Percutaneous radiofrequency ablation of HCC: reduced ablation duration and increased ablation size using single, internally cooled electrodes with an optimized pulsing algorithm.

Purpose: To assess the use of optimized radiofrequency (RF) to achieve larger, spherical ablation volumes with short application duration for hepatocellular carcinoma (HCC).

Materials And Methods: Twenty-two patients (M: = 17:5, median age 69.6 year, range 63-88) with 28 HCCs due to HCV + liver cirrhosis underwent RFA.

Optimization and characterization of a novel internally-cooled radiofrequency ablation system with optimized pulsing algorithm in an bovine liver.

To prospectively characterize and optimize radiofrequency energy deposition to determine ideal parameters for achieving large ablation zones. An internally-cooled RF system was used to perform 214 ablations in 72 bovine livers. Tip exposure (1-5 cm), electrode current (400-2500 mA), and application duration (3-15 min) were systematically varied.

Hypertonic Sodium Chloride Preinjectate Increases In Vivo Radiofrequency Ablation Size: Histological and Magnetic Resonance Imaging Findings.

Background And Objectives: Emphasis has been placed on methods to enlarge monopolar radiofrequency (RF) lesion size for pain management. Ex vivo research has suggested that fluid modulation may be an effective method to enlarge lesion zone. To date, these findings have not been confirmed in vivo.

Factors that affect radiofrequency heat lesion size.

Objective: This study aims to compare radiofrequency (RF) heat lesion size across electrodes and generator settings available for interventional pain management.

Methods: Monopolar lesions are generated ex vivo in animal tissue using sharp cannulae with tip diameters 23, 22, 20, 18, 16 gauge; tip lengths 5, 6, 10, 15 mm; set temperatures 60, 70, 80, 90°C; set times 1, 1.5, 2, 3, 5, 10 minutes.

Ultrastructural changes in axons following exposure to pulsed radiofrequency fields.

Pulsed radiofrequency (PRF) fields applied by an electrode to neural structures, such as the peripheral sensory nociceptor axons and dorsal root ganglion, are clinically effective in reducing pain and other neuropathic syndromes. However, a full understanding of the underlying mechanisms by which this occurs has not yet been clarified. In this study, PRF is applied to the afferent axons of the sciatic nerves of rats.

Bayesian population modeling of effective connectivity.

A hierarchical model based on the Multivariate Autoregessive (MAR) process is proposed to jointly model neurological time-series collected from multiple subjects, and to characterize the distribution of MAR coefficients across the population from which those subjects were drawn. Thus, inference about effective connectivity between brain regions may be generalized beyond those subjects studied. The posterior on population- and subject-level connectivity parameters are estimated in a Variational Bayesian (VB) framework, and structural model parameters are chosen by the corresponding evidence criteria.

Electric and thermal field effects in tissue around radiofrequency electrodes.

Objective: A study is carried out of the spatial distribution and time dependence of electric and thermal fields in the tissue around a radiofrequency (RF) electrode used in pain therapy. Finite-element calculation of the fields is performed, and results are compared with ex vivo tissue data. Field predictions are made for continuous and for pulsed RF applications.

Investigations of a minimally invasive method for treatment of spinal malignancies with LINAC stereotactic radiation therapy: accuracy and animal studies.

Purpose: A new method for stereotactic irradiation of spinal malignancies is presented, with evaluations of the theoretic and practical limitations of localization accuracy and the implementation of the method in swine.

Materials And Methods: In a percutaneous procedure, a minimum of three small (1.7-mm-diameter) titanium markers are permanently affixed to a vertebra.