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Background Diagnostic workup of small pulmonary nodules often requires follow-up CT scans to confirm nodule growth before invasive diagnostics or treatment. Purpose To confirm prior results from the International Early Lung Cancer Action Program (I-ELCAP) on quantifying decreases in lung cancer prognosis by using two large databases, the National Lung Screening Trial (NLST) and International Association for the Study of Lung Cancer (IASLC). Materials and Methods In this retrospective study, a model was developed to predict cure rates based on size of solid nodules using the NLST (August 2002 to summer 2007) and IASLC (January 2011 to December 2019) databases, focusing on stage I non-small cell lung cancer (NSCLC). Kaplan-Meier methods were used to calculate 10-year lung cancer-specific survival and 5-year overall survival rates for different tumor sizes. Tumor diameter increases after 90-, 180-, and 365-day delays were estimated using volume doubling times (VDTs) of 60, 120, and 240 days corresponding to fast, moderate, and slow tumor growth. Initial and delayed lung cancer cure rates were assessed across nine scenarios of time delays and tumor growth rates and compared with the previous results of the I-ELCAP database. Results Using regression models based on 166 NLST and 22 590 IASLC patients with NSCLC, 10-year lung cancer-specific survival and 5-year overall survival, respectively, for tumors 4.0-20.0 mm in diameter were estimated. For a 20.0-mm tumor with a 60-day VDT in the NLST database, the lung cancer-specific survival decreased from 83.4% to 76.5%, 66.8%, and 32.3% after 90, 180, and 365 days, respectively. The IASLC database showed similar decreases in 5-year overall survival, from 81.2% to 73.4%, 62.4%, and 23.3% after 90, 180, and 365 days, respectively. Comparison across NLST, IASLC, and I-ELCAP databases revealed minor variations in lung cancer cure rates between 79.9% and 83.4%, with reductions of 6.9%-8.3% after a 180-day delay with a 120-day VDT. Conclusion The NLST and IASLC databases confirmed prior estimates from the I-ELCAP database for the decrease in lung cancer prognosis due to diagnostic delays. © RSNA, 2024 Supplemental material is available for this article. See also the editorial by Park and Lee in this issue.

Background Solid costal pleura-attached noncalcified nodules (CP-NCNs) less than 10.0 mm with lentiform, oval, or semicircular (LOS) or triangular shapes and smooth margins on baseline low-dose CT scans from the Mount Sinai Early Lung and Cardiac Action Program (MS-ELCAP) were reviewed, and it was determined that they can be followed up at the first annual screening rather than having a shorter-term work-up. Purpose To determine whether the same criteria could be used for solid CP-NCNs newly identified at annual screening examinations. Materials and Methods With use of the same MS-ELCAP database, all new solid CP-NCNs measuring 30.0 mm or less were identified at 4425 annual screening examinations between 2010 and 2019. In addition, to ensure that no malignant CP-NCNs met the criteria, all solid malignant CP-NCNs of 30.0 mm or less in the International Early Lung Cancer Action Program, or I-ELCAP, database of 111 102 annual screening examinations from the 76 participating institutions between 1992 and 2019 were identified; Mount Sinai is one of these institutions. All identified solid CP-NCNs were reviewed-with the radiologists blinded to diagnosis-for shape (triangular, LOS, polygonal, round, or irregular), margin (smooth or nonsmooth), pleural attachment (broad or narrow), and the presence of emphysema and/or fibrosis within 10.0 mm of each CP-NCN. Intra- and interreader readings were performed, and agreements were determined by using the B-statistic. Results Of the 76 new solid CP-NCNs, 21 were lung cancers. Benign CP-NCNs were smaller than malignant ones (median diameter, 4.2 mm vs 11 mm; P < .001), had a different shape distributions, more frequently had smooth margins (67% vs 14%; P < .001), and less frequently had emphysema (38% vs 81%; P = .003) or fibrosis (3.6% vs 19%; P = .045) within a 10.0 mm radius. All 22 solid CP-NCNs less than 10.0 mm in average diameter with triangular or LOS shapes and smooth margins were benign, and none of the 21 solid malignant CP-NCNs had these characteristics. Intra- and interobserver agreement for triangular or LOS-shaped CP-NCNs with smooth margins was almost perfect (0.77 and 0.69, respectively). Conclusion The same follow-up recommendation developed for baseline costal pleura-attached noncalcified nodules (CP-NCNs) can be used for CP-NCNs newly identified at annual screening rounds. © RSNA, 2021.

Background Pulmonary nodule features have been used to differentiate benign from malignant nodules. Purpose To determine the frequency of solid noncalcified nodules attached to the costal pleura (CP-NCNs) at baseline low-dose CT and to identify key features of benignity. Materials and Methods A retrospective review was performed of baseline low-dose CT scans obtained in 8730 participants in the Mount Sinai Early Lung and Cardiac Action Program screening cohort between 1992 and 2019. Participants with one or more solid CP-NCNs between 3.0 mm and 30.0 mm in average diameter were included. For each CP-NCN, the size, location, shape (lentiform, oval, or semicircular [LOS]; triangular; polygonal; round; or irregular), margin (smooth or nonsmooth), and attachment to the costal pleura (broad or narrow) were documented. The manifestation of emphysema and fibrosis within a 10-mm radius of the CP-NCN was determined. Multivariable logistic regression analysis, with synthetic minority oversampling techniques, was used. Results The 569 eligible participants (average age, 62 years ± 9 [standard deviation]; 343 women) had 943 solid CP-NCNs, of which 934 (99.0%) were benign and nine (1.0%) were malignant. Multivariable analysis showed that five shapes could be consolidated into three (LOS and/or triangular, round and/or polygonal, and irregular shape); pleural attachment was not a significant independent predictor (odds ratio, 1.24; P = .70); and interaction terms of size with shape (odds ratio, 0.73; P = .005) and margin were significant (odds ratio, 0.80; P = .001). All 603 CP-NCNs less than 10.0 mm with LOS or triangular shapes and smooth margins were benign. Conclusion All baseline noncalcified solid nodules attached to the costal pleura less than 10.0 mm in average diameter with lentiform, oval, semicircular, or triangular shapes and smooth margins were benign; thus, for these nodules, an annual repeat scan in 1 year, rather than a more immediate work-up, is recommended. © RSNA, 2020 Online supplemental material is available for this article. See also the editorial by Godoy in this issue.

