Uncommon Causes of Interlobular Septal Thickening on CT Images and Their Distinguishing Features.

Interlobular septa thickening (ILST) is a common and easily recognized feature on computed tomography (CT) images in many lung disorders. ILST thickening can be smooth (most common), nodular, or irregular. Smooth ILST can be seen in pulmonary edema, pulmonary alveolar proteinosis, and lymphangitic spread of tumors. Nodular ILST can be seen in the lymphangitic spread of tumors, sarcoidosis, and silicosis. Irregular ILST is a finding suggestive of interstitial fibrosis, which is a common finding in fibrotic lung diseases, including sarcoidosis and usual interstitial pneumonia. Pulmonary edema and lymphangitic spread of tumors are the commonly encountered causes of ILST. It is important to narrow down the differential diagnosis as much as possible by assessing the appearance and distribution of ILST, as well as other pulmonary and extrapulmonary findings. This review will focus on the CT characterization of the secondary pulmonary lobule and ILST. Various uncommon causes of ILST will be discussed, including infections, interstitial pneumonia, depositional/infiltrative conditions, inhalational disorders, malignancies, congenital/inherited conditions, and iatrogenic causes. Awareness of the imaging appearance and various causes of ILST allows for a systematic approach, which is important for a timely diagnosis. This study highlights the importance of a structured approach to CT scan analysis that considers ILST characteristics, associated findings, and differential diagnostic considerations to facilitate accurate diagnoses.

CT-based pleural effusion volume estimation formula demonstrates low accuracy and reproducibility for traumatic hemothorax.

PURPOSE: We aimed to evaluate the accuracy and reproducibility of the CT-based volume estimation formula V = d2 * h, where d and h represent the maximum depth and height of the effusion, for acute traumatic hemothorax. MATERIALS & METHODS: Prospectively identified patients with CT showing acute traumatic hemothorax were considered. Volumes were retrospectively estimated using d2 * h, then manually measured on axial images. Subgroup analysis was performed on borderline-sized hemothorax (200-400 mL). Measurements were repeated by three non-radiologists. Bland-Altman analysis was used to assess agreement between the two methods and agreement between raters for each method. RESULTS: A total of 46 patients (median age 34; 36 men) with hemothorax volume 23-1622 mL (median 191 mL, IQR 99-324 mL) were evaluated. Limits of agreement between estimates and measured volumes were -718 - +842 mL (± 202 mL). Borderline-sized hemothorax (n = 13) limits of agreement were -300 - +121 mL (± 114 mL). Of all hemothorax, 85 % (n = 39/46) were correctly stratified as over or under 300 mL, and of borderline-sized hemothorax, 54 % (n = 7/13). Inter-rater limits of agreement were -251 - +350, -694 - +1019, and -696 - +957 for the estimation formula, respectively, and -124 - +190, -97 - +111, and -96 - +46 for the measured volume. DISCUSSION: An estimation formula varies with actual hemothorax volume by hundreds of mL. There is low accuracy in stratifying hemothorax volumes close to 300 mL. Variability between raters was substantially higher with the estimation formula than with manual measurements.

CT Angiography for the Detection of Pulmonary Embolism: Role of Tube Voltage and Contrast Injection Rate on Diagnostic Confidence.

RATIONALE AND OBJECTIVES: Pulmonary CTA is the current standard method to assess for suspected pulmonary embolism. In some instances, the test results in low confidence interpretations. Our purpose was to compare the diagnostic confidence for three different scan protocols. MATERIALS AND METHODS: Pulmonary CTA images from 401 patients were retrospectively analyzed. 202 studies used a tube voltage of 120 kVp and a contrast injection rate of 4 cc/s, 99 studies 120 kVp and 5 cc/s, and 100 studies 100 kVp and 4 cc/s. The level of diagnostic confidence was extracted from the final clinical reports. For each study, attenuation of the pulmonary artery, image noise, signal-to-noise ratio (SNR), and radiation dose were compared. RESULTS: The 120 kVp, 5 cc/s protocol resulted in high diagnostic confidence in 84% of cases, more than with the 120 kVp, 4cc/s (65%) and the 100 kVp protocol (65%, p < 0.004). The 100 kVp protocol had a lower radiation dose, higher image noise, lower SNR, but equal and higher attenuation values of the pulmonary artery. CONCLUSION: The reduction of tube voltage to 100 kVp at 4 cc/s maintains diagnostic confidence with lower radiation exposure, but does not equal the higher confidence achieved with 120 kVp at 5cc/s.

