Effect of high- and low-energy entrance surface dose allocation ratio for two-shot dual-energy subtraction imaging on low-contrast resolution

IntroductionDual-energy subtraction (DES) imaging can obtain chest radiographs with high contrast between nodules and healthy lung tissue, and evaluating of chest radiography and evaluating exposure conditions is crucial to obtain a high-quality diagnostic image. This study aimed to investigate the effect of the dose allocation ratio of entrance surface dose (ESD) between high- and low-energy projection in low-contrast resolution of soft-tissue images for two-shot DES imaging in digital radiography using a contrast-detail phantom (CD phantom).MethodsA custom-made phantom mimicking a human chest that combined a CD phantom, polymethylmethacrylate square plate, and an aluminum plate (1–3 mm) was used. The tube voltage was 120 kVp (high-energy) and 60 kVp (low-energy). The ESD was changed from 0.1 to 0.5 mGy in 0.1 mGy increments. Dose allocation ratio of ESD between 120 kVp and 60 kVp projection was set at 1:1, 1:2, 1:3, and 2:1. Inverse image quality figure (IQF_inv) was calculated from the custom-made phantom images.ResultsWhen the total ESD and aluminum thickness were constant, no significant difference in IQF_inv was observed under most conditions of varied dose allocation ratio. Similarly, when the total ESD and the dose allocation ratio were constant, there was no significant difference in IQF_inv based on the aluminum plate thickness.ConclusionUsing IQF_inv to evaluate the quality of the two-shot DES image suggested that dose allocation ratio did not have a significant effect on low-contrast resolution of soft-tissue images.Implications for practiceThe present results provide useful information for determining exposure conditions for two-shot DES imaging.     

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.     

Hepatic Hilar Nerve Block for Adjunctive Analgesia during Percutaneous Thermal Ablation of Hepatic Tumors: A Retrospective Analysis

PurposeTo determine whether hepatic hilar nerve block techniques reduce analgesic and sedation requirements during percutaneous image-guided thermal ablation of hepatic tumors.Materials and MethodsA single-center retrospective cohort analysis was performed of 177 patients (median age, 67 years; range, 33–86 years) who underwent percutaneous image-guided thermal ablation of liver tumors. All patients were treated utilizing local anesthetic and moderate sedation between November 2018 and November 2021 at a tertiary level hospital, with or without the administration of a hepatic hilar nerve block. Univariable and multivariable linear regression analyses were performed to determine the relationship between the administration of the hilar nerve block and fentanyl and midazolam dosages.ResultsA total of 114 (64%) patients received a hilar nerve block in addition to procedural sedation, and 63 (36%) patients received procedural sedation alone. There were no significant differences in the baseline demographic and tumor characteristics between the cohorts. The procedure duration was longer in the hilar block cohort than in the unblocked cohort (median, 95 vs 82 minutes; P = .0012). The technical success rate (98% in both the cohorts, P = .93) and adverse event rate (11% vs 3%, P = .14) were not significantly different between the cohorts. After adjusting for patient and tumor characteristics, ablation modality, and procedure and ablation durations, hilar nerve blocks were associated with lower fentanyl (?18.4%, P = .0045) and midazolam (?22.7%, P = .0007) dosages.ConclusionsHepatic hilar nerve blocks significantly decrease the fentanyl and midazolam requirements during thermal ablation of hepatic tumors, without a significant change in the technical success or adverse event rates.     

Prostatic Artery Embolization Using 100–300-μm Trisacryl Gelatin Microspheres to Treat Lower Urinary Tract Symptoms Attributable to Benign Prostatic Hyperplasia: A Single-Center Outcomes Analysis with Medium-Term Follow-up