Objectives: The goal of this work is to determine the optimal projection to detect breast masses on Chest CT., Methods: Institutional Review Board (HIPPA compliant) approval was obtained with a waiver of consent. 10 image pairs of Chest CT images containing breast masses were selected for review by 10 chest radiologists: the pairs consisted of axial, sagittal, coronal and axial MIP images (MIP images) with each projection compared to a MIP and with one another. For each pair, the image where the mass was most conspicuous was recorded., Results: MIPs were preferred to any cross sectional projection 82% of the time; sagittal (63%) or coronal (63%) images were preferred to the axial projection. When sagittal and coronal images were compared there was no preference., Conclusions: MIP images should be obtained and reviewed for breast pathology; sagittal or coronal projections may provide additional information., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Objectives: To evaluate risk factors for prevalence and progression of aortic valve calcification (AVC) in lung cancer screening participants and also to assess the sensitivity and reliability of visual AVCs on low-dose CT (LDCT) for predicting aortic stenosis (AS) in high-risk smokers., Methods: We reviewed 1225 consecutive participants in annual LDCT screening for lung cancer at the Mount Sinai Hospital between 2010 and 2017. Sensitivity and specificity of moderate/severe AVC score on LDCT to identify AS on echocardiogram were calculated for 126 participants who had both within 12 months. Using regression analyses, risk factors for AVC at baseline, for progression, and for new AVC on annual rounds of screening were identified. Reliability of AVC assessment on LDCT was assessed by comparing visual AVC scores (1) with standard-dose, electrocardiography (ECG)-gated CT for 31 participants who had both within 12 months and (2) with Agatston scores of 1225 participants and by determining (3) the intra-reader agreement of 1225 participants., Results: Visual AVC scores on LDCT had substantial agreement with the severity of AS on echocardiography and substantial inter-observer and excellent intra-observer agreement. Sensitivity and specificity of moderate/severe visual AVC scores for moderate/severe AS on echocardiogram were 100% and 94%, respectively. Significant predictors for baseline AVC were male sex (OR = 2.52), age (OR 10 years  = 2.87), and coronary artery calcification score (OR = 1.18), the significant predictor for AVC progression after baseline was pack-years of smoking (HR 10 packyears  = 1.14), and significant predictors for new AVC on annual LDCT were male sex (HR = 1.51), age (HR 10 years  = 2.17), CAC (HR = 1.09)  and BMI (HR = 1.06)., Conclusions: AVC scores on LDCT should be documented, especially in lung cancer screening program., Key Points: • LDCT screening for lung cancer provides an opportunity to identify lung cancer and cardiovascular disease in asymptomatic smokers. • Visual aortic valve calcification scores could be reliably evaluated on LDCT and had substantial agreement with the severity of aortic valve stenosis on echocardiography. • Sensitivity and specificity of moderate/severe visual AVC scores on LDCT for moderate/severe AS on echocardiogram were 100% and 94%, respectively.

Purpose: To improve outcomes for lung cancer through low-dose computed tomography (LDCT) early lung cancer detection. The International Association for the Study of Lung Cancer is developing the Early Lung Imaging Confederation (ELIC) to serve as an open-source, international, universally accessible environment to analyze large collections of quality-controlled LDCT images and associated biomedical data for research and routine screening care., Methods: ELIC is an international confederation that allows access to efficiently analyze large numbers of high-quality computed tomography (CT) images with associated de-identified clinical information without moving primary imaging/clinical or imaging data from its local or regional site of origin. Rather, ELIC uses a cloud-based infrastructure to distribute analysis tools to the local site of the stored imaging and clinical data, thereby allowing for research and quality studies to proceed in a vendor-neutral, collaborative environment. ELIC's hub-and-spoke architecture will be deployed to permit analysis of CT images and associated data in a secure environment, without any requirement to reveal the data itself (ie, privacy protecting). Identifiable data remain under local control, so the resulting environment complies with national regulations and mitigates against privacy or data disclosure risk., Results: The goal of pilot experiments is to connect image collections of LDCT scans that can be accurately analyzed in a fashion to support a global network using methodologies that can be readily scaled to accrued databases of sufficient size to develop and validate robust quantitative imaging tools., Conclusion: This initiative can rapidly accelerate improvements to the multidisciplinary management of early, curable lung cancer and other major thoracic diseases (eg, coronary artery disease and chronic obstructive pulmonary disease) visualized on a screening LDCT scan. The addition of a facile, quantitative CT scanner image quality conformance process is a unique step toward improving the reliability of clinical decision support with CT screening worldwide.

Purpose: Clinical management decisions arising from the baseline round for lung cancer screening are the most challenging, as findings have accumulated over a lifetime and may be of no clinical concern. To minimize unnecessary harms and costs of workup prior to the first, annual repeat screening, workup should be limited to participants with the highest suspicion of lung cancer while still aiming to identify small, early lung cancers., Methods: We compared recommendations for immediate, delayed (by 3 or 6 months) workup to assess growth at a malignant rate, and the resulting overall and potential biopsies of three baseline screening protocols: I-ELCAP, the two scenarios of ACR-LungRADS, and the European Consortium. For each protocol, the efficiency ratio (ER) of each recommendation was calculated by dividing the number of participants recommended for that workup by the number of resulting lung cancer diagnoses. The ER for potential biopsies was calculated, assuming that biopsies were performed on all participants recommended for immediate workup as well as those diagnosed with lung cancer after delayed workup., Results: For I-ELCAP, ACR-LungRADS Scenario 1, ACR-LungRADS Scenario 2, and the European consortium, the overall ER was 13.9, 18.3, 18.3, and 31.9, respectively, and for potential biopsies, it was 2.2, 8.1, 3.2, and 4.4, respectively. ER for immediate workup was 2.9, 8.6, 3.9, and 5.6, respectively, and for delayed workup was 36.1, 160.3, 57.8, and 111.9, respectively., Conclusions: I-ELCAP recommendations had the lowest ER values for overall, immediate, and delayed workup, and for potential biopsies., Key Points: • Small differences in protocol thresholds can lead to many unnecessary diagnostic workups. • I-ELCAP recommendations were the most efficient for immediate and overall workup, and potential biopsies. • Definition of a "positive result" and recommendations for further workup in the baseline round needs to be continually reevaluated and updated.

After years of assessment through controlled clinical trials, low-dose CT screening for lung cancer is becoming part of clinical practice. As with any cancer screening test, those undergoing lung cancer screening are not being evaluated for concerning signs or symptoms, but are generally in good health and proactively trying to prevent premature death. Given the resultant obligation to achieve the screening aim of early diagnosis while also minimizing the potential for morbidity from workup of indeterminate but ultimately benign screening abnormalities, careful implementation of screening with conformance to currently recognized best practices and a focus on quality assurance is essential. In this review, we address the importance of each component of the screening process to optimize the effectiveness of CT screening, discussing options for quality assurance at each step. We also discuss the potential added advantages, quality assurance requirements and current status of quantitative imaging biomarkers related to lung cancer screening. Finally, we highlight suggestions for improvements and needs for further evidence in evaluating the performance of CT screening as it transitions from the research trial setting into daily clinical practice.

Objective: Determine the frequency of moderate-to-severe hepatic steatosis (HS) in asymptomatic participants in a low-dose CT (LDCT) screening program for lung cancer, to identify risk factors, and develop recommendations., Methods: Baseline LDCT scans of the chest of 170 participants in an IRB-approved study between August 2011 and April 2016 were reviewed. Demographic variables, comorbidities, and liver function tests were documented. Hepatic and splenic attenuation values hounsfield unit (HU) were measured. Regression analyses were performed., Results: Average liver attenuation was 57.6HU (standard deviation (SD) 9.3) and average liver/spleen (L/S) ratio was 1.3 (SD 0.3). Liver attenuation was <40HU for 9 (5.3%), liver/spleen (L/S) ratio <0.8 for 6 (3.5%), and either <40HU or L/S ratio <0.8 for 9 (5.3%). Male sex (p=0.004), diabetes (p=0.0005), emphysema (p=0.03), and high BMI (p=0.0006) were significant predictors of HS. Aspartate aminotransferase (p=0.0018) and alanine aminotransferase (p=0.012) were negatively correlated with liver attenuation. Reduced serum levels of alpha-1-antitrypsin may be a common factor of emphysema and HS., Conclusion: LDCT can detect HS in asymptomatic participants with frequencies similar to previous reports. If liver attenuation is below 40HU and/or L/S ratio below 0.8, further evaluation of HS to the primary care physician or liver specialist is recommended., (Copyright © 2017. Published by Elsevier B.V.)

