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Background A categorical CT assessment scheme for suspicion of pulmonary involvement of coronavirus disease 2019 (COVID-19 provides a basis for gathering scientific evidence and improved communication with referring physicians. Purpose To introduce the COVID-19 Reporting and Data System (CO-RADS) for use in the standardized assessment of pulmonary involvement of COVID-19 on unenhanced chest CT images and to report its initial interobserver agreement and performance. Materials and Methods The Dutch Radiological Society developed CO-RADS based on other efforts for standardization, such as the Lung Imaging Reporting and Data System or Breast Imaging Reporting and Data System. CO-RADS assesses the suspicion for pulmonary involvement of COVID-19 on a scale from 1 (very low) to 5 (very high). The system is meant to be used in patients with moderate to severe symptoms of COVID-19. The system was evaluated by using 105 chest CT scans of patients admitted to the hospital with clinical suspicion of COVID-19 and in whom reverse transcription-polymerase chain reaction (RT-PCR) was performed (mean, 62 years ± 16 [standard deviation]; 61 men, 53 with positive RT-PCR results). Eight observers used CO-RADS to assess the scans. Fleiss κ value was calculated, and scores of individual observers were compared with the median of the remaining seven observers. The resulting area under the receiver operating characteristics curve (AUC) was compared with results from RT-PCR and clinical diagnosis of COVID-19. Results There was absolute agreement among observers in 573 (68.2%) of 840 observations. Fleiss κ value was 0.47 (95% confidence interval [CI]: 0.45, 0.47), with the highest κ value for CO-RADS categories 1 (0.58, 95% CI: 0.54, 0.62) and 5 (0.68, 95% CI: 0.65, 0.72). The average AUC was 0.91 (95% CI: 0.85, 0.97) for predicting RT-PCR outcome and 0.95 (95% CI: 0.91, 0.99) for clinical diagnosis. The false-negative rate for CO-RADS 1 was nine of 161 cases (5.6%; 95% CI: 1.0%, 10%), and the false-positive rate for CO-RADS category 5 was one of 286 (0.3%; 95% CI: 0%, 1.0%). Conclusion The coronavirus disease 2019 (COVID-19) Reporting and Data System (CO-RADS) is a categorical assessment scheme for pulmonary involvement of COVID-19 at unenhanced chest CT that performs very well in predicting COVID-19 in patients with moderate to severe symptoms and has substantial interobserver agreement, especially for categories 1 and 5. © RSNA, 2020 Online supplemental material is available for this article.

Purpose: To study interreader variability for classifying pulmonary opacities at CT as perifissural nodules (PFNs) and determine how reliably radiologists differentiate PFNs from malignancies. Materials and Methods: CT studies were obtained retrospectively from the National Lung Screening Trial (2002-2009). Nodules were eligible for the study if they were noncalcified, solid, within the size range of 5 to 10 mm, and scanned with a section thickness of 2 mm or less. Six radiologists classified 359 nodules in a cancer-enriched data set as PFN, non-PFN, or not applicable. Nodules classified as not applicable by at least three radiologists were excluded, leaving 316 nodules for post-hoc statistical analysis. Results: The study group contained 22.2% cancers (70 of 316). The median proportion of nodules classified as PFNs was 45.6% (144 of 316). All six radiologists uniformly classified 17.7% (56 of 316) of the nodules as PFNs. The Fleiss k was 0.50. Compared with non-PFNs, nodules classified as PFNs were smaller and more often located in the lower lobes and attached to a fissure (P , .001). Thirteen (18.6%) of 70 cancers were misclassified 21 times as PFNs. Individual readers' misclassification rates ranged from 0% (0 of 125) to 4.9% (eight of 163). Of 13 misclassified malignancies, 11 were in the upper lobes and two were attached to a fissure. Conclusion: There was moderate interreader agreement when classifying nodules as perifissural nodules. Less than 2.5% of perifissural nodule classifications were misclassified lung cancers (21 of 865) in this cancer-enriched study. Allowing nodules classified as perifissural nodules to be omitted from additional follow-up in a screening setting could substantially reduce the number of unnecessary scans; excluding perifissural nodules in the upper lobes would greatly decrease the misclassification rate.

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.

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.