PurposeTo report medium-term outcomes of prostatic artery embolization (PAE) using 100–300-μm trisacryl gelatin microspheres to treat lower urinary tract symptoms (LUTS) from benign prostatic hyperplasia (BPH) and to evaluate how cone-beam computed tomography-measured prostate gland volume (PGV), median lobe enlargement (MLE), age, and Charlson Comorbidity Index (CCI) affect these results.Materials and MethodsSeventy-four consecutive patients who underwent PAE from April 2014 through August 2018 were retrospectively reviewed. Patients had International Prostate Symptom Score (IPSS) >12, Quality of Life (QoL) score >2, prostate gland volume (PGV) >40 mL, age older than 45 years, and medical therapy failure. Twelve patients were excluded for bladder pathology or prostate cancer. Patients (n = 62, age = 71.8 ± 9.3 years, CCI = 3.5 ± 1.7, PGV = 174 ± 110 mL) had pre-procedure IPSS = 22.4 ± 5.6, QoL score = 4.4 ± 0.9, and post-void residual (PVR) = 172 ± 144 mL. Post-procedure values were compared to baseline at 1, 3, 6, 12, and 24 months. Associations between outcomes and PGV, MLE, age, and CCI were evaluated. Adverse event recording used Clavien-Dindo classification.ResultsOne month after PAE (n = 37), IPSS improved to 7.6 ± 5.2 (P < .0001) and QoL score improved to 1.7 ± 1.4 (P < .0001). At 3 months (n = 32), improvements continued, with IPSS = 6.4 ± 5.1 (P < .0001), QoL score = 1.2 ± 1.2 (P < .0001), PVR = 53 ± 41 mL (P < .001), and PGV = 73 ± 38 mL (P < .0001). Results were sustained at 6 months (n = 35): IPSS = 6.4 ± 4.1 (P < .0001), QoL score = 1.2 ± 1.2 (P < .0001), PVR = 68 ± 80 mL (P < .0001), PGV = 60 ± 19 mL (P < .001). At 12 months, patients (n = 26) had IPSS = 7.3 ± 5.5 (P < .0001), QoL score = 1.2 ± 0.8 (P <.0001), PVR = 89 ± 117 mL (P < .0001), PGV = 60 ± 48 mL (P < .01). At 24 months, patients (n = 8) had IPSS = 8.0 ± 5.4 (P < .0001), QoL score = 0.7 ± 0.5 (P < .0001), PVR = 91 ± 99mL (P = 0.17), and PGV = 30 ± 5mL (P = .11). Improvements were independent of PGV, MLE, age, and CCI. Two grade II urinary infections occurred.ConclusionsPAE with 100–300-μm microspheres produced sustained substantial improvements in LUTS, PGV, and PVR, which were independent of baseline PGV, MLE, age, or CCI.     

Metal artefact reduction in low-dose computed tomography: Benefits of tin prefiltration versus postprocessing of dual-energy datasets over conventional CT imaging

IntroductionThe purpose of this study was to determine the potential for metal artefact reduction in low-dose multidetector CT as these pose a frequent challenge in clinical routine. Investigations focused on whether spectral shaping via tin prefiltration, virtual monoenergetic imaging or virtual blend imaging (VBI) offers superior image quality in comparison with conventional CT imaging.MethodsUsing a third-generation dual-source CT scanner, two cadaveric specimens with different metal implants (dental, cervical spine, hip, knee) were examined with acquisition protocols matched for radiation dose with regards to tube voltage and current. In order to allow for precise comparison, and due to the relatively short scan lengths, automatic tube current modulation was disabled. Specifically, the following scan protocals were examined: conventional CT protocols (100/120 kVp), tin prefiltration (Sn 100/Sn 150 kVp), VBI and virtual monoenergetic imaging (VME 100/120/150 keV). Mean attenuation and image noise were measured in hyperdense and hypodense artefacts, in artefact-impaired and artefact-free soft tissue. Subjective image quality was rated independently by three radiologists.ResultsObjectively, Sn 150 kVp allowed for the best reduction of hyperdense streak artefacts (p < 0.001), while VME 150 keV and Sn 150 kVp protocols facilitated equally good reduction of hypodense artefacts (p = 0.173). Artefact-impaired soft tissue attenuation was lowest in Sn 150 kVp protocols (p ≤ 0.011), whereas all VME showed significantly less image noise compared to conventional or tin-filtered protocols (p ≤ 0.001). Subjective assessment favoured Sn 150 kVp regarding hyperdense streak artefacts and delineation of cortical bone (p ≤ 0.005). The intraclass correlation coefficient was 0.776 (95% confidence interval: 0.712–0.831; p < 0.001) indicating good interrater reliability.ConclusionIn the presence of metal implants in our cadaveric study, tin prefiltration with 150 kVp offers superior artefact reduction for low-dose CT imaging of osseous tissue compared with virtual monoenergetic images of dual-energy datasets. The delineation of cortical boundaries seems to benefit particularly from spectral shaping.Implications for practiceLow-dose CT imaging of osseous tissue in combination with tin prefiltration allows for superior metal artefact reduction when compared to virtual monoenergetic images of dual-energy datasets. Employing this technique ought to be considered in daily routine when metal implants are present within the scan volume as findings suggest it allows for radiation dose reduction and facilitates diagnosis relevant to further treatment.     

