A Multicenter Study of Needle Size and Safety for Splenic Biopsy.

Background Splenic biopsy is rarely performed because of the perceived risk of hemorrhagic complications. Purpose To evaluate the safety of large bore (≥18 gauge) image-guided splenic biopsy. Materials and Methods This retrospective study included consecutive adult patients who underwent US- or CT-guided splenic biopsy between March 2001 and March 2022 at eight academic institutions in the United States. Biopsies were performed with needles that were 18 gauge or larger, with a comparison group of biopsies with needles smaller than 18 gauge. The primary outcome was significant bleeding after the procedure, defined by the presence of bleeding at CT performed within 30 days or angiography and/or surgery performed to manage the bleeding. Categorical variables were compared using the χ2 test and medians were compared using the Mann-Whitney test. Results A total of 239 patients (median age, 63 years; IQR, 50-71 years; 116 of 239 [48.5%] female patients) underwent splenic biopsy with an 18-gauge or smaller needle and 139 patients (median age, 58 years [IQR, 49-69 years]; 66 of 139 [47.5%] female patients) underwent biopsy with a needle larger than 18 gauge. Bleeding was detected in 20 of 239 (8.4%) patients in the 18-gauge or smaller group and 11 of 139 (7.9%) in the larger than 18-gauge group. Bleeding was treated in five of 239 (2.1%) patients in the 18-gauge or smaller group and one of 139 (1%) in the larger than 18-gauge group. No deaths related to the biopsy procedure were recorded during the study period. Patients with bleeding after biopsy had smaller lesions compared with patients without bleeding (median, 2.1 cm [IQR, 1.6-5.4 cm] vs 3.5 cm [IQR, 2-6.8 cm], respectively; P = .03). Patients with a history of lymphoma or leukemia showed a lower incidence of bleeding than patients without this history (three of 90 [3%] vs 28 of 288 [9.7%], respectively; P = .05). Conclusion Bleeding after splenic biopsy with a needle 18 gauge or larger was similar to biopsy with a needle smaller than 18 gauge and seen in 8% of procedures overall, with 2% overall requiring treatment. © RSNA, 2024 Supplemental material is available for this article. See also the editorial by Grant in this issue.

Management of twin reversed arterial perfusion (TRAP) sequence with microwave ablation: A case report and review of the literature.

Twin reversed arterial perfusion (TRAP) sequence carries a high mortality risk to the "pump twin." Management involves disrupting blood flow to the acardiac mass. In this case, the pregnant patient presented at 20 weeks 6 days with Stage IIb TRAP Sequence and underwent percutaneous ultrasound-guided microwave ablation (MWA) of the acardiac mass at 21 weeks 0 days. The probe traversed the thorax of the acardiac mass and ablated the confluence of the umbilical vessels. A healthy child was delivered at 33 weeks 5 days gestation. This report demonstrates the utility of MWA in TRAP sequence and describes a novel approach.

A comparison study of microwave ablation vs. histotripsy for focal liver treatments in a swine model.

OBJECTIVE: To compare the acute and chronic safety and treatment effects of non-invasive hepatic histotripsy vs. percutaneous microwave (MW) ablation in a healthy porcine model. METHODS: This was a dual-arm study in which each animal (n = 14) received either a single hepatic microwave (n = 6) or histotripsy (n = 6 single treatment; n = 2 double treatment) under ultrasound guidance. The goal was to create 2.5-3.0 cm short-axis treatments in similar locations across modalities. Animals were survived for 1 month with contrast-enhanced CT imaging on days 0, 2, 7, 14, and 28. On day 28, necropsy and histopathology were performed. RESULTS: All procedures were well-tolerated. MW ablation zones were longer and more oblong, but equivalent in the short axes to histotripsy zones on immediate post-procedure CT (p < 0.001 and p = 0.45, respectively). Overall, MW volumes were larger (21.4 cm3 vs. 13.4 cm3; p = 0.001) and histotripsy treatment zones were more spherical (p = 0.007). Histotripsy zones were close to the prescribed size (p < 0.001). Over the study period, histotripsy treatment zones decreased in volume while microwave ablation zones slightly increased (-83% vs. +17%, p = 0.001). There were several imaging-only findings: Branch portal vein thrombus with both histotripsy (7/8) and MW (6/6), hematoma in 2/6 MW only, and a gallbladder injury in 1/6 MW animals. The ablation zones demonstrated complete cellular destruction for both modalities. CONCLUSION: Histotripsy was associated with more spherical treatments, fewer biliary complications, and greater treatment zone involution. Hepatic MW and histotripsy treatment in a normal porcine model appear at least equally effective for creating treatment zones with a similar safety profile. KEY POINTS: • Microwave ablation and histotripsy for liver treatment in a healthy porcine model yield equivalent procedural tolerance and cellular destruction. • Histotripsy was associated with more spherical treatments, fewer biliary complications, and greater treatment zone involution over the 28-day follow-up period. • These findings confirm the safety and efficacy of hepatic histotripsy and support the pursuit of clinical trials to further evaluate the translatability of these results.