Item does not contain fulltext PURPOSE: To examine the morphologic characteristics of focal fatty foci in the myocardium of patients with tuberous sclerosis complex (TSC) at computed tomography (CT). MATERIALS AND METHODS: Institutional review board approval was obtained, and patient informed consent was waived. Fifty-five patients with TSC (mean age, 37 years; range, 16-67 years; 22 male patients) who had CT results available that included at least the basal portions of the heart were included. Fifty-five age- and sex-matched control subjects without TSC were selected from a CT database. Images were reviewed for the presence of areas of fat attenuation in the depicted portions of the myocardium. Descriptive statistics and the McNemar test for case-control comparisons were used. RESULTS: CT results demonstrated foci of fat attenuation within the myocardium in 35 (64%) of 55 patients with TSC. Foci were well circumscribed and focal and located in the interventricular septum, left ventricle wall, right ventricle wall, and papillary muscles. Size varied between 3 x 1 mm and 62 x 31 mm. Multiple lesions were seen in 19 patients. In the control group, only one (2%) lesion with fat attenuation was found (P < .001). Its linear shape and subendocardial location in the left ventricular wall differed from the morphology of fatty foci seen in patients with TSC. CONCLUSION: Despite incomplete depiction of the heart with CT, the majority of patients with TSC demonstrated well-circumscribed foci of fat attenuation in the myocardium that were not present in age- and sex-matched control subjects. This suggests that such fatty foci may be another characteristic of TSC.

PURPOSE: To retrospectively determine the maximum compression ratio at which compressed images are indistinguishable from the original by using a three-dimensional (3D) wavelet algorithm. MATERIALS AND METHODS: The protocol of this study was approved by the local Institutional Review Board and informed consent was waived. Sixty emergency abdominal computed tomographic (CT) scans of patients (31 men, 29 women; mean age +/- standard deviation, 50.8 years +/- 20.1; range, 17-80 years) with acute abdominal pain were subjected to lossy irreversible three-dimensional Joint Photographic Experts Group 2000 (3D-JPEG2000) compression by using four compression ratios (4:1, 8:1, 12:1, and 16:1). Groups contained five patients for each of 12 common diagnoses for acute abdominal pain. Images were obtained by using a multidetector CT scanner (Sensation Cardiac 64; Siemens, Forcheim, Germany) with 3- and 6-mm-thick sections. Three radiologists independently compared one case-relevant image per patient with the original image at different compression ratios. They had to determine which image was the original by using a forced-choice, two-alternative model and to subjectively rank image quality. For analysis, a binomial test was used, a Bonferroni correction was applied, and a P value of .01 indicated a significant difference. RESULTS: Images compressed at ratios of 4:1 and 8:1 were visually indistinguishable and essentially indistinguishable, respectively, from the original images (P > .01 for all readers). For the 12:1 and 16:1 ratios, all readers definitively (P < .001) identified the original images. CONCLUSION: The highest 3D-JPEG2000 compression ratio for abdominal CT scans, at which compressed images are essentially indistinguishable from the original, is 8:1

Purpose: To prospectively assess the precision of semiautomated volume measurements of pulmonary nodules at low-dose multi-detector row computed tomography (CT) and to investigate the influence of nodule size, segmentation algorithm, and inspiration level. Materials and Methods: This study had institutional review board approval; written informed consent was obtained from all patients. Between June 2004 and March 2005, 20 patients (15 men, five women; age range, 40-84 years; mean age, 57 years) referred for chest CT for known lung metastases under-went two additional low-dose chest CT examinations without contrast material (collimation, 16 x 0.75 mm). Between these examinations, patients got off and on the table to simulate the conditions for a follow-up examination. Noncalcified solid pulmonary nodules between 15 and 500 mm(3) that did not abut vessel or pleura were measured in both studies by using widely applied commercial semiautomated software. Interscan variability was established with the Bland and Altman approach. The impact of nodule shape (spherical or nonspherical) on measurement variability was assessed by using one-way analysis of variance, while the contributions of mean nodule volume and change in lung volume were investigated with univariate linear regression for completely (group A) and incompletely (group B) segmented nodules. Results: Two hundred eighteen eligible nodules (volume range, 16.4-472.7 mm(3); 106 spherical, 112 nonspherical) were evaluated. The 95% confidence interval for difference in measured volumes was -21.2%, 23.8% ( mean difference, 1.3%). The precision of nodule segmentation was highly dependent on nodule shape (P

