Early lung cancer detection, mucosal, and alveolar imaging

Automatic lesion detection for narrow-band imaging bronchoscopy

Purpose

Early detection of cancer is crucial for lung cancer patients, as it determines disease prognosis. Lung cancer typically starts as bronchial lesions along the airway walls. Recent research has indicated that narrow-band imaging (NBI) bronchoscopy enables more effective bronchial lesion detection than other bronchoscopic modalities. Unfortunately, NBI video can be hard to interpret because physicians currently are forced to perform a time-consuming subjective visual search to detect bronchial lesions in a long airway-exam video. As a result, NBI bronchoscopy is not regularly used in practice. To alleviate this problem, we propose an automatic two-stage real-time method for bronchial lesion detection in NBI video and perform a first-of-its-kind pilot study of the method using NBI airway exam video collected at our institution.

Approach

Given a patient's NBI video, the first method stage entails a deep-learning-based object detection network coupled with a multiframe abnormality measure to locate candidate lesions on each video frame. The second method stage then draws upon a Siamese network and a Kalman filter to track candidate lesions over multiple frames to arrive at final lesion decisions.

Results

Tests drawing on 23 patient NBI airway exam videos indicate that the method can process an incoming video stream at a real-time frame rate, thereby making the method viable for real-time inspection during a live bronchoscopic airway exam. Furthermore, our studies showed a 93% sensitivity and 86% specificity for lesion detection; this compares favorably to a sensitivity and specificity of 80% and 84% achieved over a series of recent pooled clinical studies using the current time-consuming subjective clinical approach.

Conclusion

The method shows potential for robust lesion detection in NBI video at a real-time frame rate. Therefore, it could help enable more common use of NBI bronchoscopy for bronchial lesion detection.

Efficient procedure planning for comprehensive lymph node staging bronchoscopy

Purpose: For a patient at risk of having lung cancer, accurate disease staging is vital as it dictates disease prognosis and treatment. Accurate staging requires a comprehensive sampling of lymph nodes within the chest via bronchoscopy. Unfortunately, physicians are generally unable to plan and perform sufficiently comprehensive procedures to ensure accurate disease staging. We propose a method for planning comprehensive lymph node staging procedures. Approach: Drawing on a patient's chest CT scan, the method derives a multi-destination tour for efficient navigation to a set of lymph nodes. We formulate the planning task as a traveling salesman problem. To solve the problem, we apply the concept of ant colony optimization (ACO) to derive an efficient airway tour connecting the target nodes. The method has three main steps: (1) CT preprocessing, to define important chest anatomy; (2) graph and staging zone construction, to set up the necessary data structures and clinical constraints; and (3) tour computation, to derive the staging plan. The plan conforms to the world standard International Association for the Study of Lung Cancer (IASLC) lymph node map and recommended clinical staging guidelines. Results: Tests with a patient database indicate that the method derives optimal or near-optimal tours in under a few seconds, regardless of the number of target lymph nodes (mean tour length = 1.4% longer than the optimum). A brute force optimal search, on the other hand, generally cannot reach a solution in under 10 min. for patients exhibiting > 16 nodes, and other methods provide poor solutions. We also demonstrate the method's utility in an image-guided bronchoscopy system. Conclusions: The method provides an efficient computational approach for planning a comprehensive lymph node staging bronchoscopy. In addition, the method shows promise for driving an image-guided bronchoscopy system or robotics-assisted bronchoscopy system tailored to lymph node staging.

Advanced bronchoscopic techniques for the diagnosis and treatment of peripheral lung cancer

Lung cancer is the leading cause of cancer related deaths worldwide. As a result of the increasing use of chest CT scans and lung cancer screening initiatives, there is a rapidly increasing need for lung lesion analysis and - in case of confirmed cancer - treatment. A desirable future concept is the one-stop outpatient bronchoscopic approach including navigation to the tumor, malignancy confirmation and immediate treatment. Several novel bronchoscopic diagnostic and treatment concepts are currently under evaluation contributing to this concept. As the majority of suspected malignant lung lesions develop in the periphery of the lungs, improved bronchoscopic navigation to the target lesion is of key importance. Fortunately, the field of interventional pulmonology is evolving rapidly and several advanced bronchoscopic navigation techniques are clinically available, allowing an increasingly accurate tissue diagnosis of peripheral lung lesions. Additionally, multiple bronchoscopic treatment modalities are currently under investigation. This review will provide a concise overview of advanced bronchoscopic techniques to diagnose and treat peripheral lung cancer by describing their working mechanisms, strengths and weaknesses, identifying knowledge gaps and indicating future developments. The desired one-step concept of bronchoscopic 'diagnose and treat' peripheral lung cancer is on the horizon.

