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Background Confirming that subsolid adenocarcinomas show exponential growth is important because it would justify using volume doubling time to assess their growth. Purpose To test whether the growth of lung adenocarcinomas manifesting as subsolid nodules at chest CT is accurately represented by an exponential model. Materials and Methods Patients with lung adenocarcinomas manifesting as subsolid nodules surgically resected between January 2005 and May 2018, with three or more longitudinal CT examinations before resection, were retrospectively included. Overall volume (for all nodules) and solid component volume (for part-solid nodules) were measured over time. A linear mixed-effects model was used to identify the growth pattern (linear, exponential, quadratic, or power law) that best represented growth. The interactions between nodule growth and clinical, CT morphologic, and pathologic parameters were studied. Results Sixty-nine patients (mean age, 70 years ± 9 [standard deviation]; 48 women) with 74 lung adenocarcinomas were evaluated. Overall growth and solid component growth were better represented by an exponential model (adjusted

These recommendations for measuring pulmonary nodules at computed tomography (CT) are a statement from the Fleischner Society and, as such, incorporate the opinions of a multidisciplinary international group of thoracic radiologists, pulmonologists, surgeons, pathologists, and other specialists. The recommendations address nodule size measurements at CT, which is a topic of importance, given that all available guidelines for nodule management are essentially based on nodule size or changes thereof. The recommendations are organized according to practical questions that commonly arise when nodules are measured in routine clinical practice and are, together with their answers, summarized in a table. The recommendations include technical requirements for accurate nodule measurement, directions on how to accurately measure the size of nodules at the workstation, and directions on how to report nodule size and changes in size. The recommendations are designed to provide practical advice based on the available evidence from the literature; however, areas of uncertainty are also discussed, and topics needing future research are highlighted. © RSNA, 2017 Online supplemental material is available for this article.

Item does not contain fulltext Purpose To quantify the reproducibility and accuracy of experienced thoracic radiologists in differentiating between subsolid and solid pulmonary nodules at CT. Materials and Methods The institutional review board of Beth Israel Deaconess Medical Center approved this multicenter study. Six thoracic radiologists, with a mean of 21 years of experience in thoracic radiology (range, 17-22 years), selected images of 10 solid and 10 subsolid nodules to create a database of 120 nodules; this selection served as the reference standard. Each radiologist then interpreted 120 randomly ordered nodules in two different sessions that were separated by a minimum of 3 weeks. The radiologists classified whether or not each nodule was subsolid. Inter- and intraobserver agreement was assessed with a κ statistic. The number of correct classifications was calculated and correlated with nodule size by using Bland-Altman plots. The relationship between disagreement and nodule morphologic characteristics was analyzed by calculating the intraclass correlation coefficient. Results Interobserver agreement (κ) was 0.619 (range, 0.469-0.745; 95\% confidence interval (CI): 0.576, 0.663) and 0.670 (range, 0.440-0.839; 95\% CI: 0.608, 0.733) for interpretation sessions 1 and 2, respectively. Intraobserver agreement (κ) was 0.792 (95\% CI: 0.750, 0.833). Averaged for interpretation sessions, correct classification was achieved by all radiologists for 58\% (70 of 120) of nodules. Radiologists agreed with their initial determination (the reference standard) in 77\% of cases (range, 45\%-100\%). Nodule size weakly correlated with correct classification (long axis: Spearman rank correlation coefficient, rs = 0.161 and P = .049; short axis: rs = 0.128 and P = .163). Conclusion The reproducibility and accuracy of thoracic radiologists in classifying whether or not a nodule is subsolid varied in the retrospective study. This inconsistency may affect surveillance recommendations and prognostic determinations. (©) RSNA, 2015 Online supplemental material is available for this article.