The Role of Imaging in the Management of Suspected or Known COVID-19 Pneumonia. A Multidisciplinary Perspective.

Coronavirus disease (COVID-19) is an illness caused by a novel coronavirus that has rapidly escalated into a global pandemic leading to an urgent medical effort to better characterize this disease biologically, clinically, and by imaging. In this review, we present the current approach to imaging of COVID-19 pneumonia. We focus on the appropriate use of thoracic imaging modalities to guide clinical management. We also describe radiologic findings that are considered typical, atypical, and generally not compatible with COVID-19. Furthermore, we review imaging examples of COVID-19 imaging mimics, such as organizing pneumonia, eosinophilic pneumonia, and other viral infections.

The Role of Imaging in the Management of Suspected or Known COVID-19 Pneumonia: A Multidisciplinary Perspective.

COVID-19 is an illness caused by a novel coronavirus that has rapidly escalated into a global pandemic leading to an urgent medical effort to better characterize this disease biologically, clinically and by imaging. In this review, we present the current approach to imaging of COVID-19 pneumonia. We focus on the appropriate utilization of thoracic imaging modalities to guide clinical management. We will also describe radiologic findings that are considered typical, atypical and generally not compatible with of COVID-19 infection. Further, we review imaging examples of COVID-19 imaging mimics, such as organizing pneumonia, eosinophilic pneumonia and other viral infections.

WITHDRAWN: Radiology Extenders: Impact on Throughput and Accuracy for Routine Chest Radiographs.

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CT Volumetry and Basic Texture Analysis as Surrogate Markers in Advanced Non-small-cell Lung Cancer.

INTRODUCTION: We evaluated volumetric tumor measurements and computed tomography texture analysis as prognostic indicators in patients with advanced non-small-cell lung cancer when compared with the unidimensional tumor size measurements used in Response Evaluation Criteria in Solid Tumors (RECIST). PATIENTS AND METHODS: In a retrospective review, computed tomography examinations in 77 patients with advanced non-small-cell lung cancer were evaluated before and after 2 cycles of chemotherapy. Baseline and changes in tumor diameter, volume, and texture were analyzed. Survival was analyzed with Cox regression analysis and Kaplan-Meier survival statistics. RESULTS: Cox regression analysis demonstrated that only change in tumor volume (exp(B) = 1.006; P = .02) and the initial sum of the largest target lesion diameters predicted survival (exp(B) = 1.013; P = .02). Kaplan-Meier statistics demonstrated that patients with an initial sum of the largest target lesion diameters less than 88 mm had median survival time of 587 days (95% confidence interval [CI], 269-905 days), compared with the survival of those with larger tumor burden of 407 days (95% CI, 235-579 days). Patients in whom tumor volume decreased by more than 29% had a median survival time of 622 days (95% CI, 448-796 days), compared with 305 days for those with less decrease (95% CI, 34-240 days). CONCLUSION: This study demonstrates that change in lung tumor volume is a better marker of patient survival than change of unidimensional diameter measurements in our cohort. If confirmed in larger studies, this suggests that volumetry might improve clinical decision-making for individual patients and allow for faster assessment of new treatments.

CT perfusion imaging of lung cancer: benefit of motion correction for blood flow estimates.