To compare the diagnostic performance of multidetector computed tomography (CT) and magnetic resonance (MR) imaging in patients clinically suspected of having a scaphoid fracture and who had normal initial radiographs, with radiographs obtained 6 weeks after trauma as the reference standard.The ethics committee approved the study, and all patients gave written informed consent. Twenty-nine patients (17 male, 12 female; age range, 17-62 years; mean age, 34 years +/- 13) underwent multidetector CT and MR imaging within 6 days after trauma. CT data were obtained with 0.5-mm collimation. For image review, 0.7-mm-thick multiplanar reformations were performed in transverse, coronal, and sagittal planes relative to the wrist. The 1.0-T MR examination consisted of coronal and transverse short inversion time inversion-recovery, coronal and transverse T1-weighted spin-echo, and coronal volume-rendered T2-weighted gradient-echo sequences. Two radiologists analyzed the CT and MR images. A binomial test was used to evaluate the significance of the differences between MR imaging and CT in detection of scaphoid fractures and cortical involvement (P.05).The 6-week follow-up radiographs depicted a scaphoid fracture in 11 (38%) patients. Eight patients had a cortical fracture, while three patients had only a bandlike lucency within the trabecular portion of the scaphoid. MR imaging depicted all 11 fractures but only three [corrected] cortical fractures. Multidetector CT depicted all eight cortical fractures but failed to depict trabecular fractures. No false-positive fractures were seen on MR or CT images. Differences between MR imaging and CT were not significant for the detection of scaphoid fractures (P = .25) but were significant for cortical involvement (P = .03).Multidetector CT is highly accurate in depicting occult cortical scaphoid fractures but appears inferior to MR imaging in depicting solely trabecular injury. MR imaging is inferior to multidetector CT in depicting cortical involvement.

To assess prospectively the effect of section width in multi-detector row computed tomographic (CT) evaluation of patients with acute flank pain who are suspected of having or known to have urinary stone disease.This study was approved by the ethics committee of the authors' university, and written informed consent was obtained from all patients. One hundred forty-seven patients (age range, 11-101 years; mean, 51.4 years +/- 18.7 [standard deviation]) suspected of having urinary stone disease underwent unenhanced multi-detector row CT. CT was performed with four detector rows, a section thickness of 1.0 mm, an effective tube current-time product of 100 mAs, and a tube voltage of 120 kVp (CT dose index, 11.4 mGy). From these data, three sets of transverse images were reconstructed with section widths of 1.5, 3.0, and 5.0 mm and approximately 50% of overlap each. Scans were evaluated in varying random orders by two radiologists for the number, size, and location of uroliths and nephroliths and for the presence of phleboliths, renal cysts, and secondary signs of obstruction. The significance of differences between the numbers of detected calcifications and the numbers of associated abnormalities on the scans obtained with varying section widths was tested with the McNemar test at a P level of less than .05. Spearman rho rank correlation coefficients were calculated to assess the correlation between the presence of uroliths and the presence of secondary signs.Uroliths were found in 72 of 147 (49.0%) patients, and nephroliths were found in 16 patients (10.9%). There was no significant difference between section widths of 1.5 and 3.0 mm with regard to the number of detected stones (264 uroliths and 61 nephroliths for both protocols). Transverse sections 5.0-mm wide revealed significantly fewer uroliths (n = 231; P.001) and nephroliths (n = 47; P.016). The final diagnosis was changed in four of 72 patients. All missed renal and ureteral stones measured less than 3 mm in diameter.Overlapping 3-mm sections are sufficient for the detection of urinary stone disease. Small calculi (3 mm) may be missed on 5.0-mm-thick sections.