Objective: The objective of this study is to evaluate measurement variability in volumetric assessment of pulmonary nodules on low-dose CT images with a view toward determining how this variability is influenced by nodule size., Materials and Methods: A large CT screening database was reviewed to identify solid pulmonary nodules that had remained stable in size on the basis of findings from at least three scans obtained over a 2-year period. Two software packages (Lung VCAR and syngo.via) were used to assess the nodule volume on the two most recent CT scans, which were obtained at a slice thickness of 0.625 mm. The percentage of volume change was calculated for each nodule. The SD of the percentage of volume change was determined for nodules in each of the following nodule diameter size categories: less than 4 mm, 4-5 mm, 6-9 mm, and 10 mm or larger. The diameter was the mean of the length and width in the CT image that represented the largest cross-sectional area of the nodule., Results: The 171 stable nodules that were identified in 117 CT screening participants (median age, 61 years) ranged in size from 2.2 to 18.7 mm. The time between acquisition of the first and last CT images ranged from 3.7 to 17.8 years (median, 11.5 years). For each of the four categories of diameter size (< 4, 4-5, 6-9, and ≥ 10 mm), the SD of the percentage of volume change was 20.4%, 17.7%, 14.6%, and 3.7%, with the use of Lung VCAR, and 59.5%, 24.3%, 9.1%, and 6.2%, with the use of syngo.via, respectively. The SD decreased with increasing nodule diameter, with the use of both software packages., Conclusion: Measurement variability decreased with increasing nodule diameter for both software packages and was different between the two software packages.

Objective: The objective of our study was to determine how often death occurred from lung cancers that manifested as part-solid nodules in the National Lung Screening Trial (NLST)., Materials and Methods: NLST radiologists classified nodules as solid, ground-glass, or mixed. All lung cancers classified as mixed nodules by NLST radiologists were reviewed by four experienced radiologists and reclassified as solid, nonsolid, or part-solid nodules. When possible, volume doubling times (VDTs) were calculated separately for the entire nodule and for the solid component of the nodule., Results: Of 88 screening-diagnosed lung cancer cases identified by the NLST radiologists as mixed nodules, study radiologists confirmed that 19 were part-solid nodules. All the part-solid nodules were present at baseline (time 0), and none of the patients with a part-solid nodule had lymph node enlargement at CT before diagnosis or metastases at resection. Multilobar stage IV (T4N0M1) bronchioloalveolar carcinoma was diagnosed in one patient 25.0 months after study randomization, and the patient died 67.9 months after randomization. All 18 patients with a solitary or dominant part-solid nodule underwent surgery, and none died of lung cancer. From randomization, the average time to diagnosis was 18.6 months and the average time of follow-up was 79.2 months. On the last CT examination performed before diagnosis, the average size of the solid component of the part-solid nodules was 9.2 mm (SD, 4.9); the solid component was larger than 10 mm in five patients. The median VDT based on the entire nodule was 476 days, and the median VDT based on the solid component alone was 240 days., Conclusion: None of the patients with lung cancer manifesting as a solitary or dominant part-solid nodule had lymph node enlargement or metastases at pathology, and none died of lung cancer within the follow-up time of the NLST.

Objective: To compare long-term survival rates of patients with first, primary, clinical stage IA nonsmall cell lung cancer from a large cohort undergoing computed tomography screening with and without mediastinal lymph node resection (MLNR) under an Institutional Review Board-approved common protocol from 1992 to 2014., Background: Assessing survival differences of patients with and without MLNR manifesting as solid and subsolid nodules., Methods: Long-term Kaplan-Meier (K-M) survival rates for those with and without MLNR were compared and Cox regression analyses were used to adjust for demographic, computed tomography, and surgical covariates., Results: The long-term K-M rates for 462 with and 145 without MLNR was 92% versus 96% (P = 0.19), respectively. For 203 patients with a subsolid nodule, 151 with and 52 without MLNR, the rate was 100%. For the 404 patients with a solid nodule, 311 with and 93 without MLNR, the rate was 87% versus 94% (P = 0.24) and Cox regression showed no statistically significant difference (P = 0.28) when adjusted for all covariates. Risk of dying increased significantly with increasing decades of age (hazard ratio [HR] 2.3, 95% confidence interval [CI] 1.4-3.8), centrally located tumor (HR 2.5, 95% CI 1.2-5.2), tumor size 21 to 30 mm (HR 2.7, 95% CI 1.2-6.0), and invasion beyond the lung stroma (HR 3.0, 95% CI 1.4-6.1). For the 346 patients with MLNR, tumor size was 20 mm or less; K-M rates for the 269 patients with and 169 patients without MLNR were also not significantly different (HR 2.1, P = 0.24)., Conclusions: It is not mandatory to perform MLNR when screen-diagnosed nonsmall cell lung cancer manifests as a subsolid nodule.

Objectives: The aim of this study was to understand the effect of rounding nodule size measurements on the frequency of positive results in the setting of lung cancer screening., Methods: Four methods for determining nodule size were compared, including rounding each individual length and width measurement and also rounding the overall average. These were applied to the International Early Lung Cancer Action Program database, in which we determined the frequency of a positive result by using standard size thresholds of 6.0 mm on baseline screening and 3.0 mm on repeat scanning. We also explored how rounding influences the ability to measure growth according to a predefined cutoff value of 1.5 mm as required in the Lung Computed Tomography Screening Reporting and Data System (Lung-RADS) (version 1.0)., Results: Each method for rounding increased the frequency of positive results compared with that with no rounding. The largest increases-28.9% and 22.3% for the baseline and repeat round, respectively-occurred when rounding was used for both the individual length and width measurements and again for the final diameter. If the 1.5-mm increase in size were used for determining growth, a 4-mm nodule would need to have a volume doubling time of 130.6 days or less to demonstrate growth in 6 months (Lung-RADS category 3) whereas a 6-mm nodule would need volume doubling time of 93.2 days to demonstrate growth in 3 months (Lung-RADS category 4A). In addition, rounding can have the effect of having nodules that appear to not be growing meet the criteria for growth and vice versa., Conclusions: Rounding influences the frequency of positive results and growth assessment, substantially decreasing the efficiency of screening., (Copyright © 2017 International Association for the Study of Lung Cancer. Published by Elsevier Inc. All rights reserved.)

