Incidence of lung nodules found in patients undergoing lung volume reduction

The development and validation of a radiomic nomogram for the preoperative prediction of lung adenocarcinoma

Background

Accurate diagnosis of early lung cancer from small pulmonary nodules (SPN) is challenging in clinical setting. We aimed to develop a radiomic nomogram to differentiate lung adenocarcinoma from benign SPN.

Methods

This retrospective study included a total of 210 pathologically confirmed SPN (≤ 10 mm) from 197 patients, which were randomly divided into a training dataset (n = 147; malignant nodules, n = 94) and a validation dataset (n = 63; malignant nodules, n = 39). Radiomic features were extracted from the cancerous volumes of interest on contrast-enhanced CT images. The least absolute shrinkage and selection operator (LASSO) regression was used for data dimension reduction, feature selection, and radiomic signature building. Using multivariable logistic regression analysis, a radiomic nomogram was developed incorporating the radiomic signature and the conventional CT signs observed by radiologists. Discrimination and calibration of the radiomic nomogram were evaluated.

Results

The radiomic signature consisting of five radiomic features achieved an AUC of 0.853 (95% confidence interval [CI]: 0.735–0.970), accuracy of 81.0%, sensitivity of 82.9%, and specificity of 77.3%. The two conventional CT signs achieved an AUC of 0.833 (95% CI: 0.707–0.958), accuracy of 65.1%, sensitivity of 53.7%, and specificity of 86.4%. The radiomic nomogram incorporating the radiomic signature and conventional CT signs showed an improved AUC of 0.857 (95% CI: 0.723–0.991), accuracy of 84.1%, sensitivity of 85.4%, and specificity of 81.8%. The radiomic nomogram had good calibration power.

Conclusion

The radiomic nomogram might has the potential to be used as a non-invasive tool for individual prediction of SPN preoperatively. It might facilitate decision-making and improve the management of SPN in the clinical setting.

Computed Tomography-Based Radiomic Features for Diagnosis of Indeterminate Small Pulmonary Nodules

OBJECTIVE

This study aimed to determine the potential of radiomic features extracted from preoperative computed tomography to discriminate malignant from benign indeterminate small (≤10 mm) pulmonary nodules.

METHODS

A total of 197 patients with 210 nodules who underwent surgical resections between January 2011 and March 2017 were analyzed. Three hundred eighty-five radiomic features were extracted from the computed tomographic images. Feature selection and data dimension reduction were performed using the Kruskal-Wallis test, Spearman correlation analysis, and principal component analysis. The random forest was used for radiomic signature building. The receiver operating characteristic curve analysis was used to evaluate the model performance.

RESULTS

Fifteen principal component features were selected for modeling. The area under the curve, sensitivity, specificity, and accuracy of the prediction model were 0.877 (95% confidence interval [CI], 0.795-0.959), 81.8% (95% CI, 72.0%-90.9%), 77.4% (95% CI, 63.9%-89.3%), and 80.0% (95% CI, 72.0%-86.7%) in the validation cohort, respectively.

CONCLUSIONS

Computed tomography-based radiomic features showed good discriminative power for benign and malignant indeterminate small pulmonary nodules.

Evidence of mycobacterial disease in COPD patients with lung volume reduction surgery; the importance of histological assessment of specimens: a cohort study

Background

Patients with COPD are at risk of non-tuberculous mycobacterial infection (NTM). This study examined the histology of lung tissue from COPD patients following lung volume reduction with particular focus on evidence of mycobacterial infection.

Methods

Retrospective histological study of 142 consecutive lung volume reduction surgical specimens (126 separate patients) at Royal Brompton Hospital between 2000 – 2013, with prospectively collected preoperative data on exacerbation rate, lung function and body mass index.

Results

92% of patients had at least one other histological diagnosis in addition to emphysema. 10% of specimens had histological evidence of mycobacterial infection, one with co-existent aspergilloma. Mycobacteria were only identified in those patients with granulomas that were necrotising. These patients had higher exacerbation rates, lower TLCO and FEV₁.

Conclusion

A proportion of severe COPD patients will have evidence of mycobacterial infection despite lack of clinical and radiological suspicion. This may have implications for long-term management of these patients.