PURPOSE: CT perfusion (CTP) imaging assessment of treatment response in advanced lung cancer can be compromised by respiratory motion. Our purpose was to determine whether an original motion correction method could improve the reproducibility of such measurements. MATERIALS AND METHODS: The institutional review board approved this prospective study. Twenty-one adult patients with non-resectable non-small-cell lung cancer provided written informed consent to undergo CTP imaging. A motion correction method that consisted of manually outlining the tumor margins and then applying a rigid manual landmark registration algorithm followed by the non-rigid diffeomorphic demons algorithm was applied. The non-motion-corrected and motion-corrected images were analyzed with dual blood supply perfusion analysis software. Two observers performed the analysis twice, and the intra- and inter-observer variability of each method was assessed with Bland-Altman statistics. RESULTS: The 95% limits of agreement of intra-observer reproducibility for observer 1 improved from -84.4%, 65.3% before motion correction to -33.8%, 30.3% after motion correction (r = 0.86 and 0.97, before and after motion correction, p < 0.0001 for both) and for observer 2 from -151%, 96% to -49 %, 36 % (r = 0.87 and 0.95, p < 0.0001 for both). The 95% limits of agreement of inter-observer reproducibility improved from -168%, 154% to -17%, 25%. CONCLUSION: The use of a motion correction method significantly improves the reproducibility of CTP estimates of tumor blood flow in lung cancer. KEY POINTS: • Tumor blood flow estimates in advanced lung cancer show significant variability. • Motion correction improves the reproducibility of CT blood flow estimates in advanced lung cancer. • Reproducibility of blood flow measurements is critical to characterize lung tumor biology and the success of treatment in lung cancer.

Assessing response to treatment in non--small-cell lung cancer: role of tumor volume evaluated by computed tomography.

INTRODUCTION: We set out to investigate whether volumetric tumor measurements allow for a prediction of treatment response, as measured by patient survival, in patients with advanced non-small-cell lung cancer (NSCLC). MATERIALS AND METHODS: Patients with nonresectable NSCLC (stage III or IV, n = 100) who were repeatedly evaluated for treatment response by computed tomography (CT) were included in a Health Insurance Portability and Accountability Act (HIPAA)-compliant retrospective study. Tumor response was measured by comparing tumor volumes over time. Patient survival was compared with Response Evaluation Criteria in Solid Tumors (RECIST) using Kaplan-Meier survival statistics and Cox regression analysis. RESULTS: The median overall patient survival was 553 days (standard error, 146 days); for patients with stage III NSCLC, it was 822 days, and for patients with stage IV disease, 479 days. The survival differences were not statistically significant (P = .09). According to RECIST, 5 patients demonstrated complete response, 39 partial response, 44 stable disease, and 12 progressive disease. Patient survival was not significantly associated with RECIST class, the change of the sum of tumor diameters (P = .98), nor the change of the sum of volumetric tumor dimensions (P = .17). CONCLUSION: In a group of 100 patients with advanced-stage NSCLC, neither volumetric CT measurements of changes in tumor size nor RECIST class significantly predicted patient survival. This observation suggests that size response may not be a sufficiently precise surrogate marker of success to steer treatment decisions in individual patients.

Radiofrequency ablation of post-incisional atrial flutter and high-output heart failure in a patient with interrupted inferior vena cava and hereditary hemorrhagic telangiectasia.

A 61-year-old female with a history of secundum atrial septal defect repair and hereditary hemorrhagic telangiectasia presented with epistaxis. She was found to have atypical atrial flutter with 2:1 atrioventricular conduction. Radiofrequency ablation was planned, but inferior vena cava interruption precluded right atrial (RA) access. The RA was then accessed through both subclavian veins, and activation mapping revealed a dense atriotomy scar in the posterolateral inferior RA. Wavefront propagation proceeded caudally through an area of slow conduction confined by the atriotomy scar. Atypical atrial flutter terminated during a second radiofrequency application to an isthmus confined by 2 regions of dense scar. The arrhythmia did not recur, although the patient later experienced typical atrial flutter and atrial fibrillation. High-output heart failure due to systemic arteriovenous shunt was confirmed by cardiac catheterization and improved markedly with bevacizumab therapy.