To compare observer performance with a flat-panel liquid crystal display (LCD) monitor and with a high-resolution gray-scale cathode-ray tube (CRT) monitor in the detection of simulated support catheters on bedside chest radiographs.The ethics committee did not require approval or patient informed consent when this study began. Because of a change in regulations, before images were acquired the nature of the study and procedures were explained to patients or their relatives, and consent was then obtained. A total of 131 catheter fragments (12-14 per radiograph) were superimposed over 10 anteroposterior bedside chest radiographs obtained with storage phosphor technology. Images were displayed on an LCD monitor (1536 x 2048 matrix) and a CRT monitor (2048 x 2560 matrix). Five radiologists independently located the catheter fragments and rated their confidence in detection with bright and subdued ambient light. A two-way analysis of variance and the Friedman test were used for statistical analysis.There was no significant difference for either display type with respect to correctly detected catheter fragments (mean sensitivity, 56.6% and 56.0% for the CRT and the LCD monitors, respectively, with bright light and 61.2% for both monitors with subdued light). With both display types, detection rate with bright light decreased significantly (P.05). False-positive rates and confidence ratings were not significantly affected by monitor type or ambient light.In a study with simulation of clinical conditions, performance of the LCD monitor and high-resolution CRT monitor for detection of support catheters on bedside chest radiographs was equivalent. With both displays, detection performance was equally reduced with bright ambient light.

To evaluate the performance of the most recent generation of storage phosphor plates for the detection of low-contrast catheter material on bedside chest radiographs.In 10 patients in the intensive care unit, bedside chest radiographs were obtained with a 400-speed conventional screen-film system and with storage phosphor plates with exposure levels comparable to a 200-, 400-, or 800-speed conventional system. The chest radiograph was divided into 20 regions, 60% of which were superimposed with low-contrast catheter fragments. Six observers independently assessed the presence of catheter fragments by using a receiver operating characteristic (ROC) methodology.Detection performance (mean area under the ROC curve [Az]) with the storage phosphor plates was significantly superior to that with the screen-film system (Az = 0.76) at all three dose levels (Az = 0.88, 0.87, and 0.83 for 200-, 400-, and 800-speed doses, respectively; P.05). Increasing the dose to a 200-speed system did not significantly increase detection performance compared with that with the 400-speed digital radiographs (Az = 0.88 vs 0.87). Dose reduction to 800 speed significantly deteriorated the detection performance (Az = 0.83) compared with that with the 400- and 200-speed digital radiographs, respectively.The most recent generation of storage phosphor plates is superior to a 400-speed screen-film system for the detection of catheter material, even at an exposure level of 800 speed.

The ability to resolve the fine linear structures of interstitial lung disease is one measure of the limiting performance characteristics of an imaging system. Conventional screen-film radiography was compared with six algorithms of isodose storage phosphor digital radiography (0.2-mm x 10-bit pixel matrix) in the detection of interstitial lung abnormality documented by means of computed tomography in 40 patients with abnormalities and 25 healthy control subjects. Performance was evaluated with an analysis of variance (the Fisher paired comparison test; P less than .05) of the average receiver operating characteristic area of 2,730 observations by six readers. The moderately and the more markedly high-frequency edge-enhanced algorithms of storage phosphor digital radiographs were equivalent in performance to screen-film radiography. The default mode, low- and medium-frequency edge-enhanced algorithms, and gray scale reversed mode of storage phosphor digital radiography were inferior to screen-film radiography. The authors conclude that high-frequency edge-enhanced algorithms can perform as well as screen-film radiography in the detection of interstitial disease.

Conventional film radiography (FR) and six postprocessing algorithms of isodose storage phosphor digital radiography (SR) (0.2-mm X 10-bit pixel matrix) were compared in the evaluation of 40 mediastinal and 30 pulmonary lesions in 60 patients who underwent computed tomography of the chest. The six SR algorithms varied among each other in only one image parameter. One algorithm approximated conventional image characteristics. The other five algorithms were designed to optimize imaging of the mediastinum and tested the effects of gray-scale reversal, adjustment of optical density, a linear instead of a sigmoid gradation curve, and moderate edge enhancement of high and medium spatial frequencies. Performance was evaluated by calculating the average area under the receiver operating characteristic curve (Az) of 5,040 observations by six readers. Post-processing with high-frequency edge enhancement and density optimization for the mediastinum significantly improved performance of SR over FR in the detection of mediastinal lesions (Az = .80 +/- .02 vs .73 +/- .01, respectively). Gray-scale reversal significantly decreased performance (Az = .64 +/- .03). All SR algorithms that were postprocessed to optimize imaging of the mediastinum were significantly inferior to FR in the detection of pulmonary lesions.

