Michel Gingras

Probability of Cancer in Pulmonary Nodules Detected on First Screening CT

BACKGROUND Major issues in the implementation of screening for lung cancer by means of low-dose computed tomography (CT) are the definition of a positive result and the management of lung nodules detected on the scans. We conducted a population-based prospective study to determine factors predicting the probability that lung nodules detected on the first screening low-dose CT scans are malignant or will be found to be malignant on follow-up. METHODS We analyzed data from two cohorts of participants undergoing low-dose CT screening. The development data set included participants in the Pan-Canadian Early Detection of Lung Cancer Study (PanCan). The validation data set included participants involved in chemoprevention trials at the British Columbia Cancer Agency (BCCA), sponsored by the U.S. National Cancer Institute. The final outcomes of all nodules of any size that were detected on baseline low-dose CT scans were tracked. Parsimonious and fuller multivariable logistic-regression models were prepared to estimate the probability of lung cancer. RESULTS In the PanCan data set, 1871 persons had 7008 nodules, of which 102 were malignant, and in the BCCA data set, 1090 persons had 5021 nodules, of which 42 were malignant. Among persons with nodules, the rates of cancer in the two data sets were 5.5% and 3.7%, respectively. Predictors of cancer in the model included older age, female sex, family history of lung cancer, emphysema, larger nodule size, location of the nodule in the upper lobe, part-solid nodule type, lower nodule count, and spiculation. Our final parsimonious and full models showed excellent discrimination and calibration, with areas under the receiver-operating-characteristic curve of more than 0.90, even for nodules that were 10 mm or smaller in the validation set. CONCLUSIONS Predictive tools based on patient and nodule characteristics can be used to accurately estimate the probability that lung nodules detected on baseline screening low-dose CT scans are malignant. (Funded by the Terry Fox Research Institute and others; ClinicalTrials.gov number, NCT00751660.).

Computer Vision Tool and Technician as First Reader of Lung Cancer Screening CT Scans

Objectives: To implement a cost‐effective low‐dose computed tomography (LDCT) lung cancer screening program at the population level, accurate and efficient interpretation of a large volume of LDCT scans is needed. The objective of this study was to evaluate a workflow strategy to identify abnormal LDCT scans in which a technician assisted by computer vision (CV) software acts as a first reader with the aim to improve speed, consistency, and quality of scan interpretation. Methods: Without knowledge of the diagnosis, a technician reviewed 828 randomly batched scans (136 with lung cancers, 556 with benign nodules, and 136 without nodules) from the baseline Pan‐Canadian Early Detection of Lung Cancer Study that had been annotated by the CV software CIRRUS Lung Screening (Diagnostic Image Analysis Group, Nijmegen, The Netherlands). The scans were classified as either normal (no nodules ≥1 mm or benign nodules) or abnormal (nodules or other abnormality). The results were compared with the diagnostic interpretation by Pan‐Canadian Early Detection of Lung Cancer Study radiologists. Results: The overall sensitivity and specificity of the technician in identifying an abnormal scan were 97.8% (95% confidence interval: 96.4–98.8) and 98.0% (95% confidence interval: 89.5–99.7), respectively. Of the 112 prevalent nodules that were found to be malignant in follow‐up, 92.9% were correctly identified by the technician plus CV compared with 84.8% by the study radiologists. The average time taken by the technician to review a scan after CV processing was 208 ± 120 seconds. Conclusions: Prescreening CV software and a technician as first reader is a promising strategy for improving the consistency and quality of screening interpretation of LDCT scans.