To quantify the potential effect of geographic factors on the frequency of honorary authorship in four major radiology journals.In this institutional review board-approved study, an electronic survey was sent to first authors of all original research articles published in American Journal of Roentgenology, European Radiology, Journal of Magnetic Resonance Imaging, and Radiology during 2 years (July 2009 through June 2011). Questions addressed guidelines used for determining authorship, perception of honorary authorship, and demographic information. Univariate analysis was performed by using χ(2) tests. Multiple-variable logistic regression models were used to assess independent factors associated with the perception of honorary authorship.Of 1398 first authors, 328 (23.5%) responded. Of these, 91 (27.7%) perceived that at least one coauthor did not make sufficient contributions to merit authorship, and 165 (50.3%) stated that one or more coauthors performed only "nonauthor" tasks according to International Committee of Medical Journal Editors (ICMJE) criteria. The perception of honorary authorship was significantly higher (P ≤ .0001) among respondents from Asia and Europe than from North America and in institutions where a section or department head was automatically listed as coauthor. A significantly lower (P ≤ .0001) perception of honorary authorship was associated with adherence to ICMJE criteria and with policies providing lectures or courses on publication ethics.Perceived honorary authorship was substantially higher among respondents from Asia and Europe than from North America. Perceived honorary authorship was lower with adherence to the ICMJE guidelines and policies providing lectures or courses on publication ethics.

Immunoglobulin G4–related disease is an uncommon immune-mediated systemic fibroinflammatory condition that can affect any organ system.

Item does not contain fulltext The Fleischner Society Guidelines for management of solid nodules were published in 2005, and separate guidelines for subsolid nodules were issued in 2013. Since then, new information has become available; therefore, the guidelines have been revised to reflect current thinking on nodule management. The revised guidelines incorporate several substantive changes that reflect current thinking on the management of small nodules. The minimum threshold size for routine follow-up has been increased, and recommended follow-up intervals are now given as a range rather than as a precise time period to give radiologists, clinicians, and patients greater discretion to accommodate individual risk factors and preferences. The guidelines for solid and subsolid nodules have been combined in one simplified table, and specific recommendations have been included for multiple nodules. These guidelines represent the consensus of the Fleischner Society, and as such, they incorporate the opinions of a multidisciplinary international group of thoracic radiologists, pulmonologists, surgeons, pathologists, and other specialists. Changes from the previous guidelines issued by the Fleischner Society are based on new data and accumulated experience. (c) RSNA, 2017 Online supplemental material is available for this article. An earlier incorrect version of this article appeared online. This article was corrected on March 13, 2017.

Item does not contain fulltext This report is to complement the original Fleischner Society recommendations for incidentally detected solid nodules by proposing a set of recommendations specifically aimed at subsolid nodules. The development of a standardized approach to the interpretation and management of subsolid nodules remains critically important given that peripheral adenocarcinomas represent the most common type of lung cancer, with evidence of increasing frequency. Following an initial consideration of appropriate terminology to describe subsolid nodules and a brief review of the new classification system for peripheral lung adenocarcinomas sponsored by the International Association for the Study of Lung Cancer (IASLC), American Thoracic Society (ATS), and European Respiratory Society (ERS), six specific recommendations were made, three with regard to solitary subsolid nodules and three with regard to multiple subsolid nodules. Each recommendation is followed first by the rationales underlying the recommendation and then by specific pertinent remarks. Finally, issues for which future research is needed are discussed. The recommendations are the result of careful review of the literature now available regarding subsolid nodules. Given the complexity of these lesions, the current recommendations are more varied than the original Fleischner Society guidelines for solid nodules. It cannot be overemphasized that these guidelines must be interpreted in light of an individual's clinical history. Given the frequency with which subsolid nodules are encountered in daily clinical practice, and notwithstanding continuing controversy on many of these issues, it is anticipated that further refinements and modifications to these recommendations will be forthcoming as information continues to emerge from ongoing research.

To quantify the frequency of perceived honorary authorship in radiologic journals and to identify specific factors that increase its prevalence.This study qualified for exempt status by the institutional review board. An electronic survey was sent to first authors of all original research articles published in Radiology and European Radiology over 3 years. Questions included guidelines used for determining authorship, contributions of coauthors, the perception of honorary authorship, and demographic information. Univariable analysis of sample proportions was performed by using χ(2) tests. Multivariable logistic regression models were used to assess the independent factors that were associated with the probability of perceiving honorary authorship.Of the 392 (29.3%) of 1338 first authors who responded to the survey, 102 (26.0%) perceived that one or more coauthors did not make sufficient contributions to merit being included as an author. Of the 392 respondents, 231 (58.9%) stated that one or more coauthors performed only "nonauthor" tasks according to International Committee of Medical Journal Editors criteria. Factors associated with an increased first-author perception of honorary authorship included lower academic rank (adjusted odds ratio [OR]: 2.89; 95% confidence interval [CI]: 1.66, 5.06), as well as working in an environment in which the section or department head was automatically listed as an author (adjusted OR: 3.80; 95% CI: 2.13, 6.79). The percentage of honorary authorship was significantly higher (P = .019) among respondents who did not follow journal requirements for authorship.The rate of perceived honorary authorship (overall, 26.0%) was substantially more frequent among respondents of lower academic rank and in those working in an environment in which their section or department head was automatically listed as an author.http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.11101500/-/DC1.

