Collaboration to Improve Neuroprotection and Neuropromotion in the NICU: A Quality Improvement Initiative.

Implementation of neuroprotective and neuropromotive (NP2) strategies is essential to optimize outcomes for premature infants. Developmental care, once an addition to medical care, is now recognized by the NICU team as foundational to support long-term neurodevelopment of micropremature infants. A group approach to education and sharing implementation processes can result in collaborative and individual center improvements. This article includes examples of quality improvement (QI) education and tools inspired by implementation of NP2 strategies in a consortium of 11 NICUs in the United States and Canada. Process change guided by potentially better practices are key; however, consistency of application must be included to ensure success. Assessment of NP2 practices via use of surveys and practice audits are described. Increases occurred in family NP2 education and provision of support during painful experiences. There were also increases in skin-to-skin holding, 2-person caregiving, and focus on reducing unnecessary painful procedures.

Early small-bowel ischemia: dual-energy CT improves conspicuity compared with conventional CT in a swine model.

PURPOSE: To compare dual-energy computed tomography (CT) with conventional CT for the detection of small-bowel ischemia in an experimental animal model. MATERIALS AND METHODS: The study was approved by the animal care and use committee and was performed in accordance with the Guide for Care and Use of Laboratory Animals issued by the National Research Council. Ischemic bowel segments (n = 8) were created in swine (n = 4) by means of surgical occlusion of distal mesenteric arteries and veins. Contrast material-enhanced dual-energy CT and conventional single-energy CT (120 kVp) sequences were performed during the portal venous phase with a single-source fast-switching dual-energy CT scanner. Attenuation values and contrast-to-noise ratios of ischemic and perfused segments on iodine material-density, monospectral dual-energy CT (51 keV, 65 keV, and 70 keV), and conventional 120-kVp CT images were compared. Linear mixed-effects models were used for comparisons. RESULTS: The attenuation difference between ischemic and perfused segments was significantly greater on dual-energy 51-keV CT images than on conventional 120-kVp CT images (mean difference, 91.7 HU vs 47.6 HU; P < .0001). Conspicuity of ischemic segments was significantly greater on dual-energy iodine material-density and 51-keV CT images than on 120-kVp CT images (mean contrast-to-noise ratios, 4.9, 4.3, and 2.1, respectively; P < .0001). Although attenuation differences on dual-energy 65- and 70-keV CT images were not significantly different from those on 120-kVp images (55.0 HU, 45.8 HU, and 47.6 HU, respectively; 65 keV vs 120 kVp, P = .15; 70 keV vs 120 kVp, P = .46), the contrast-to-noise ratio was greater for the 65- and 70-keV images than for the 120-kVp images (4.4, 4.1, and 2.1 respectively; P < .0005). CONCLUSION: Dual-energy CT significantly improved the conspicuity of the ischemic bowel compared with conventional CT by increasing attenuation differences between ischemic and perfused segments on low-kiloelectron volt and iodine material density images.

Creation of short microwave ablation zones: in vivo characterization of single and paired modified triaxial antennas.

PURPOSE: To characterize modified triaxial microwave antennas configured to produce short ablation zones. MATERIALS AND METHODS: Fifty single-antenna and 27 paired-antenna hepatic ablations were performed in domestic swine (N = 11) with 17-gauge gas-cooled modified triaxial antennas powered at 65 W from a 2.45-GHz generator. Single-antenna ablations were performed at 2 (n = 16), 5 (n = 21), and 10 (n = 13) minutes. Paired-antenna ablations were performed at 1-cm and 2-cm spacing for 5 (n = 7 and n = 8, respectively) and 10 minutes (n = 7 and n = 5, respectively). Mean transverse width, length, and aspect ratio of sectioned ablation zones were measured and compared. RESULTS: For single antennas, mean ablation zone lengths were 2.9 cm ± 0.45, 3.5 cm ± 0.55, and 4.2 cm ± 0.40 at 2, 5, and 10 minutes, respectively. Mean widths were 1.8 cm ± 0.3, 2.0 cm ± 0.32, and 2.5 cm ± 0.25 at 2, 5, and 10 minutes, respectively. For paired antennas, mean length at 5 minutes with 1-cm and 2-cm spacing and 10 minutes with 1-cm and 2-cm spacing was 4.2 cm ± 0.9, 4.9 cm ± 1.0, 4.8 cm ± 0.5, and 4.8 cm ± 1.3, respectively. Mean width was 3.1 cm ± 1.0, 4.4 cm ± 0.7, 3.8 cm ± 0.4, and 4.5 cm ± 0.7, respectively. Paired-antenna ablations were more spherical (aspect ratios, 0.72-0.79 for 5-10 min) than single-antenna ablations (aspect ratios, 0.57-0.59). For paired-antenna ablations, 1-cm spacing appeared optimal, with improved circularity and decreased clefting compared with 2-cm spacing (circularity, 0.85 at 1 cm, 0.78 at 2 cm). CONCLUSIONS: Modified triaxial antennas can generate relatively short, spherical ablation zones. Paired-antenna ablations were rounder and larger in transverse dimension than single antenna ablations, with 1-cm spacing optimal for confluence of the ablation zone.

