Lung ultrasound could reduce X-ray after major lung resection.

OBJECTIVES: This study evaluated the role of ultrasound in postoperative care after major lung resection. BACKGROUND: High accuracy of lung ultrasound imaging was proved in various medical fields. The experience with ultrasound after thoracic surgery is limited. METHODS: Patients scheduled for major lung resection were consecutively included in a prospective study comparing two modalities of imaging examinations, namely those employing ultrasound and X-ray in the diagnoses of pneumothorax and pleural effusion. Two examinations were performed. One after recovery from anaesthesia, the second before chest tube removal. RESULTS: Forty-eight patients underwent 87 examinations. X-ray and ultrasound examinations showed substantial and fair agreements for pneumothorax (Cohen's kappa coefficients 0.775 and 0.397) and slight and substantial agreements for pleural effusion (Cohen's kappa coefficients 0.036 and 0.611). The sensitivity bounds for pneumothorax were 45.5-58.5 % at the first and 29.7-59.4 % at the second examination. Sensitivity bounds for pleural effusion were 0-86.2 % at the first and 32.6-36.9 % at the second examination. Except for two cases of pneumothorax being missed by X-ray imaging, the rest of mismatches were clinically irrelevant conditions with no impact on clinical decision and patient's outcome. CONCLUSION: The use of ultrasound can reduce the number of X-ray examinations and thus lower the radiation exposure after major lung resections (Tab. 4, Ref. 30).

Dielectric-loaded coaxial-slot antenna for interstitial microwave hyperthermia: longitudinal control of heating patterns.

In this paper, the microwave interstitial antenna with the dielectric load in part near the tip is introduced to realize the tip-heating and to improve the dependence of the heating patterns on the insertion depth. Numerical simulations using the Finite Difference Time Domain (FDTD) method have been conducted at the frequency of 915 MHz for four different configurations of the coaxial-slot antenna inserted into a catheter: the media between the antenna and the catheter are (a) no, (b) a thin air layer, (c) a thin dielectric layer, and (d) a thin air layer and a dielectric load in part near the tip. The diameter of the antenna including the catheter is sufficiently small for minimally invasive therapy. Comparison of the SARs for the four configurations makes it clear that the dielectric-loaded antenna can realize the best tip-heating and suppress the hot spot near the surface of the human body. Dependence of the SAR distributions on the insertion depth of the antenna has also been examined. It is found from the investigation that the dielectric-loaded antenna has little dependence on the insertion depth.