Radiographic evaluation of the potential lung volume reduction surgery candidate

Delineating the extent and distribution of emphysema is an essential component of the evaluation of candidates for lung volume reduction surgery (LVRS). Imaging also may identify contraindications to LVRS, including bronchiectasis and pleural scarring. The chest X-ray is of limited utility in LVRS evaluation. Chest computed tomography (CT) scanning is an essential component of the evaluation, demonstrating the presence of emphysema and its amount and distribution. Clinical experience has shown that a substantial minority of chest CT scans will also demonstrate pulmonary nodules, some of which represent lung cancers. Published series, including the National Emphysema Treatment Trial, consistently demonstrate that patients with upper lobe predominant or heterogeneous emphysema are most likely to benefit from LVRS. Heterogeneity and distribution can also be assessed by radionuclide ventilation perfusion scanning, but this modality adds little additional information to CT scanning.

Peripheral solitary pulmonary nodule: CT findings in patients with pulmonary emphysema

PURPOSE

To analyze retrospectively the computed tomographic (CT) features of peripheral noncalcified solitary pulmonary nodules in patients with and those without emphysema.

MATERIALS AND METHODS

The authors' institutional review board required neither its approval nor patient informed consent for this retrospective study. The authors retrospectively reviewed 2-mm-thick CT images of 41 nodules (21 malignant, 20 benign) in 41 patients with emphysema (age range, 58-88 years; mean, 71.9 years) and 40 nodules (20 malignant, 20 benign) in 40 patients without emphysema (age range, 50-85 years; mean, 69.2 years). Two radiologists who were unaware of the diagnosis independently evaluated the shape and margin of the nodule, recorded the presence of ground-glass opacities and air bronchograms, and classified nodules into two diagnostic categories: malignant and benign. Final decisions were reached by consensus. For quantitative assessment of the nodules, the fractal dimensions of the nodule interfaces and circularity of the nodule shape were calculated with an image-processing program, and the percentage of the nodule surrounded by emphysema was obtained. Statistical comparisons were made with a chi(2) or Fisher exact test and the Mann-Whitney U test.

RESULTS

In patients with emphysema, there were no significant differences in fractal dimension, circularity, or frequency of lobulation or spiculation between malignant and benign nodules. Of the 41 nodules in patients with emphysema, 26 (63%) were correctly diagnosed. Thirteen benign nodules (65%) were diagnosed as malignant in patients with emphysema. Of the 40 nodules in nonemphysematous lungs, 37 (93%) were correctly diagnosed. The mean percentage of emphysema around the nodule was greater for misdiagnosed nodules than for correctly diagnosed nodules (P = .003).

CONCLUSION

Malignant and benign nodules associated with emphysema exhibited considerably more overlap in CT features than did nodules in nonemphysematous lungs.

Impact of low-dose CT on lung cancer screening

Despite advances in therapy, the prognosis of lung cancer remains dismal due to the fact that most cases of lung cancer are diagnosed at advanced stages, when the chance of cure is poor. In cases detected at early stages prognosis is better. Unfortunately, early lung cancer usually causes no symptoms and is, consequently, rarely diagnosed. Therefore, screening for early asymptomatic lung cancer with diagnostic procedures appears promising particularly as risk factors for lung cancer are well known (cigarette smoking, occupational asbestos exposure and others) and screening could, therefore, focus on these risk groups. In the past, screening trials using analysis of sputum cytology and to some extent chest radiography have failed to demonstrate a reduction in lung-cancer mortality with screening, probably due to insufficient sensitivity of these tests for early lung cancer. During the last decade the introduction of spiral computed tomography (CT) has provided a technique with a much higher sensitivity for small lung cancers. Feasibility studies using low-radiation-dose CT demonstrated a high proportion of non-small-cell lung cancer at the initial examination (prevalence) with decreasing numbers of detected cancers at follow-up (incidence). The proportion of early-stage tumors was high both at prevalence and incidence examinations. The rate of invasive procedures for benign lesions was low; most indeterminate lesions could be classified with non-invasive diagnostic approaches. The proportion of interval cancers (cancers diagnosed by symptoms between two screening CT scans) was low. As, however, these one-arm feasibility trials are not appropriate to assess a potential mortality reduction through CT screening, prospective randomised multicenter trials were recently initiated in several countries to analyse the effect of CT screening on lung-cancer mortality.