Objective: The purpose of this study was to assess the frequencies of identifying participants with part-solid nodules, of diagnostic pursuit, of diagnoses of lung cancer, and long-term lung cancer survival in baseline and annual repeat rounds of CT screening in the International Early Lung Cancer Action Project., Materials and Methods: Screenings were performed under a common protocol. Participants with solid, nonsolid, and part-solid nodules and the diagnoses of lung cancer were documented., Results: Part-solid nodules were identified in 2892 of 57,496 (5.0%) baseline screening studies; 567 (19.6%) of these nodules resolved or decreased in size. Diagnostic pursuit led to the diagnosis of adenocarcinoma in 79 cases, all clinical stage I. At resection, one nodule (12-mm solid component) had a single N2 metastasis. A new part-solid nodule was identified in 541 of 64,677 (0.8%) annual repeat screenings; 377 (69.7%) of these nodules resolved or decreased in size. In eight cases among the 541, the diagnosis of adenocarcinoma manifesting as a part solid nodule was made; on retrospective review the nodule originally had been a nonsolid nodule. In another 20 cases, the cancer originally had manifested as a nonsolid nodule but had progressed to become part-solid at annual repeat screening before any diagnosis was pursued. These 28 annual repeat cases of lung cancer were all pathologic stage IA. Of the 107 cases of lung cancer (79 baseline cases and 28 annual repeat cases), 106 were surgically resected, and one baseline case was followed up with imaging for 4 years. The lung cancer survival rate was 100% with a median follow-up period from diagnosis of 89 months (interquartile range, 52-134 months)., Conclusion: Lung cancers manifesting as part-solid nodules at repeat screening studies all started as nonsolid nodules. Among 107 cases of adenocarcinoma manifesting as a part-solid nodule, a single lymph node metastasis was found in a single case (solid component, 12 mm).

Purpose To validate the recommendation of performing annual follow-up of nonsolid nodules (NSNs) identified by computed tomographic (CT) screening for lung cancer, all cases of lung cancer manifesting as NSN in the National Lung Screening Trial (NLST) were reviewed. Materials and Methods Institutional review board and informed consent were waived for this study. The NLST database was searched to identify all participants with at least one NSN on CT scan with lung cancer as the cause of death (COD) documented by the NLST endpoint verification process. Among the 26 722 participants, 2534 (9.4%) had one or more NSNs, and lung cancer as the COD occurred for 48 participants. On review, 21 of the 48 patients had no NSN in the cancerous lobe, which left 27 patients whose CT scans were reviewed by four radiologists: Group A (n = 12) were cases of lung cancer as the COD because of adenocarcinoma, and group B (n = 15) were cases of lung cancer as the COD because of other cell types. Frequency of lung cancer as the COD because of NSN and the time from randomization to diagnosis within these groups was determined. Results Six of the 12 patients in group A had no NSN in the cancerous lobe whereas the remaining six patients had a dominant solid or part-solid nodule in the lobe that rapidly grew in four patients, was multifocal in one patient, and had a growing NSN in one patient in whom diagnosis was delayed for over 3 years. Five of the 15 patients in group B had no NSN, and for the remaining 10 patients, lung cancer as the COD was not because of NSN. Conclusion It seems unlikely that patients with lung cancer as the COD occurred with solitary or dominant NSN as long as annual follow-up was performed. This lends further support that lung cancers that manifest as NSNs have an indolent course and can be managed with annual follow-up. © RSNA, 2016.

Purpose: To address the frequency of identifying nonsolid nodules, diagnosing lung cancer manifesting as such nodules, and the long-term outcome after treatment in a prospective cohort, the International Early Lung Cancer Action Program., Materials and Methods: A total of 57,496 participants underwent baseline and subsequent annual repeat computed tomographic (CT) screenings according to an institutional review board, HIPAA-compliant protocol. Informed consent was obtained. The frequency of participants with nonsolid nodules, the course of the nodule at follow-up, and the resulting diagnoses of lung cancer, treatment, and outcome are given separately for baseline and annual repeat rounds of screening. The χ(2) statistic was used to compare percentages., Results: A nonsolid nodule was identified in 2392 (4.2%) of 57,496 baseline screenings, and pathologic pursuit led to the diagnosis of 73 cases of adenocarcinoma. A new nonsolid nodule was identified in 485 (0.7%) of 64,677 annual repeat screenings, and 11 had a diagnosis of stage I adenocarcinoma; none were in nodules 15 mm or larger in diameter. Nonsolid nodules resolved or decreased more frequently in annual repeat than in baseline rounds (322 [66%] of 485 vs 628 [26%] of 2392, P < .0001). Treatment of the cases of lung cancer was with lobectomy in 55, bilobectomy in two, sublobar resection in 26, and radiation therapy in one. Median time to treatment was 19 months (interquartile range [IQR], 6-41 months). A solid component had developed in 22 cases prior to treatment (median transition time from nonsolid to part-solid, 25 months). The lung cancer-survival rate was 100% with median follow-up since diagnosis of 78 months (IQR, 45-122 months)., Conclusion: Nonsolid nodules of any size can be safely followed with CT at 12-month intervals to assess transition to part-solid. Surgery was 100% curative in all cases, regardless of the time to treatment., (© RSNA, 2015)

Objective: To compare Agatston with Ordinal Scores for the extent of coronary artery calcification (coronary artery calcium) using nongated low-dose computed tomography (CT) scans., Materials and Methods: A total of 631 asymptomatic participants had CT scans from 2010 to 2013. Their Ordinal and Agatston Score were classified into categories., Results: The Ordinal Score Categories showed excellent agreement (weighted kappa of 0.83; 95% confidence interval: 0.79-0.88) with the Agatston Score Categories., Conclusions: The use of the Ordinal Score is readily obtained on low-dose CT scans that are used for CT screening for lung cancer and these scores are useful for risk stratification of coronary artery disease., (Copyright © 2015. Published by Elsevier Inc.)

The International Early Lung Cancer Action Program (I-ELCAP) used a novel study design that provided quantitative information about annual CT screening for lung cancer. The results stimulated additional studies of lung cancer screening and ultimately led to the National Lung Screening Trial (NLST) being initiated in 2002, as the initial report in 1999 was sufficiently compelling to reawaken interest in screening for lung cancer. The authors think that the I-ELCAP and NLST "story" provides a strong argument for relevant agencies to consider alternative study designs for the public funding of studies aimed at evaluating the effectiveness of screening and other medical trials., (Copyright © 2015 Elsevier Inc. All rights reserved.)

The Quantitative Imaging Biomarker Alliance (QIBA) is a multidisciplinary consortium sponsored by the RSNA to define processes that enable the implementation and advancement of quantitative imaging methods described in a QIBA profile document that outlines the process to reliably and accurately measure imaging features. A QIBA profile includes factors such as technical (product-specific) standards, user activities, and relationship to a clinically meaningful metric, such as with nodule measurement in the course of CT screening for lung cancer. In this report, the authors describe how the QIBA approach is being applied to the measurement of small pulmonary nodules such as those found during low-dose CT-based lung cancer screening. All sources of variance with imaging measurement were defined for this process. Through a process of experimentation, literature review, and assembly of expert opinion, the strongest evidence was used to define how to best implement each step in the imaging acquisition and evaluation process. This systematic approach to implementing a quantitative imaging biomarker with standardized specifications for image acquisition and postprocessing for a specific quantitative measurement of a pulmonary nodule results in consistent performance characteristics of the measurement (eg, bias and variance). Implementation of the QIBA small nodule profile may allow more efficient and effective clinical management of the diagnostic workup of individuals found to have suspicious pulmonary nodules in the course of lung cancer screening evaluation., (Copyright © 2015 American College of Radiology. Published by Elsevier Inc. All rights reserved.)