Artificial Intelligence-Aided Selection of Needle Pathways: Proof-of-Concept in Percutaneous Lung Biopsies.

PURPOSE: To evaluate the concordance between lung biopsy puncture pathways determined by artificial intelligence (AI) and those determined by expert physicians. MATERIALS AND METHODS: An AI algorithm was created to choose optimal lung biopsy pathways based on segmented thoracic anatomy and emphysema in volumetric lung computed tomography (CT) scans combined with rules derived from the medical literature. The algorithm was validated using pathways generated from CT scans of randomly selected patients (n = 48) who had received percutaneous lung biopsies and had noncontrast CT scans of 1.25-mm thickness available in picture archiving and communication system (PACS) (n = 28, mean age, 68.4 years ± 9.2; 12 women, 16 men). The algorithm generated 5 potential pathways per scan, including the computer-selected best pathway and 4 random pathways (n = 140). Four experienced physicians rated each pathway on a 1-5 scale, where scores of 1-3 were considered safe and 4-5 were considered unsafe. Concordance between computer and physician ratings was assessed using Cohen's κ. RESULTS: The algorithm ratings were statistically equivalent to the physician ratings (safe vs unsafe: κ¯=0.73; ordinal scale: κ¯=0.62). The computer and physician ratings were identical in 57.9% (81/140) of cases and differed by a median of 0 points. All least-cost "best" pathways generated by the algorithm were considered safe by both computer and physicians (28/28) and were judged by physicians to be ideal or near ideal. CONCLUSIONS: AI-generated lung biopsy puncture paths were concordant with expert physician reviewers and considered safe. A prospective comparison between computer- and physician-selected puncture paths appears indicated in addition to expansion to other anatomic locations and procedures.

Percutaneous CT-Guided Abdominal and Pelvic Biopsies: Comparison of an Electromagnetic Navigation System and CT Fluoroscopy.

PURPOSE: To compare electromagnetic navigation (EMN) with computed tomography (CT) fluoroscopy for guiding percutaneous biopsies in the abdomen and pelvis. MATERIALS AND METHODS: A retrospective matched-cohort design was used to compare biopsies in the abdomen and pelvis performed with EMN (consecutive cases, n = 50; CT-Navigation; Imactis, Saint-Martin-d'Hères, France) with those performed with CT fluoroscopy (n = 100). Cases were matched 1:2 (EMN:CT fluoroscopy) for target organ and lesion size (±10 mm). RESULTS: The population was well-matched (age, 65 vs 65 years; target size, 2.0 vs 2.1 cm; skin-to-target distance, 11.4 vs 10.7 cm; P > .05, EMN vs CT fluoroscopy, respectively). Technical success (98% vs 100%), diagnostic yield (98% vs 95%), adverse events (2% vs 5%), and procedure time (33 minutes vs 31 minutes) were not statistically different (P > .05). Operator radiation dose was less with EMN than with CT fluoroscopy (0.04 vs 1.2 µGy; P < .001), but patient dose was greater (30.1 vs 9.6 mSv; P < .001) owing to more helical scans during EMN guidance (3.9 vs 2.1; P < .001). CT fluoroscopy was performed with a mean of 29.7 tap scans per case. In 3 (3%) cases, CT fluoroscopy was performed with gantry tilt, and the mean angle out of plane for EMN cases was 13.4°. CONCLUSIONS: Percutaneous biopsies guided by EMN and CT fluoroscopy were closely matched for technical success, diagnostic yield, procedure time, and adverse events in a matched cohort of patients. EMN cases were more likely to be performed outside of the gantry plane. Radiation dose to the operator was higher with CT fluoroscopy, and patient radiation dose was higher with EMN. Further study with a wider array of procedures and anatomic locations is warranted.