Knowledge, Attitudes, and Behaviors Regarding Pneumococcal Vaccines in Adults 65 Years and Older in Primary Care in Wisconsin.

INTRODUCTION: Although shared decision-making is highly valued, its implementation in clinical practice is suboptimal. Shared decision-making was included in the Centers for Disease Control and Prevention (CDC) recommendations for the pneumococcal conjugate vaccine 13 valent for older adults. As a first step to develop and test clinician educational resources to facilitate shared decision-making for pneumococcal vaccines for older adults, we completed a needs assessment to identify knowledge gaps, attitudes, and behaviors. METHODS: Primary care clinicians, pharmacists, and patient care staff completed a questionnaire on shared decision-making and pneumococcal vaccines. After the CDC recommended new pneumococcal vaccines and eliminated the role of shared decision-making, a revised questionnaire was distributed to additional clinicians in an effort to increase the sample size. RESULTS: Knowledge of pneumococcal vaccine recommendations was high among those who responded to knowledge questions (48 of 75 respondents). Although 96% of respondents believed shared decision-making for use of pneumococcal vaccines in adults 65 years or older was feasible, 25% responded that it would be "somewhat difficult" to explain potential harms and benefits of PCV13. DISCUSSION: Although shared decision-making was reported to be feasible, challenges implementing it are ongoing. Knowledge gaps regarding pneumococcal vaccines were observed, highlighting the need for ongoing medical education with changing vaccine recommendations.

Understanding the Family Context: A Qualitative Descriptive Study of Parent and NICU Clinician Experiences and Perspectives.

Enabling individualized decision-making for patients requires an understanding of the family context (FC) by healthcare providers. The FC is everything that makes the family unique, from their names, preferred pronouns, family structure, cultural or religious beliefs, and family values. While there is an array of approaches for individual clinicians to incorporate the FC into practice, there is a paucity of literature guiding the process of collecting and integrating the FC into clinical care by multidisciplinary interprofessional teams. The purpose of this qualitative study is to explore the experience of families and Neonatal Intensive Care Unit (NICU) clinicians with information sharing around the FC. Our findings illustrate that there are parallel and overlapping experiences of sharing the FC for families and clinicians. Both groups describe the positive impact of sharing the FC on building and sustaining relationships and on personalization of care and personhood. The experience by families of revolving clinicians and the risks of miscommunication about the FC were noted as challenges to sharing the FC. Parents described the desire to control the narrative about their FC, while clinicians described seeking equal access to the FC to support the family in the best way possible related to their clinical role. Our study highlights how the quality of care is positively impacted by clinicians' appreciation of the FC and the complex relationship between a large multidisciplinary interprofessional team and the family in an intensive care unit, while also highlighting the difficulties in its practical application. Knowledge learned can be utilized to inform the development of processes to improve communication between families and clinicians.

High-powered microwave ablation with a small-gauge, gas-cooled antenna: initial ex vivo and in vivo results.

