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At least 811 records · Page 45
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

Percutaneous Thermal Ablation with Ultrasound Guidance. Fusion Imaging Guidance to Improve Conspicuity of Liver Metastasis

PurposeTo assess whether fusion imaging-guided percutaneous microwave ablation (MWA) can improve visibility and targeting of liver metastasis that were deemed inconspicuous on ultrasound (US).Materials and MethodsMWA of liver metastasis not judged conspicuous enough on US was performed under CT/US fusion imaging guidance. The conspicuity before and after the fusion imaging was graded on a five-point scale, and significance was assessed by Wilcoxon test. Technical success, procedure time, and procedure-related complications were evaluated.ResultsA total of 35 patients with 40 liver metastases (mean size 1.3 ± 0.4 cm) were enrolled. Image fusion improved conspicuity sufficiently to allow fusion-targeted MWA in 33 patients. The time required for image fusion processing and tumors’ identification averaged 10 ± 2.1 min (range 5–14). Initial conspicuity on US by inclusion criteria was 1.2 ± 0.4 (range 0–2), while conspicuity after localization on fusion imaging was 3.5 ± 1 (range 1–5, p < 0.001). Technical success rate was 83% (33/40) in intention-to-treat analysis and 100% in analysis of treated tumors. There were no major procedure-related complications.ConclusionsFusion imaging broadens the scope of US-guided MWA to metastasis lacking adequate conspicuity on conventional US. Fusion imaging is an effective tool to increase the conspicuity of liver metastases that were initially deemed non visualizable on conventional US imaging.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2019

Monitoring of Thermal-Induced Changes in Liver Stiffness During Controlled Hyperthermia and Microwave Ablation in an Ex Vivo Bovine Model Using Point Shear Wave Elastography

Purpose: To investigate liver stiffness changes—evaluated by point shear wave elastography (pSWE)—in controlled hyperthermia and microwave ablation (MWA) in an ex vivo animal model. Materials and Methods: Five samples of ex vivo bovine liver were uniformly heated to temperatures ranging from 40 to 100 °C. B-mode ultrasound imaging and pSWE were acquired simultaneously, and shear wave velocity (SWV) was measured in a region of interest (ROI). The threshold value of SWV at 60 °C (avg60) was identified. Subsequently, MWA was performed in 11 liver samples at 60 W until avg60 + 0.5 m/s was reached. SWV was measured in ROIs at 10–40 mm from the antenna feed. The correlation of mean values of SWV with location (within, border, or outside necrotic area) at gross pathology was evaluated. Results: In controlled hyperthermia experiments, a steep transition in liver stiffness was observed at 63.0 ± 2.4 °C (SWV 3.54 ± 0.68 m/s). Avg60 was of 2.5 m/s. In 8/9 MWA experiments, interrupted when SWV of 3 m/s was measured, the ROI was at the inner side of the necrotic area border at pathology (accuracy 89%). No correlation between SWV values for outside, border, and within necrosis could be identified. Conclusions: pSWE can provide a velocity threshold predictive of the presence of coagulation necrosis during MWA in ex vivo liver model. However, pSWE is not able to reliably capture changes in stiffness within, at the border, and outside the necrotic zone in this experimental model.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2019

Intratumoral Injection of Hypertonic Glucose in Treating Refractory Pneumothorax Caused by Microwave Ablation: a Preliminary Study

Purpose: The purpose of this technical report is to describe the technique of intratumoral injection of hypertonic glucose combined with low-negative pressure drainage to treat refractory pneumothorax (RP) after microwave ablation (MWA) of lung tumors. Materials and Methods: Between September 2016 and May 2018, four patients who developed RP after MWA of peripheral lung cancer were managed by a combined method, including intratumoral injection of hypertonic glucose and catheter drainage under low-negative pressure. Blood gas values were recorded and compared before the treatment and one-week posttreatment. All patients were followed up for at least one month to monitor the possible recurrence of pneumothorax by chest CT. Results: All patients were successfully treated. One patient received the intratumoral injection of hypertonic glucose twice, while the remaining three patients received a single injection. The technical success rate was 100%. Dyspnea related to RP was significantly relieved in all patients, and PaO{sub 2} and SaO{sub 2} values were higher than those measured before treatment. No patient suffered a recurrence of pneumothorax during the follow-up. Conclusion: The combined method of intratumoral injection of hypertonic glucose and continuous catheter drainage under low-negative pressure might be an effective method to manage RP caused by MWA.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2019