A Comparison of Histotripsy and Percutaneous Cryoablation in a Chronic Healthy Swine Kidney Model.

PURPOSE: To compare the safety and efficacy of histotripsy with cryoablation in a chronic human-scale normal porcine kidney model. MATERIALS AND METHODS: Eighteen female domestic swine were divided evenly into histotripsy and cryoablation treatment arms. A planned 2-3 cm diameter treatment was performed under ultrasound (histotripsy) or ultrasound and computed tomography (CT) guidance (cryoablation). Contrast-enhanced CT and serum blood analysis were performed immediately postprocedure and on day 7, with either immediate killing (n = 3) or continued survival to day 30 (n = 6), at which time contrast-enhanced CT, serum blood analysis, and necropsy were performed. Animal welfare, treatment zone appearance, procedure-related adverse events, and histopathology of the treatment zones and surrounding tissues were assessed. RESULTS: Histotripsy treatment zones (mean ±standard deviation diameters, 2.7 ± 0.12 × 2.4 ± 0.19 × 2.4 ± 0.26 cm; volume, 8.3 ± 1.9 cm3) were larger than cryoablation zones (mean diameters, 2.2 ± 0.19 × 1.9 ± 0.13 × 1.7 ± 0.19 cm; volume, 3.9 ± 0.8 cm3; P < .001). At 30 days, histotripsy and cryoablation treatment zone volumes decreased by 96% and 83% on CT, respectively (P < .001). Perirenal hematomas were present after 8 of 9 (89%) cryoablation (mean volume, 22.2 cm3) and 1 of 9 (11%, P < .001) histotripsy (volume, 0.4 cm3) procedures, with active arterial extravasation in 4 of 9 (44%) cryoablation and no histotripsy animals (P = .206). All 9 histotripsy animals and 5 of 9 (56%) cryoablation animals had collecting system debris (P = .042). Changes in serum creatinine were similar between the groups (P = .321). CONCLUSIONS: Other than a higher rate of bleeding after cryoablation, the safety and early efficacy of histotripsy and cryoablation were comparable for creating treatment zones in a chronic normal porcine kidney model.

Microwave Ablation as Bridging to Liver Transplant for Patients with Hepatocellular Carcinoma: A Single-Center Retrospective Analysis.

PURPOSE: To evaluate the efficacy and safety of microwave (MW) ablation as first-line locoregional therapy (LRT) for bridging patients with hepatocellular carcinoma (HCC) to liver transplant. MATERIALS AND METHODS: This retrospective study evaluated 88 patients who received percutaneous MW ablation for 141 tumors as first-line LRT for HCC and who were listed for liver transplantation at a single medical center between 2011 and 2019. The overall survival (OS) rate statuses after liver transplant, waitlist retention, and disease progression were evaluated using the Kaplan-Meier techniques. RESULTS: Among the 88 patients (72 men and 16 women; mean age, 60 years; Model for End-Stage Liver Disease score, 11.2) who were listed for transplant, the median waitlist time was 9.4 months (interquartile range, 5.5-18.9). Seventy-one (80.7%) patients received transplant after a median waitlist time of 8.5 months. Seventeen (19.3%) patients were removed from the waitlist; of these, 4 (4.5%) were removed because of tumors outside of the Milan criteria (HCC-specific dropout). No difference in tumor size or alpha-fetoprotein was observed in the transplanted versus nontransplanted patients at the time of ablation (2.1 vs 2.1 cm and 34.4 vs 34.7 ng/mL for transplanted vs nontransplanted, respectively; P > .05). Five (5.1%) of the 88 patients experienced adverse events after ablation; however, they all recovered. There were no cases of tract seeding. The local tumor progression (LTP) rate was 7.2%. The OS status after liver transplant at 5 years was 76.7%, and the disease-specific survival after LTP was 89.6%, with a median follow-up of 61 months for all patients. CONCLUSIONS: MW ablation appears to be safe and effective for bridging patients with HCC to liver transplant without waitlist removal from seeding, adverse events, or LTP.

CT Fluoroscopy for Image-Guided Procedures: Physician Radiation Dose During Full-Rotation and Partial-Angle CT Scanning.