Pulmonary nodules on multi-detector row CT scans: performance comparison of radiologists and computer-aided detection

PURPOSE

To compare the performance of radiologists and of a computer-aided detection (CAD) algorithm for pulmonary nodule detection on thin-section thoracic computed tomographic (CT) scans.

MATERIALS AND METHODS

The study was approved by the institutional review board. The requirement of informed consent was waived. Twenty outpatients (age range, 15-91 years; mean, 64 years) were examined with chest CT (multi-detector row scanner, four detector rows, 1.25-mm section thickness, and 0.6-mm interval) for pulmonary nodules. Three radiologists independently analyzed CT scans, recorded the locus of each nodule candidate, and assigned each a confidence score. A CAD algorithm with parameters chosen by using cross validation was applied to the 20 scans. The reference standard was established by two experienced thoracic radiologists in consensus, with blind review of all nodule candidates and free search for additional nodules at a dedicated workstation for three-dimensional image analysis. True-positive (TP) and false-positive (FP) results and confidence levels were used to generate free-response receiver operating characteristic (ROC) plots. Double-reading performance was determined on the basis of TP detections by either reader.

RESULTS

The 20 scans showed 195 noncalcified nodules with a diameter of 3 mm or more (reference reading). Area under the alternative free-response ROC curve was 0.54, 0.48, 0.55, and 0.36 for CAD and readers 1-3, respectively. Differences between reader 3 and CAD and between readers 2 and 3 were significant (P < .05); those between CAD and readers 1 and 2 were not significant. Mean sensitivity for individual readings was 50% (range, 41%-60%); double reading resulted in increase to 63% (range, 56%-67%). With CAD used at a threshold allowing only three FP detections per CT scan, mean sensitivity was increased to 76% (range, 73%-78%). CAD complemented individual readers by detecting additional nodules more effectively than did a second reader; CAD-reader weighted kappa values were significantly lower than reader-reader weighted kappa values (Wilcoxon rank sum test, P < .05).

CONCLUSION

With CAD used at a level allowing only three FP detections per CT scan, sensitivity was substantially higher than with conventional double reading.

Clinical applications of PET in oncology

Positron emission tomography (PET) provides metabolic information that has been documented to be useful in patient care. The properties of positron decay permit accurate imaging of the distribution of positron-emitting radiopharmaceuticals. The wide array of positron-emitting radiopharmaceuticals has been used to characterize multiple physiologic and pathologic states. PET is used for characterizing brain disorders such as Alzheimer disease and epilepsy and cardiac disorders such as coronary artery disease and myocardial viability. The neurologic and cardiac applications of PET are not covered in this review. The major utilization of PET clinically is in oncology and consists of imaging the distribution of fluorine 18 fluorodeoxyglucose (FDG). FDG, an analogue of glucose, accumulates in most tumors in a greater amount than it does in normal tissue. FDG PET is being used in diagnosis and follow-up of several malignancies, and the list of articles supporting its use continues to grow. In this review, the physics and instrumentation aspects of PET are described. Many of the clinical applications in oncology are mature and readily covered by third-party payers. Other applications are being used clinically but have not been as carefully evaluated in the literature, and these applications may not be covered by third-party payers. The developing applications of PET are included in this review.

Pseudo tumors of the lung after lung volume reduction surgery

We describe 2 patients who underwent lung volume reduction surgery, who postoperatively had computed tomographic scans that showed symptomatic mass lesions suggestive of malignancy and an inhaled foreign body. Investigations excluded these conditions with the remaining likely diagnosis of pseudotumor secondary to buttressing material. These potential sequelae of lung volume reduction surgery should be recognized in follow-up investigations.

Small pulmonary nodules: detection at chest CT and outcome

PURPOSE

To determine the outcome of pulmonary nodules less than 1 cm in diameter detected at chest computed tomography (CT).

MATERIALS AND METHODS

Reports of chest CT performed during 6 months were reviewed to find patients with pulmonary nodules smaller than 1 cm in long axis for which repeat CT was recommended. Records were studied to determine whether follow-up had been performed, the initial nodules had changed in size, or nodules had been resected.