To determine the familiarity of radiologists with the Fleischner Society guidelines for management of small lung nodules and to assess whether their decisions for nodule management are consistent with these recommendations.Institutional review board exemption was granted for this electronic survey, which was sent to a sample of 7000 radiologists randomly selected from the Radiological Society of North America (RSNA) directory. Three clinical scenarios for nodule management were presented. Information about policies and guidelines for nodule management, awareness of published guidelines, and respondent demographics was obtained. Associations between these parameters and management recommendations were assessed by using a chi(2) test. Respondents were also asked about tube current settings for routine chest computed tomographic examinations and those performed solely for nodule follow-up.Of 834 respondents (response rate, 11.9%), 649 (77.8%) were aware of the Fleischner Society guidelines and 490 (58.8%) worked in practices that employed them or similar guidelines. Management selections were consistent with the Fleischner guidelines in 34.7%-60.8% of responses for the three scenarios. A significantly higher rate of concordance was associated with awareness of the Fleischner guidelines, presence of written policies based on them, a teaching practice setting, practice in a group with at least one member having chest radiology fellowship training, and fewer than 5 years of experience practicing radiology (P.05 for all associations). The spectrum of tube current settings used was similar between the subgroups of respondents who were aware and those who were unaware of the Fleischner guidelines.Among survey respondents, there was high awareness and adoption of the Fleischner guidelines, but radiologists showed varying degrees of conformance with these recommendations. Future efforts are necessary to bridge the gap between awareness and implementation of these evidence-based guidelines.

To assess forced expiratory tracheal collapsibility in healthy volunteers by using multidetector computed tomography and to compare the results with the current diagnostic criterion for tracheomalacia.An institutional review board approved this HIPAA-compliant study. After informed consent was obtained, 51 healthy volunteers (age range, 25-75 years) with normal spirometry results and no history of smoking or risk factors for tracheomalacia were prospectively studied. Volunteers were imaged with a 64-detector row scanner, with spirometric monitoring at total lung capacity and during forced exhalation, with 40 mAs, 120 kVp, and 0.625-mm detector collimation. Cross-sectional area and sagittal and coronal diameters of the trachea were measured 1 cm above the aortic arch and 1 cm above the carina. The percentage of expiratory collapse, the reduction in sagittal and coronal diameters, and the number of participants exceeding the current diagnostic criterion (50% expiratory reduction in cross-sectional area) for tracheomalacia were calculated.The final study population included 25 men and 26 women (mean age, 50 years). The mean percentage of expiratory reduction in tracheal lumen cross-sectional area was 54.34% +/- 18.6 (standard deviation) in the upper trachea and 56.14% +/- 19.3 in the lower trachea. Forty (78%) participants exceeded the current diagnostic criterion for tracheomalacia in the upper and/or lower trachea. Decreases in cross-sectional area of the upper and lower trachea correlated well with decreases in sagittal (r = 0.807 and 0.688, respectively) and coronal (r = 0.779 and 0.751, respectively) diameters (P.001 for each correlation).Healthy volunteers demonstrate a wide range of forced expiratory tracheal collapse, frequently exceeding the current diagnostic criterion for tracheomalacia.

Members of the Fleischner Society compiled a glossary of terms for thoracic imaging that replaces previous glossaries published in 1984 and 1996 for thoracic radiography and computed tomography (CT), respectively. The need to update the previous versions came from the recognition that new words have emerged, others have become obsolete, and the meaning of some terms has changed. Brief descriptions of some diseases are included, and pictorial examples (chest radiographs and CT scans) are provided for the majority of terms.