PURPOSE: To determine physician radiation exposure when using partial-angle computed tomography (CT) fluoroscopy (PACT) vs conventional full-rotation CT and whether there is an optimal tube/detector position at which physician dose is minimized. MATERIALS AND METHODS: Physician radiation dose (entrance air kerma) was measured for full-rotation CT (360°) and PACT (240°) at all tube/detector positions using a human-mimicking phantom placed in a 64-channel multidetector CT. Parameters included 120 kV, 20- and 40-mm collimation, and 100 mA. The mean, standard deviation, and increase/decrease in physician dose compared with a full-rotation scan were reported. RESULTS: Physician radiation exposure during CT fluoroscopy with PACT was highly dependent on the position of the tube/detector during scanning. The lowest PACT physician dose was when the physician was on the detector side (center view angle 116°; -35% decreased dose vs full-angle CT). The highest PACT physician dose was with the physician on the tube side (center view angle 298°; +34% increased dose vs full-angle CT), all doses P <.05 vs full-rotation CT. CONCLUSIONS: Partial-angle CT has the potential to both significantly increase or decrease physician radiation dose during CT fluoroscopy-guided procedures. The detector/tube position has a profound effect on physician dose. The lowest dose during PACT was achieved when the physician was located on the detector side (ie, distant from the tube). This data could be used to optimize CT fluoroscopy parameters to reduce physician radiation exposure for PACT-capable scanners.

Percutaneous Lung Biopsy with Pleural and Parenchymal Blood Patching: Results and Complications from 1,112 Core Biopsies.

PURPOSE: To evaluate the outcomes of computed tomography (CT) fluoroscopy-guided core lung biopsies with emphasis on diagnostic yield, complications, and efficacy of parenchymal and pleural blood patching to avoid chest tube placement. METHODS: This is a single-center retrospective analysis of CT fluoroscopy-guided percutaneous core lung biopsies between 2006 and 2020. Parenchymal blood patching during introducer needle withdrawal was performed in 74% of cases as a preventive measure, and pleural blood patching was the primary salvage maneuver for symptomatic or growing pneumothorax in 60 of 83 (72.2%) applicable cases. RESULTS: A total of 1,029 patients underwent 1,112 biopsies (532 men; mean age, 66 years; 38.6%, history of emphysema; lesion size, 16.7 mm). The diagnostic yield was 93.6% (1,032/1,103). Fewer complications requiring intervention were observed in patients who underwent parenchymal blood patching (5.7% vs 14.2%, P < .001). Further intervention was required in 83 of 182 pneumothorax cases, which included the following: (a) pleural blood patch (5.4%, 60/1,112), (b) chest tube placement without a pleural blood patch attempt (1.5%, 17/1,112), and (c) simple aspiration (0.5%, 6/1,112). Pleural blood patch as monotherapy was successful in 83.3% (50/60) of cases without need for further intervention. The overall chest tube rate was 2.6% (29/1,112). Emphysema was the only significant risk factor for complications requiring intervention (P ≤ .001). CONCLUSIONS: Parenchymal blood patching during introducer needle withdrawal decreased complications requiring intervention. Salvage pleural blood patching reduced the frequency of chest tube placement for pneumothorax.

Reorganizing Cross-Sectional Interventional Procedures Practice During the Coronavirus Disease (COVID-19) Pandemic.

OBJECTIVE. The purpose of this article is to present strategies and guidelines that can be implemented in the performance of cross-sectional interventional procedures during the coronavirus disease (COVID-19) pandemic. CONCLUSION. Radiologists who perform cross-sectional interventional procedures can take several steps to minimize the risks to patients and radiology personnel, including screening referred patients to decide which procedures can be postponed, using appropriate personal protective equipment (PPE), minimizing the number of people involved in procedures, preserving PPE when possible, and applying proper room and equipment cleaning measures.

Radiofrequency and microwave ablation in a porcine liver model: non-contrast CT and ultrasound radiologic-pathologic correlation.

