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Purpose: To evaluate whether a commercial AI tool for intracranial hemorrhage (ICH) detection on head CT exhibited sociodemographic biases., Methods: Our retrospective study reviewed 9736 consecutive, adult non-contrast head CT scans performed between November 2021 and February 2022 in a single healthcare system. Each CT scan was evaluated by a commercial ICH AI tool and a board-certified neuroradiologist; ground truth was defined as final radiologist determination of ICH presence/absence. After evaluating the AI tool's aggregate diagnostic performance, sub-analyses based on sociodemographic groups (age, sex, race, ethnicity, insurance status, and Area of Deprivation Index [ADI] scores) assessed for biases. χ 2 test or Fisher's exact tests evaluated for statistical significance with p ≤ 0.05., Results: Our patient population was 50% female (mean age 60 ± 19 years). The AI tool had an aggregate accuracy of 93% [9060/9736], sensitivity of 85% [1140/1338], specificity of 94% [7920/ 8398], positive predictive value (PPV) of 71% [1140/1618] and negative predictive value (NPV) of 98% [7920/8118]. Sociodemographic biases were identified, including lower PPV for patients who were females (67.3% [62,441/656] vs. 72.7% [699/962], p = 0.02), Black (66.7% [454/681] vs. 73.2% [686/937], p = 0.005), non-Hispanic/non-Latino (69.7% [1038/1490] vs. 95.4% [417/437]), p = 0.009), and who had Medicaid/Medicare (69.9% [754/1078]) or Private (66.5% [228/343]) primary insurance (p = 0.003). Lower sensitivity was seen for patients in the third quartile of national (78.8% [241/306], p = 0.001) and state ADI scores (79.0% [22/287], p = 0.001)., Conclusions: In our healthcare system, a commercial AI tool had lower performance for ICH detection than previously reported and demonstrated several sociodemographic biases., (© 2024. The Author(s), under exclusive licence to American Society of Emergency Radiology (ASER).)

Purpose: To determine the frequency of malignancy of nonperifissural juxtapleural nodules (JPNs) measuring 6 to < 10 mm in a subset of low-dose chest computed tomographies from the National Lung Cancer Screening Trial and the rate of down-classification of such nodules in Lung-Reporting and Data System (RADS) 2.0 compared with Lung-RADS 1.1., Materials and Methods: A secondary analysis of a subset of the National Lung Screening Trial was performed. An exemption was granted by the Institutional Review Board. The dominant noncalcified nodule measuring 6 to <10 mm was identified on all available prevalence computed tomographies. Nodules were categorized as pleural or nonpleural. Benign or malignant morphology was recorded. Initial and updated categories based on Lung-RADS 1.1 and Lung-RADS 2.0 were assigned, respectively. The impact of the down-classification of JPN was assessed. Both classification schemes were compared using the McNemar test ( P < 0.01)., Results: A total of 2813 patients (62 ± 5 y, 1717 men) with 4408 noncalcified nodules were studied. One thousand seventy-three dominant nodules measuring 6 to <10 mm were identified. Three hundred forty-eight (32.4%) were JPN. The updated scheme allowed down-classification of 310 JPN from categories 3 (n = 198) and 4A (n = 112) to category 2. We, therefore, estimate a 4.8% rate of down-classification to category 2 in the entire National Lung Screening Trial screening group. Two/348 (0.57%) JPN were malignant, both nonbenign in morphology. The false-positive rate decreased in the updated classification ( P < 0.01)., Conclusion: This study demonstrates the low malignant potential of benign morphology JPN measuring 6 mm to <10 mm. The Lung-RADS 2.0 approach to JPN is estimated to reduce short-term follow-ups and false-positive results., Competing Interests: The authors declare no conflict of interest., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