The role of aortic wall CT attenuation measurements for the diagnosis of acute aortic syndromes.

OBJECTIVES: To determine if measurements of aortic wall attenuation can improve the CT diagnosis of acute aortic syndromes. METHODS: CT reports from a ten year period were searched for acute aortic syndromes (AAS). Studies with both an unenhanced and a contrast enhanced (CTA) series that had resulted in the diagnosis of intramural hematoma (IMH) were reviewed. Diagnoses were confirmed by medical records. The attenuation of aortic wall abnormalities was measured. The observed attenuation threshold was validated using studies from 39 new subjects with a variety of aortic conditions. RESULTS: The term "aortic dissection" was identified in 1206, and IMH in 124 patients' reports. IMH was confirmed in 31 patients, 21 of whom had both unenhanced and contrast enhanced images. All 21 had pathologic CTA findings, and no CTA with IMH was normal. Attenuation of the aortic wall was greater than 45 HUs on the CTA images in all patients with IMH. When this threshold was applied to the new group, sensitivity for diagnosing AAS was 100% (19/19), and specificity 94% (16/17). Addition of unenhanced images did not improve accuracy. CONCLUSIONS: Measurements of aortic wall attenuation in CTA have a high negative predictive value for the diagnosis of acute aortic syndromes.

Causes of death of patients with lung cancer.

CONTEXT: The causes of death for patients with lung cancer are inadequately described. OBJECTIVE: To categorize the immediate and contributing causes of death for patients with lung cancer. DESIGN: The autopsies from 100 patients who died of lung cancer between 1990 and February 2011 were analyzed. RESULTS: Tumor burden was judged the immediate cause of death in 30 cases, including 26 cases of extensive metastases and 4 cases with wholly or primarily lung tumor burden (causing respiratory failure). Infection was the immediate cause of death for 20 patients, including 8 with sepsis and 12 with pneumonia. Complications of metastatic disease were the immediate causes of death in 18 cases, including 6 cases of hemopericardium from pericardial metastases, 3 from myocardial metastases, 3 from liver metastases, and 3 from brain metastases. Other immediate causes of death were pulmonary hemorrhage (12 cases), pulmonary embolism (10 cases, 2 tumor emboli), and pulmonary diffuse alveolar damage (7 cases). From a functional (pathophysiologic) perspective, respiratory failure could be regarded as the immediate cause of death (or mechanism of death) in 38 cases, usually because of a combination of lung conditions, including emphysema, airway obstruction, pneumonia, hemorrhage, embolism, resection, and lung injury in addition to the tumor. For 94 of the 100 patients, there were contributing causes of death, with an average of 2.5 contributing causes and up to 6 contributing causes of death. CONCLUSIONS: The numerous and complex ways lung cancer kills patients pose a challenge for efforts to extend and improve their lives.

Prevalence of aortic root dilation in patients with CT angiography of the aorta.

PURPOSE: To investigate the prevalence of aortic root dilation in patients who underwent CT angiography of the thoracic aorta. MATERIALS AND METHODS: In 95 patients, 64-slice multislice computed tomography was performed for evaluation of the thoracic aorta. Measurements of the annulus, sinuses of valsalva (SOV), sinotubular junction (STJ), and maximum ascending aorta (AAo) were made by double oblique multiplanar reformation (MPR). For the AAo, STJ, and SOV, dilation was defined as greater than 40 mm; for annulus, the dilation criterion was greater than 27 mm. RESULTS: Overall, 52 patients were diagnosed with a dilated AAo. Of those patients with dilated AAo, 28 patients had a dilated annulus, 27 patients had dilated SOV, and 11 patients had STJ dilation. Forty-three patients presented with normal AAo; 12 patients had annulus dilation; 12 patients had SOV dilation; and 4 patients had STJ dilation. In patients with dilated AAo, 38% also had a dilated annulus, 52% showed SOV dilation, and 21% presented with STJ dilation, compared to 28% annulus dilation, 28% SOV dilation, and 9% STJ dilation in patients with an AAo of normal caliber. CONCLUSION: Our data indicate a higher prevalence of aortic root dilation among patients with dilated AAo.