Purpose: The goal of this study was to compare intra-procedural radiofrequency (RF) and microwave ablation appearance on non-contrast CT (NCCT) and ultrasound to the zone of pathologic necrosis.Materials and methods: Twenty-one 5-min ablations were performed in vivo in swine liver with (1) microwave at 140 W, (2) microwave at 70 W, or (3) RF at 200 W (n = 7 each). CT and US images were obtained simultaneously at 1, 3, and 5 min during ablation and 2, 5, and 10 min post-ablation. Each ablation was sectioned in the plane of the ultrasound image and underwent vital staining to delineate cellular necrosis. CT was reformatted to the same plane as the ultrasound transducer and transverse diameters of gas and hypoechoic/hypoattenuating zones at each time point were measured. CT, ultrasound and gross pathologic diameter measurements were compared using Student's t-tests and linear regression.Results: Visible gas and the hypoechoic zone on US images were more predictive of the pathologic ablation zone than on NCCT images (p < 0.05). The zone of necrosis was larger than the zone of visible gas on US (mean 3.2 mm for microwave, 6.4 mm for RF) and NCCT (7.6 mm microwave, 13.9 mm RF) images (p < 0.05). The zone of visible gas and hypoechoic zone on US are more predictive of pathology with microwave ablations when compared with RF ablations (p < 0.05).Conclusion: When evaluating images during energy delivery, US is more accurate than CT and microwave- more predictable than RF-ablation based on correlation with in-plane pathology.

Microwave ablation of the liver in a live porcine model: the impact of power, time and total energy on ablation zone size and shape.

Objective: To explore various microwave (MW) time/power combinations to achieve maximum single-probe system performance in a live pig liver model.Methods: Fifty-one microwave ablations performed in 12 female pigs using the following time/power combinations: 65 W for 10 min (65W 10MIN), ramped from 20 to 65 W (RAMPED), 95 W pulses with cooling periods (95W PULSED), 40 W for 16 min 15 s (LOW POWER), 1 min 95 W pulse then 8 min 65 W then a second 1 min 95 W pulse (BOOKEND 95W) and 65 W for 15 min (65W 15MIN). Temperatures 1.5 cm from the antenna were measured. Livers were excised, and ablations were measured and compared.Results: At fixed overall energy, LOW POWER produced ablation zones with the smallest volume compared to 65W 10MIN, RAMPED and 95W PULSED. At a fixed time of 10-min, BOOKEND 95W protocol achieved wider and larger ablation zones than 65W 10MIN (p = 0.038, p = 0.008) and 95W PULSED (p = 0.049, p = 0.004). The 65W 15MIN combination had significantly larger diameters (p = 0.026), larger lengths (p = 0.014) and larger volumes (p = 0.005) versus 65W 10MIN. Maximum temperatures were highest with BOOKEND 95W (62.9 °C) and 65 W 15 MIN (63.0 °C) and lowest with LOW POWER (45.9 °C), p = 0.009.Conclusions: Low power ablations, even if controlled for total energy delivery, create small ablation zones. High peak powers are associated with larger ablation zones and high margin temperatures if cooling pauses are avoided. Ramping and pulsing protocols with interleaved cooling appear to be of no benefit versus continuous 65 W for creating large ablation zones.

Ultra-Low Radiation Dose CT Fluoroscopy for Percutaneous Interventions: A Porcine Feasibility Study.

Purpose To determine the feasibility of ultra-low-dose (ULD) CT fluoroscopy for performing percutaneous CT-guided interventions in an in vivo porcine model and to compare radiation dose, spatial accuracy, and metal artifact for conventional CT versus CT fluoroscopy. Materials and Methods An in vivo swine model was used (n = 4, ∼50 kg) for 20 procedures guided by 246 incremental conventional CT scans (mean, 12.5 scans per procedure). The procedures were approved by the Institutional Animal Care and Use Committee and performed by two experienced radiologists from September 7, 2017, to August 8, 2018. ULD CT fluoroscopic acquisitions were simulated by using only two of 984 conventional CT projections to locate and reconstruct the needle, which was superimposed on a previously acquired and motion-compensated CT scan. The authors (medical physicists) compared the ULD CT fluoroscopy results to those of conventional CT for needle location, radiation dose, and metal artifacts using Deming regression and generalized mixed models. Results The average distance between the needle tip reconstructed using conventional CT and ULD CT fluoroscopy was 1.06 mm. Compared with CT fluoroscopy, the estimated dose for a percutaneous procedure, including planning acquisitions, was 0.99 mSv (21% reduction) for patients (effective dose) and 0.015 µGy (97% reduction) for physicians (scattered dose in air). Metal artifacts were statistically significantly reduced (P < .001, bootstrapping), and the average registration error of the motion compensation was within 1-3 mm. Conclusion Ultra-low-dose CT fluoroscopy has the potential to reduce radiation exposure for intraprocedural scans to patients and staff by a factor of approximately 500 times compared with conventional CT acquisition, while maintaining image quality without metal artifacts. © RSNA, 2019.