Sacroiliac Joint Ablation Using MR-HIFU

The sacroiliac joint is the culprit in 15–30% of patients with chronic lumbar back pain. Ablation of the posterior sensory nerves supplying the joint is an established treatment option before arthrodesis. We report the successful application of MR-HIFU in a patient with therapy–refractory pain using the Sonalleve MR-HIFU system. The outpatient procedure was performed under spinal anaesthesia and analgosedation. The ramus dorsalis of L5 as well as the lateral branches of the ramus dorsalis S1–S3 was targeted, and tissue peak temperature per sonication was controlled using MR-thermometry. There were no post-interventional complications. Clinical improvement began 4 days post-intervention with complete resolution of the pain after 1 month.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2018

Thermally induced dispersive optical bistability in silver nanosuspensions produced by pulsed laser ablation method

The thermally induced optical bistability in prepared silver (Ag) nanosuspensions have been studied experimentally, using Fabry–Perot and Mach–Zehnder interferometry methods. Two Ag nanosuspensions of different sizes were produced by different fluences of pulsed laser ablation method in distilled water. The pulsed Nd:YAG laser of 7 ns pulse width, 1064 nm wavelength and different fluences was employed to produce Ag nanosuspensions. Experimental observations were performed by an ultraviolet–visible–near infrared spectrophotometry. Structure and size of prepared Ag nanoparticles were diagnosed using transmission electron microscope images. Fabry–Perot and Mach–Zehnder interferometry methods were used to carry out the optical bistability process in prepared Ag nanosuspensions. In two considered interferometers, the obtained phase shifts of the hysteresis loops based on the optical bistability are inversely proportional to the nonlinear refractive index of samples and thickness of Ag nanosuspensions cells. Results indicate that the induced thermal effect of the optical bistability can be tuned by modifying parameters such as the nonlinear refractive index and applied interferometry methods. Hence, a desirable situation for the thermo-optical effects of the optical bistability can be easily realized in Ag nanosuspensions.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2017

Structure and Properties of Nanoparticles Fabricated by Laser Ablation of Bulk Metal Copper Targets in Water and Ethanol

Colloidal solutions of nanoparticles (NPs) are prepared by nanosecond pulsed laser ablation (upon exposure to Nd:YAG laser radiation at a wavelength of 1064 nm with a pulse duration of 7 ns) of a copper target in water and ethyl alcohol. Their composition, structure, and optical properties are investigated. It is shown that monovalent Cu{sub 2}O NPs are mainly formed in water, whereas metal Cu NPs are mainly formed in ethanol. The nonlinear transmission of colloids at wavelengths of 532 and 1064 nm is investigated. It is established that they effectively limit the nanosecond laser pulse power at a wavelength of 532 nm.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2018

Corrosion Inhibition of Cold-rolled Low Carbon Steel with Pulse Fiber Laser Ablation in Water

This study aims at the use of a fiber laser for modifying the surface properties of cold-rolled low carbon steel via a pulse laser ablation technique in water. The effect on the corrosion behavior of the fiber laser-treated metal surface was investigated in NaCl and HCl environments. Electrochemical tests showed significant improvement in the corrosion resistance of the laser-treated sample in NaCl, with an increase in open-circuit potential (OCP) from − 0.65 to − 0.60 V and an inhibition efficiency of 89.22% as obtained from the impedance study. Such improvement was less significant in an acidic environment. Lower corrosion rates of 20.9 mpy and 5.819 × 10{sup 3} mpy were obtained for the laser-treated samples in neutral and acidic electrolytes, respectively, than the corrosion rates obtained for the as-received samples (33.2 mpy and 11.98 × 10{sup 3} mpy). Morphological analysis indicated a passive film built by spherical grains of regular size on the metal surface after laser treatment. The corrosion inhibition effects in NaCl were evident by the nonexistence of the common corrosion products of lepidocrocite and crystalline structures that were seen on as-received samples; only polyhedral crystals with micrograins grown on them were seen covering the laser-treated surface. Therefore, the laser treatment using a fiber laser source improved the corrosion resistance of cold-rolled low carbon steel.

36 MATERIALS SCIENCE↗
DOE OSTI2017

The Characterization of Laser Ablation Patterns and a New Definition of Resolution in Matrix Assisted Laser Desorption Ionization Imaging Mass Spectrometry (MALDI-IMS)

Matrix assisted laser desorption ionization imaging mass spectrometry (MALDI-IMS) is a technique that has seen a sharp rise in both use and development. Despite this rapid adoption, there have been few thorough investigations into the actual physical mechanisms that underlie the acquisition of IMS images. We therefore set out to characterize the effect of IMS laser ablation patterns on the surface of a sample. We also concluded that the governing factors that control spatial resolution have not been correctly defined and therefore propose a new definition of resolution. .