4D Flow MR Imaging to Improve Microwave Ablation Prediction Models: A Feasibility Study in an In Vivo Porcine Liver

PurposeTo characterize the effect of hepatic vessel flow using 4-dimensional (4D) flow magnetic resonance (MR) imaging and correlate their effect on microwave ablation volumes in an in vivo non-cirrhotic porcine liver model.Materials and MethodsMicrowave ablation antennas were placed under ultrasound guidance in each liver lobe of swine (n = 3 in each animal) for a total of 9 ablations. Pre- and post-ablation 4D flow MR imaging was acquired to quantify flow changes in the hepatic vasculature. Flow measurements, along with encompassed vessel size and vessel-antenna spacing, were then correlated with final ablation volume from segmented MR images.ResultsThe linear regression model demonstrated that the preablation measurement of encompassed hepatic vein size (β = –0.80 ± 0.25, 95% confidence interval [CI] –1.15 to –0.22; P = .02) was significantly correlated to final ablation zone volume. The addition of hepatic vein flow rate found via 4D flow MRI (β = –0.83 ± 0.65, 95% CI –2.50 to 0.84; P = .26), and distance from antenna to hepatic vein (β = 0.26 ± 0.26, 95% CI –0.40 to 0.92; P = .36) improved the model accuracy but not significantly so (multivariate adjusted R² = 0.70 vs univariate (vessel size) adjusted R² = 0.63, P = .24).ConclusionsHepatic vein size in an encompassed ablation zone was found to be significantly correlated with final ablation zone volume. Although the univariate 4D flow MR imaging-acquired measurements alone were not found to be statistically significant, its addition to hepatic vein size improved the accuracy of the ablation volume regression model. Pre-ablation 4D flow MR imaging of the liver may assist in prospectively optimizing thermal ablation treatment.     

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.     

Preliminary Study of Microwave Ablation for Multifocal Papillary Thyroid Microcarcinoma in Nonoperative Candidates

PurposeTo study the feasibility, safety, and effectiveness of microwave ablation (MWA) in patients with multifocal papillary thyroid microcarcinoma (PTMC).Materials and MethodsThis retrospective study included patients who underwent MWA for multifocal PTMC (number of nodules ≤3). A total of 44 patients were included, and the mean age was 43 years (SD ± 11). After ablation, progression-free survival (PFS) at 6, 12, 24, 36, and 48 months; disease progression; change in tumor size and volume; tumor disappearance rate; and adverse events (AEs) were assessed, and the feasibility, safety, and effectiveness of MWA for PTMC were evaluated on the basis of statistical analysis.ResultsThe median follow-up period was 18 months (interquartile range, 12–33 months). The PFS rates at 6, 12, 24, 36, and 48 months were 100.0%, 96.4%, 96.4%, 70.3%, and 52.7%, respectively. The disease progression rate was 11.4% (5 of 44 patients). The maximum diameter (MD) and volume of the ablation zone were larger at the 3-month follow-up than before ablation (median MD, 13.0 vs 7.0 mm; P < .001; median volume, 503.8 vs 113.0 mm³; P < .001). Subsequently, the tumors exhibited a reduction in both size and volume after 18 months (median MD, 4.0 vs 7.0 mm; P = .04; median volume, 12.6 vs 113.0 mm³; P = .055). At the end of the follow-up period, the complete response rate was 59% (26 of 44 patients). The overall AE rate was 6.8%.ConclusionsMWA is a feasible treatment for PTMC (number of nodules ≤3), and this study preliminarily demonstrated the safety and effectiveness of this technique.     