Plasma pro-surfactant protein B and lung function decline in smokers

Plasma pro-surfactant protein B (pro-SFTPB) levels have recently been shown to predict the development of lung cancer in current and ex-smokers, but the ability of pro-SFTPB to predict measures of chronic obstructive pulmonary disease (COPD) severity is unknown. We evaluated the performance characteristics of pro-SFTPB as a biomarker of lung function decline in a population of current and ex-smokers. Plasma pro-SFTPB levels were measured in 2503 current and ex-smokers enrolled in the Pan-Canadian Early Detection of Lung Cancer Study. Linear regression was performed to determine the relationship of pro-SFTPB levels to changes in forced expiratory volume in 1 s (FEV1) over a 2-year period as well as to baseline FEV1 and the burden of emphysema observed in computed tomography (CT) scans. Plasma pro-SFTPB levels were inversely related to both FEV1 % predicted (p=0.024) and FEV1/forced vital capacity (FVC) (p<0.001), and were positively related to the burden of emphysema on CT scans (p<0.001). Higher plasma pro-SFTPB levels were also associated with a more rapid decline in FEV1 at 1 year (p=0.024) and over 2 years of follow-up (p=0.004). Higher plasma pro-SFTPB levels are associated with increased severity of airflow limitation and accelerated decline in lung function. Pro-SFTPB is a promising biomarker for COPD severity and progression. High plasma pro-SFTPB levels are associated with more rapid short-term declines in FEV1 in current and ex-smokers http://ow.ly/E9Gmx

Transcatheter Aortic Valve Implantation for the Treatment of Surgical Valve Dysfunction (“Valve-in-Valve”): Assessing the Risk of Coronary Obstruction

Abstract  Acute coronary obstruction is one of the most feared complications associated with transcatheter aortic valve‐in‐valve implantation. Strategies for assessing the risk of coronary occlusion during these procedures as well as preventive measures are discussed. (J Card Surg 2012;27:682‐685)

External laser triggering of a saturable absorption Q-switching system

The jitter of a passively Q‐switched ruby laser was reduced to less than 50 ns by using external dye laser triggering.

The backward two-photon amplifier as a self-bistable device

Abstract It is shown that the gain experienced by two light beams counter-propagating in a two-photon amplifier exhibits bistability without any kind of external feedback.

Predicting Malignancy Risk of Screen Detected Lung Nodules – Mean Diameter or Volume

Objective: In lung cancer screening practice low‐dose computed tomography, diameter, and volumetric measurement have been used in the management of screen‐detected lung nodules. The aim of this study was to compare the performance of nodule malignancy risk prediction tools using diameter or volume and between computer‐aided detection (CAD) and radiologist measurements. Methods: Multivariable logistic regression models were prepared by using data from two multicenter lung cancer screening trials. For model development and validation, baseline low‐dose computed tomography scans from the Pan‐Canadian Early Detection of Lung Cancer Study and a subset of National Lung Screening Trial (NLST) scans with lung nodules 3 mm or more in mean diameter were analyzed by using the CIRRUS Lung Screening Workstation (Radboud University Medical Center, Nijmegen, the Netherlands). In the NLST sample, nodules with cancer had been matched on the basis of size to nodules without cancer. Results: Both CAD‐based mean diameter and volume models showed excellent discrimination and calibration, with similar areas under the receiver operating characteristic curves of 0.947. The two CAD models had predictive performance similar to that of the radiologist‐based model. In the NLST validation data, the CAD mean diameter and volume models also demonstrated excellent discrimination: areas under the curve of 0.810 and 0.821, respectively. These performance statistics are similar to those of the Pan‐Canadian Early Detection of Lung Cancer Study malignancy probability model with use of these data and radiologist‐measured maximum diameter. Conclusion: Either CAD‐based nodule diameter or volume can be used to assist in predicting a nodules malignancy risk.

Stimulated two‐photon processes: Effects of the radiation frequencies ratio on the gain spectrum induced by a focused pump

It is shown that the calculated gain spectrum of the radiation generated by a two‐photon process, evaluated from a high‐order approximation solution of the wave equation, is larger than the one obtained from a zero‐order approximation. The difference between the two approximations becomes very important when the ratio of the frequency of the generated radiation to that of a focused pump is large and/or when the pump power is low.