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2019

Laser Ablation Generation of Antimony Selenide Clusters: Laser Desorption Ionization (LDI) Quadrupole Ion Trap Time of Flight Mass Spectrometry

The binary system Sb-Se was studied via laser ablation using antimony-selenium mixtures made from powdered elements in various ratios generating new Sb{sub m}Se{sub n} clusters. The results show that in addition to Sb{sub m}{sup +} (m = 1–8) and Se{sub n}{sup +} (n = 2–9) clusters, a series of Sb{sub m}Se{sub n}{sup +} clusters such as SbSe{sub 1–8}{sup +}, Sb{sub 2}Se{sub 1–6}{sup +}, Sb{sub 3}Se{sub 1–5}{sup +}, Sb{sub 4}Se{sub 1–3}{sup +}, and Sb{sub 5}Se{sub 1,2}{sup +} is generated. In addition, some low intensity oxidized clusters like Se{sub 6}O{sub 2}{sup +}, Se{sub 7}O{sub 2}{sup +}, and SbSe{sub 2-6}O{sub 5}{sup +} and partially hydroxylated clusters (SbSeO{sub 2}H{sub 7}{sup +}, SbSe{sub 5}O{sub 4}H{sup +}) are also formed. In total, 24 new antimony selenide clusters were generated. The knowledge gained can contribute to the elucidation of the structure of Sb{sub m}Se{sub n} glasses. .

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2019

TiO{sub 2} Photocatalyzed Oxidation of Drugs Studied by Laser Ablation Electrospray Ionization Mass Spectrometry

In drug discovery, it is important to identify phase I metabolic modifications as early as possible to screen for inactivation of drugs and/or activation of prodrugs. As the major class of reactions in phase I metabolism is oxidation reactions, oxidation of drugs with TiO{sub 2} photocatalysis can be used as a simple non-biological method to initially eliminate (pro)drug candidates with an undesired phase I oxidation metabolism. Analysis of reaction products is commonly achieved with mass spectrometry coupled to chromatography. However, sample throughput can be substantially increased by eliminating pretreatment steps and exploiting the potential of ambient ionization mass spectrometry (MS). Furthermore, online monitoring of reactions in a time-resolved way would identify sequential modification steps. Here, we introduce a novel (time-resolved) TiO{sub 2}-photocatalysis laser ablation electrospray ionization (LAESI) MS method for the analysis of drug candidates. This method was proven to be compatible with both TiO{sub 2}-coated glass slides as well as solutions containing suspended TiO{sub 2} nanoparticles, and the results were in excellent agreement with studies on biological oxidation of verapamil, buspirone, testosterone, andarine, and ostarine. Finally, a time-resolved LAESI MS setup was developed and initial results for verapamil showed excellent analytical stability for online photocatalyzed oxidation reactions within the set-up up to at least 1 h. .

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2021

Towards synthetic L 1 0 -FeNi: Detecting the absence of cubic symmetry in Laser-Ablated Fe-Ni nanoparticles

The L 1 0 crystal structure underlines an important class of chemically ordered alloys that exhibits uniaxial magnetocrystalline anisotropy. The near-equiatomic L 1 0 -FeNi extracted from meteorites has demonstrated intriguing magnetic properties for permanent magnet applications. However, the synthesis of this chemically ordered non-cubic structure has been a longstanding challenge. Here, in this work, we demonstrate the absence of cubic symmetry in near-equiatomic Fe-Ni nanoparticles synthesized by picosecond-pulsed laser ablation in liquids. The non-cubic phase detected in these particles can only be L 1 0 -FeNi or hexagonal close-packed (HCP) FeNi, and the absence of cubic symmetry was unequivocal. The orientation relationship between the non-cubic phase and the adjacent cubic phase was characterized by a series of transmission electron microscopy (TEM) techniques, which consistently suggests that the formation of the non-cubic phase involves a martensitic transformation process.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Cost-Effectiveness Analysis of Stereotactic Body Radiation Therapy Compared With Radiofrequency Ablation for Inoperable Colorectal Liver Metastases

