Incidental Lung Nodules on Cross-sectional Imaging: Current Reporting and Management
Pulmonary nodules are the most common incidental finding in the chest, particularly on computed tomographs that include a portion or all of the chest, and may be encountered more frequently with increasing utilization of cross-sectional imaging. Established guidelines address the reporting and management of incidental pulmonary nodules, both solid and subsolid, synthesizing nodule and patient features to distinguish benign nodules from those of potential clinical consequence. Standard nodule assessment is essential for the accurate reporting of nodule size, attenuation, and morphology, all features with varying risk implications and thus management recommendations.
Medical Student Engagement and Educational Value of a Remote Clinical Radiology Learning Environment: Creation of Virtual Read-Out Sessions in Response to the COVID-19 Pandemic
RATIONALE AND OBJECTIVES/OBJECTIVE:The need for social distancing has resulted in rapid restructuring of medical student education in radiology. While students traditionally spend time learning in the reading room, remote clinical learning requires material shared without direct teaching at the radiology workstation. Can remote clinical learning meet or exceed the educational value of the traditional in-person learning experience? Can student engagement be matched or exceeded in a remote learning environment? MATERIALS AND METHODS/METHODS:To replace the in-person reading room experience, a small-group learning session for medical students named Virtual Read-Out (VRO) was developed using teleconferencing software. After Institutional Review Board approval, two student groups were anonymously surveyed to assess differences in student engagement and perceived value between learning environments: "Conventional" students participating in the reading room (before the pandemic) and "Remote" students participating in VRO sessions. Students reported perceived frequency of a series of five-point Likert statements. Based on number of respondents, an independent t-test was performed to determine the significance of results between two groups. RESULTS:Twenty-seven conventional and 41 remote students responded. Remote students reported modest but significantly higher frequency of active participation in reviewing radiology exams (p < 0.05). There was significantly lower frequency of reported boredom among Remote students (p < 0.05). There was no significant difference in perceived educational value between the two groups. CONCLUSION/CONCLUSIONS:Students report a high degree of teaching quality, clinical relevance, and educational value regardless of remote or in-person learning format. Remote clinical radiology education can be achieved with equal or greater student interaction and perceived value in fewer contact hours than conventional learning in the reading room.
Quantitative Computed Tomographic Evaluation of Lung Nodules
Congenital Coronary Artery Anomalies and Implications
This pictorial essay presents cases of congenital coronary artery anomalies, including congenital anomalies of origin, course, and termination. Familiarity with atypical coronary anatomy and clinical presentation may facilitate appropriate diagnosis and management, particularly as cardiac and thoracic computed tomographic utilization increases.
Image Quality on Dual-energy CTPA Virtual Monoenergetic Images: Quantitative and Qualitative Assessment
RATIONALE AND OBJECTIVES/OBJECTIVE:This study aims to determine the optimal photon energy for image quality of the pulmonary arteries (PAs) on dual-energy computed tomography (CT) pulmonary angiography (CTPA) utilizing low volumes of iodinated contrast. MATERIALS AND METHODS/METHODS:The study received institutional review board exemption and was Health Insurance Portability and Accountability Act compliant. Adults (nâ€‰=â€‰56) who underwent dual-energy CTPA with 50-60â€‰cc of iodinated contrast on a third-generation dual-source multidetector CT were retrospectively and consecutively identified. Twelve virtual monoenergetic kiloelectron volt (keV) image data sets (40-150â€‰keV, 10-keV increments) were generated with a second-generation noise-reducing algorithm. Standard regions of interest were placed on main, right, left, and right interlobar pulmonary arteries; pectoralis muscle; and extrathoracic air. Attenuation [mean CT number (Hounsfield unit, HU)], noise [standard deviation (HU)], signal to noise (SNR), and contrast to noise ratio were evaluated. Three blinded chest radiologists rated (from 1 to 5, with 5 being theâ€‰best) randomized monoenergetic and weighted-average images for attenuation and noise. Pâ€‰<.05 was considered significant. RESULTS:Region of interest mean CT number increased as keV decreased, with 40â€‰keV having the highest value (Pâ€‰<â€‰.001). Mean SNR was highest for 40-60â€‰keV (Pâ€‰<.05) (14.5-14.7) and was higher (Pâ€‰<.05) than all remaining energies (90-150â€‰keV) for all vessel regions combined. Contrast to noise ratio was highest for 40â€‰keV (Pâ€‰<.001) and decreased as keV increased. SNR was highest at 60 and 70â€‰keV, only slightly higher than 40-50â€‰keV (Pâ€‰<.05). Reader scores for 40-50â€‰keV were greater than other energies and weighted-average images (Pâ€‰<.05). CONCLUSIONS:Kiloelectron volt images of 40-50â€‰keV from the second-generation algorithm optimize attenuation on dual-energy CTPA and can potentially aid in interpretation and avoiding nondiagnostic examinations.