PURPOSE: To evaluate the performance of a gas-cooled, high-powered microwave system. MATERIALS AND METHODS: Investigators performed 54 ablations in ex vivo bovine livers using three devices-a single 17-gauge cooled radiofrequency(RF) electrode; a cluster RF electrode; and a single 17-gauge, gas-cooled microwave (MW) antenna-at three time points (n = 6 at 4 minutes, 12 minutes, and 16 minutes). RF power was applied using impedance-based pulsing with maximum 200 W generator output. MW power of 135 W at 2.45 GHz was delivered continuously. An approved in vivo study was performed using 13 domestic pigs. Hepatic ablations were performed using single applicators and the above-mentioned MW and RF generator systems at treatment times of 2 minutes (n = 7 MW, n = 6 RF), 5 minutes (n = 23 MW, n = 8 RF), 7 minutes (n = 11 MW, n = 6 RF), and 10 minutes (n = 7 MW, n = 9 RF). Mean transverse diameter and length of the ablation zones were compared using analysis of variance (ANOVA) with post-hoc t tests and Wilcoxon rank-sum tests. RESULTS: Single ex vivo MW ablations were larger than single RF ablations at all time points (MW mean diameter range 3.5-4.8 cm 4-16 minutes; RF mean diameter range 2.6-3.1 cm 4-16 minutes) (P < .05). There was no difference in mean diameter between cluster RF and MW ablations (RF 3.3-4.4 cm 4-16 minutes; P = .4-.9). In vivo lesion diameters for MW (and RF) were as follows: 2.6 cm ± 0.72 (RF 1.5 cm ± 0.14), 3.6 cm ± 0.89 (RF 2.0 cm ± 0.4), 3.4 cm ± 0.87 (RF 1.8 cm ± 0.23), and 3.8 cm ± 0.74 (RF 2.1 cm ± 0.3) at 2 minutes, 5 minutes, 7 minutes, and 10 minutes (P < .05 all time points). CONCLUSIONS: Gas-cooled, high-powered MW ablation allows the generation of large ablation zones in short times.

Temperature isotherms during pulmonary cryoablation and their correlation with the zone of ablation.

PURPOSE: To determine the expected ablation zone size and associated isotherms when using clinically available percutaneous cryoprobes for pulmonary cryoablation in a porcine lung model. MATERIALS AND METHODS: Seven ablations were performed in the lungs of three adult pigs using clinically available 2.4-mm cryoprobes (Endocare, Inc, Irvine, California) and a 10-minute double-freeze protocol. Five 18-gauge thermocouples were positioned at 5-mm increments (ie, 5, 10, 15, 20, and 25 mm) from the cryoprobe. Real-time tissue temperatures were recorded during the cryoablation. The isotherms obtained during the ablation and the pathological ablation zones were measured. RESULTS: The pathologic zone of complete necrosis had a mean diameter of 2.4 + or - 0.2 cm, with a mean area of 4.6 + or - 0.6 cm(2) and a circularity of 0.95 + or - 0.04. In comparison, the mean diameter (+ or - standard deviation) of the 0 degrees C, -20 degrees C, and -40 degrees C isotherms were 3.1 + or - 0.2 cm, 2.3 + or - 0.3 cm, and 1.8 + or - 0.4 cm, respectively. The -20 degrees C isotherm was most closely related to the pathologic zone of ablation. CONCLUSIONS: This study establishes the temperature isotherms and associated ablation zone size that can be expected with modern percutaneous cryoprobes in an in vivo porcine lung model.

Biological Evidence in Adult and Adolescent Sexual Assault Cases: Timing and Relationship to Arrest.

This study examined the timing of the crime laboratory report relative to arrests in sexual assault cases and explored the relationship between biological evidence and arrest in those cases in which the crime laboratory report came first and thus could have influenced the arrest decision. A random sample (N = 528) of cases that occurred between 2008 and 2010 and included a report to police was drawn from a Massachusetts statewide database of medical reports on sexual assault cases. Data from medical providers were merged with data abstracted from crime laboratory reports and with data requested from police departments. The vast majority (91.5%) of arrests took place before crime laboratory analysis could be conducted. The crime laboratory report was available before or near in time to the arrest in 11 cases. These cases were significantly more likely than other cases to have DNA profiles of the assailant, DNA matches to the suspect, and a match to another investigation in the FBI's CODIS DNA database. Given that the probable cause needed to make an arrest in these cases was presumably established only after crime laboratory analysis was available, DNA may have helped lead to the arrest in these cases. However, these results should be interpreted very cautiously, because statistically significant results in early, small studies can have inflated effect sizes and often do not replicate in future studies. Because most arrests occur well before biological evidence is available, improvements in recovering biological evidence may have modest effects on arrest rates, though they may impact arrest rates by identifying more serial offenders. Future research on the relationship of biological evidence to arrest should use methods to increase sample size of relevant cases, such as oversampling cases with later arrests and using case control study designs. Future studies should also use case abstraction and interview methods to explore how police use biological evidence to make arrests.