Purpose: To conduct a cost-effectiveness analysis to determine whether stereotactic body radiation therapy (SBRT) is a cost-effective therapy compared with radiofrequency ablation (RFA) for patients with unresectable colorectal cancer (CRC) liver metastases. Methods and Materials: A cost-effectiveness analysis was conducted using a Markov model and 1-month cycle over a lifetime horizon. Transition probabilities, quality of life utilities, and costs associated with SBRT and RFA were captured in the model on the basis of a comprehensive literature review and Medicare reimbursements in 2014. Strategies were compared using the incremental cost-effectiveness ratio, with effectiveness measured in quality-adjusted life years (QALYs). To account for model uncertainty, 1-way and probabilistic sensitivity analyses were performed. Strategies were evaluated with a willingness-to-pay threshold of $100,000 per QALY gained. Results: In base case analysis, treatment costs for 3 fractions of SBRT and 1 RFA procedure were $13,000 and $4397, respectively. Median survival was assumed the same for both strategies (25 months). The SBRT costs $8202 more than RFA while gaining 0.05 QALYs, resulting in an incremental cost-effectiveness ratio of $164,660 per QALY gained. In 1-way sensitivity analyses, results were most sensitive to variation of median survival from both treatments. Stereotactic body radiation therapy was economically reasonable if better survival was presumed (>1 month gain) or if used for large tumors (>4 cm). Conclusions: If equal survival is assumed, SBRT is not cost-effective compared with RFA for inoperable colorectal liver metastases. However, if better local control leads to small survival gains with SBRT, this strategy becomes cost-effective. Ideally, these results should be confirmed with prospective comparative data.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2016

Comparison of the Effectiveness of Radiofrequency Ablation With Stereotactic Body Radiation Therapy in Inoperable Stage I Non-Small Cell Lung Cancer: A Systemic Review and Pooled Analysis

Purpose: To performed a systematic review and pooled analysis to compare clinical outcomes of stereotactic body radiation therapy (SBRT) and radiofrequency ablation (RFA) for the treatment of medically inoperable stage I non-small cell lung cancer. Methods and Materials: A comprehensive literature search for published trials from 2001 to 2012 was undertaken. Pooled analyses were performed to obtain overall survival (OS) and local tumor control rates (LCRs) and adverse events. Regression analysis was conducted considering each study's proportions of stage IA and age. Results: Thirty-one studies on SBRT (2767 patients) and 13 studies on RFA (328 patients) were eligible. The LCR (95% confidence interval) at 1, 2, 3, and 5 years for RFA was 77% (70%-85%), 48% (37%-58%), 55% (47%-62%), and 42% (30%-54%) respectively, which was significantly lower than that for SBRT: 97% (96%-98%), 92% (91%-94%), 88% (86%-90%), and 86% (85%-88%) (P<.001). These differences remained significant after correcting for stage IA and age (P<.001 at 1 year, 2 years, and 3 years; P=.04 at 5 years). The effect of RFA was not different from that of SBRT on OS (P>.05). The most frequent complication of RFA was pneumothorax, occurring in 31% of patients, whereas that for SBRT (grade ≥3) was radiation pneumonitis, occurring in 2% of patients. Conclusions: Compared with RFA, SBRT seems to have a higher LCR but similar OS. More studies with larger sample sizes are warranted to validate such findings.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2018

A Prospective Phase 2 Study Evaluating Safety and Efficacy of Combining Stereotactic Body Radiation Therapy With Heat-based Ablation for Centrally Located Lung Tumors

Stereotactic body radiation therapy (SBRT) and heat-based ablation (HBA) are both potentially safe and effective treatments for primary and metastatic lung tumors. Both are suboptimal for centrally located tumors, with SBRT having a higher risk of significant toxicity and HBA having lower efficacy. This study evaluates the safety and efficacy of combination SBRT-HBA to determine whether combined treatment can result in superior outcomes to each treatment alone.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2023

Advancing Elemental and Isotopic Analysis of Uranium Mineral Inclusions: Rapid Screening via Laser-Induced Breakdown Spectroscopy and High-Resolution Laser Ablation-ICP-MS Mapping

The work presented herein employs two laser-based analytical techniques (laser-induced breakdown spectroscopy (LIBS) and laser ablation – inductively coupled plasma – mass spectrometry (LA-ICP-MS)) to spatially determine the elemental and isotopic composition of uranium bearing minerals. Uniquely, this work leverages the high-speed applicability of LIBS to “screen” the sample(s) for their elemental constituents. After determining the location of the uranium inclusions (via LIBS), high-resolution LA-ICP-MS was employed to further characterize the inclusions. The high-resolution (sub-µm) capabilities of LA-ICP-MS were able to extract important information from the uranium minerals including discerning its chemical form (e.g., finchite from carnotite, Sr- and K-bearing uranyl vanadates, respectively) as well as their 235 U/ 238 U isotopic composition. This approach, LIBS followed by LA-ICP-MS, significantly reduces the analysis time (~95 %) in comparison to employing a LA-ICP-MS only approach. Furthermore, this work presented a novel approach to analyzing inclusions via a particle/inclusion analysis tool which is commercially available within the iolite 4 software. This tool allowed for a more accurate characterization of the isotopic distribution of the inclusions, as well as allowing for rapid sizing of the inclusions. Finally, this analytical approach could readily be applied to other sample types in which the target species (e.g., µm-sized inclusions) are embedded in complex matrices (e.g., cm-sized samples).

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