Evaluation of Technical Success,Efficacy, and Safety of Portomesenteric Venous Intervention following Nontransplant Hepatobiliary or Pancreatic Surgery

PurposeTo evaluate technical success, efficacy and safety of portomesenteric venous (PMV) intervention for PMV stenosis or occlusion following nontransplant hepatobiliary or pancreatic (HPB) surgery.Materials and MethodsA retrospective review identified 42 patients (mean age 60 y) with PMV stenosis (n = 33; 79%) or occlusion (n = 9; 21%) who underwent attempted PMV intervention following HPB surgery between June 1, 2011, and April 1, 2018. Main outcomes were technical success, primary patency rates, and complications. Technical success was compared by venous pathology and primary PMV patency based on anticoagulation status after the procedure using Fisher exact test. Rates of primary patency by stent group were estimated using Kaplan-Meier method.ResultsTechnical success was 91% (n = 38/42) and significantly higher in patients with stenosis (n = 33/33; 100%) vs occlusion (n = 5/9; 56%) (P = .001). Primary presenting symptom resolved in 28 (87%) patients, including 6 (100%) patients with gastrointestinal bleeding. At mean imaging follow-up of 8.6 months ± 8.8, primary stent patency was 76%. There was no significant difference in primary stent patency based on anticoagulation status after the procedure (P = .48). There were 2 (4.8%) periprocedural complications.ConclusionsPortomesenteric venoplasty and stent placement following nontransplant HPB surgery is safe with a high rate of technical success if performed before chronic occlusion.     

High-Suspicion Subcentimeter Thyroid Nodules: Cost Effectiveness of Active Surveillance versus Fine Needle Aspiration

PurposeTo compare the cost-benefit of active surveillance (AS) against immediate fine needle aspiration (FNA) of sonographically suspicious subcentimeter thyroid nodules.Materials and MethodsA Markov model was constructed to compare the cost-benefit of 3 strategies from the point of discovery until death: (a) Surveillance of all nodules, (b) Surveillance of nodules with positive cytology, and (c) Surgery of nodules with positive cytology. The reference case was a 40-year-old woman with a sonographically suspicious subcentimeter thyroid nodule. Transition probabilities, costs, and health state utilities were derived from the literature. Sensitivity analyses were performed to evaluate model uncertainty. Willingness-to-pay threshold was set at $100,000/quality-adjusted life year.ResultsSurveillance of nodules with positive cytology dominated in the reference scenario and was cost-beneficial over Surveillance of all nodules, independent of the utility of AS. Surveillance of all nodules was cost-beneficial only at a life expectancy of <2.6 years or surveillance duration of <4 years.ConclusionsWhile current guidelines recommend AS of sonographically suspicious subcentimeter nodules, the results of this study suggest that immediate FNA (Surveillance of nodules with positive cytology) is more cost-beneficial than AS (Surveillance of all nodules). Patients with positive cytology on FNA may subsequently opt for AS (Surveillance of nodules with positive cytology) or surgery (Surgery of nodules with positive cytology) according to their level of comfort (ie, utility) with AS.     

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.     