Pulmonary thermal ablation: comparison of radiofrequency and microwave devices by using gross pathologic and CT findings in a swine model.

PURPOSE: To compare the performance of equivalently sized radiofrequency and microwave ablation applicators in a normal porcine lung model. MATERIALS AND METHODS: All experiments were approved by an institutional animal care and use committee. A total of 18 ablations were performed in vivo in normal porcine lungs. By using computed tomographic (CT) fluoroscopic guidance, a 17-gauge cooled triaxial microwave antenna (n = 9) and a 17-gauge cooled radiofrequency (RF) electrode (n = 9) were placed percutaneously. Ablations were performed for 10 minutes by using either 125 W of microwave power or 200 W of RF power delivered with an impedance-based pulsing algorithm. CT images were acquired every minute during ablation to monitor growth. Animals were sacrificed after the procedure. Ablation zones were then excised and sectioned transverse to the applicator in 5-mm increments. Minimum and maximum diameter, cross-sectional area, length, and circularity were measured from gross specimens and CT images. Comparisons of each measurement were performed by using a mixed-effects model; P < .05 was considered to indicate a significant difference. RESULTS: Mean diameter (3.32 cm +/- 0.19 [standard deviation] vs 2.70 cm +/- 0.23, P < .001) was 25% larger with microwave ablation and mean cross-sectional area (8.25 cm(2) +/- 0.92 vs 5.45 cm(2) +/- 1.14, P < .001) was 50% larger with microwave ablation, compared with RF ablation. With microwave ablation, the zones of ablation were also significantly more circular in cross section (mean circularity, 0.90 +/- 0.06 vs 0.82 +/- 0.09; P < .05). One small pneumothorax was noted during RF ablation but stabilized without intervention. CONCLUSION: Microwave ablation with a 17-gauge high-power triaxial antenna creates larger and more circular zones of ablation than does a similarly sized RF applicator in a preclinical animal model. Microwave ablation may be a more effective treatment of lung tumors.

Radiofrequency ablation: simultaneous application of multiple electrodes via switching creates larger, more confluent ablations than sequential application in a large animal model.

PURPOSE: To compare radiofrequency (RF) ablations created by using a sequential technique to those created simultaneously by using a switching algorithm in ex vivo and in vivo liver models. MATERIALS AND METHODS: RF ablation was performed by using either sequential or switched application of three cooled electrodes in a 2-cm triangular array in ex vivo bovine liver (28 total ablations) and in vivo swine liver (12 total ablations) models. For sequential ablations, electrodes were powered for 12 minutes each with a 5-minute rest interval between activations to simulate electrode repositioning. Switched ablations were created by using a multiple-electrode switching system for 12 minutes. Temperatures were measured during ex vivo experiments at four points in the ablation zone. Ablation zones were measured for minimum and maximum diameter, cross-sectional area, and isoperimetric ratio. Mann-Whitney and Wilcoxon matched pairs tests were used to identify differences between groups. RESULTS: The switched application created larger and more circular zones of ablation than did the sequential application, with mean (+/-standard deviation) ex vivo cross-sectional areas of 25.4 cm(2) +/- 5 .3 and 18.8 cm(2) +/- 6.6 (P = .001), respectively, and mean in vivo areas of 17.1 cm(2) +/- 5.1 and 13.2 cm(2) +/- 4.2 (P < .05). Higher temperatures and more rapid heating occurred with the switched application; switched treatments were 74% faster than sequential treatments (12 vs 46 minutes). In the sequential group, subsequent ablations grew progressively larger due to local ischemia. CONCLUSIONS: Switched application of three electrodes creates larger, more confluent ablations in less time than sequential application. Thermal synergy and ablation-induced ischemia both substantially influence multiple-electrode ablations.