The purpose of this statement is to describe and define the phenotypic abnormalities that can be identified on visual and quantitative evaluation of computed tomographic (CT) images in subjects with chronic obstructive pulmonary disease (COPD), with the goal of contributing to a personalized approach to the treatment of patients with COPD. Quantitative CT is useful for identifying and sequentially evaluating the extent of emphysematous lung destruction, changes in airway walls, and expiratory air trapping. However, visual assessment of CT scans remains important to describe patterns of altered lung structure in COPD. The classification system proposed and illustrated in this article provides a structured approach to visual and quantitative assessment of COPD. Emphysema is classified as centrilobular (subclassified as trace, mild, moderate, confluent, and advanced destructive emphysema), panlobular, and paraseptal (subclassified as mild or substantial). Additional important visual features include airway wall thickening, inflammatory small airways disease, tracheal abnormalities, interstitial lung abnormalities, pulmonary arterial enlargement, and bronchiectasis.

To assess retrospectively the effect of the Joint Photographic Experts Group 2000 (JPEG2000) compression ratio on the quality of thin-section computed tomographic (CT) images.In this institutional review board-approved investigation (protocol 238/2004), thin-section CT images were subjected to irreversible JPEG2000 compression by using five compression ratios (3:1, 5:1, 7:1, 9:1, and 11:1). Three radiologists independently evaluated 60 thin-section CT images, of various diseases, that were obtained with single-detector (weighted dose index, 14.4 mGy) and multidetector (weighted dose index, 9.8 mGy) CT. Toggling between the original and compressed images, readers had to identify the original image by using a forced-choice two-alternative model and to subjectively rank the quality of what they believed to be the compressed image. To assess the reader's ability to distinguish the compressed from the original image, a binomial test was used. Bonferroni correction was applied for all multiple tests.Images compressed with a ratio of 3:1 were not distinguishable from original images (P.2 for all readers). With use of the 5:1 ratio, minor differences in appearance between the compressed and original images were seen by one of the three readers. With use of higher compression ratios (/=7:1), all readers (P.001) recognized the original image. The quality of more than 90% of the images compressed with a 7:1 or higher ratio was substantially degraded. Single-detector and multidetector CT results were not significantly different.The highest ratio that yielded visually lossless compression of thin-section CT images was 3:1. With the 5:1 ratio, there was minor image quality loss, while use of higher compression ratios (/=7:1) caused substantial degradation of image quality and potential loss of diagnostic information.

The results of the analysis by Yip et al support consideration of somewhat larger nodule-size thresholds than those previously recommended for screening-encountered nodules and are consistent with our evolving understanding of this subject.

To retrospectively determine the potential of organ-based tube current modulation ( OBTCM organ-based tube current modulation ) to reduce the radiation dose delivered to breast tissue by computed tomography (CT) by determining breast angular position in relation to the zones of decreased versus increased radiation.The authors obtained institutional review board approval for this study and patients' written informed consent. In two academic centers (center A: Beth Israel Deaconess Medical Center, Boston, Mass; and center B: Hôpital André Vésale, Montignies-le-Tilleul, Belgium), data were collected from clinical thoracic CT examinations performed in 498 women (mean age, 60 years; age range, 18-95 years) in the supine position and 34 women (mean age, 53 years; age range, 18-84 years) in the prone position. One radiologist in each center determined breast tissue location and measured its inner and outer boundaries with respect to the isocenter of the CT examination. The percentages of women with breast tissue within and those with breast tissue outside the zone of decreased radiation delivered by OBTCM organ-based tube current modulation were determined. The location of breast tissue was correlated with patient age and with sagittal and coronal diameters of the thorax by using the Student t test, Fisher exact test, and Pearson correlation.None of the women lying in the supine position had the entirety of the breast tissue located within the reduced-dose zone. Breast tissue was located in the increased-dose zone in 99% of women lying supine and in 82% of women lying prone.The breast angular position of almost all women was higher than the angular limit of the reduced versus the increased dose in OBTCM organ-based tube current modulation . No woman, regardless of supine or prone position, had all breast tissue within the reduced-dose zone.