In this review, we summarize early pulmonary complications related to cancer therapy in children and highlight characteristic findings on imaging that should be familiar to a radiologist reviewing imaging from pediatric cancer patients., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Background The American College of Radiology updated Lung Imaging Reporting and Data System (Lung-RADS) version 1.0 to version 1.1 in May 2019, with the two key changes involving perifissural nodules (PFNs) and ground-glass nodules (GGNs) now designated as a negative screening result. This study examines the effects of these changes using National Lung Screening Trial (NLST) data. Purpose To determine the frequency of PFNs and GGNs reclassified from category 3 or 4A to the more benign category 2 in the updated Lung-RADS version 1.1, as compared with Lung-RADS version 1.0, using CT scans from the NLST. Materials and Methods In this secondary analysis of the NLST, the authors studied all noncalcified nodules (NCNs) found on the incident scan. Nodules were evaluated using criteria from both Lung-RADS version 1.0 and version 1.1, which were compared to determine changes in the number of nodules deemed benign. A McNemar test was used to assess statistical significance. Results A total of 2813 patients (mean age ± standard deviation, 62 years ± 5; 1717 men) with 4408 NCNs were studied. Of the largest 1092 solid NCNs measuring at least 6 mm but less than 10 mm, 216 (19.8%) were deemed PFNs (category 2) using Lung-RADS version 1.1. Eleven of the 1092 solid NCNs (1.0%) were malignant, but none were PFNs. Of 161 GGNs, three (1.9%) were category 3 according to Lung-RADS version 1.0, of which two (66.7%) were down-classified to category 2 with version 1.1. One of the three down-categorized GGNs (version 1.1) proved to be malignant (false-negative finding). Statistically significant improvement for Lung-RADS version 1.1 was found for total nodules ( P < .01) and PFNs ( P < .01), but not GGNs ( P = .48). Conclusion This secondary analysis of National Lung Screening Trial data shows that Lung Imaging Reporting and Data System version 1.1 decreased the number of false-positive results. This was related to the down-classification of perifissural nodules in the range of 6 up to 10 mm. The increase in allowable nodule size for ground-glass nodules in category 2 from 20 mm (version 1.0) to 30 mm (version 1.1) showed no benefit. © RSNA, 2021 See also the editorial by Mayo and Lam in this issue.

Objective: The purpose of this study is to determine whether imaging features of right heart failure seen on CT performed before transcatheter aorta valve replacement (TAVR) predict poor outcomes after the procedure., Materials and Methods: We retrospectively evaluated findings on CT performed before TAVR for 505 consecutive patients seen from 2014 to 2018. Of these patients, 300 underwent TAVR. Patient demographic characteristics and clinical and procedural data were recorded. Imaging features, including signs of right heart failure, left heart failure, lung disease, coronary artery disease, and concomitant mitral valve and apparatus calcifications were evaluated. The primary outcome was all-cause mortality at 1 year after TAVR. Patients were divided into two groups: those who were alive (group 1) and those who had died (group 2) by 1 year after TAVR. These groups were compared using the Mann-Whitney U test and the Pearson chi-square and Fisher exact tests when applicable. Multivariate logistic regression with a backward stepwise approach was performed. Results were correlated with echo-cardiography findings., Results: A total of 31 patients (10.3%) died within 1 year of TAVR. The presence and size of pericardial effusions were strongly associated with mortality within 1 year after TAVR ( p = 0.002). Pericardial effusion was noted in 25 patients in group 1 (9.3%) and eight patients in group 2 (25.8%). Increased size of the main pulmonary artery was associated with death ( p = 0.024), with a median main pulmonary artery size of 2.9 cm (interquartile range, 2.6-3.3 cm) in group 1 and 3.2 cm (interquartile range, 2.9-3.5 cm) in group 2. In multivariate analysis, pericardial effusion size and pulmonary artery size, both of which are indicative of right heart failure, were predictors of death, independent of the routinely used clinical Society of Thoracic Surgeons score (AUC, 0.758; 95% CI, 0.671-0.845). Depressed right ventricular ejection fraction, as identified on echocardiography, was associated with mortality within 1 year after TAVR ( p = 0.034), further corroborating the CT findings., Conclusion: Features related to right heart failure on pre-TAVR CT were associated with increased all-cause mortality within the first year after TAVR, even after adjustment for the Society of Thoracic Surgeons score. Such imaging findings can help in further risk stratification of patients before TAVR.