OBJECTIVE. Appropriate radiologic interpretation of screening CT can minimize unnecessary workup and intervention. This is particularly challenging in the baseline round. We report on the quality assurance process we developed for the International Early Lung Cancer Action Program. MATERIALS AND METHODS. After initial training at the coordinating center, radiologists at 10 participating institutions and at the center independently interpreted the first 100 baseline screenings. The radiologist at the institutions had access to the center interpretations before issuing the final reports. After the first 100 screenings, the interpretations were jointly discussed. This report summarizes the results of the initial 100 dual interpretations at the 10 institutions. RESULTS. The final institution interpretations agreed with the center in 895 of the 1000 interpretations. Compared with the center, the frequency of positive results was higher at eight of the 10 institutions. The most frequent reason of discrepant interpretations was not following the protocol (n = 55) and the least frequent was not identifying a nodule (n = 3). CONCLUSION. The quality assurance process helped focus educational programs and provided an excellent vehicle for review of the protocol with participating physicians. It also suggests that the rate of positive results can be reduced by such measures.

Objective: The purpose of this study was to review the records of patients with diagnoses of lung cancer in annual repeat rounds of CT screening in the International Early Lung Cancer Action Program to determine whether the cancer could have been identified in the previous round of screening., Materials and Methods: Three radiologists reviewed the scans of 104 lung cancer patients and assigned the findings to one of three categories: 1, cancer was not visible at previous CT screening; 2, cancer was visible at previous CT screening but not identified; 3, abnormality was identified at previous CT screening but not classified as malignant. Nodule size, nodule consistency, cell type, and stage at the previous screening and when identified for further workup for each of the three categories were tabulated., Results: Twenty-four (23%) patients had category 1 findings; 56 (54%) category 2; and 24 (23%) category 3. When diagnosed, seven (29%) category 1, 10 (18%) category 2, and four (17%) category three cancers had progressed beyond stage I. All cancers seen in retrospect were in clinical stage I at the previous screening. Category 1 cancers, compared with categories 2 and 3, had faster growth rates, were less frequently adenocarcinomas (29% vs 54% and 67%, p = 0.01), and were more often small cell carcinomas (29% vs 14% and 12%, p = 0.12)., Conclusion: Lung cancers found on annual repeat screenings were frequently identified in the previous round of screening, suggesting that review of the varied appearance and incorporation of advanced image display may be useful for earlier detection.

Purpose: To determine the usefulness of alternative nodule size thresholds in a population undergoing computed tomographic (CT) screening for lung cancer and to compare the reported International Early Lung Cancer Action Program ( I-ELCAP International Early Lung Cancer Action Program ) results with the National Lung Screening Trial ( NLST National Lung Screening Trial ) results., Materials and Methods: The institutional review board approved this retrospective analysis. Informed consent was obtained according to HIPAA compliance. Findings in the CT cohort in the NLST National Lung Screening Trial of 25 813 participants who underwent baseline CT in 2002-2004 were reviewed. The frequency of solid and part-solid pulmonary nodules and the lung cancer diagnoses using an alternative nodule threshold of 5.0, 6.0, 7.0, 8.0, and 9.0 mm were determined. Proportional reduction in the frequency of positive results and their 95% confidence intervals using each of the alternative thresholds were calculated., Results: The frequency of positive results in the baseline round in the CT arm of the NLST National Lung Screening Trial using the definition of a positive result of any parenchymal, solid or part-solid, noncalcified nodule of 5.0 mm or larger was 15.8% (4080 of 25 813). Using alternative thresholds of 6.0, 7.0, 8.0, and 9.0 mm, the frequencies of positive results were 10.5% (2700 of 25 813, 7.2% (1847 of 25 813), 5.3% (1362 of 25 813), and 4.1% (1007 of 25 813), respectively, and the corresponding proportional reduction in additional CT scans would have been 33.8% (1380 of 1480), 54.7% (2233 of 4080), 66.6% (2718 of 4080), and 73.8% (3013 of 4080), respectively. Concomitantly, the proportion of lung cancer diagnoses determined within the first 12 months would be delayed up to 9 months for 0.9% (two of 232), 2.6% (six of 232), 6.0% (14 of 232), and 9.9% (23 of 232) of the patients, respectively., Conclusion: The NLST National Lung Screening Trial results are similar to those previously reported for the I-ELCAP International Early Lung Cancer Action Program and suggest that, even for high-risk participants in the NLST National Lung Screening Trial , higher thresholds of nodule size should be considered and prospectively evaluated.

Systematic reviews are utilized in evidence-based medicine and are increasingly being used to help guide standards, guidelines, and clinical practice. The National Lung Screening Trial results prompted such a review of lung cancer screening literature. The review was endorsed by five major medical societies. We aimed at assessing its accuracy. Two independent groups of two reviewers reviewed the systematic review, including its source literature. Errors were placed into three major categories and tabulated: (i) selection of studies, (ii) misrepresentation of published reports, and (iii) errors in calculation and rounding. A total of 151 errors were found. There were 13 errors in selection of studies, 124 errors due to misrepresentation of published reports, and 14 errors in calculations and rounding. The extent of these errors raises concern about the credibility of the conclusions of the recent lung cancer screening systematic review. A process that allows for a thorough checking of data included in systematic reviews should be established.

Purpose: To (a) perform a pilot study comparing radiologists' reading of breast density at computed tomography (CT) of the chest with breast density readings from mammography performed in the same patient and (b) compare a subset of these with computer-derived measurements of breast density at CT., Materials and Methods: The institutional review board waived informed consent for this HIPAA-compliant retrospective review of mammograms and chest CT scans from 206 women obtained within 1 year of each other. Two radiologists with expertise in interpreting mammographic and CT findings independently reviewed the mammograms and CT scans and classified each case into one of the four breast density types defined by the Breast Imaging Reporting and Data System of the American College of Radiology. Interreader agreements for the mammographic density types and CT density grades were determined by using the Cohen weighted κ statistic. The intrareader correlation coefficient was determined in a subset of CT images. In another subset of 40 cases, the agreement of the semiautomated computer-derived measurements of breast density with the consensus of the two radiologists was assessed., Results: Interreader agreement was higher for the CT density grades than for the mammographic density types, with 0.79 (95% confidence interval [CI]: 0.73, 0.85) versus 0.62 (95% CI: 0.54, 0.70). The intrareader reliability of breast density grades on CT images was 0.88. The computer-derived breast density measurements agreed with those of the radiologists in 36 (90%) cases. When four cases were manually adjusted for the complex anatomy, there was agreement for all cases., Conclusion: Preliminary results suggest that on further validation, breast density readings at CT may provide important additional risk information on CT of the chest and that computer-derived measurements may be helpful in such assessment., (© RSNA, 2013.)