Management of Incidental Lung Nodules: Current Strategy and Rationale
Incidentally detected lung nodules are increasingly common in routine diagnostic computed tomography (CT) imaging. Formal management recommendations for incidental nodules, such as those outlined by the Fleischner Society, must therefore reflect a balance of malignancy risk and the clinical context in which nodules are discovered. Nodule size, attenuation, morphology, and location all influence the likelihood of malignancy and, thus, the necessity and timing of follow-up according to current Fleischner recommendations. As technological advancements in CT imaging continue, there may be greater reliance on advanced computerized analysis of lung nodule features to help determine the risk of clinically significant disease.
Lepidic Predominant Pulmonary Lesions (LPL): CT-based Distinction From More Invasive Adenocarcinomas Using 3D Volumetric Density and First-order CT Texture Analysis
RATIONALE AND OBJECTIVES: This study aimed to differentiate pathologically defined lepidic predominant lesions (LPL) from more invasive adenocarcinomas (INV) using three-dimensional (3D) volumetric density and first-order texture histogram analysis of surgically excised stage 1 lung adenocarcinomas. MATERIALS AND METHODS: This retrospective study was institutional review board approved and Health Insurance Portability and Accountability Act compliant. Sixty-four cases of pathologically proven stage 1 lung adenocarcinoma surgically resected between September 2006 and October 2015, including LPL (n = 43) and INV (n = 21), were evaluated using high-resolution computed tomography. Quantitative measurements included nodule volume, percent solid volume (% solid), and first-order texture histogram analysis including skewness, kurtosis, entropy, and mean nodule attenuation within each histogram quartile. Binomial logistic regression models were used to identify the best set of parameters distinguishing LPL from INV. RESULTS: Univariate analysis of 3D volumetric density and histogram features was statistically significant between LPL and INV groups (P < .05). Accuracy of a binomial logistic model to discriminate LPL from INV based on size and % solid was 85.9%. With optimized probability cutoff, the model achieves 81% sensitivity, 76.7% specificity, and area under the receiver operating characteristic curve of 0.897 (95% confidence interval, 0.821-0.973). An additional model based on size and mean nodule attenuation of the third quartile (Hu_Q3) of the histogram achieved similar accuracy of 81.3% and area under the receiver operating characteristic curve of 0.877 (95% confidence interval, 0.790-0.964). CONCLUSIONS: Both 3D volumetric density and first-order texture analysis of stage 1 lung adenocarcinoma allow differentiation of LPL from more invasive adenocarcinoma with overall accuracy of 85.9%-81.3%, based on multivariate analyses of either size and % solid or size and Hu_Q3, respectively.
Low dose computed tomography pulmonary angiography protocol for imaging pregnant patients: Can dose reduction be achieved without reducing image quality?
OBJECTIVE: To assess the effect of low dose computed tomography pulmonary angiography (CTPA) on radiation dose in pregnant patients. MATERIALS AND METHODS: An old CTPA protocol for pregnant patients was compared to a new protocol. Protocol changes included: decreased kVp; increased contrast injection rate; imaging after shallow inspiration. Patients undergoing CTPA before (phase 1 group) or after (phase 2 group) the protocol change, were assessed. RESULTS: Effective dose was lower in the phase 2 group (0.95 v 1.66 mSv; p<0.001). Quantitative noise was lower in the phase 1 group (p<0.001). CONCLUSION: Low dose CTPA tailored for pregnancy reduces dose in pregnant patients.
CT pulmonary angiography of adult pulmonary vascular diseases: Technical considerations and interpretive pitfalls
Computed tomography pulmonary angiography (CTPA) has become the primary imaging modality for evaluating the pulmonary arteries. Although pulmonary embolism is the primary indication for CTPA, various pulmonary vascular abnormalities can be detected in adults. Knowledge of these disease entities and understanding technical pitfalls that can occur when performing CTPA are essential to enable accurate diagnosis and allow timely management. This review will cover a spectrum of acquired abnormalities including pulmonary embolism due to thrombus and foreign bodies, primary and metastatic tumor involving the pulmonary arteries, pulmonary hypertension, as well as pulmonary artery aneurysms and stenoses. Additionally, methods to overcome technical pitfalls and interventional treatment options will be addressed.
Intracardiac Embolized Prostate Brachytherapy Seeds: Imaging Features in Patients Undergoing Electrocardiogram-Gated Cardiac Computed Tomography
OBJECTIVE: This study aims to provide the first description of the computed tomographic (CT) appearances of intracardiac embolized brachytherapy seeds in patients undergoing electrocardiogram (ECG)-gated cardiac CT. METHODS: The institutional Picture Archive and Communication System was searched for male patients who underwent enhanced ECG-gated cardiac CT, and reports were searched for the key words "metallic," "prostate," "brachytherapy," "radiation," "embolized," and "radioactive." Each study was identified and examined for an intracardiac metallic object conforming to the size of a prostate seed. RESULTS: Between January 01, 2005, and June 30, 2014, a total of 3206 male patients underwent ECG-gated cardiac CT. Five patients (0.15%) had a history of prostate cancer and an intracardiac metallic object with CT imaging characteristics consistent with an embolized prostate seed. In all 5 patients, the seeds were embedded in the trabeculations of the inferior aspect of the basal right ventricular free wall. CONCLUSIONS: Intracardiac embolized brachytherapy seeds appear as small objects with surrounding metallic artifact characteristically embedded in the inferior aspect of the basal right ventricular free wall.