OBJECTIVE. Coronavirus disease (COVID-19) is a global pandemic. Studies in the radiology literature have suggested that CT might be sufficiently sensitive and specific in diagnosing COVID-19 when used in lieu of a reverse transcription-polymerase chain reaction test; however, this suggestion runs counter to current society guidelines. The purpose of this article is to critically review some of the most frequently cited studies on the use of CT for detecting COVID-19. CONCLUSION. To date, the radiology literature on COVID-19 has consisted of limited retrospective studies that do not substantiate the use of CT as a diagnostic test for COVID-19.

Introduction: Visualization of left atrial (LA) anatomy using image integration modules has been associated with decreased radiation exposure and improved procedural outcome when used for guidance of pulmonary vein isolation (PVI) in atrial fibrillation (AF) ablation. We evaluated the CARTOSEG™ CT Segmentation Module (Biosense Webster, Inc.) that offers a new CT-specific semiautomatic reconstruction of the atrial endocardium., Methods: The CARTOSEG™ CT Segmentation Module software was assessed prospectively in 80 patients undergoing AF ablation. Using preprocedural contrast-enhanced computed tomography (CE-CT), cardiac chambers, coronary sinus (CS), and esophagus were semiautomatically segmented. Segmentation quality was assessed from 1 (poor) to 4 (excellent). The reconstructed structures were registered with the electroanatomic map (EAM). PVI was performed using the registered 3D images., Results: Semiautomatic reconstruction of the heart chambers was successfully performed in all 80 patients with AF. CE-CT DICOM file import, semiautomatic segmentation of cardiac chambers, esophagus, and CS was performed in 185 ± 105, 18 ± 5, 119 ± 47, and 69 ± 19 seconds, respectively. Average segmentation quality was 3.9 ± 0.2, 3.8 ± 0.3, and 3.8 ± 0.2 for LA, esophagus, and CS, respectively. Registration accuracy between the EAM and CE-CT-derived segmentation was 4.2 ± 0.9 mm. Complications consisted of one perforation (1%) which required pericardiocentesis, one increased pericardial effusion treated conservatively (1%), and one early termination of ablation due to thrombus formation on the ablation sheath without TIA/stroke (1%). All targeted PVs (n  =  309) were successfully isolated., Conclusions: The novel CT- CARTOSEG™ CT Segmentation Module enables a rapid and reliable semiautomatic 3D reconstruction of cardiac chambers and adjacent anatomy, which facilitates successful and safe PVI., (© 2017 Wiley Periodicals, Inc.)

Purpose of Review: The purpose of this study was to provide an overview of the clinical applications of PET-MR in the setting of cardiac imaging with emphasis on specific scenarios where both techniques together provided added information., Recent Findings: Synergy of cardiac PET and MR fusion may hold similar promise eliminating ionizing radiation and improving tissue contrast. Future development of new hybrid scanners, use of new imaging tracers, and clinical applications are significant factors which will influence its use. Both positron emission tomography (PET) and cardiac magnetic resonance imaging (CMR) provide important anatomic and physiologic information with regard to the heart. Being able to combine the data from these two examinations in a hybrid technique allows for a more complete evaluation of cardiac pathology. While hybrid PET-CT has already established the utility of a combined imaging approach, the use of CMR in lieu of CT allows for elimination of ionizing radiation and for improved tissue contrast.