Background: Low-dose computed tomography screening for lung cancer can reduce mortality among high-risk persons, but "false-positive" findings may result in unnecessary evaluations with attendant risks. The effect of alternative thresholds for defining a positive result on the rates of positive results and cancer diagnoses is unknown., Objective: To assess the frequency of positive results and potential delays in diagnosis in the baseline round of screening by using more restrictive thresholds., Design: Prospective cohort study., Setting: Multi-institutional International Early Lung Cancer Action Program., Patients: 21 136 participants with baseline computed tomography performed between 2006 and 2010., Measurements: The frequency of solid and part-solid pulmonary nodules and the rate of lung cancer diagnosis by using current (5 mm) and more restrictive thresholds of nodule diameter., Results: The frequency of positive results in the baseline round by using the current definition of positive result (any parenchymal, solid or part-solid, noncalcified nodule ≥5.0 mm) was 16% (3396/21 136). When alternative threshold values of 6.0, 7.0, 8.0 and 9.0 mm were used, the frequencies of positive results were 10.2% (95% CI, 9.8% to 10.6%), 7.1% (CI, 6.7% to 7.4%), 5.1% (CI, 4.8% to 5.4%), and 4.0% (CI, 3.7% to 4.2%), respectively. Use of these alternative definitions would have reduced the work-up by 36%, 56%, 68%, and 75%, respectively. Concomitantly, lung cancer diagnostics would have been delayed by at most 9 months for 0%, 5.0% (CI, 1.1% to 9.0%), 5.9% (CI, 1.7 to 10.1%), and 6.7% (CI, 2.2% to 11.2%) of the cases of cancer, respectively., Limitation: This was a retrospective analysis and thus whether delays in diagnosis would have altered outcomes cannot be determined., Conclusion: These findings suggest that using a threshold of 7 or 8 mm to define positive results in the baseline round of computed tomography screening for lung cancer should be prospectively evaluated to determine whether the benefits of decreasing further work-up outweigh the consequent delay in diagnosis in some patients.

Objective: The objectives of this study were to determine the frequency of lung cancers associated with a discrete cystic airspace and to characterize the morphologic and pathologic features of the cancer and the cystic airspace., Materials and Methods: We reviewed all diagnosed cases of lung cancer resulting from baseline screening (n=595) and annual screening (n=111) in the International Early Lung Cancer Action Program to identify those abutting or in the wall of a cystic airspace. We also reviewed the pathologic specimens., Results: A total of 26 lung cancers were identified abutting or in the wall of a cystic airspace. Of these, 13 were identified at baseline (13/595, 2%) and 13 at annual screening (13/111, 12%), which was significant (p<0.0001). The median circumferential portion of wall involved was less for the annual cancers than for the baseline ones, but this difference did not reach significance (90° vs 240°, p=0.07). The diagnosis was adenocarcinoma in all but three cases. Histologic analysis showed that the cystic space was a bulla, a fibrous walled cyst without a defined lining, or a pleural bleb and that in all but one case, the tumor was eccentric relative to the airspace and the wall of the airspace was unevenly thickened., Conclusion: At annual repeat CT screening, the finding of an isolated cystic airspace with increased wall thickness should raise the suspicion of lung cancer.

Background: Prognosis is incompletely known for small-cell lung carcinoma (SCLC) detected by CT screening of at-risk subjects., Methods: A multinational study of baseline and annual repeat CT screening for lung cancer of 48,037 at-risk subjects yielded 48 persons (median age 68 years) with SCLC. Stage (tumor, node, metastasis system) distribution and death rates were compared with those of 7960 usual-care SCLC subjects (chi-square or Fisher exact testing, as appropriate), as reported by the International Association for the Study of Lung Cancer. Cure was estimated by Kaplan-Meier analysis., Results: Forty-four (92%) of the patients were asymptomatic at screening CT detection of their SCLC; four (8%) presented with cancer-related symptoms before the next scheduled repeat screening. SCLC was diagnosed in clinical stages IA and IV in 16 (33%) and 7 (15%), respectively, of 48 patients, compared to 211 (3%) and 4530 (57%), respectively, of the 7960 patients in the usual-care study (P<0.0001). Tumor diameter was ≤3.0 cm for each of the 16 subjects in clinical stage I. The percentage of clinical stage I SCLC-related deaths within 5 years was lower in the screening study than in the usual-care study (44% vs. 71%, P=0.03), as was also the percentage of advanced stage (IIIB plus IV) SCLC-related deaths (62% vs. 94%, P<0.0001)., Conclusions: Compared to usual-care detection of SCLC, CT screening identified a shift toward early stage and away from late stage disease, and was associated with a decrease in deaths from the disease., (Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.)

Purpose: To empirically address the distribution of the volume doubling time (VDT) of lung cancers diagnosed in repeat annual rounds of computed tomographic (CT) screening in the International Early Lung Cancer Action Program (I-ELCAP), first and foremost with respect to rates of tumor growth but also in terms of cell types., Materials and Methods: All CT screenings in I-ELCAP from 1993 to 2009 were performed according to HIPAA-compliant protocols approved by the institutional review boards of the collaborating institutions. All instances of first diagnosis of primary lung cancer after a negative screening result 7-18 months earlier were identified, with symptom-prompted diagnoses included. Lesion diameter was calculated by using the measured length and width of each cancer at the time when the nodule was first identified for further work-up and at the time of the most recent prior screening, 7-18 months earlier. The length and width were measured a second time for each cancer, and the geometric mean of the two calculated diameters was used to calculate the VDT. The χ(2) statistic was used to compare the VDT distributions., Results: The median VDT for 111 cancers was 98 days (interquartile range, 108). For 56 (50%) cancers it was less than 100 days, and for three (3%) cancers it was more than 400 days. Adenocarcinoma was the most frequent cell type (50%), followed by squamous cell carcinoma (19%), small cell carcinoma (19%), and others (12%). Lung cancers manifesting as subsolid nodules had significantly longer VDTs than those manifesting as solid nodules (P < .0001)., Conclusion: Lung cancers diagnosed in annual repeat rounds of CT screening, as manifest by the VDT and cell-type distributions, are similar to those diagnosed in the absence of screening.

Introduction: Computed tomography-guided transthoracic fine-needle aspiration (FNA) is a highly sensitive technique for diagnosing malignancy in pulmonary nodules; however, there is great uncertainty regarding the reliability of a benign result. The goal of this study was to characterize the clinical, radiologic, and technical variables associated with a false negative result., Methods: We performed a consecutive series review of patients who had an initial benign result from an FNA between January 2002 and December 2004. Medical charts were reviewed to identify patients with false negative and true negative results and determine which variables were associated with a missed diagnosis., Results: One hundred and seventy patients underwent an FNA biopsy yielding an initial benign result and had adequate clinical follow-up. Eighteen of these proved to be false negatives and 152 were true negative. Compared with the patients with true negatives, those with false negative results had significantly larger nodules (mean, 27 mm versus 17 mm, p = 0.04), fewer imaging adjustments per needle pass (4.5 versus 6.4, p = 0.01), a higher proportion in whom the needle tip was not documented within the lesion (24% versus 5%, p =0.04), and a higher pneumothorax rate at any point during the procedure (50% versus 22%, p =0.04). When these variables were considered jointly, pneumothorax (p = 0.006), solitary nodule (p = 0.04), and the radiologist who performed the procedure (p = 0.04) were significant predictors of false negative results., Conclusions: Factors that were associated with false negative results include increased size of lesion, fewer adjustments of the needle, lack of positive cultures, and the occurrence of a pneumothorax. A benign FNA biopsy result should have the procedure reviewed to ensure the results are reliable.

