Endobronchial high-intensity ultrasound for thermal therapy of pulmonary malignancies: simulations with patient-specific lung models

Abstract

Objective: This study investigates the feasibility of endobronchial ultrasound applicators for thermal ablation of lung tumors using acoustic and biothermal simulations. Methods: Endobronchial ultrasound applicators with planar (10 mm width) or tubular transducers (6 mm outer diameter (OD)) encapsulated by expandable coupling balloons (10 mm OD) are considered for treating tumors from within major airways; smaller catheter-based applicators with tubular transducers (1.7-4 mm OD) and coupling balloons (2.5-5 mm OD) are considered within deep lung airways. Parametric studies were applied to evaluate transducer configurations, tumor size and location, effects of acoustic reflection and absorption at tumor-lung parenchyma interfaces, and the utility of lung flooding for enhancing accessibility. Patient-specific anatomical lung models, with various geometries and locations of tumors, were developed for further evaluation of device performance and treatment strategies. Temperature and thermal dose distributions were calculated and reported. Results: Large endobronchial applicators with planar or tubular transducers (3-7 MHz, 5 min) can thermally ablate tumors attached to major bronchi at up to 3 cm depth, where reflection and attenuation of normal lung localize tumor heating; with lung flooding, endobronchial applicators can ablate $2 cm diameter tumors with up to $2 cm separation from the bronchial wall, without significant heating of intervening tissue. Smaller catheter-based tubular applicators can ablate tumors up to 2-3 cm in diameter from deep lung airways (5-9 MHz, 5 min). Conclusion: Simulations demonstrate the feasibility of endobronchial ultrasound applicators to deliver thermal coagulation of 2-3 cm diameter tumors adjacent to or accessible from major and deep lung airways.

Acoustically-Activated Liposomal Nanocarriers to Mitigate the Side Effects of Conventional Chemotherapy with a Focus on Emulsion-Liposomes

“…This helped eliminate the total absorbance or reflection of acoustic energy, with highly selective penetration of HIFU causing a local increase in the temperature of ex vivo tumor tissue by 7.5-fold than the flooded lung tissue. Furthermore, flooded lung tissues showed a 100% successful sonographic tumor detection rate compared to atelectatic lungs, which were only 43% [ 80 , 81 ].…”

Complete Lung Ultrasound Using Liquid Filling: A Review of Methods Regarding Sonographic Findings and Clinical Relevance

“…Recent work investigated optimal HIFU settings and providing treatment planning modalities [36]. Challenging, are optimal design settings, avoiding beam defocusing and rib heating, which requires modern HIFU modalities such as non-thermal histotripsy [37] or endobronchial insonation [38].…”

Development of non-invasive flexible directional microwave ablation for central lung cancer: a simulation study

“…In particular, excessive damage to normal lung tissue may occur in transbronchial MWA treatment because the catheter antenna, under the structural constraints of the bronchia, cannot be placed at the center of the lung tumor to increase coverage of the symmetric ablation zone on the tumor (Liu et al 2019, Miller and Cheng 2024, Wang et al 2024. Thus, this study aims to computationally develop a novel non-invasive flexible directional (FD) MWA for the potential precision treatment of central lung cancer surrounding the bronchia.…”