Methylene Blue/Collagen Mixture for CT-Guided Presurgical Lung Nodule Marking: High Efficacy and Safety

PurposeTo assess outcomes of computed tomography (CT)-guided methylene blue/collagen marking of preoperative lung nodules before video-assisted thoracoscopic surgery (VATS) and robotic-assisted thoracic surgery (RATS).Materials and MethodsA retrospective cohort study assessing 25 methylene blue/collagen solution CT-guided lung nodule localization procedures on 26 nodules in 25 patients was performed. The procedures were performed by a fellowship-trained radiologist 1–2 hours before scheduled surgery under local anesthesia. Approximately 4–6 ml of methylene blue/collagen solution was injected in a perinodular location under CT guidance with a 19-gauge trocar needle and along the track to the visceral pleural surface. Post-procedural CT images confirmed appropriate lung nodule location marking.ResultsPerinodular CT-guided trocar needle placement was achieved in all marking procedures (n = 26/26). Increased consolidation near the target nodule was also demonstrated in all patients on the post-procedural localized CT scans. One patient with moderate emphysema developed a small to moderate-sized pneumothorax (∼20%–30%), and an 8-Fr thoracentesis catheter was placed under CT guidance before surgery. There was no bleeding or hemoptysis in any patient. Methylene blue/collagen solution was readily visible by the thoracic surgeon in association with all target nodules. One patient required conversion to open procedure due to the proximal portion of the right lower lobe pulmonary artery segmental branch. Of the 26 identified nodules, pathology specimens confirmed the adequacy of nodule resection in all cases.ConclusionsPreoperative CT-guided methylene blue/collagen solution injection offers a safe and highly effective technique for marking subpleural lung nodules undergoing VATS or RATS.     

Quantitative Dual-Energy CT Image Guidance for Thermochemical Ablation: In Vivo Results in the Rabbit VX2 Model

PurposeTo evaluate the feasibility of using dual-energy computed tomography (CT) and theranostic cesium hydroxide (CsOH) for image guidance of thermochemical ablation (TCA) in a rabbit VX2 tumor model.Materials and MethodsIn vivo experiments were performed on New Zealand white rabbits, where VX2 tumor fragments (0.3 mL) were inoculated into the right and left flanks (n = 16 rabbits, 32 tumors). Catheters were placed in the approximate center of 1- to 2-cm diameter tumors under ultrasound guidance. TCA was delivered in 1 of 3 treatment groups: untreated control, 5-M TCA, or 10-M TCA. The TCA base reagent was doped with 250-mM CsOH. Dual-energy CT was performed before and after TCA. Cesium (CS)-specific images were postprocessed on the basis of previous phantom calibrations to determine Cs concentration. Line profiles were drawn through the ablation center. Twenty-four hours after TCA, subjects were euthanized, and the resulting damage was evaluated with histopathology.ResultsCs was detected in 100% of treated tumors (n = 21). Line profiles indicated highest concentrations at the injection site and decreased concentrations at the tumor margins, with no Cs detected beyond the ablation zone. The maximum detected Cs concentration ranged from 14.39 to 137.33 mM. A dose-dependent trend in tissue necrosis was demonstrated between the 10-M TCA and 5-M TCA treatment groups (P = .0005) and untreated controls (P = .0089).ConclusionsDual-energy CT provided image guidance for delivery, localization, and quantification of TCA in the rabbit VX2 model.     

Impact of the Ablative Margin on Local Tumor Progression after Radiofrequency Ablation for Lung Metastases from Colorectal Carcinoma: Supplementary Analysis of a Phase II Trial (MLCSG-0802)