Background: Computed tomography (CT) is a useful and necessary part of many emergency department (ED) assessments. However, the costs of imaging and the health risks associated with radiation exposure have sparked national efforts to reduce CT ordering in EDs., Study Objective: We analyzed CT ordering habits prior to and following implementation of a feedback tool at a community hospital., Methods: In this intervention study, we identified the CT-ordering habits of physicians and mid-level care providers (physician assistants and nurse practitioners) at baseline and after implementation of a system that sent quarterly feedback reports comparing their ordering habits with those of their peers. Variability in ordering and subgroup analyses by body region were included in these reports., Results: We examined the records of 104,454 patients seen between October 1, 2013 and December 31, 2014. There were 5552 or 21.0% of patients seen during the baseline period that underwent CT imaging. We observed an absolute reduction in imaging of 2.3% (95% confidence interval 1.7-2.8%) after implementation, avoiding approximately $400,000 in costs, 22 days of scanning time, and radiation exposure equivalent to 33,000 chest films annually. These changes occurred across physicians and mid-level providers, regardless of the number years of practice or board certification., Conclusions: Implementation of a feedback mechanism reduced CT use by emergency medicine practitioners, with concomitant reductions in cost and radiation exposure. The change was similar across levels of medical care. Future studies will examine the effect of the feedback reporting system at other institutions in our hospital network., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Unlabelled: The association between main pulmonary artery (MPA) size and pulmonary arterial hypertension (PAHTN) is well established; however, the clinical utility of routine measurement of MPA is uncertain due to considerable overlap between normal patients and those with pulmonary hypertension. The lack of diagnostic accuracy could be further degraded by variability among the radiologists. It is unknown whether the addition of right and left pulmonary artery measurements would improve accuracy or further impair it. The purposes of this study are to verify the accuracy of a proposed cutoff value for the size of MPA in the diagnosis PAHTN, to determine the interrater agreement for this measurement, and to determine whether addition of right pulmonary artery (RPA) and left pulmonary artery (LPA) measurement or simple assessment of patient comorbidities can improve the accuracy., Materials and Methods: Patients undergoing both cardiac catheterization and chest computed tomography (CT) within 3 months of each other at a large university hospital between January 2010 and December 2012 were identified. Patients with prior cardiac surgery or congenital heart disease and critically ill patients were excluded from the study population. Patients with pericardial disease or severe lung disease documented on CT examinations were also excluded. From the remaining patients, 45 patients with normal pulmonary artery pressure and 50 patients with proven pulmonary hypertension were selected. Demographic data and clinical information was collected from medical records of these patients. Three radiologists with different years of experience in cardiothoracic imaging measured the MPA, RPA, and LPA diameters on axial images using an electronic ruler on 3D work stations independently and were masked to the patient clinical symptoms, diagnosis, and each other's measurement to prevent bias. Association between MPA diameter (MPAD) and patient characteristics assessed by one-way analysis of variance for scalar measures. Each reader's measurements were used to construct a separate receiver operating curve (ROC) to assess optimal MPA threshold. The ability of an MPA measurement threshold to correctly identify PAHTN was assessed using chi-squared. Chi-squared was also used to assess the effect of categorical comorbidities on false positive diagnosis., Results: None of the demographic data or patients' factors (age, gender, height, weight, body surface area, and body mass index) were related to the size of MPAD. The distribution of the MPAD was normal in both groups. Based on prior literature, MPAD (≥3.15cm) was selected as the cutoff value to diagnose PAHTN. Review of ROCs did not suggest a superior cutoff value for any reader. Using this threshold per case interrater agreement was good, kappa values >0.65. Based on an average measurement for all three readers, MPAD was 82% sensitive and 62% specific for PAHTN. Limiting positive diagnosis to those subjects with both MPAD ≥3.15 and either enlarged RPA diameter (RPAD) or LPAD diminished sensitivity but did not improve specificity. Defining positive study as the presence of any dilated artery (MPAD, RPAD, or LPAD) increased sensitivity to 94% but decreased specificity to 27%. Comorbidities that might cause fluctuating mean pulmonary artery pressures could not be shown to account for false positive studies. The 29 true negative patients and 16 false positive patients did not differ in the prevalence of obstructive sleep apnea/home oxygen use or documented congestive heart failure/low ejection fraction., Conclusion: Previously proposed threshold of MPAD ≥3.15cm is likely optimal but is not specific for identifying patient with PAHTN. Interobserver differences in MPAD measurement do not account this inaccuracy. Incorporation or RPA and LPA measurement does not improve diagnostic accuracy of PAHTN, and assessment of comorbidities does not easily identify likely false positive cases. Diagnosis of PAHTN based solely on CT examinations of the chest may not be sufficiently accurate for clinical use., (Published by Elsevier Inc.)