RESULTS

A total of 3,446 chest CT examinations were performed, with 334 patients meeting inclusion criteria. Three patients underwent nodule resection and had pathologic examination results positive for cancer; 185 underwent follow-up, of whom 13 had results excluded as indeterminate. In the remaining 172 patients, 88 had incomplete characterization because of follow-up of less than 2 years, which left 84 with nodule characterization at follow-up. When these 84 patients were combined with the three patients with nodule resection, the number yielded was 87 patients. Seventy-seven of 87 had benign nodules because of resolution or 2-year stability, and 10 of 87 had malignant nodules because of growth or positive histologic examination results. Nine of 10 with malignant nodules had a known primary neoplasm.

CONCLUSION

CT commonly helped identify small nodules. Increase in size occurred infrequently and almost exclusively in patients with a known malignancy.

Pulmonary function tests in preoperative pulmonary evaluation

Pulmonary function testing (PFT) is used extensively by pulmonary specialists to address two common clinical questions: (1) What is the risk of a postoperative pulmonary complication in an individual with lung disease? and (2) Will the patient be able to tolerate lung resection surgery? Today, there are numerous tests available to measure pulmonary function; making judicious use of these tests essential. In this article, the authors describe significant postoperative pulmonary complications, and discuss the surgical and patient factors contributing to the risk of these complications. They provide an evidence-based approach using pulmonary function data to determine an individual patient's risk for pulmonary complications associated with three types of surgical procedures-upper abdominal, cardiac, and lung resection-and discuss recommendations for risk education.

Advances in radiologic assessment of chronic obstructive pulmonary disease

Chest radiography allows detection of moderate and severe emphysema but does not allow quantitation of severity of disease or detection of mild emphysema. Chest radiography is helpful in assessing complications of emphysema such as pneumothorax or secondary infection of a bulla. HRCT provides a detailed image of emphysematous lung disease comparable to that of macroscopic pathologic appearance. The main role of HRCT in patients with COPD is in the preoperative assessment of patients being considered for bullectomy or LVRS.

Lung volume reduction surgery for emphysema

Over the past decades, extensive literature has been published regarding surgical therapies for advanced COPD. Lung-volume reduction surgery would be an option for a significantly larger number of patients than classic bullectomy or lung transplantation. Unfortunately, the initial enthusiasm has been tempered by major questions regarding the optimal surgical approach, safety, firm selection criteria, and confirmation of long-term benefits. In fact, the long-term follow-up reported in patients undergoing classical bullectomy should serve to caution against unbridled enthusiasm for the indiscriminate application of LVRS. Those with the worst long-term outcome despite favourable short-term improvements after bullectomy have consistently been those with the lowest pulmonary function and significant emphysema in the remaining lung who appear remarkably similar to those being evaluated for LVRS. With this in mind, the National Heart, Lung and Blood Institute partnered with the Health Care Finance Administration to establish a multicenter, prospective, randomized study of intensive medical management, including pulmonary rehabilitation versus the same plus bilateral (by MS or VATS), known as the National Emphysema Treatment Trial. The primary objectives are to determine whether LVRS improves survival and exercise capacity. The secondary objectives will examine effects on pulmonary function and HRQL, compare surgical techniques, examine selection criteria for optimal response, identify criteria to determine those who are at prohibitive surgical risk, and examine long-term cost effectiveness. It is hoped that data collected from this novel, multicenter collaboration will place the role of LVRS in a clearer perspective for the physician caring for patients with advanced emphysema.

Small solitary pulmonary nodules

We now are detecting an increasing number of SPN that are difficult to diagnose. Many of the techniques we traditionally have relied on were developed when the average size of detected nodules was larger, and these techniques are of limited diagnostic usefulness for small nodules. In the past, recognition of the need for noninvasive differentiation between benign and malignant nodules led to the development of many useful diagnostic techniques. The ever increasing number of small nodules now being detected will stimulate new approaches. In the future, as in the past, many of these will be based on previously developed concepts. Because a majority of these small nodules will be benign, it will be important to develop reliable methods of determining which patients need further evaluation both from a patient management and cost-effectiveness perspective. Criteria will need to be developed based on the initial CT appearance of the nodule, clinical information about the patient, and subsequent CT using the latest decision analytic techniques and databases. Finally, increased interest in predicting the aggressiveness of a lung cancer, once it has been discovered, could lead to further changes in staging criteria.

