The peripheral pulmonary lesion - bronchoscopic techniques to improve diagnosis
Date
2020
Authors
Wong, Michelle Xin Zhi
Editors
Advisors
Jersmann, Hubertus
Nguyen, Phan
Holmes, Mark
Nguyen, Phan
Holmes, Mark
Journal Title
Journal ISSN
Volume Title
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Thesis
Citation
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Abstract
Lung cancer is a leading cause of cancer-related deaths worldwide. This is no different in Australia where it is the main cause of cancer-related mortality, and the fifth most commonly cancer diagnosed in Australians. The recent National Lung Screening Trial demonstrated an improvement in mortality when patients deemed high risk for lung cancer underwent annual screening with low dose computed tomography imaging. Nearly 25% of participants were shown to have imaging suspicious for lung cancer. In light of these results, and with the possibility of increased uptake of screening, it is very likely that the incidence of identified peripheral pulmonary lesions (PPL) will only continue to rise. In evaluating PPLs, standard bronchoscopic investigation involves obtaining transbronchial forceps biopsies (TB-FB). However TBFB has variable diagnostic sensitivity, influenced by factors such as lesion size and position. The introduction of radial endobronchial ultrasound (RP-EBUS) has helped improve diagnostic yields further. Ultrasound images obtained by the miniprobe reflect the underlying structure of the peripheral lesion being examined and RPEBUS is now a well-established technique in the evaluation of PPLs. The overall aim of this thesis was to examine innovative bronchoscopic techniques which could further aid diagnostic yield in investigating PPLs. Methods (i) Radial Endobronchial Ultrasound Greyscale Texture Analysis Using Whole-Lesion Analysis Can Characterise Benign and Malignant Lesions without Region-of-Interest Selection Bias Custom software was developed to analyse RP-EBUS images based on first and second order greyscale texture features. Unconstrained ROIs were mapped onto lesions. Features from expert and nonexpert defined ROIs were compared, as were results of image analysis to tissue histology. (ii) Radial Endobronchial Ultrasound with Transbronchial Cryobiopsy versus Radial EBUS alone for the Diagnosis of Peripheral Pulmonary Lesions Prospective, single-centre randomised controlled trials of patients with PPLs. Patients were randomised to receive either one transbronchial cryobiopsy (TB-CB) sample, or 5 TB-FB samples. Results (i) Greyscale texture analysis of RP-EBUS images using unconstrained regions of interest (ROIs) demonstrated 5 features which were significantly different between benign and malignant lesions. Highest positive predictive values were associated with maximal and range of pixel intensities. No significant differences were seen between expert and non-expert-defined ROIs. (ii) 28 lesions were evaluated with overall diagnostic yield 76.7%. Diagnostic yields of TB-CB and TB-FB were 91.7% and 68.8% respectively (p=0.14). Median size of TB-CB was 7.0mm compared to 2.55mm (p<0.0001). There were no major complications with either technique. Conclusion Timely diagnosis of PPLs is critical to enable disease staging and to guide initiation of appropriate definitive treatment. Greyscale image analysis and texture analysis using the whole RP-EBUS image as a ROI can assist in distinguishing between malignant and benign lesions. This is a potentially valuable additional clinical tool in the diagnosis of peripheral lesions. However further validation is required. Cryotherapy has provided an alternative method of obtaining transbronchial biopsies (TBBs). Not only does it provide significantly larger biopsy sample, which is advantageous for further immunohistochemical and molecular analysis, but it also could be superior in diagnosing lesions which are not easily accessible by TB-FB.
School/Discipline
Adelaide Medical School
Dissertation Note
Thesis (MPhil) -- University of Adelaide, Adelaide Medical School, 2021
Provenance
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