We thought it would be helpful to our authors to summarize our suggestions for avoiding a number of the most common errors and problem issues in statistical analysis that we encounter in submissions to Radiology. © RSNA, 2009

To compare subjective visual grading of pulmonary emphysema with macroscopic morphometry and computed tomographic (CT) densitometry.In 62 consecutive patients who underwent thinsection CT before surgical lung resection, emphysema was objectively quantified with computer-assisted macroscopic morphometry and CT densitometry. The percentage of lung macroscopically occupied by emphysema was compared with the percentage occupied on CT scans by pixels with attenuation values lower than a predefined threshold (CT densitometry). Three readers with varying degrees of expertise subjectively graded emphysema with visual assessment at two reading sessions. Data from objective quantification and subjective grading were analyzed with correlation coefficients, and interobserver and intraobserver agreement were calculated.Subjective grading of emphysema showed less agreement with the macroscopic reference standard results (r = 0.439-0.505; P.05) than with objective CT densitometric results (r = 0.555-0.623; P.001). The 95% CIs for the intercepts of the linear regression lines were suggestive of systematic subjective overestimation of emphysema by all three readers. Interobserver agreement was moderate (kappa = 0.431-0.589). Intraobserver agreement was good to excellent (kappa = 0.738-0.936). The expertise of individual readers did not substantially influence results.Systematic overestimation and moderate interobserver agreement may compromise subjective visual grading of emphysema, which suggests that subjective visual grading should be supplemented with objective methods to achieve precise, reader-independent quantification of emphysema.

To analyze the influence of computed tomographic (CT) window settings on bronchial wall thickness and to define appropriate window settings for its evaluation.Three inflation-fixed lungs were scanned with a section thickness of 1.5 mm by using a high-spatial-frequency algorithm. Wall thickness in 10 bronchial specimens was measured with planimetry. Window centers were altered in a range of -200 to -900 HU and window widths in a range of 400-1,500 HU. Relative and absolute differences between CT and planimetric values were calculated. CT and planimetric measures were correlated. Inter- and intraobserver variabilities were determined.Window widths less than 1,000 HU resulted in a substantial overestimation of bronchial wall thickness, whereas widths greater than 1,400 HU resulted in an underestimation of bronchial wall thickness. There was no interaction between "width" and "center" regarding their influence on bronchial walls (F = 0.23; P = .99). Correlation between CT and planimetry was statistically significant (r = .85; P = .0001). Differences between the two observers were not statistically significant; results of the measurements of the two observers correlated well (r = .97; P = .001).Bronchial wall thickness on thin-section CT scans should be evaluated with window centers between -250 and -700 HU and with window widths greater than 1,000 HU. Other than window settings, notably window widths less than 1,000 HU, can lead to substantial artificial thickening of bronchial walls.

To evaluate the diagnostic potential of spiral computed tomography (CT) performed after the administration of cholangiographic contrast material (spiral CT cholangiography) in patients with suspected obstructive biliary disease.After infusion of meglumine iodoxamate, 29 patients underwent upper abdominal spiral CT with subsequent three-dimensional rendering of the biliary tract. In 27 patients, the presence, site, and extent of biliary obstruction were compared with that at endoscopic retrograde cholangiography (ERC).Spiral CT cholangiography correctly depicted biliary obstruction in 14 of 27 patients, with no false-positive or false-negative cases. In one patient, the precise length of a common bile duct stenosis could not be assessed with spiral CT cholangiography. ERC demonstrated intrahepatic ductal stenoses more clearly in two patients. In two patients with hilar cholangiocarcinomas, spiral CT cholangiography depicted undrained areas not seen with ERC.Spiral CT cholangiography allows accurate assessment of the biliary system in patients with suspected obstructive biliary disease.

We discuss the drawbacks of the term low dose and explain why we believe that this term should no longer be used, and we summarize preferable approaches used to quantify CTrelated radiation dose.

