Dr. rer. nat. Frank Wolfram
Chirurgie II / Lung Cancer Centre
SRH Wald-Klinikum Gera
Straße des Friedens 122
Tel: 0365 82-83151
Presented Monday morning 10:40, May 13, 2019
177th ASA Meeting, Louisville, KY
Lung is known as a total acoustic absorber which in turn makes the use therapeutic ultrasound for local lung tumour treatment unsuitable.
By replacing pulmonary gas with saline, acoustic transmission can be achieved. Such One Lung Filling (OLF) has been studied intensively showing no cardio pulmonary deficiencies and is an accepted procedure in pneumology for clearance from proteinosis or silica dust.
Our aim is to combine OLF and therapeutic ultrasound where the cancerous lung is flooded while the contralateral side maintains ventilated. During stable OLF, central lung cancer tissue could be treated non-invasively using therapeutic ultrasound (HIFU). In order to understand ultrasound interaction in such flooded condition, the acoustic conditions were investigated and their impact on the lung cancer ablation process discussed.
For this study preclinical ex and in-vivo models have been used. Determination of acoustic parameter was performed using a broad band immersion technique. Lung cancers and flooded lung show a speed of sound and impedance as known solid tissue, whilst flooded lung show a significant lower attenuation. HIFU induces in adeno carcinoma temperatures above the ablative threshold (80°C), whilst the same acoustic dose in flooded lung only a non-lethal temperature rise (43°C) causes. Sonographic examinations revealed complete visibility of lung cancer and lung metastases.
During OLF atypical, but superior acoustic conditions for application of therapeutic ultrasound exists. Sonography is an excellent guiding modality providing a 100% tumor demarcation. The HIFU interacts with the malignant tissue leaving healthy lung parenchyma unaffected.
These findings suggest valuable benefits for future clinical implementation. Most lung cancer are inoperable at diagnosis due to poor lung function or advanced stage, the parenchyma sparing property of Lung HIFU could help to reduce tumor load while preserving lung function without toxicity. Additionally, the repeatability of therapeutic ultrasound can provide iterative treatment in case of recurrence or new metastasis.