Microwave ablation versus radiofrequency ablation in the kidney: high-power triaxial antennas create larger ablation zones than similarly sized internally cooled electrodes.

PURPOSE: To determine whether microwave ablation with high-power triaxial antennas creates significantly larger ablation zones than radiofrequency (RF) ablation with similarly sized internally cooled electrodes. MATERIALS AND METHODS: Twenty-eight 12-minute ablations were performed in an in vivo porcine kidney model. RF ablations were performed with a 200-W pulsed generator and either a single 17-gauge cooled electrode (n = 9) or three switched electrodes spaced 1.5 cm apart (n = 7). Microwave ablations were performed with one (n = 7), two (n = 3), or three (n = 2) 17-gauge triaxial antennas to deliver 90 W continuous power per antenna. Multiple antennas were powered simultaneously. Temperatures 1 cm from the applicator were measured during two RF and microwave ablations each. Animals were euthanized after ablation and ablation zone diameter, cross-sectional area, and circularity were measured. Comparisons between groups were performed with use of a mixed-effects model with P values less than .05 indicating statistical significance. RESULTS: No adverse events occurred during the procedures. Three-electrode RF (mean area, 14.7 cm(2)) and single-antenna microwave (mean area, 10.9 cm(2)) ablation zones were significantly larger than single-electrode RF zones (mean area, 5.6 cm(2); P = .001 and P = .0355, respectively). No significant differences were detected between single-antenna microwave and multiple-electrode RF. Ablation zone circularity was similar across groups (P > .05). Tissue temperatures were higher during microwave ablation (maximum temperature of 123 degrees C vs 100 degrees C for RF). CONCLUSIONS: Microwave ablation with high-power triaxial antennas created larger ablation zones in normal porcine kidneys than RF ablation with similarly sized applicators.

Microwave ablation with triaxial antennas tuned for lung: results in an in vivo porcine model.

PURPOSE: To prospectively determine in swine the size and shape of coagulation zones created in normal lung tissue by using small-diameter triaxial microwave antennas and to prospectively quantify the effects of bronchial occlusion and multiple antennas on the coagulation zone. MATERIALS AND METHODS: The study was approved by the research animal care and use committee, and all husbandry and experimental studies were compliant with the National Research Council's Guide for the Care and Use of Laboratory Animals. Twenty-four coagulation zones (three per animal) were created at thoracotomy in eight female domestic swine (mean weight, 55 kg) by using a microwave ablation system with 17-gauge lung-tuned triaxial antennas. Ablations were performed for 10 minutes each by using (a) a single antenna, (b) a single antenna with bronchial occlusion, and (c) an array of three antennas powered simultaneously. The animals were sacrificed immediately after ablation. The coagulation zones were excised en bloc and sectioned into approximately 4-mm slices for measurement of size, shape, and circularity. Analysis of variance and two-sample t tests were used to identify differences between the three ablation groups. RESULTS: The overall mean diameters of coagulation achieved with a single antenna and bronchial occlusion (4.11 cm +/- 1.09 [standard deviation]) and with multiple-antenna arrays (4.05 cm +/- 0.69) were significantly greater than the overall mean diameter achieved with a single antenna alone (3.09 cm +/- 0.83) (P = .016 for comparison with multiple antennas, P = .032 for comparison with bronchial occlusion). No significant differences in size were seen between the coagulation zones created with bronchial occlusion and those created with multiple antennas (P = .68). The coagulation zones in all groups were very circular (isoperimetric ratio > 0.80) at cross-sectional analysis. CONCLUSION: A 17-gauge triaxial microwave ablation system tuned for lung tissue yielded large circular zones of coagulation in vivo in porcine lungs. The coagulation zones created with bronchial occlusion and multiple antennas were significantly larger than those created with one antenna.

Does selective intubation increase ablation zone size during pulmonary cryoablation?