Purpose: The purpose of the study was to determine whether a model-based iterative reconstruction (MBIR) technique improves diagnostic confidence and detection of pulmonary embolism (PE) compared with hybrid iterative reconstruction (HIR) and filtered back projection (FBP) reconstructions in patients undergoing computed tomography pulmonary angiography., Materials and Methods: The study was approved by our institutional review board. Fifty patients underwent computed tomography pulmonary angiography at 100 kV using standard departmental protocols. Twenty-two of 50 patients had studies positive for PE. All 50 studies were reconstructed using FBP, HIR, and MBIR. After image randomization, 5 thoracic radiologists and 2 thoracic radiology fellows graded each study on a scale of 1 (very poor) to 5 (ideal) in 4 subjective categories: diagnostic confidence, noise, pulmonary artery enhancement, and plastic appearance. Readers assessed each study for the presence of PE. Parametric and nonparametric data were analyzed with repeated measures and Friedman analysis of variance, respectively., Results: For the 154 positive studies (7 readers × 22 positive studies), pooled sensitivity for detection of PE was 76% (117/154), 78.6% (121/154), and 82.5% (127/154) using FBP, HIR, and MBIR, respectively. PE detection was significantly higher using MBIR compared with FBP (P = 0.016) and HIR (P = 0.046). Because of nonsignificant increase in FP studies using HIR and MBIR, accuracy with MBIR (88.6%), HIR (87.1%), and FBP (87.7%) was similar. Compared with FBP, MBIR led to a significant subjective increase in diagnostic confidence, noise, and enhancement in 6/7, 6/7, and 7/7 readers, respectively. Compared with HIR, MBIR led to significant subjective increase in diagnostic confidence, noise, and enhancement in 5/7, 5/7, and 7/7 readers, respectively. MBIR led to a subjective increase in plastic appearance in all 7 readers compared with both FBP and HIR., Conclusions: MBIR led to significant increase in PE detection compared with FBP and HIR. MBIR led to qualitative improvements in diagnostic confidence, perceived noise, and perceived enhancement compared with FBP and HIR.

Objective: The purpose of this study was to determine whether use of iterative reconstruction (IR) can improve performance of a pulmonary embolism computer-aided detection (PE CAD) prototype., Materials and Methods: Images were collected from 40 consecutive pulmonary CT angiographic examinations in which PE was found and 26 studies in which it was not found for use as control cases. All images were reconstructed with filtered back projection (FBP) and six levels of a hybrid IR algorithm. The studies were evaluated with a prototype PE CAD system, and its performance was comparatively assessed on the basis of reconstruction type on a per-embolus and a per-study basis., Results: Use of the hybrid IR algorithm led to a significant and progressive decrease in false-positive marks made by PE CAD compared with those made by radiologists on FBP reconstructions (239 false-positive marks for FBP and 154, 136, 125, 116, 107, and 98 false-positive marks for the six hybrid IR [HIR] levels). Specificity improved with increasing HIR level (45.6% for level 6; 30.3% for FBP). However, compared with FBP, increasing levels of HIR resulted in a progressive decrease in per-embolism sensitivity (70.3% for FBP; 55.4% for HIR level 6) and, with the exception of HIR level 4, a progressive decrease in per-study sensitivity (97.5% for FBP; 85.0% for HIR level 6). Overall accuracy was highest for HIR level 1 (77.3%)., Conclusion: The use of IR leads to a significant reduction in false-positive marks by PE CAD at a cost of decreasing sensitivity. Very high levels of IR, which had the lowest sensitivities, should be avoided if being used concomitantly with PE CAD.

