Minimally invasive techniques for the diagnosis of peripheral pulmonary nodules:

Safe Motion Planning for Steerable Needles Using Cost Maps Automatically Extracted from Pulmonary Images

Lung cancer is the deadliest form of cancer, and early diagnosis is critical to favorable survival rates. Definitive diagnosis of lung cancer typically requires needle biopsy. Common lung nodule biopsy approaches either carry significant risk or are incapable of accessing large regions of the lung, such as in the periphery. Deploying a steerable needle from a bronchoscope and steering through the lung allows for safe biopsy while improving the accessibility of lung nodules in the lung periphery. In this work, we present a method for extracting a cost map automatically from pulmonary CT images, and utilizing the cost map to efficiently plan safe motions for a steerable needle through the lung. The cost map encodes obstacles that should be avoided, such as the lung pleura, bronchial tubes, and large blood vessels, and additionally formulates a cost for the rest of the lung which corresponds to an approximate likelihood that a blood vessel exists at each location in the anatomy. We then present a motion planning approach that utilizes the cost map to generate paths that minimize accumulated cost while safely reaching a goal location in the lung.

Toward Transoral Peripheral Lung Access: Combining Continuum Robots and Steerable Needles

Lung cancer is the most deadly form of cancer in part because of the challenges associated with accessing nodules for diagnosis and therapy. Transoral access is preferred to percutaneous access since it has a lower risk of lung collapse, yet many sites are currently unreachable transorally due to limitations with current bronchoscopic instruments. Toward this end, we present a new robotic system for image-guided trans-bronchoscopic lung access. The system uses a bronchoscope to navigate in the airway and bronchial tubes to a site near the desired target, a concentric tube robot to move through the bronchial wall and aim at the target, and a bevel-tip steerable needle with magnetic tracking to maneuver through lung tissue to the target under closed-loop control. In this work, we illustrate the workflow of our system and show accurate targeting in phantom experiments. Ex vivo porcine lung experiments show that our steerable needle can be tuned to achieve appreciable curvature in lung tissue. Lastly, we present targeting results with our system using two scenarios based on patient cases. In these experiments, phantoms were created from patient-specific computed tomography information and our system was used to target the locations of suspicious nodules, illustrating the ability of our system to reach sites that are traditionally inaccessible transorally.

Motion Planning for a Three-Stage Multilumen Transoral Lung Access System

Lung cancer is the leading cause of cancer-related death, and early-stage diagnosis is critical to survival. Biopsy is typically required for a definitive diagnosis, but current low-risk clinical options for lung biopsy cannot access all biopsy sites. We introduce a motion planner for a multilumen transoral lung access system, a new system that has the potential to perform safe biopsies anywhere in the lung, which could enable more effective early-stage diagnosis of lung cancer. The system consists of three stages in which a bronchoscope is deployed transorally to the lung, a concentric tube robot pierces through the bronchial tubes into the lung parenchyma, and a steerable needle deploys through a properly oriented concentric tube and steers through the lung parenchyma to the target site while avoiding anatomical obstacles such as significant blood vessels. A sampling-based motion planner computes actions for each stage of the system and considers the coupling of the stages in an efficient manner. We demonstrate the motion planner's fast performance and ability to compute plans with high clearance from obstacles in simulated anatomical scenarios.

Nodule characterization: subsolid nodules

In this review, we focus on the radiologic, clinical, and pathologic aspects primarily of solitary subsolid pulmonary nodules. Particular emphasis will be placed on the pathologic classification and correlative computed tomography (CT) features of adenocarcinoma of the lung. The capabilities of fluorodeoxyglucose positron emission tomography-CT and histologic sampling techniques, including CT-guided biopsy, endoscopic-guided biopsy, and surgical resection, are discussed. Finally, recently proposed management guidelines by the Fleischner Society and the American College of Chest Physicians are reviewed.

Cost-effectiveness analysis of transbronchial needle aspiration of pulmonary lesions without endobronchial affectation

Transbronchial needle aspiration (TBNA) of pulmonary lesions without endobronchial affectation in combination with transbronchial biopsy (TBB) has been shown to increase diagnostic performance. The objective of this present study was to analyze whether the combination of TBNA with conventional TBB is a cost-effective approach.

METHODOLOGY

Ours is a prospective study that included patients with lung nodules or masses with no evidence of endobronchial lesions after flexible bronchoscopy in whom both TBNA and TBB were performed. We analyzed the additional diagnostic value, the impact of TBNA on the cost of the diagnosis and the minimum level of sensitivity required in order for TBNA combined with TBB to be considered a cost-effective diagnostic approach.