PURPOSE: To determine the effect of selective intubation on ablation zone size during pulmonary cryoablation. MATERIALS AND METHODS: Selective bronchial intubation and aeration was performed in three domestic swine. A total of 20 cryoablations (ventilated, n = 10; nonventilated, n = 10) were performed. The animals were immediately sacrificed, and their lungs were removed and sectioned along the axis of ablation in 5-mm intervals. The diameter and area of the ablation zone were recorded, and the isoperimetric ratio (measure of circularity) and estimated volume were calculated. RESULTS: There was no significant difference in maximum diameter, minimum diameter, area, circularity, or estimated volume of the ablation zones between the aerated and nonaerated groups (mean diameter, 2.4 cm vs 2.4 cm, respectively, P = .99; area, 4.6 cm(2) vs 4.8 cm(2), P = .7; circularity, 0.94 vs 0.94, P = .99; estimated volume, 11.5 cm(3) vs 11.3 cm(3), P = .99). CONCLUSIONS: In contrast to radiofrequency ablation, selective bronchial intubation did not have a significant effect on the resulting ablation zones. This suggests that selective intubation may not be warranted in the setting of pulmonary cryoablation.

Multiple-electrode radiofrequency ablation of hepatic malignancies: initial clinical experience.

OBJECTIVE: The objective of our study was to retrospectively analyze our initial clinical experience with percutaneous multiple-electrode radiofrequency ablation and evaluate its safety and efficacy for treating hepatic malignancies. MATERIALS AND METHODS: Thirty-eight malignant hepatic tumors (mean diameter, 2.7 cm; range, 0.7-10.0 cm) in 23 patients (12 men and 11 women; mean age, 65 years; range, 40-84 years) were treated in 26 radiofrequency ablation sessions with an impedance-based multiple-electrode system. One, two, or three (mean, 2.4) 17-gauge electrodes were placed, and tumors were ablated using a combination of CT and sonography for guidance and monitoring. Electrodes were placed in close proximity (mean spacing: two electrodes, 1.0 cm; three electrodes, 1.4 cm) to treat large tumors or were used independently to treat several tumors simultaneously. Contrast-enhanced CT scans were obtained immediately after ablation to determine technical success and evaluate for complications. Follow-up CT scans at 1, 3, 6, 9, and 12 months (mean, 4 months) after ablation were obtained to assess for tumor progression and new metastases. RESULTS: Local control was achieved in 37 of 38 tumors, 34 of which were treated in one session. Ablations created with closely spaced electrodes had a mean diameter of 4.9 cm. The total ablation time was reduced by approximately 54% compared with an equivalent number of ablations performed with a single-electrode system (1,014 vs 2,196 minutes). Three complications occurred: one death from a presumed postprocedure pulmonary embolus, one pneumothorax, and one asymptomatic perihepatic hemorrhage. CONCLUSION: Multiple-electrode radiofrequency ablation appears to be a safe and effective means of achieving local control in large or multiple hepatic malignancies at short-term follow-up.

Harmonizing databases? Developing a quasi-experimental design to evaluate a public mental health re-entry program.

Our study is the first-ever initiative to merge administrative databases in Massachusetts to evaluate an important public mental health program. It examines post-incarceration outcomes of adults with serious mental illness (SMI) enrolled in the Massachusetts Department of Mental Health (DMH) Forensic Transition Team (FTT) program. The program began in 1998 with the goal of transitioning offenders with SMI released from state and local correctional facilities utilizing a core set of transition activities. In this study we evaluate the program's effectiveness using merged administrative data from various state agencies for the years 2007-2011, comparing FTT clients to released prisoners who, despite having serious mental health disorders, did not meet the criterion for DMH services. By systematically describing our original study design and the barriers we encountered, this report will inform future efforts to evaluate public programs using merged administrative databases and electronic health records.

Optimizing the protocol for pulmonary cryoablation: a comparison of a dual- and triple-freeze protocol.