The aortic root: comparison of measurements from ECG-gated CT angiography with transthoracic echocardiography.

PURPOSE: The purpose of this study was to compare the measurements of the aortic root obtained from electrocardiographically (ECG)-gated computed tomography (CT) angiography (CTA) to the measurements obtained from transthoracic echocardiography (TTE). MATERIALS AND METHODS: This was a retrospective study in a patient population scanned at our institution between December 2005 and January 2007 with retrospectively ECG-gated CTA. ECG-gated CTA was performed with a 64-section helical CT scanner (Light speed, VCT, GE, Milwaukee, WI). Sixty-eight patients; 51 men and 17 women were included in this study. Aortic root diameters were measured by using double oblique reconstruction from axial source images. The TTE measurements of the aortic root were obtained from the reports that were performed within 2 months of CTA. RESULTS: The average aortic root diameter measured by TTE was 33+/-4.1 mm; on CTA it was 36.9+/-3.8 mm. The median difference between the 2 measurements was 3.9 mm which was significant (P<0.0001). In patients whose aortic root measurements with CTA were normal, the TTE measurements were also normal. However, in the group of patients with dilated aortic roots by CTA, TTE measurements were significantly lower and many were normal. In the group of patients with dilated aortic root by TTE, the CTA measurements of the aortic root were similarly increased. CONCLUSIONS: Retrospective comparison of TTE and CTA measurements of the aortic root reveal that TTE measurements are substantially lower or even normal in patients found to have dilated aortic root by CTA.

Pulmonary lobe segmentation in CT examinations using implicit surface fitting.

Lobe identification in computed tomography (CT) examinations is often an important consideration during the diagnostic process as well as during treatment planning because of their relative independence of each other in terms of anatomy and function. In this paper, we present a new automated scheme for segmenting lung lobes depicted on 3-D CT examinations. The unique characteristic of this scheme is the representation of fissures in the form of implicit functions using Radial Basis Functions (RBFs), capable of seamlessly interpolating "holes" in the detected fissures and smoothly extrapolating the fissure surfaces to the lung boundaries resulting in a "natural" segmentation of lung lobes. A previously developed statistically based approach is used to detect pulmonary fissures and the constraint points for implicit surface fitting are selected from detected fissure surfaces in a greedy manner to improve fitting efficiency. In a preliminary assessment study, lobe segmentation results of 65 chest CT examinations, five of which were reconstructed with three section thicknesses of 0.625 mm, 1.25 mm, and 2.5 mm, were subjectively and independently evaluated by two experienced chest radiologists using a five category rating scale (i.e., excellent, good, fair, poor, and unacceptable). Thirty-three of 65 examinations (50.8%) with a section thickness of 0.625 mm were rated as either "excellent" or "good" by both radiologists and only one case (1.5%) was rated by both radiologists as "poor" or "unacceptable." Comparable performance was obtained with a slice thickness of 1.25 mm, but substantial performance deterioration occurred in examinations with a section thickness of 2.5 mm. The advantages of this scheme are its full automation, relative insensitivity to fissure completeness, and ease of implementation.

Flat panel volume computed tomography of the coronary arteries.