Objective: Our objective was to assess the usefulness of emphysema scores in predicting death from COPD and lung cancer., Methods: Emphysema was assessed with low-dose CT scans performed on 9,047 men and women for whom age and smoking history were documented. Each scan was scored according to the presence of emphysema as follows: none, mild, moderate, or marked. Follow-up time was calculated from time of CT scan to time of death or December 31, 2007, whichever came first. Cox regression analysis was used to calculate the hazard ratio (HR) of emphysema as a predictor of death., Results: Median age was 65 years, 4,433 (49%) were men, and 4,133 (46%) were currently smoking or had quit within 5 years. Emphysema was identified in 2,637 (29%) and was a significant predictor of death from COPD (HR, 9.3; 95% CI, 4.3-20.2; P < .0001) and from lung cancer (HR, 1.7; 95% CI, 1.1-2.5; P = .013), even when adjusted for age and smoking history., Conclusions: Visual assessment of emphysema on CT scan is a significant predictor of death from COPD and lung cancer.

Purpose: To determine whether computed tomographic (CT) attenuation values correlate with the histologic measurements of a lung cancer manifesting as a nonsolid nodule and to quantify the extent to which the tumor replaces the airspace within the nodule., Materials and Methods: Informed consent was obtained to analyze images from CT and pathologic examination under an institutional review board-approved protocol. Fifteen patients who had undergone resection of nonsolid lung cancer were evaluated. On the basis of the CT attenuation values of nonsolid nodules, nonneoplastic lung, soft tissue, and air, the overall proportion of soft tissue in the nodule and nonneoplastic lung and the difference between these two measures were calculated. The analogous measures were obtained from a representative digitized histologic slide. The area of each nodule and the proportion of air within it were measured, and the proportion of soft tissue in the nodule and nonneoplastic lung and the difference between the two were calculated. The difference between the two proportions at CT and histologic examination are the proportions attributable to the cancer on the basis of CT and histologic examinations, respectively. Linear regression was performed to assess the relationship between these measures., Results: The average proportions of soft tissue in the nodule at CT and histologic examination were 48% and 69%, respectively, and they showed significant correlation with each other (P = .02); in addition, each showed significant correlation with the attenuation of the nodule (P < .0001 and P = .02, respectively). The difference between the proportions of soft tissue in nodule and nonneoplastic lung at CT and histologic examination were 37% and 30%, respectively, and both were independent of the tumor diameter (P = .26 and P = .41)., Conclusion: The proportion of soft tissue within a nonsolid nodule is correlated with attenuation at CT. This allows for measurement of change within the nodule. An increase of 100 HU in nodule attenuation represents an approximately 10% increase in tumor volume., (© RSNA, 2012.)

Background: Radiation dose from diagnostic imaging procedures is not monitored in patients undergoing surgery for lung cancer. Evidence suggests an increased lifetime risk of malignancy of 1.0% per 100 millisieverts (mSv). As such, recommendations are to restrict healthcare and radiation workers to a maximum dose of 50 mSv per year or to 100 mSv over a three-year period. The purpose of this study was to estimate cumulative effective doses of radiation in patients undergoing lung cancer resection and to determine predictors of increased exposure., Methods: We identified 94 consecutive patients undergoing resection for non-small cell lung cancer. Radiologic procedures performed from one year prior to resection until two years postresection were recorded. Estimates of effective doses (mSv) were obtained from published literature and institutional records. Predictors of dose greater than 50 mSv per year and greater than 100 mSv per three years were examined statistically., Results: The majority of patients (median age = 67 years) had stage IA cancer (52%). In the three-year period, patients had 1,958 radiologic studies (20.8/patient) including 398 computed tomographic (CT) scans (4.23/patient) and 211 positron emission tomography (PET) scans (2.24 per patient). The three-year median estimated radiation dose was 84.0 mSv (interquartile range, 44.1 to 123.2 mSv). The highest dose was in the preoperative year. In any one year, 66% of patients received more than 50 mSv, while 19% received over 100 mSv. Over the three-year period, 43.6% of patients exceeded 100 mSv. The majority of the radiation (89.8%) was from CT or PET scans. On multivariate analysis, a history of previous malignancy (odds ratio [OR] 3.8; confidence interval [CI] 1.14 to 12.7), postoperative complications (OR 6.16; CI 1.42 to 26.6), and postoperative surveillance with PET-CT (OR 13.2; CI 4.34 to 40.3) predicted exposure greater than 100 mSv over the three-year period., Conclusions: This study demonstrates that lung cancer patients often receive a higher dose of radiation than that considered safe for healthcare and radiation workers. The median cumulative dose reported in this study could potentially increase the individual estimated lifetime cancer risk by as much as 0.8%. Although risk-benefit considerations are clearly different between these groups, strategies should be in place to decrease radiation doses during the preoperative workup and postoperative period., (Copyright © 2011 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.)

Objective: Emphysema is a disease of the lung characterized by the destruction of the alveolar sac walls. Several quantitative densitometric measures of emphysema from wholelung CT have been proposed for evaluating disease severity and progression. However, a concern with these quantitative measures has been the large interscan variability observed during longitudinal studies of emphysema. To account for and reduce inherent measure variability, this work implements and evaluates the use of a multivariate random-effects model for correcting longitudinal variation in densitometric scores of emphysema due to inspiration., Materials and Methods: The method of multivariate compensation was validated on three of the most commonly reported densitometric measures of emphysema: the emphysema index, histogram percentile, and fractal dimension. Two short-interval, zero-change datasets, one for model development (n = 105) and one for validation (n = 106), were retrospectively identified and used to ensure that all variation was caused by inherent measure variability., Results: A statistically significant (F test, p < 0.001) reduction of 42.40% in measurement limits of agreement could be obtained after model application, with compensated emphysema metric differences showing 31-33% of the variance compared with uncompensated metric variance., Conclusion: Compensation was still effective when the trained model was applied to the second validation dataset. Multivariate compensation was found to be useful in reducing interscan measurement variability and should be applied to future longitudinal studies of emphysema.

Purpose: To identify characteristic computed tomographic (CT) and computer-derived features of hamartomas manifesting as small pulmonary nodules., Methods: Individuals with a diagnosis of hamartoma were identified among participants in the International Early Lung Cancer Action Program and were included if there thin section CT images that included the entire nodule. The CT findings were reviewed to determine the nodule consistency (solid, part-solid, nonsolid), nodule diameter (average of length and width), shape (round, lobulated, neither) and edge (smooth, not smooth). Computer measures of nodule compactness, sphericity, surface regularity and gradient (change in gray-scale between the nodule and the surrounding parenchyma) were determined. Volume doubling time (VDT) was also determined for those with at least two scans with similar imaging acquisitions., Results: A total of 21 cases of hamartomas that had histologic or cytologic confirmation were identified. The median age was 60 and 12 (57%) were men. Average diameter was 10.7 mm (5-20.7 mm). All were solid in consistency and were described by the radiologist as having either round or lobulated shape with a smooth edge. None had pathognomonic radiologic findings for hamartoma. Computer measures demonstrated that all were compact and spherical, with a regular surface and a sharp margin between the nodule and surrounding parenchyma. Of nine on whom the VDT could be calculated, eight had VDTs longer than 450 days., Conclusion: Both radiologist and computer derived features of small hamartomas suggest a consistent presentation for these lesions which may be helpful in distinguishing them from other types of nodules., (Copyright © 2011. Published by Elsevier Inc.)