Risk Factors for Complications and Nondiagnostic Results following 1,155 Consecutive Percutaneous Core Renal Mass Biopsies.

PURPOSE: The purpose of this study was to evaluate patient, tumor and technical factors associated with procedural complications and nondiagnostic findings following percutaneous core renal mass biopsy. MATERIALS AND METHODS: We reviewed core renal mass biopsies from 2000 to 2017. Complications at 30 days or less were graded using the Clavien-Dindo system. Univariate and multivariable analyses were done to evaluate associations between clinical characteristics and the risk of complications or nondiagnostic findings. RESULTS: Of the 1,155 biopsies performed in a total of 965 patients procedural complications were identified in 24 patients (2.2%), including 5 (0.4%) with major complications (Clavien 3a or greater). No patients were identified with tumor seeding of the biopsy tract. Patient age, body mass index, gender, Charlson comorbidity index, smoking, mass diameter, nephrometry score, number of cores and prior biopsy were not associated with complication risk (p = 0.06 to 0.53). Complications were not increased for patients on aspirin or those with low platelets (25,000 to 160,000/µl blood) or a mildly elevated INR (international normalized ratio) (1.2 to 2.0, p = 0.16, 0.07 and 0.50, respectively). The complication risk was not increased during the initial 50 cases of a radiologist or when a trainee was present (p = 0.35 and 0.12, respectively). Nondiagnostic findings were present in 14.6% of biopsies. Independent predictors included cystic features, contrast enhancement, mass diameter and skin-to-mass distance (p <0.001, 0.002, 0.02 and 0.049, respectively). Radiologist experience was not associated with the nondiagnostic rate (p = 0.23). Prior nondiagnostic biopsy was not associated with an increased nondiagnostic rate on subsequent attempts (19.2% vs 14.2%, p = 0.23). CONCLUSIONS: Procedural complications following biopsy are rare even with low serum platelets, a mildly elevated INR or when the patient remains on aspirin. Cystic features, hypo-enhancement on imaging, a smaller mass diameter and a longer skin-to-tumor distance increase the risk of nondiagnostic findings.

Tumor location does not impact oncologic outcomes for percutaneous microwave ablation of clinical T1a renal cell carcinoma.

OBJECTIVE: To evaluate the impact of anterior tumor location on oncologic efficacy, complication rates, and procedure duration for 151 consecutive biopsy-proven clinical T1a renal cell carcinoma (RCC) treated with percutaneous microwave (MW) ablation. METHODS: This single-center retrospective study was performed under a waiver of informed consent. One hundred forty-eight consecutive patients (103 M/45 F; median age 67 years, IQR 61-73) with 151 cT1a biopsy-proven RCC (median diameter 2.4 cm, IQR 1.9-3.0) were treated with percutaneous MW ablation between March 2011 and August 2017. Patient and procedural data collected included Charlson comorbidity index (CCI), RENAL nephrometry score (NS), use of hydrodisplacement, MW antennas/generator output/time, and procedure time (PT). Data were stratified by anterior, posterior, and midline tumor location and compared with the Kruskal-Wallis or chi-squared tests. The Kaplan-Meier method was used for survival analyses. RESULTS: Tumor size, NS, and use/volume of hydrodisplacement were similar for posterior and anterior tumors (p > 0.05). Patients with anterior tumors had a higher CCI (3 vs 4, p = 0.001). Median PT for posterior and anterior tumors was similar (100 vs 108 min, p = 0.26). Single session technical success and primary efficacy were achieved for all 151 tumors including 61 posterior and 67 anterior tumors. The 4 (3%) Clavien III-IV complications and 6 (4%) local recurrences were not associated with tumor location (p > 0.05). Three-year RFS, CSS, and OS were 95% (95% CI 0.87, 0.98), 100% (95% CI 1.0, 1.0), and 96% (95% CI 0.89, 0.98), respectively. CONCLUSIONS: The safety and efficacy of percutaneous microwave ablation for anterior and posterior RCC are similar. KEY POINTS: • The safety profile for percutaneous microwave ablation of anterior and posterior T1a renal cell carcinoma is equivalent. • Percutaneous microwave ablation of T1a renal cell carcinoma provides durable oncologic control regardless of tumor location. • Placement of additional microwave antennas and use of hydrodisplacement are associated with longer procedure times.

Percutaneous Microwave Tumor Ablation Is Safe in Patients with Cardiovascular Implantable Electronic Devices: A Single-Institutional Retrospective Review.