The purpose of this study was to compare a double freeze-thaw protocol to a triple freeze-thaw protocol for pulmonary cryoablation utilizing an in vivo porcine lung model. A total of 18 cryoablations were performed in normal porcine lung utilizing percutaneous technique with 9 each in a double- (10-5-10) and triple-freeze (3-3-7-7-5) protocol. Serial noncontrast CT images were obtained during the ablation. CT imaging findings and pathology were reviewed. No imaging changes were identified during the initial freeze cycle with either protocol. However, during the first thaw cycle, a region of ground glass opacity developed around the probe with both protocols. Because the initial freeze was shorter with the triple freeze-thaw protocol, the imaging findings were apparent sooner with this protocol (6 vs. 13 min). Also, despite a shorter total freeze time (15 vs. 20 min), the ablation zone identified with the triple freeze-thaw protocol was not significantly different from the double freeze-thaw protocol (mean diameter: 1.67 ± 0.41 cm vs. 1.66 ± 0.21 cm, P = 0.77; area: 2.1 ± 0.48 cm(2) vs. 1.99 ± 0.62 cm(2), P = 0.7; and circularity: 0.95 ± 0.04 vs. 0.96 ± 0.03, P = 0.62, respectively). This study suggests that there may be several advantages of a triple freeze-thaw protocol for pulmonary cryoablation, including earlier identification of the imaging findings associated with the ablation, the promise of a shorter procedure time or larger zones of ablation, and theoretically, more effective cytotoxicity related to the additional freeze-thaw cycle.

Microwave ablation with multiple simultaneously powered small-gauge triaxial antennas: results from an in vivo swine liver model.

PURPOSE: To prospectively investigate the ability of a single generator to power multiple small-diameter antennas and create large zones of ablation in an in vivo swine liver model. MATERIALS AND METHODS: Thirteen female domestic swine (mean weight, 70 kg) were used for the study as approved by the animal care and use committee. A single generator was used to simultaneously power three triaxial antennas at 55 W per antenna for 10 minutes in three groups: a control group where antennas were spaced to eliminate ablation zone overlap (n=6; 18 individual zones of ablation) and experimental groups where antennas were spaced 2.5 cm (n=7) or 3.0 cm (n=5) apart. Animals were euthanized after ablation, and ablation zones were sectioned and measured. A mixed linear model was used to test for differences in size and circularity among groups. RESULTS: Mean (+/-standard deviation) cross-sectional areas of multiple-antenna zones of ablation at 2.5- and 3.0-cm spacing (26.6 cm(2) +/- 9.7 and 32.2 cm(2) +/- 8.1, respectively) were significantly larger than individual ablation zones created with single antennas (6.76 cm(2) +/- 2.8, P<.001) and were 31% (2.5-cm spacing group: multiple antenna mean area, 26.6 cm(2); 3 x single antenna mean area, 20.28 cm(2)) to 59% (3.0-cm spacing group: multiple antenna mean area, 32.2 cm(2); 3 x single antenna mean area, 20.28 cm(2)) larger than 3 times the mean area of the single-antenna zones. Zones of ablation were found to be very circular, and vessels as large as 1.1 cm were completely coagulated with multiple antennas. CONCLUSION: A single generator may effectively deliver microwave power to multiple antennas. Large volumes of tissue may be ablated and large vessels coagulated with multiple-antenna ablation in the same time as single-antenna ablation.

Multiple-electrode radiofrequency ablation: comparison with a conventional cluster electrode in an in vivo porcine kidney model.

PURPOSE: To compare multiple-electrode radiofrequency (RF) ablation versus RF ablation with a cluster electrode in an in vivo porcine kidney model. MATERIALS AND METHODS: Thirteen female pigs (mean weight, 45 kg) were used for the study. In each animal, RF ablations were performed for 12 minutes with a conventional cluster electrode in one kidney (controls, n = 13) and a multiple-electrode configuration in the contralateral organ. Multiple-electrode ablations were performed with electrodes 1.5 cm apart (group 1, n = 7) or 2.0 cm apart (group 2, n = 6). The mean maximum temperature at the electrode tips was determined. After each animal was euthanized, the kidneys were removed and the ablation zones were sectioned into 5-mm transverse slices. A representative slice was stained with 2,3,5-triphenyl-2H-tetrazolium chloride. Standard ablation zone metrics were measured and differences between groups were analyzed for statistical significance. RESULTS: The mean maximum ablation zone diameter was 3.0 cm +/- 0.6 (SD) for controls, compared with 5.0 cm +/- 0.5 for group 1 (P < .0001) and 4.4 cm +/- 1.0 for group 2 (P = .002). Mean ablation zone minimum diameter was higher for group 1 (P = .002) and group 2 (P = .03) than for controls. Isoperimetric ratios were lowest for group 2 (P = .04 vs controls) whereas the highest temperatures at the electrode tips were observed with group 1 (P = .02 vs controls). CONCLUSION: In normal porcine kidney, multiple-electrode RF ablation produced larger zones of ablation than a cluster electrode. Efficacy was greater when electrodes were spaced 1.5 cm apart than when they were spaced 2.0 cm apart.