Hypermethylation of the PTTG1IP promoter leads to low expression in early-stage non-small cell lung cancer

Despite the clinical requirement for early diagnosis, the early events in lung cancer and their mechanisms are not fully understood. Pituitary tumor transforming gene 1 binding factor (PTTG1IP) is a tumor-associated gene; however, to the best of our knowledge, its association with lung cancer has not been reported. The present study analyzed PTTG1IP expression in early-stage non-small cell lung cancer (NSCLC) samples and investigated its epigenetic regulatory mechanisms. The results revealed that the mRNA level of PTTG1IP in NSCLC tissues was significantly downregulated by 43% compared with that in adjacent tissues. In addition, overexpression of this gene significantly inhibited cell proliferation. According to data from The Cancer Genome Atlas, a significant negative correlation was identified between the PTTG1IP gene methylation level and expression level in lung adenocarcinoma and lung squamous cell carcinoma cases. Reduced representation bisulfite sequencing (RRBS) analysis of six paired early-stage NSCLC tissue samples indicated that the CpG island shore of the PTTG1IP promoter is hypermethylated in lung cancer tissues, which was further validated in 12 paired early-stage NSCLC samples via bisulfite amplicon sequencing. Following treatment with 5-aza-2′-deoxycytidine to reduce DNA methylation in the promoter region, the PTTG1IP mRNA level increased, indicating that the PTTG1IP promoter DNA methylation level negatively regulates PTTG1IP transcription. In conclusion, in early-stage NSCLC, the PTTG1IP gene is regulated by DNA methylation in its promoter region, which may participate in the development and progression of lung cancer.

Next-generation sequencing of circulating tumor DNA for detection of gene mutations in lung cancer: implications for precision treatment

Background

Lung cancer remains a major global health problem, which causes millions of deaths annually. Because the prognosis is mainly determined by the stage of lung cancer, precise early diagnosis is of great significance to improve the survival and prognosis. Circulating tumor DNA (ctDNA) has been recognized as a sensitive and specific biomarker for the detection of early- and late-stage lung cancer, and next-generation sequencing (NGS) of ctDNA has been accepted as a noninvasive tool for early identification and monitoring of cancer mutations. This study aimed to assess the value of NGS-based ctDNA analysis in detecting gene mutations in lung cancer patients.

Methods

A total of 101 subjects with pathological diagnosis of lung cancer were enrolled, and blood samples were collected. ctDNA samples were prepared and subjected to NGS assays.

Results

There were 31 cases harboring 40 gene mutations, and EGFR was the most frequently mutated gene (27.72%). In addition, there were seven cases with double mutations and one case with triple mutations, with EGFR p.T790M mutation exhibiting the highest frequency.

Conclusion

Our findings demonstrate that NGS of ctDNA is effective in detecting gene mutations in lung cancer patients, and may be used as a liquid biopsy for lung cancer, which facilitates the development of precision treatment regimens for lung cancer.

New trends in interventional pulmonology

PURPOSE OF REVIEW

As the field of interventional pulmonology continues to expand and develop at a rapid pace, anesthesiologists are increasingly called upon to provide well tolerated anesthetic care during these procedures. These patients may not be candidates for surgical treatment and often have multiple comorbidities. It is important for anesthesiologists to familiarize themselves with these procedures and their associated risks and complications.

RECENT FINDINGS

The scope of the interventional pulmonologist's practice is varied and includes both diagnostic and therapeutic procedures. Bronchial thermoplasty is now offered as endoscopic treatment of severe asthma. Endobronchial lung volume reduction procedures are currently undergoing clinical trials and may become more commonplace. Interventional pulmonologists are performing medical thoracoscopy for the treatment and diagnosis of pleural disorders. Interventional radiologists are performing complex pulmonary procedures, often requiring anesthesia.

SUMMARY

The review summarizes the procedures now commonly performed by interventional pulmonologists and interventional radiologists. It discusses the anesthetic considerations for and common complications of these procedures to prepare anesthesiologists to safely care for these patients. Investigational techniques are also described.

Efficient Bronchoscopic Video Summarization

Bronchoscopy enables many minimally invasive chest procedures for diseases such as lung cancer and asthma. Guided by the bronchoscope's video stream, a physician can navigate the complex three-dimensional (3-D) airway tree to collect tissue samples or administer a disease treatment. Unfortunately, physicians currently discard procedural video because of the overwhelming amount of data generated. Hence, they must rely on memory and anecdotal snapshots to document a procedure. We propose a robust automatic method for summarizing an endobronchial video stream. Inspired by the multimedia concept of the video summary and by research in other endoscopy domains, our method consists of three main steps: 1) shot segmentation, 2) motion analysis, and 3) keyframe selection. Overall, the method derives a true hierarchical decomposition, consisting of a shot set and constituent keyframe set, for a given procedural video. No other method to our knowledge gives such a structured summary for the raw, unscripted, unedited videos arising in endoscopy. Results show that our method more efficiently covers the observed endobronchial regions than other keyframe-selection approaches and is robust to parameter variations. Over a wide range of video sequences, our method required on average only 6.5% of available video frames to achieve a video coverage = 92.7%. We also demonstrate how the derived video summary facilitates direct fusion with a patient's 3-D chest computed-tomography scan in a system under development, thereby enabling efficient video browsing and retrieval through the complex airway tree.