PurposeTo explore what extent of ablative margin depicted by computed tomography (CT) immediately after radiofrequency (RF) ablation is required to reduce local tumor progression (LTP) for colorectal cancer (CRC) lung metastases.Materials and MethodsThis retrospective study was undertaken as a supplementary analysis of a previous prospective trial. Seventy patients (49 men and 21 women; mean age ± standard deviation, 64.9 years ± 10.6 years) underwent RF ablation for CRC lung metastases, and 95 tumors that were treated in the trial and followed up with CT at least 12 months after RF ablation were evaluated. The mean tumor size was 1.0 cm ± 0.5 cm. The ablative margin was estimated as the shortest distance between the outer edge of the tumor and the surrounding ground-glass opacity on CT obtained immediately after RF ablation. The impact of the ablative margin on LTP was evaluated using logistic regression analysis. Multivariate logistic regression analysis was also performed to identify the risk factors for LTP. The result was validated with multivariate logistic regression applying a bootstrap method (1,000 times resampling).ResultsThe mean ablative margin was 2.7 mm ± 1.3 (range, 0.4–7.3 mm). LTP developed in 6 tumors (6%, 6/95) 6–19 months after RF ablation. The LTP rate was significantly higher when the margin was less than 2 mm (P = .023). A margin of <2 mm was also found to be a significant factor for LTP (P = .048) on multivariate analysis and validated using the bootstrap method (P = .025).ConclusionsAn ablative margin of at least 2 mm is important to reduce LTP after RF ablation for CRC lung metastases.     

Endovascular Outcomes in Aortic Arch Repair with Double and Triple Parallel Stent Grafts

PurposeTo report early and midterm outcomes of treating thoracic aortic aneurysm (TAA) and aortic dissection (AD) involving zone 1 and zone 0 with multiple parallel stent grafts (PSGs).Materials and MethodsFrom February 2011 to August 2018, 31 of 1,806 patients (1.7%) who underwent thoracic endovascular aortic repair (TEVAR) with double PSGs (DPSGs) (n = 20) or triple PSGs (TPSGs) (n = 11) were retrospectively reviewed. Procedures were performed in high-risk patients who had TAA or AD involving zone 1 or zone 0.ResultsFifteen patients (48.4%) who presented with symptomatic or impending rupture underwent urgent or emergent TEVAR with DPSGs or TPSGs. Nineteen patients (61.3%) were treated for zone 0 disease. Technical and clinical success rates were 70.0% for DPSG cohort and 45.5% for TPSG cohort. Intraoperative type Ia endoleak was observed in 30% of DPSG cohort and 45.5% of TPSG cohort. One patient in the DPSG cohort died of aortic sinus rupture intraoperatively. Minor stroke during the 30-day postoperative period was more frequent in the TPSG cohort (P = .042). Mean duration of follow-up was 28.9 months ± 17.7. The TPSG cohort had a higher incidence of major adverse events (72.7% vs 25.0%, P = .021). The most common adverse events were endoleaks (12.9%), endograft migration (9.7%), PSG stenosis or occlusion (6.5%), retrograde dissection (6.5%), and stroke (3.2%). Endograft migrations were more common in TPSG cohort (27.3%, P = .037). Overall mortality rate was 16.1% (5/31) perioperatively and during follow-up. There were no statistical differences in overall survival and reintervention-free survival.ConclusionsIn the context of TEVAR with multiple PSGs for aortic arch repair, TPSGs may have a high risk of major complications.     

Prostatic Artery Embolization—Anatomic Predictors of Technical Outcomes

PurposeTo determine if cone-beam CT and digital subtraction angiography analysis of pelvic arterial anatomy has predictive value for radiation exposure and technical success of prostatic artery embolization (PAE).Materials and MethodsThis prospective, nonrandomized, single-center study included 104 consecutive patients with lower urinary tract symptoms secondary to benign prostatic hyperplasia. Cone-beam CT was performed in 160/208 (76.9%) hemipelves to determine prostatic artery (PA) origin. Classification of pelvic arterial tortuosity was possible in 73/104 (70.2%) patients. Learning curves of 2 interventionalists who performed 86.5% of PAEs were analyzed.ResultsTortuosity of pelvic arteries was classified as mild in 25 (34.2%) patients median age 64 years, moderate in 40 (54.8%) patients median age 69 years, and severe in 8 (11.0%) patients median age 70 years (mild vs moderate, P = .002; mild vs severe, P = .019); median fluoroscopy times were 24, 36, and 46 minutes (P = .008, P = .023); median contrast volumes were 105, 122.5, and 142 mL (P = .029, P = .064); and bilateral PAE rates were 84.0%, 77.5%, and 62.5% (P = .437), respectively. PA origin from superior vesical artery was most frequent (27.5%) and showed higher dose area product (median 402.4 vs 218 Gy ∙ cm², P = .033) and fluoroscopy time (median 42.5 vs 27 min, P = .01) compared with PA origin from obturator artery, which was least frequent. Interventionalist experience revealed significant impact on procedure times (median 159 vs 130 min, P = .006).ConclusionsTortuosity of pelvic arteries was more frequent in older patients and predicted worse technical outcomes of PAE. PA origin from obturator artery was associated with lower dose area product and fluoroscopy time, especially compared with PA origin from superior vesical artery. Interventionalist experience showed significant influence on technical outcome.     

