ABSTRACT
INTRODUCTION: This study aimed to determine if the Biosentry™ Plug Device (BPD), a prophylactic sealant used to prevent pneumothorax after lung biopsies, reduced post-lung biopsy pneumothorax rates, and other complications compared to no device utilization. METHODS: This single institution, retrospective cohort study included patients who received a lung biopsy in the Department of Interventional Radiology from May 1, 2015 to August 31, 2017. Data such as sex, race, ethnicity, chronic obstructive pulmonary disease status, degree of lung bullae if present, smoking status, and use of BPD were recorded. Decisions to use BPD were based on operator preference. A chi squared analysis was used with a p value greater than 0.05 considered significant. RESULTS: The study included 521 patients who underwent a lung biopsy during the study timeframe. Of these, 74 (14.2%) received the BPD, while 447 (85.8%) did not. One-hundred ninety (36.4%) had a pneumothorax within one month of the lung biopsy. Of the total 190 that experienced pneumothorax, 36.7% of non-BPD biopsies resulted in pneumothorax, while 35.1% of BPD biopsies resulted in pneumothorax (p value = 0.7970; degrees of freedom = 1). CONCLUSIONS: These findings indicated that BPD may not reduce pneumothorax incidence nor limit the severity of complications in patients.
ABSTRACT
Microwave ablation (MWA) is a minimally invasive thermal therapy modality increasingly employed for the treatment of tumors and benign disease. For successful treatment, complete thermal coverage of the tumor and margin of surrounding healthy tissue must be achieved. Currently available interstitial antennas for MWA have cylindrically symmetric radiation patterns. Thus, when treating targets in proximity to critical structures, caution must be taken to prevent unintended thermal damage. A novel coaxial antenna design for MWA with an asymmetrical cylindrical heating pattern is presented in this paper. This radiation pattern is achieved by employing a hemicylindrical reflector positioned at a critical distance from a conventional coaxial monopole antenna. Finite-element method simulations were employed to optimize the geometric dimensions of the antenna with the objective of minimizing the antenna reflection coefficient at the 2.45-GHz operating frequency, and maximizing volume of the ablation zone. Prototype antennas were fabricated and experimentally evaluated. Simulations indicated an optimal S11 of -32 dB at 2.45 GHz in close agreement with experimental measurements of -29 dB. Ex vivo experiments were performed to validate simulations and observe effects to the antennas' heating pattern with the varying input power and geometry of the reflector. Ablation zones up to 20 mm radially were observed in the forward direction, with minimal heating (less than 4 mm) behind the reflector.