RESULTS

Thirty-six patients were included in the study, 25 of whom were males. TBB reached a histologic diagnosis in 39% of the cases, and its combination with TBNA diagnosed 47%. The mean diameter of the lesions was significantly greater in the positive TBNA cases compared with the negative cases (31 vs. 23mm; p=0,034). The cost analysis did not show the additional TBNA to be more cost-effective, despite demonstrating greater diagnostic sensitivity. The minimum sensitivity required for TBNA combined with TBB to be considered a cost-effective approach was 88%.

CONCLUSION

The contribution of TBNA to TBB in the diagnosis of lung nodules or masses without associated endobronchial lesions does not seem to justify the additional economic cost.

[Study on solitary pulmonary nodules: correlation between diameter and clinical manifestation and pathological features]

背景与目的

孤立性肺结节（solitary pulmonary nodules, SPN）是临床诊治的难题之一，不同直径大小SPN的临床及病例特点可能各不相同。本研究旨在探讨SPN直径大小与临床及病理之间的关系。

方法

收集2000年1月-2009年7月在北京大学人民医院胸外科经手术切除明确病理诊断的SPN患者共390例。其中男性212例，女性178例。平均年龄57.1岁；结节最大径平均2.02 cm。按SPN最大径进行分组，其中最大径≤0.5 cm 16例（A组），0.5 cm-1 cm 58例（B组），1 cm-2 cm 163例（C组），2 cm-3 cm 153例（D组），比较各组的临床表现及病理特点。

结果

肿瘤剜除术20例，楔形切除153例，肺叶切除217例。术后病理：良性病变130例（33.3%），恶性病变260例（66.7%）。58.5%的SPN不伴有临床症状，随着结节直径增大，出现临床症状的比率有逐渐增高趋势。A、B、C、D四组的恶性比率分别为43.7%、50.0%、63.2%、79.1%，随着结节直径增大，恶性肿瘤机率显著增加，差异有统计学意义（χ²=22.535, P < 0.001）。单因素及多因素Logistic回归分析结果显示，SPN直径大小是良恶性判断的独立危险因素（OR=1.922, P < 0.001）。本组14例患者术前观察时间达到或超过2年，其中10例术后为恶性，观察期间无增大者7例，3例证实为恶性（42.9%）。

结论

SPN直径大小与患者是否伴有临床症状相关，是病理性质判断的重要危险因素。临床发现的SPN应早期诊断，及时治疗。

Multivariate study of predictive factors for clearly defined lung lesions without visible endobronchial lesions in transbronchial biopsy

BACKGROUND

Although the diagnostic validity and predictive factors for the diagnostic yield of transbronchial biopsy (TBB) of clearly defined pulmonary lesions with no visible endobronchial lesion have been analyzed in numerous studies, very few have used multivariate analysis techniques to evaluate the validity of TBB as a diagnostic tool or to analyze the independent influence of clearly dependent variables, such as the bronchus sign and lesion size.

METHODS

We retrospectively analyzed all cases in which this type of lesion underwent TBB under fluoroscopic control between 2006 and 2008. The analyzed variables included lesion size, localization, the presence of the bronchus sign, and the final result obtained. We performed a descriptive analysis of the TBB results and a multivariate analysis of the predictive factors for the results using logistic regression techniques.

RESULTS

A total of 273 patients (206 males, 75.5%) were included in the study. The average lesion diameter was 34 (± 16) mm, with 24% 2 cm or smaller. Twenty-eight percent of the lesions were localized in the lower lobes and 32% in the peripheral third of the lung. The bronchus sign was present in 28% of the patients. Seventy-eight percent of the patients had primary or metastatic malignant lung lesions, the rest were benign lesions of diverse etiology. TBB was diagnostic in 45.4% of cases. In the multivariate analysis, the only independent predictors of outcome were malignant etiology (OR = 4.8; 95% CI = 2.210.4), diameter >20 mm (OR = 3.6; 95% CI = 1.8-7.3), and the presence of the bronchus sign (OR = 2.4; 95% CI = 1.3-4.3).

CONCLUSIONS

TBB of lesions clearly delimited without an endobronchial lesion can lead to diagnosis in almost half of the patients. The nature of the lesion, diameter >20 mm, and the presence of the bronchus sign are independent predictors of outcome.