RATIONALE AND OBJECTIVES: Multidetector-row computed tomography (MDCT) has evolved into a sensitive diagnostic tool for the noninvasive detection of coronary artery stenosis, but remains limited by spatial resolution. Flat panel volume computed tomography (fpVCT) offers a higher spatial resolution. In a postmortem investigation of autopsy specimens, the accuracies of fpVCT for measuring the severity of coronary artery stenosis and the size of atherosclerotic plaque components were determined. METHODS AND MATERIALS: In 25 autopsy cases, hearts were isolated, the left anterior descending coronary arteries filled with contrast agent, and depicted with a prototype fpVCT unit with a slice thickness of 0.25 mm. Transections of the left anterior descending coronary arteries were reconstructed and compared with histopathologic sections using light microscopy. RESULTS: FpVCT measurements of luminal stenosis (r = 0.81), total plaque area (r = 0.88), calcified plaque area (r = 0.92), noncalcified plaque area (r = 0.83), and lipid core size (r = 0.67; P < .02) correlated well with histopathology (P < .0001). The limits of agreement for measuring any plaque component were three times smaller than those reported for MDCT. CONCLUSIONS: Postmortem coronary fpVCT provides an accurate and reproducible method for the quantitative assessment of both luminal stenosis and atherosclerotic plaque size. Because of its high spatial resolution, the method should be sufficiently accurate to reliably detect the lipid pools of vulnerable plaques.

A Computational geometry approach to automated pulmonary fissure segmentation in CT examinations.

Identification of pulmonary fissures, which form the boundaries between the lobes in the lungs, may be useful during clinical interpretation of computed tomography (CT) examinations to assess the early presence and characterization of manifestation of several lung diseases. Motivated by the unique nature of the surface shape of pulmonary fissures in 3-D space, we developed a new automated scheme using computational geometry methods to detect and segment fissures depicted on CT images. After a geometric modeling of the lung volume using the marching cubes algorithm, Laplacian smoothing is applied iteratively to enhance pulmonary fissures by depressing nonfissure structures while smoothing the surfaces of lung fissures. Next, an extended Gaussian image based procedure is used to locate the fissures in a statistical manner that approximates the fissures using a set of plane "patches." This approach has several advantages such as independence of anatomic knowledge of the lung structure except the surface shape of fissures, limited sensitivity to other lung structures, and ease of implementation. The scheme performance was evaluated by two experienced thoracic radiologists using a set of 100 images (slices) randomly selected from 10 screening CT examinations. In this preliminary evaluation 98.7% and 94.9% of scheme segmented fissure voxels are within 2 mm of the fissures marked independently by two radiologists in the testing image dataset. Using the scheme detected fissures as reference, 89.4% and 90.1% of manually marked fissure points have distance

Progression of coronary atherosclerosis after heart transplantation on electron-beam computed tomography.

RATIONALE AND OBJECTIVES: Cardiac transplant vasculopathy is the most important long-term complication of heart transplantation, with overlapping features with conventional, atherosclerotic coronary artery disease. The aim of this study was to determine the progression of coronary artery disease after heart transplantation by measuring total coronary calcium load. MATERIALS AND METHODS: After heart transplantation, 185 patients were serially examined using electron-beam computed tomography for coronary calcium load for clinical reasons. The mean time between the initial examination and the follow-up scan was 566 days (range, 126-1,436). Coronary calcium load was measured by the Agatston method, and the total calcium scores at both examinations were compared between patients taking and those not taking lipid-lowering medications (statins). RESULTS: Patients not taking statins (n = 94) displayed a median annualized percentage increase in total calcium score of 0 Agatston units, whereas patients taking at least the lowest recommended daily dose of a statin (n = 84) displayed an annualized percentage decrease of 11 Agatston units. The difference was not statistically significant (Wilcoxon's rank-sum test, P = .35). Only 17 patients had increases of > 24 Agatston units, and eight of them were taking statins (chi(2) test, P = .99). CONCLUSION: The annual rate of progression of coronary calcium load after heart transplantation is low. In this investigation, no beneficial effects of statins could be detected.