Fully Integrated Laser Guidance for CT-Based Punctures: A Study in Phantoms and Patients

PurposeTo test the hypothesis of equal or even superior applicability and accuracy of a fully integrated, laser-based computed tomography (CT) navigation system compared with conventional CT guidance for percutaneous interventions.Materials and MethodsCT-guided punctures were first performed in phantoms. Four radiologists with different experience levels (2 residents (L.B., C.D.) and 2 board-certified radiologists (B.M., K.R.) performed 48 punctures using both conventional image-guided and laser-guided approaches. Subsequently, 12 punctures were performed in patients during a clinical pilot trial. Phantom targets required an in-plane or a single-/double-angulated, out-of-plane approach. Planning and intervention time, control scan number, radiation exposure, and accuracy of needle placement (measured by deviation of the needle tip to the designated target) were assessed for each guidance technique and compared (Mann-Whitney U test and t test). Patient interventions were additionally analyzed for applicability in a clinical setting.ResultsThe application of laser guidance software in the phantom study and in 12 human patients in a clinical setting was both technically and clinically feasible in all cases. The mean planning time (P = .009), intervention time (P = .005), control scan number (P < .001), and radiation exposure (P = .013) significantly decreased for laser-navigated punctures compared with those for conventional CT guidance and especially in punctures with out-of-plane-trajectories. The accuracy significantly increased for laser-guided interventions compared with that for conventional CT (P < .001).ConclusionsInterventional radiologists with differing levels of experience performed faster and more accurate punctures for out-of-plane trajectories in the phantom models, using a new, fully integrated, laser-guided CT software and demonstrated excellent clinical and technical success in initial clinical experiments.     

Use of the Covera Stent Graft for the Treatment of Dysfunctional or Thrombosed Arteriovenous Grafts: A Retrospective Analysis of 64 Patients

PurposeTo retrospectively evaluate the safety and effectiveness of the Covera stent graft (SG) for the treatment of dysfunctional or thrombosed arteriovenous grafts (AVGs).Materials and MethodsWithin 29 months (February 2016–August 2018), 79 patients underwent Covera SG placement in the authors’ department for the treatment of dysfunctional AVGs. Data were available for 64 patients who underwent 64 procedures, using 64 devices. Minimum follow-up was 6 months, unless reintervention occurred. Mean follow-up was 277 days (6–923 days). Treatment characteristics were 51 cases with venous-graft anastomosis (VGA) stenosis (79.7%), 13 cases of puncture zone stenosis (20.3%), 14 cases of in SG stenosis (21.9%), 8 cases of pseudoaneurysm treatment (12.5%) (1 treatment area might have had more than 1 characteristic). Thirty-six patients presented with thrombosis (56.2%), and 31 of 64 case were de novo treatment areas (48.4%). Primary outcome measurements were technical success and post-intervention primary patency (PIPP) at 6 months, whereas secondary outcome measurements included factors influencing primary outcome.ResultsTechnical success was 100%. Median PIPP was 336 days, and 73.6% of treatment areas were patent at 6 months. There were no significant differences in terms of PIPP when de novo treatment areas were compared with restenotic areas (519 vs. 320 days, respectively; P = .1); patients who presented with versus those who presented without thrombosis (320 vs. 583 days, respectively; P = .07); puncture zone stenosis or elsewhere (329 vs. 686 days, respectively; P = .52); and VGA stenosis or elsewhere (336 vs. 335 days, respectively; P = .9).ConclusionsUse of the Covera SG for AVG treatment was safe and effective in every type of treatment area presented in this retrospective analysis.     