The risk of electromagnetic interference between microwave (MW) ablation and cardiac implantable electronic devices (CIEDs), ie, pacemakers and defibrillators, has not been fully evaluated. Fourteen MW ablations (kidney, n = 8; liver, n = 5; lung, n = 1) were performed in 13 patients with CIEDs in normal operating mode. Electrocardiography tracings, cardiovascular complications, tumor size, tumor-to-CIED distance, and tumor-to-device lead distance were recorded. Mean tumor size was 2.9 cm, mean tumor-to-CIED distance was 26.4 cm (range, 9-30 cm), and mean tumor-to-lead distance was 12.1 cm (range, 3.5-20 cm). No device-based cardiovascular complications or class C or higher complications per Society of Interventional Radiology criteria were identified. MW ablation appears to be safe in select patients with CIEDs.

Robotically-Assisted Sonic Therapy for Renal Ablation in a Live Porcine Model: Initial Preclinical Results.

PURPOSE: To demonstrate the feasibility of Robotically Assisted Sonic Therapy (RAST)-a noninvasive and nonthermal focused ultrasound therapy based on histotripsy-for renal ablation in a live porcine model. MATERIALS AND METHODS: RAST ablations (n = 11) were performed in 7 female swine: 3 evaluated at 1 week (acute) and 4 evaluated at 4 weeks (chronic). Treatment groups were acute bilateral (3 swine, 6 ablations with immediate computed tomography [CT] and sacrifice); chronic single kidney (3 swine, 3 ablations; CT at day 0, week 1, and week 4 after treatment, followed by sacrifice); and chronic bilateral (1 swine, 2 ablations). Treatments were performed using a prototype system (VortxRx; HistoSonics, Inc) and targeted a 2.5-cm-diameter sphere in the lower pole of each kidney, intentionally including the central collecting system. RESULTS: Mean treatment time was 26.4 minutes. Ablations had a mean diameter of 2.4 ± 0.3 cm, volume of 8.5 ± 2.4 cm3, and sphericity index of 1.00. Median ablation volume decreased by 96.1% over 4 weeks. Histology demonstrated complete lysis with residual blood products inside the ablation zone. Temporary collecting system obstruction by thrombus was observed in 4/11 kidneys (2 acute and 2 chronic) and resolved by 1 week. There were no urinary leaks, main vessel thromboses, or adjacent organ injuries on imaging or necropsy. CONCLUSIONS: In this normal porcine model, renal RAST demonstrated complete histologic destruction of the target renal tissue while sparing the urothelium.

E4206: AMG 706 and Octreotide in Patients with Low-Grade Neuroendocrine Tumors.

LESSONS LEARNED: Rate of progression-free survival at a particular point in time, i.e., a landmark analysis, is a difficult endpoint for a heterogenous malignancy such as neuroendocrine cancer.Landmark analyses can also be complicated by evolution in the standard of care during the conduct of a clinical trial.Improvements in biomarker development would be useful in developing future clinical trials in NET to better tailor individualized therapies and assess for possible efficacy endpoints. BACKGROUND: Neuroendocrine tumors (NETs) are rare malignancies of the gastrointestinal (GI) tract that are highly vascularized and overexpress vascular-endothelial growth factor (VEGF). Sunitinib has demonstrated efficacy in the pancreatic subset of NET. This study explored the activity of another oral VEGF inhibitor, AMG 706 or motesanib, a multikinase inhibitor that targets receptor tyrosine kinases, including VEGFR1, VEGFR2, VEGFR3, KIT, RET, and PDGFR (IC50s = 2, 3, 6, 8, 59, and 84 nM, respectively). METHODS: This was a single-arm, first-line, phase II study run through the Eastern Cooperative Oncology Group. Patients with low-grade NET (as defined by central confirmation of Ki-67 of 0%-2%) were administered a flat dose of 125 mg per day orally combined with octreotide long acting-repeatable (LAR) for patients who had been on a stable dose. The primary objective was to determine the 4-month progression-free survival (PFS). RESULTS: Forty-four patients were evaluated per protocol. The 4-month PFS was 78.5%. The partial response rate was 13.6% (6/44), stable disease was 54.5% (24/44), 9.1% (4/44) had progressive disease, and 10/44 were not evaluable for response. Common toxicities included fatigue, hypertension, nausea, and headache, and most were grade 1-2. Median PFS was 8.7 months, and overall survival was 27.5 months. CONCLUSION: Motesanib (AMG 706) demonstrated a 4-month PFS that met the per-protocol definition of efficacy. Fatigue and hypertension were the most common toxicities, and few grade 3-4 toxicities were encountered. The progression-free survival of 8.7 months in all NETs merits further study.