A retrospective analysis of magnetic resonance (MR) imaging studies of 78 patients with acute cervical spinal cord injuries was undertaken to determine which observations related directly to the neurologic injury. All MR imaging studies were performed on a 1.5-T unit and assessed with respect to 14 parameters related to the bony spine, ligaments, prevertebral soft tissues, intervertebral disks, and spinal cord. Forty-eight patients also underwent non-contrast material-enhanced thin-section computed tomography (CT) of the cervical spine. MR imaging was the definitive modality in the assessment of soft-tissue injury, especially in the evaluation of the spinal cord and intervertebral disks. All patients with a neurologic deficit had abnormal spinal cords at MR imaging. Intramedullary hemorrhage was predictive of a complete lesion. The degree of associated bone and soft-tissue injury had no bearing on the extent of spinal cord injury or neurologic deficit. Patients with residual cord compression following reduction demonstrated greater neurologic compromise than those without compression.

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.

To assess the renal tolerance of 1.0 mol/L gadobutrol as an electrically neutral contrast agent at magnetic resonance (MR) imaging in patients with impaired renal function.Twenty-one patients with impaired renal function were enrolled in this prospective randomized study and classified into two subgroups according to their creatinine clearance: group 1 (n = 12), less than 80 mL/min (1.33 mL/sec) and greater than 30 mL/min (0.50 mL/sec); group 2 (n = 9), less than 30 mL/min (0.50 mL/sec) and not requiring dialysis. Gadobutrol (1.0 mol/L) was injected intravenously at randomly assigned doses of either 0.1 or 0.3 mmol per kilogram of body weight. Changes in vital signs, clinical chemistry, and urinalysis results, including creatinine clearance, were monitored before, at 6 hours, and then every 24 hours until 72 hours (group 1) or 120 hours (group 2) after intravenous injection of gadobutrol. Hematologic results were checked every other day.No serious adverse event occurred, and no clinically relevant changes in vital signs, hematologic results, clinical chemistry, or urinalysis results were detected in the observation period. Markers for glomerular filtration (creatinine, cystatin C, beta2-microglobulin, creatinine clearance) and tubular function (N-acetyl-beta-D-glucosaminidase, alpha1-microglobulin) were unaffected by gadobutrol in both groups.Gadobutrol did not affect renal function and, therefore, proved to be a safe MR contrast agent in patients with impaired renal function. Even in patients with marginal excretory function (creatinine clearance,30 mL/min [0.50 mL/sec]), prehydration or treatment with diuretics or hemodialysis are not required after the administration of gadobutrol.

To compare selenium detectors with three conventional and digital detector systems for the detection of simulated pulmonary lesions.Templates containing nodules, linear structures, and micronodular opacities were superimposed over an anthropomorphic chest phantom. The authors compared lesion detection with use of storage phosphor radiography (250 speed), selenium radiography (250 speed) with an antiscatter grid, selenium radiography (450 speed) without an antiscatter grid, an asymmetric screen-film system (400 speed), and a conventional screen-film system (250 speed). Detection performance of 10 radiologists was compared by using a multireader-multicase receiver operating characteristic analysis of variance.For the detection of nodules, no statistically significant differences between imaging modes were seen. For the detection of micronodules and linear lesions, both selenium techniques were superior to all other modes (P.05). In addition, the asymmetric screen-film radiographs were inferior (P.05) to the conventional screen-film radiographs and to storage phosphor radiographs for the detection of micronodules.The selenium detector improves detection of simulated fine linear and low-contrast micronodular details and appears to be superior to other detector systems for chest radiography.

To compare a high-contrast asymmetric screen-film system with a conventional screen-film combination and storage phosphor radiographs for detection of simulated chest lesions.To test the diagnostic performance of these three systems, the authors used three types of simulated lesions that were superimposed over the chests of 10 patients and an anthropomorphic phantom. In the patient and phantom study, a total of 1,350 observations by each of the eight radiologists were analyzed by means of receiver operating characteristics.In the patient study, mediastinal nodules were better visualized with high-contrast asymmetric screen-film and storage phosphor radiographs compared with the conventional screen-film system. For visualization of pulmonary nodules, the high-contrast asymmetric screen-film system was best. Micronodules were poorly visualized on high-contrast asymmetric screen-film and storage phosphor radiographs, but only in the phantom study.The high-contrast asymmetric screen-film system combines the advantages of conventional screen-film radiographs with improved visualization of the mediastinum.