Effect of Median Lobe Enlargement on Early Prostatic Artery Embolization Outcomes

PurposeTo evaluate outcomes after prostatic artery embolization (PAE) in patients with severe intravesical prostatic protrusion (IPP).Materials and MethodsThis was a retrospective, single health system, 2-hospital study from April 2015 to December 2018 of 54 patients who underwent elective PAE procedures (age mean 67.5 years; standard deviation [SD] 8.5). The cohort had a mean ellipsoid prostate volume of 100.1 cm³ (SD 56.7), a mean baseline International Prostate Symptom Score (IPSS) of 18.7 (SD 8.2), a mean baseline quality of life (QOL) score of 4.1 (SD 1.4), and a median follow-up of 38 days (range 10–656 days). Outcomes including IPSS and QOL score reduction (where a lower QOL score indicates an improvement in QOL), and clinical success were compared between severe (≥10 mm) and nonsevere (<10 mm) IPP patients. A linear regression model was used to examine the impact of IPP on these outcomes.ResultsNo significant differences in patient characteristics were found between nonsevere (n = 17) and severe (n = 37) IPP patients. Both cohorts showed IPSS reduction (nonsevere 6.0, P = .0397; severe 8.2, P < .0001) and QOL score reduction (nonsevere 1.0, P = .102; severe 2.0, P < .0001). No significant differences in IPSS or QOL score reduction were found between the cohorts (P = .431 and P = .127). Linear regression found that baseline IPP was not a significant contributor to the outcomes (IPSS: R² = .5, P < .0001; IPP: P = .702; QOL: R² = .5, P = .0003; IPP: P = .108).ConclusionsThere were no significant differences in early outcomes in PAE between patients with severe and nonsevere IPP.     

Computed Tomography Evaluation of In Vivo Pulmonary Cryoablation Zone Sizes

PurposeTo evaluate ablation zone sizes in patients undergoing pulmonary tumor cryoablation with 14-gauge cryoablation probes.Materials and MethodsA single-center retrospective analysis of all consecutive patients who underwent cryoablation of pulmonary tumors with 1 or more 14-gauge probes (August 2017 to June 2020) was performed. Intraprocedural and 1–2-month postprocedural chest computed tomography (CT) scans were evaluated to characterize pulmonary lesions, ice balls, and ablation zones. Single-probe 14-gauge ablation zone volumes were compared with manufacturer reference isotherms and single- and 2-probe ablation zones from a prior investigation of 17-gauge probes. Overall survival and local recurrence–free survival were calculated to 3 years.ResultsForty-seven pulmonary malignancies in 42 patients (women, 50%; mean age, 75.2 years ± 11.5) underwent cryoablation with 1 (n = 35), 2 (n = 10), or 3 (n = 2) cryoablation probes. One- to 2-month follow-up CT images were available for 30 of the 42 patients. The mean cryoablation zone volumes at 1–2 months when 1 (n = 21), 2 (n = 8), and 3 (n = 1) probes were used were 5.0 cm³ ± 2.3, 37.5 cm³ ± 20.5, and 28.4 cm³, respectively. The mean single-probe follow-up ablation zone volume was larger than that previously reported for 17-gauge probes (3.0 cm³ ± 0.3) (P < .001) but smaller than manufacturer-reported isotherms (11.6 cm³ for ?40 °C isotherm) and the 2-probe ablation zone volume with 17-gauge devices (12.9 cm³ ± 2.4) (for all, P < 001). The 3-year overall survival and local recurrence–free survival were 69% (95% confidence interval [CI], 53%–89%) and 87% (95% CI, 74%–100%), respectively.ConclusionsFourteen-gauge probes generate larger ablation volumes than those generated by 17-gauge probes. Manufacturer-reported isotherms are significantly larger than actual cryoablation zones. Cryoablation can attain low rates of local recurrence.