Chronic obstructive pulmonary disease (COPD) is an increasing cause of morbidity and mortality worldwide and results in substantial social and economic burdens. COPD is a heterogeneous disease with both extrapulmonary and pulmonary components. The pulmonary component is characterized by an airflow limitation that is not fully reversible. In the authors' opinion, none of the currently available classifications combining airflow limitation measurements with clinical parameters is sufficient to determine the prognosis and treatment of a particular patient with COPD. With regard to the causes of airflow limitation, CT can be used to quantify the two main contributions to COPD: emphysema, and small airways disease (a narrowing of the airways). CT quantification--with subsequent COPD phenotyping--can contribute to improved patient care, assessment of COPD progression, and identification of severe COPD with increasing risk of mortality. Small airways disease can be quantified through measurements reflecting morphology, quantification of obstruction, and changes in airways walls. This article details these three approaches and concludes with perspectives and directions for further research.

We believe that our readers are interested in investigations describing physicians’ performance of specific techniques under reasonably realistic conditions. The simulation of such realistic conditions, however, does not only require thorough reporting of variability between observers and techniques; it also requires a sufficiently high number of observers.

To test the hypothesis that lateral radiography adds no clinically relevant information to that acquired with posteroanterior (PA) radiography in individuals with positive purified protein derivative (PPD) skin test results.As part of routine practice, all 875 adults with positive PPD skin test results at pre-employment examinations performed at a medical center during 2007 underwent PA and lateral chest radiography. In this institutional review board-approved HIPAA-compliant study, the patient informed consent requirement was waived. Two radiologists retrospectively and independently interpreted each radiograph for evidence of abnormalities that were indicative of acute or chronic tuberculosis (TB) infection. First, only the PA radiograph was analyzed. Thereafter, both the PA radiograph and the lateral radiograph were analyzed together to determine if any observed finding was identified on only the lateral radiograph. If a finding was seen on both images, a determination was made as to whether the finding on the lateral radiograph changed the radiologist's decision based on the PA radiograph alone.The PA radiograph revealed abnormalities in all 91 (10.4%) subjects with positive findings at radiography. The lateral radiograph revealed no abnormality in 75 subjects (83.4%). All abnormalities seen on lateral radiographs were also seen on PA radiographs. When abnormalities were seen on both images, the information on the lateral image never caused the radiologist to change the decision he or she made on the basis of the PA image alone.In a pre-employment setting, one PA radiograph is sufficient for TB screening of individuals with positive PPD skin test results. Elimination of the acquisition of lateral radiographs would substantially reduce radiation exposure.

PURPOSE: To prospectively investigate the effect of radiation dose reduction on the visual quantification of air trapping at expiratory thin-section computed tomography (CT). MATERIALS AND METHODS: In this ethical committee-approved study, 27 lung transplant recipients (12 women, 15 men; mean age, 54 years +/- 2 [standard error of the mean]) underwent expiratory thin-section CT at 140 kVp and 80 mAs (effective). All patients gave written informed consent. Dose reduction corresponding to 60, 40, and 20 mAs (effective) was simulated. The extent of air trapping in both original and dose-reduced studies was scored by three independent readers. The effects of tube current-time product, reader, reading session, and body mass index on average air trapping scores were assessed with analysis of variance. Agreements between and within observers were assessed with a weighted kappa statistic. Subjective scores for diagnostic confidence were attributed (3 = high, 2 = medium, 1 = low), and their means were calculated for each tube current-time product value. RESULTS: No significant effect on average air trapping scores as a result of tube current-time product (P = .222), reader (P = .217), reading session (P = .705), or body mass index (P = .505) could be detected. At 80 mAs, agreement between readers was excellent; agreement decreased to good or moderate at lower tube current settings. Agreement within readers decreased with a decrease in dose but remained good even at 20 mAs. Confidence also decreased, with mean scores decreasing from 2.33 +/- 0.73 (standard deviation) to 1.04 +/- 0.19 when dose decreased. CONCLUSION: At 140 kVp, the tube current-time product can be reduced from 80 to 20 mAs without impairing the visual quantification of air trapping at expiratory thin-section CT and with acceptable decreases in agreement between and within readers and in reader confidence