To evaluate the role of spiral computed tomography (CT) in diagnosis of renal arterial stenoses.In 22 patients with suspected renovascular hypertension, spiral CT angiography of the renal arteries was compared with arterial digital subtraction angiography (DSA). For each patient, the peak transit time t (from intravenous injection to maximum enhancement of the abdominal aorta) was determined with a bolus injection of 15 mL of contrast medium. Spiral scanning started at the level of the superior mesenteric artery with a delay of t + 5 seconds after the start of injection of 100-150 mL of contrast medium.Spiral CT angiography demonstrated multiple renal arteries in five patients. A renal artery stenosis or occlusion was found in 15 of 22 patients (22 of 54 arteries). All findings were confirmed with arterial DSA. Vessel contrast on spiral CT scans was good to excellent in 19 of 22 patients. For diagnosis, axial-section and multiplanar reformatted images were superior to three-dimensional surface reconstructions and maximum-intensity projections.Spiral CT angiography is a promising screening method for renal artery stenosis.

Observer performance with four unsharp mask filtering algorithms for storage phosphor chest radiographs was compared with that with conventional screen-film radiographs in the detection of three types of simulated lung disease: nodules, fine lines, and micronodule clusters. Previously studied parameter sets (small [1.4-mm] and medium [5-mm] filter masks) and two new parameter sets (large [2.5-cm] and ultralarge [7-cm] masks) were compared by means of receiver operating characteristic analysis. With medium and small masks, nodule detection was inferior to that achieved with other modes. Use of ultralarge masks decreased the detection of lines compared with detection with conventional screen-film radiographs. Although detection of micronodule clusters was worse with digital images than with conventional screen-film radiographs, results with large and ultralarge masks were better than with small masks. Overall, filtering with large masks was best suited for simultaneously matching linear, nodular, and micronodular structures. These results suggest that lesion-specific processing of digital chest images is not necessary.

To determine the impact of reduced hard-copy size on diagnostic performance of digital radiography, screen-film chest radiographs were compared with isodose digital storage phosphor radiographs in the detection of simulated nodules, fine pulmonary lines, and micronodular opacities superimposed on the chests of 10 healthy volunteers. Digital radiographs were laser-printed in a full-size conventional format and in image lengths of two-thirds, one-half, and five-elevenths of the conventional format. Eighteen thousand observations by eight radiologists were analyzed by use of receiver operating characteristics. The detectability of lines and micronodular opacities decreased with declining image format size. In the detection of micronodular opacities, only the nearly full-size digital images were equivalent to conventional images. In the detection of linear opacities, reduction of image length by one-half or more reduced performance (analysis of variance, P less than .05). Only for the detection of nodules was no major difference found.

The advantages of imaging the chest with digital storage phosphor radiography (SR) may be nullified by its spatial resolution, which is lower than that of conventional film radiography (FR). To test the reader detection performance with the two modalities under clinical conditions, the authors compared 140-kVp isoexposure SR (system resolution: 0.2 mm, 10 bits) and FR images of a variety of chest abnormalities proved by computed tomography (CT) (157 patients, 244 abnormalities, 5,652 observations, six readers). In all tests, SR was as good as or better than FR (P less than .05). In overall detection, indicated by the average area of receiver operating characteristics, SR and FR were equivalent. SR was superior for mediastinal lesions and for pulmonary opacities greater than 2 cm in diameter. For all other types of pulmonary lesions and pleural abnormalities, SR and FR were equivalent. Currently available commercial SR systems can replace film radiographic systems in the detection of a wide variety of chest lesions. SR is likely to enable better visualization than FR in the detection of mediastinal and large pulmonary abnormalities.

The technical and diagnostic performance of simultaneously acquired low-dose (44% of standard dose) storage-phosphor digital radiographs (system resolution = 0.2 mm, 10 bits) were compared with those of standard-dose conventional bedside radiographs of the chest in 32 patients. The mean optical density (OD) of the lungs (800 measurements) was closer to the ideal density with digital radiography (1.45 OD +/- 0.20 [standard deviation] vs 1.75 OD +/- 0.53) and was less often outside the usable range (2.5% vs 42.5%). Receiver operating characteristic analysis for detection of simulated nodules and monitoring devices (nine readers, 4,608 observations) showed that digital radiography was superior to conventional radiography (P less than .05) for four of the nine readers and equivalent to conventional radiography for five readers. The authors concluded that digital radiography produces more consistent and ideal image density and performs at least as well as conventional radiography under phantom test conditions.