Microwave ablation with a single small-gauge triaxial antenna: in vivo porcine liver model.

PURPOSE: To evaluate the performance of a 17-gauge triaxial antenna at microwave ablation in an in vivo porcine liver model. MATERIALS AND METHODS: This study was approved by the institutional animal care and use committee. Thirteen female domestic pigs (mean weight, 45 kg) were used. Ablations were performed with a prototype microwave ablation system and triaxial antenna by using a constant, continuous-wave power of 68 W for 2 (n = 6), 3 (n = 6), 4 (n = 6), 5 (n = 6), 6 (n = 6), 7 (n = 13), 10 (n = 7), and 12 (n = 8) minutes. Animals were euthanized after ablation, livers were removed, and ablation zones were sliced and measured for size and roundness. A mixed linear model with animals modeled as random effects was used to test for significant differences in ablation zone metrics among time groups; post hoc tests were used to detect significant differences between time groups. RESULTS: Mean ablation zone diameters ranged from 2.05 cm +/- 0.23 (standard deviation) at 2 minutes to 2.59 cm +/- 0.53 at 12 minutes. Thirteen (32%) of 40 ablation zones with mean maximum diameters greater than 3.0 cm were observed at the 5-12-minute time groups. No significant differences in ablation zone diameter were observed among all groups (P > .05), but a trend of increasing diameter with time was noted. Mean isoperimetric ratio (a measure of roundness) for all ablation zones was 0.88 +/- 0.02, which indicates minimal heat sinking near vessels. CONCLUSION: The triaxial microwave ablation system is capable of creating relatively large, circular zones of ablation in minutes with minimal effects from local blood flow.

Unintended thermal injuries from radiofrequency ablation: protection with 5% dextrose in water.

OBJECTIVE: Radiofrequency ablation of hepatic tumors can lead to thermal injury of surrounding structures. Both saline and 5% dextrose in water (D5) have been used to displace these surrounding structures before radiofrequency ablation. The purpose of this study was to determine the relative effectiveness of these two fluids for protecting the diaphragm and lung during radiofrequency ablation. MATERIALS AND METHODS: Ten female domestic swine (mean weight, 45 kg) underwent radiofrequency ablation at open surgery. Group 1 (n = 12 lesions) was pretreated with peritoneal D5 before radiofrequency ablation. Group 2 (n = 11 lesions) was pretreated with peritoneal 0.9% saline. A 2.7-mm spacer was placed between the liver surface and diaphragm in groups 1 and 2. Group 3 (n = seven lesions) served as a control group with no pretreatment regimen. Group 4, an additional control group (n = eight lesions), consisted of animals pretreated with D5 in which a larger spacer was used. After radiofrequency ablation, the animals were sacrificed and the liver, diaphragm, and lung were removed. The extent of thermal injury to the surface of each organ was recorded. RESULTS: The animals in the D5 and saline pretreatment groups experienced fewer diaphragm injuries than the control animals (D5, p = 0.02). The smallest lesions in the lung and diaphragm were in the D5 group, followed by the saline and control groups (diaphragm, p = 0.0001; lung, p = 0.13). Diaphragm lesions were significantly smaller in the D5 and saline groups than in the control group (p = 0.0001 and 0.01, respectively). CONCLUSION: Instillation of D5 into the peritoneal cavity before hepatic radiofrequency ablation decreases the risk and severity of diaphragm and lung injuries compared with no pretreatment or pretreatment with 0.9% saline in this animal model. Pretreatment with D5 may increase both the safety of and the number of patients eligible for treatment with thermal therapies.