Purpose: To determine whether an iterative reconstruction (IR) technique (iDose, Philips Healthcare) can reduce image noise and improve image quality in obese patients undergoing computed tomographic pulmonary angiography (CTPA)., Materials and Methods: The study was Health Insurance Portability and Accountability Act compliant and approved by our institutional review board. A total of 33 obese patients (average body mass index: 42.7) underwent CTPA studies following standard departmental protocols. The data were reconstructed with filtered back projection (FBP) and 3 iDose strengths (iDoseL1, iDoseL3, and iDoseL5) for a total of 132 studies. FBP data were collected from 33 controls (average body mass index: 22) undergoing CTPA. Regions of interest were drawn at 6 identical levels in the pulmonary artery (PA), from the main PA to a subsegmental branch, in both the control group and study groups using each algorithm. Noise and attenuation were measured at all PA levels. Three thoracic radiologists graded each study on a scale of 1 (very poor) to 5 (ideal) by 4 categories: image quality, noise, PA enhancement, and "plastic" appearance. Statistical analysis was performed using an unpaired t test, 1-way analysis of variance, and linear weighted κ., Results: Compared with the control group, there was significantly higher noise with FBP, iDoseL1, and iDoseL3 algorithms (P<0.001) in the study group. There was no significant difference between the noise in the control group and iDoseL5 algorithm in the study group. Analysis within the study group showed a significant and progressive decrease in noise and increase in the contrast-to-noise ratio as the level of IR was increased (P<0.001). Compared with FBP, readers graded overall image quality as being higher using iDoseL1 (P=0.0018), iDoseL3 (P<0.001), and iDoseL5 (P<0.001). Compared with FBP, there was subjective improvement in image noise and PA enhancement with increasing levels of iDose., Conclusion: The use of an IR technique leads to qualitative and quantitative improvements in image noise and image quality in obese patients undergoing CTPA.

Lymphoma of the heart and pericardium is usually present as one aspect of disseminated disease and rarely occurs as a primary malignancy. It accounts for 1.3% of primary cardiac tumors and 0.5% of extranodal lymphomas. Cardiac lymphomas are most commonly diffuse large cell lymphomas and frequently manifest as an ill-defined, infiltrative mass. Atrial location is typical; the right atrium is most often affected. Pericardial thickening or effusion is often a common early feature of disease. Infiltration of atrial or ventricular walls with extension along epicardial surfaces is also a notable feature. At computed tomography, the attenuation of cardiac lymphoma may be similar to or lower than that of normal myocardium. At magnetic resonance imaging, it has variable signal intensity and contrast enhancement. Clinical manifestations may include pericardial effusion, cardiac arrhythmias, and a variety of nonspecific electrocardiographic abnormalities, notably first- to third-degree atrioventricular block. Treatment most commonly includes anthracycline-based chemotherapy and anti-CD20 treatment. Chemotherapy has been used alone or combined with radiation therapy. Palliative surgery has been performed, mainly for tumor debulking. The prognosis for patients with either primary or secondary lymphomatous heart involvement is usually poor; late diagnosis is one of the major factors affecting outcome.

Objective: Cardiovascular complications in patients with HIV infection include myocardial, endocardial, pericardial, and vascular diseases. The complications are caused by the HIV infection itself, opportunistic infections, HIV-related tumors, and the side effects of highly active antiretroviral therapy. The article reviews the CT and MRI findings suggestive of HIV-related cardiovascular diseases., Conclusion: The cardiovascular complications of HIV infection frequently overlap, making the diagnosis difficult. CT and MRI are useful for the noninvasive evaluation of these complications.

Acute respiratory illness is defined as one or more of the following: cough, sputum production, chest pain, or dyspnea (with or without fever). The workup of these patients depends on many factors, including clinical presentation and the suspected etiology. This study reviews the literature on the indications and usefulness of radiologic studies for the evaluation of acute respiratory illness in the immunocompetent patient. The following recommendations are the result of evidence-based consensus by the American College of Radiology Appropriateness Criteria Expert Panel on Thoracic Radiology. Chest radiographs are usually appropriate in (1) patients with positive physical examination or risk factors for pneumonia, (2) for the assessment of complicated pneumonia, or (3) in cases of emerging infections and biological warfare agents such as severe acute respiratory syndrome, H1N1, and anthrax. Computed tomography, although having a more limited role, is usually appropriate (1) in the assessment of complicated pneumonia and (2) in patients with suspected severe acute respiratory syndrome, H1N1, or anthrax and a normal radiograph.