Purpose: To assess the usefulness of ordinal scoring of the visual assessment of coronary artery calcification (CAC) on low-dose computed tomographic (CT) scans of the chest in the prediction of cardiovascular death., Materials and Methods: All participants consented to low-dose CT screening according to an institutional review board-approved protocol. The amount of CAC was assessed on ungated low-dose CT scans of the chest obtained between June 2000 and December 2005 in a cohort of 8782 smokers aged 40-85 years. The four main coronary arteries were visually scored, and each participant received a CAC score of 0-12. The date and cause of death was obtained by using the National Death Index. Follow-up time (median, 72.3 months; range, 0.3-91.9 months) was calculated as the time between CT and death, loss to follow-up, or December 31, 2007, whichever came first. Logistic regression analysis was used to determine the risk of mortality according to CAC category adjusted for age, pack-years of cigarette smoking, and sex. The same analysis to determine the hazard ratio for survival from cardiac death was performed by using Cox regression analysis., Results: The rate of cardiovascular deaths increased with an increasing CAC score and was 1.2% (43 of 3573 subjects) for a score of 0, 1.8% (66 of 3569 subjects) for a score of 1-3, 5.0% (51 of 1015 subjects) for a score of 4-6, and 5.3% (33 of 625 subjects) for a score of 7-12. With use of subjects with a CAC score of 0 as the reference group, a CAC score of at least 4 was a significant predictor of cardiovascular death (odds ratio [OR], 4.7; 95% confidence interval: 3.3, 6.8; P < .0001); when adjusted for sex, age, and pack-years of smoking, the CAC score remained significant (OR, 2.1; 95% confidence interval: 1.4, 3.1; P = .0002)., Conclusion: Visual assessment of CAC on low-dose CT scans provides clinically relevant quantitative information as to cardiovascular death., (© RSNA, 2010.)

Purpose: To measure the width of the zone of transition (ZOT) between nonaerated solid tumor and surrounding nonneoplastic lung parenchyma and determine the extent to which ZOT influences computer-derived estimates of tumor volume based on computed tomographic (CT) images., Materials and Methods: This HIPAA-compliant study was approved by the institutional research board. The histologic slide containing the maximum tumor area was digitized for 20 consecutive patients with solid adenocarcinoma. The outer border of the tumor (A2) was marked; it included all lung parenchyma having any tumor cells. The inner border of the tumor (A1) was marked; it included only solid tumor where lung parenchyma was no longer preserved. Assuming two circles with areas of A2 and A1, the corresponding two radii, R2 and R1, were calculated. The average width of the ZOT was defined as R2 minus R1. The relationship between ZOT and tumor diameter on the CT images prior to surgery was assessed by using regression analysis. The relationship between ZOT and tumor volume was assessed by using a theoretical model of idealized spheres with varying diameters., Results: The mean width of the ZOT was 0.78 mm (median, 0.48 mm). The proportional effect of ZOT on tumor volume estimates decreased with increasing tumor diameter and increased with increasing width of ZOT. Correlation between ZOT and tumor diameter was not significant (P = .87)., Conclusion: The average width of ZOT is about a single pixel width on a full field of view CT scan; thus, the ZOT can have a large effect on volume estimates, particularly for small tumors.

We retrospectively assessed the computed tomography features of intrapulmonary lymph nodes confirmed by cytology in 18 patients. The median size of the lymph nodes was 5.8 mm (range=3.3-8.5 mm). All were below the carina, and only one nodule, which was associated with an interlobar fissure, was over 20 mm from the chest wall. The nodules were oval, round, triangular, or trapezoidal; had sharply defined borders; were solid and homogenous; and were without calcification. Six nodules (33.3%) had a discrete thin tag extending to the pleura. Intrapulmonary lymph nodes can reliably be confirmed by fine needle aspiration with cytological diagnosis.

The authors characterized a commercially available foam composed of polyurethane and polyisocyanurate which is marketed for modeling parts in the aircraft, automotive, and related industries. The authors found that the foam may be suitable for use as a density reference standard in the range below -400 Hounsfield units. This range is coincident with the density of lung tissue. The foam may be helpful in making the diagnosis of lung disease more systematic.

Estimation of nodule location and size is an important pre-processing step in some nodule segmentation algorithms to determine the size and location of the region of interest. Ideally, such estimation methods will consistently find the same nodule location regardless of where the the seed point (provided either manually or by a nodule detection algorithm) is placed relative to the "true" center of the nodule, and the size should be a reasonable estimate of the true nodule size. We developed a method that estimates nodule location and size using multi-scale Laplacian of Gaussian (LoG) filtering. Nodule candidates near a given seed point are found by searching for blob-like regions with high filter response. The candidates are then pruned according to filter response and location, and the remaining candidates are sorted by size and the largest candidate selected. This method was compared to a previously published template-based method. The methods were evaluated on the basis of stability of the estimated nodule location to changes in the initial seed point and how well the size estimates agreed with volumes determined by a semi-automated nodule segmentation method. The LoG method exhibited better stability to changes in the seed point, with 93% of nodules having the same estimated location even when the seed point was altered, compared to only 52% of nodules for the template-based method. Both methods also showed good agreement with sizes determined by a nodule segmentation method, with an average relative size difference of 5% and -5% for the LoG and template-based methods respectively.

We propose a method to establish the standard chest frame of reference (CFOR) using the rib cage in a lung CT scan. Such a reference frame is essential for referring to a certain location within a chest region and may facilitate the registration across multiple scans of a given subject as well as the comparative studies within a cohort of subjects. The robustness of the established CFOR was evaluated by estimating the anatomical locations within chest in the follow-up scan given the location in the first scan. Specifically, tracheal bifurcation point of airway tree and the center of pulmonary nodule were used as the anatomical points of interest. The CFOR was also used for exploring the spatial distribution of the anatomical location for a large number of individuals. The results show that on average the point of interest can be estimated accurately within 10.3 mm for the bifurcation point and within 12.5 mm for the pulmonary nodule's center point. Further analyzing the spatial distribution of the CFOR coordinates across 86 subjects shows that we can localize the bifurcation point to the small subregion within the CFOR.

Purpose: To describe the frequency and findings of pulmonary lymphoma in asymptomatic people undergoing computed tomographic (CT) screening for lung cancer., Methods: All lymphoma diagnoses resulting from CT screening of 31 567 at-risk subjects (median age, 61 years) were identified, and the CT images were reviewed to document the lesions as to number, location, density, shape, and margin. The presence of lymphadenopathy and pleural effusion was also documented., Results: Five patients with pulmonary lymphoma were identified. The lymphoma was a B-cell lymphoma in three, Hodgkin's lymphoma in one, and malignant lymphoma in one; it was primary in four and secondary in one. One patient had two lesions; the other four patients each had one lesion. Four of the six lesions were a mass, and two were a nodule. Four of the lesions had irregular margins. Air bronchograms were seen in three. Growth assessment was useful in leading to decisions for biopsy., Conclusion: In a context of CT screening to detect lung cancer in asymptomatic volunteers, the diagnosis of pulmonary lymphoma was rare but, nevertheless, occurred in five (.016%) of 31 567 volunteers.