assisted needle insertion using the ANT-C robotic device was feasible and accurate for targeting multiple markers in a phantom model.     

Quantitative Automated Segmentation of Lipiodol Deposits on Cone-Beam CT Imaging Acquired during Transarterial Chemoembolization for Liver Tumors: A Deep Learning Approach

PurposeTo show that a deep learning (DL)–based, automated model for Lipiodol (Guerbet Pharmaceuticals, Paris, France) segmentation on cone-beam computed tomography (CT) after conventional transarterial chemoembolization performs closer to the “ground truth segmentation” than a conventional thresholding-based model.Materials and MethodsThis post hoc analysis included 36 patients with a diagnosis of hepatocellular carcinoma or other solid liver tumors who underwent conventional transarterial chemoembolization with an intraprocedural cone-beam CT. Semiautomatic segmentation of Lipiodol was obtained. Subsequently, a convolutional U-net model was used to output a binary mask that predicted Lipiodol deposition. A threshold value of signal intensity on cone-beam CT was used to obtain a Lipiodol mask for comparison. The dice similarity coefficient (DSC), mean squared error (MSE), center of mass (CM), and fractional volume ratios for both masks were obtained by comparing them to the ground truth (radiologist-segmented Lipiodol deposits) to obtain accuracy metrics for the 2 masks. These results were used to compare the model versus the threshold technique.ResultsFor all metrics, the U-net outperformed the threshold technique: DSC (0.65 ± 0.17 vs 0.45 ± 0.22, P < .001) and MSE (125.53 ± 107.36 vs 185.98 ± 93.82, P = .005). The difference between the CM predicted and the actual CM was 15.31 mm ± 14.63 versus 31.34 mm ± 30.24 (P < .001), with lesser distance indicating higher accuracy. The fraction of volume present ([predicted Lipiodol volume]/[ground truth Lipiodol volume]) was 1.22 ± 0.84 versus 2.58 ± 3.52 (P = .048) for the current model’s prediction and threshold technique, respectively.ConclusionsThis study showed that a DL framework could detect Lipiodol in cone-beam CT imaging and was capable of outperforming the conventionally used thresholding technique over several metrics. Further optimization will allow for more accurate, quantitative predictions of Lipiodol depositions intraprocedurally.