Purpose To examine the factors that affect inter- and intraobserver agreement for pulmonary nodule type classification on low-radiation-dose computed tomographic (CT) images, and their potential effect on patient management. Materials and Methods Nodules (n = 160) were randomly selected from the Dutch-Belgian Lung Cancer Screening Trial cohort, with equal numbers of nodule types and similar sizes. Nodules were scored by eight radiologists by using morphologic categories proposed by the Fleischner Society guidelines for management of pulmonary nodules as solid, part solid with a solid component smaller than 5 mm, part solid with a solid component 5 mm or larger, or pure ground glass. Inter- and intraobserver agreement was analyzed by using Cohen κ statistics. Multivariate analysis of variance was performed to assess the effect of nodule characteristics and image quality on observer disagreement. Effect on nodule management was estimated by differentiating CT follow-up for ground-glass nodules, solid nodules 8 mm or smaller, and part-solid nodules smaller than 5 mm from immediate diagnostic work-up for solid nodules larger than 8 mm and part-solid nodules 5 mm or greater. Results Pair-wise inter- and intraobserver agreement was moderate (mean κ, 0.51 [95% confidence interval, 0.30, 0.68] and 0.57 [95% confidence interval, 0.47, 0.71]). Categorization as part-solid nodules and location in the upper lobe significantly reduced observer agreement (P = .012 and P < .001, respectively). By considering all possible reading pairs (28 possible combinations of observer pairs × 160 nodules = 4480 possible agreements or disagreements), a discordant nodule classification was found in 36.4% (1630 of 4480), related to presence or size of a solid component in 88.7% (1446 of 1630). Two-thirds of these discrepant readings (1061 of 1630) would have potentially resulted in different nodule management. Conclusion There is moderate inter- and intraobserver agreement for nodule classification by using current recommendations for low-radiation-dose CT examinations of the chest. Discrepancies in nodule categorization were mainly caused by disagreement on the size and presence of a solid component, which may lead to different management in the majority of cases with such discrepancies. (©) RSNA, 2015.

PURPOSE: To determine the test performance and longitudinal evolution of air trapping for diagnosing bronchiolitis obliterans syndrome (BOS). MATERIALS AND METHODS: Over 7 years, 111 combined inspiratory and expiratory computed tomographic examinations were performed in eight healthy control subjects and 38 heart-lung transplant recipients. Functional impairment was assessed with the BOS classification. Receiver operating characteristic (ROC) analysis was performed to determine the optimal threshold of air trapping to distinguish between patients with and those without BOS and to compute sensitivity and specificity for diagnosing BOS. RESULTS: The extent of air trapping increased with BOS severity (P =.001). A threshold of 32% of air trapping is optimal for distinguishing between patients with and those without BOS and provides a sensitivity of 83%, a specificity of 89%, and an accuracy of 88%. The prevalence of BOS and positive predictive value of air trapping increased with postoperative time, but the negative predictive value of air trapping remained high throughout the study. Patients without BOS who had air trapping exceeding 32% of the parenchyma were at significantly increased risk of developing BOS (P =.004). CONCLUSION: At the threshold of 32%, air trapping is sensitive, specific, and accurate for diagnosing BOS. Patients with air trapping below 32% are unlikely to have BOS. Air trapping exceeding 32% may be an early indicator of future BOS.

To compare the uniformity of aortoiliac opacification obtained from uniphasic contrast medium injections versus individualized biphasic injections at computed tomographic (CT) angiography.Thirty-two patients with an abdominal aortic aneurysm underwent CT angiography. In 16 patients (group 1), 120 mL of contrast material was administered at a flow rate of 4 mL/sec. In the other 16 patients (group 2), biphasic injection protocols were computed by using mathematic deconvolution of each patient's time-attenuation response to a standardized test injection. Attenuation uniformity was quantified as the "plateau deviation" of enhancement values, which were calculated as the SD of the time-contiguous attenuation values observed during the 30-second scanning period.Group 2 patients received between 77 and 165 mL (mean, 115 mL) of contrast medium. Initial flow rates ranged from 4.1 to 10.0 mL/sec (mean, 6.8 mL/sec) for the first 4-6 seconds; continuing flow rates ranged from 2.0 to 4.8 mL/sec (mean, 3.1 mL/sec) for the remaining 24-26 seconds. The plateau deviation was significantly smaller in group 2 patients (19 HU) versus group 1 patients (38 HU, P.001).At CT angiography, tailored biphasic injections led to more uniform aortoiliac enhancement, compared with standard uniphasic injections of contrast medium.