Evaluation of patients undergoing lung volume reduction surgery: ancillary information available from computed tomography

AIM

A number of imaging techniques have been used for the pre-operative assessment of patients for lung volume reduction surgery (LVRS). We evaluated whether data currently acquired from perfusion scintigrams and cine MR of the diaphragm are obtainable from high resolution CT (HRCT) of the thorax.

MATERIALS AND METHODS

Thirty patients taking part in a randomized controlled trial of LVRS against maximal medical therapy were evaluated. HRCT examinations (n= 30) were scored for (i) the extent and distribution of emphysema; (ii) the extent of normal pulmonary vasculature; and (iii) diaphragmatic contour, apparent defects and herniation. On scintigraphy, (n= 28), perfusion of the lower thirds of both lungs, as a proportion of total lung perfusion (LZ/T(PERF)), was expressed as a percentage of predicted values (derived from 10 normal control subjects). On cine MR (n= 25) hemidiaphragmatic excursion and coordination were recorded.

RESULTS

Extensive emphysema was present on HRCT (60% +/- 13.2%). There was strong correlation between the extent of normal pulmonary vasculature on HRCT and on perfusion scanning (r(s)= 0.85, P< 0.00005). Hemidiaphragmatic incoordination on MR was weakly associated with hemidiaphragmatic eventration on HRCT (P= 0.04).

CONCLUSION

The strong correlation between lung perfusion assessed by HRCT and lung perfusion on scintigraphy suggests that perfusion scintigraphy is superfluous in the pre-operative evaluation of patients with emphysema for LVRS.

Diffusing capacity predicts operative mortality but not long-term survival after resection for lung cancer

OBJECTIVES

We sought to determine whether diffusing capacity influences operative mortality and long-term survival after resection for lung cancer.

METHODS

We retrospectively reviewed the case histories of patients who underwent major resection for lung cancer. The association between operative mortality and predicted postoperative diffusing capacity was examined. Long-term survival among operative survivors was compared between the groups with high and low predicted postoperative diffusing capacity.

RESULTS

The group comprised 410 patients with a mean age of 62.3 years. We performed 273 lobectomies, 35 bilobectomies, and 102 pneumonectomies. A total of 32 operative deaths (7.8%) were associated with low predicted postoperative diffusing capacity (P <.001). If we examine only operative survivors, there is no significant difference in survival data between patients with a predicted postoperative diffusing capacity of less than 50 and those with a predicted figure of 50 or more (stage I, 111 vs 90 months; stage II, 26 vs 32 months; stage IIIa 32 vs 26 months; log rank P >.5 for each). On the basis of the Cox proportional hazards model, predicted postoperative diffusing capacity did not have a statistically significant effect on long-term survival (estimated hazard ratio corresponding to a 20-point decrease in predicted postoperative diffusing capacity = 1. 13; 95% confidence interval: 0.92 to 1.37).

CONCLUSION

A poor diffusing capacity is associated with high operative mortality but does not adversely affect long-term survival after major lung resection among operative survivors. Improving the perioperative management of patients undergoing major lung resection may enable inclusion of more patients with reduced diffusing capacity in the candidate pool for surgery, thus maximizing survival for early-stage lung cancer.

Imaging of patients with severe emphysema considered for lung volume reduction surgery

Lung volume reduction surgery has recently been reintroduced as a palliative treatment for patients with severe emphysema. Selection criteria vary between centres and imaging is extensively used, but the exact role of individual techniques in the selection process is still emerging.

Lung volume reduction surgery for emphysema: out on a limb without a NETT

Lung volume reduction surgery (LVRS) has recently been rediscovered and offers the potential of improving the quality of life of patients with advanced emphysema. In this article, we discuss the historical and contemporary versions of LVRS. Although initial enthusiasm has been substantial, existing data seem insufficient to demonstrate the safety and efficacy of the procedure in comparison with conventional medical therapy. Fundamental questions remain regarding the long-term effects of an operation versus medical therapy, the optimal selection criteria, the best measures of efficacy, the mechanisms of improvement, the cost-effectiveness of the procedure, and the optimal surgical technique. Until such questions are answered, advising patients about the best management their emphysema will be difficult. The National Emphysema Treatment Trial will address many of these issues and should be embraced by both health-care providers and patients.