Ultrasound Guidance Versus CT Guidance for Peripheral Lung Biopsy: Performance According to Lesion Size and Pleural Contact.

OBJECTIVE: The purpose of this study was to compare efficacy and safety of biopsy guided by ultrasound (US) versus CT for lung lesions with pleural contact. MATERIALS AND METHODS: Among 1269 image-guided thoracic biopsies obtained at our institution between 2004 and 2016, 150 were US-guided for lung lesions with pleural contact (78 men, 72 women; mean age, 67 years). Of those, 94 were performed using US only; 56 had initial CT localization. A comparison cohort of 100 consecutive CT-guided biopsies for lung lesions with pleural contact was identified (60 men, 40 women; mean age, 65 years). Biopsy type, number of passes, sample adequacy, final pathologic results, complications, procedural time, lesion diameter, and pleural contact were recorded. Fisher exact and t tests were used for statistical analysis. RESULTS: US-guided biopsy was associated with fewer complications (7%) than CT-guided procedures (24%; p < 0.001). Mean procedure times (± SD) were shorter with US only (31 ± 16 min) than with CT only (45 ± 26 min; p < 0.001) or US with CT localization (45 ± 18 min; p < 0.001). Procedural times were longer for patients with small lesions and those with lesser pleural contact. Sample adequacy was best when core biopsy was performed with US and CT. Fewer passes were performed with US guidance than with CT guidance (mean, 3.1 ± 1.8 vs 4.4 ± 1.9, respectively, p < 0.001), with a trend toward improved pathologic adequacy (98% vs 93%, respectively, p = 0.122). Subgroup analysis showed fewer complications for lesions 31-50 mm (p = 0.029), improved sample adequacy for lesions 10-30 mm (p = 0.0032), and shorter procedural times for lesions 10-30 mm (p = 0.0001) with US than with CT. CONCLUSION: US guidance should be considered for biopsy of peripheral lung and pleural lesions larger than 10 mm, because it is safer, faster, and possibly more accurate than CT guidance.

Effect of Tumor Complexity and Technique on Efficacy and Complications after Percutaneous Microwave Ablation of Stage T1a Renal Cell Carcinoma: A Single-Center, Retrospective Study.

Purpose To evaluate the effects of tumor complexity and technique on early and midterm oncologic efficacy and rate of complications for 100 consecutive biopsy-proved stage T1a renal cell carcinomas (RCCs) treated with percutaneous microwave ablation. Materials and Methods This HIPAA-compliant, single-center retrospective study was approved by the institutional review board. The requirement to obtain informed consent was waived. Ninety-six consecutive patients (68 men, 28 women; mean age, 66 years ± 9.4) with 100 stage T1a N0M0 biopsy-proved RCCs (median diameter, 2.6 cm ± 0.8) underwent percutaneous microwave ablation between March 2011 and June 2015. Patient and procedural data were collected, including body mass index, comorbidities, tumor histologic characteristics and grade, RENAL nephrometry score, number of antennas, generator power, and duration of ablation. Technical success, local tumor progression, and presence of complications were assessed at immediate and follow-up imaging. The Kaplan-Meier method was used for survival analyses. Results Technical success was achieved for all 100 tumors (100%), including 47 moderately and five highly complex RCCs. Median clinical and imaging follow-up was 17 months (range, 0-48 months) and 15 months (range, 0-44 months), respectively. No change in estimated glomerular filtration rate was noted after the procedure (P = .49). There were three (3%) procedure-related complications and six (6%) delayed complications, all urinomas. One case of local tumor progression (1%) was identified 25 months after the procedure. Three-year local progression-free survival, cancer-specific survival, and overall survival were 88% (95% confidence interval: 0.52%, 0.97%), 100% (95% confidence interval: 1.0%, 1.0%), and 91% (95% confidence interval: 0.51%, 0.99%), respectively. Conclusion Percutaneous microwave ablation is an effective and safe treatment option for stage T1a RCC, regardless of tumor complexity. Long-term follow-up is needed to establish durable oncologic efficacy and survival relative to competing ablation modalities and surgery. © RSNA, 2017.