Background: Advances in contrast-enhanced multidetector CT enable detailed characterization of the left ventricular myocardium. Myocardial scar and border zone (BZ), as the target of ventricular tachycardia ablations, displays abnormal anatomic, dynamic, and perfusion characteristics during first-pass CT. This study assessed how contrast-enhanced CT can predict voltage-defined scar and BZ and integrate its scar reconstructions into clinical mapping systems to guide ventricular tachycardia ablations., Methods and Results: Eleven patients with ischemic cardiomyopathy underwent contrast-enhanced CT before ventricular tachycardia ablation. Segmental anatomic (end-systolic and end-diastolic wall thickness), dynamic (wall thickening, wall motion), and perfusion (hypoenhancement) characteristics were evaluated. Receiver operating characteristic curves assessed the ability of CT to determine voltage-defined scar and BZ segments. Three-dimensional epi- and endocardial surfaces and scar borders were reconstructed, coregistered, and compared to voltages using a 17-segment model. Abnormal anatomic, dynamic, and perfusion data correlated well with abnormal (<1.5 mV) endocardial voltages (r=0.77). Three-dimensional reconstruction integrated into the clinical mapping system (registration accuracy, 3.31±0.52 mm) allowed prediction of homogenous abnormal voltage (<1.5 mV) in 81.7% of analyzed segments and correctly displayed transmural extent and intramural scar location. CT hypoperfusion correlated best with scar and BZ areas and encompassed curative ablations in 82% cases., Conclusions: Anatomic, dynamic, and perfusion imaging using contrast-enhanced CT allows characterization of left ventricular anatomy and 3D scar and BZ substrate. Integration of reconstructed 3D data sets into clinical mapping systems supplements information of voltage mapping and may enable new image approaches for substrate-guided ventricular tachycardia ablation.

Chronic dyspnea of pulmonary origin raises concern for chronic obstructive pulmonary disease or interstitial lung disease. A chest radiograph is recommended as the initial imaging study. When chest radiography is nonrevealing or provides no definitive diagnosis, a high-resolution chest computed tomography is indicated. The high-resolution chest computed tomography should include expiratory imaging in patients with known or suspected air trapping.

Rationale and Objectives: The purpose of the study was to quantitatively assess the percentage of total lung parenchyma visualized on cardiac computed tomographic angiography (CTA) using standard and tight-coned fields of view (FOVs)., Materials and Methods: The authors evaluated lung volumes in 43 electrocardiogram-gated cardiac CTAs performed as part of triple rule-out/chest pain protocol CTAs over a 9-month period. Using a commercially available software package, a quantitative tissue differentiation analysis was performed using a threshold of -750 Hounsfield units to segment air in the lungs. Using each triple rule-out data set as a starting point, measurements of lung volume were performed with 2 cardiac CTA FOV scenarios, obtained by excluding the periphery of the triple rule-out volume: (1) standard cardiac CTA FOV typically used and recommended by the manufacturer and (2) tight cardiac CTA FOV maximally coned to the heart. For each scenario, the volume of the lung within the restricted FOV was compared with the overall volume of the lungs derived from the triple rule-out study, expressed as a percentage., Results: On the standard cardiac CTA FOV typically used at our institution, a mean of 58% of the lung parenchyma is included with wide variability (range, 26%-86%). On the severely limited FOV, a mean of 14% (range, 7.5%-22%) of the lung parenchyma is included., Conclusions: The percentage of lung parenchyma included in a standard FOV is considerable, although this can be mitigated by using a tight FOV, with potential exclusion of part of the cardiac anatomy. Interpreters of cardiac CTA images should have adequate training and skill in evaluating structures outside the heart.

In a patient with acute respiratory illness (cough, sputum production, chest pain, and/or dyspnea), the need for chest imaging depends on the severity of illness, age of the patient, clinical history, physical and laboratory findings, and other risk factors. Chest radiographs seem warranted when one or more of the following are present: age > or = 40; dementia; a positive physical examination; hemoptysis; associated abnormalities (leukocytosis, hypoxemia); or other risk factors, including coronary artery disease, congestive heart failure, or drug-induced acute respiratory failure. Chest CT may be warranted in complicated cases of severe pneumonia and in febrile neutropenic patients with normal or nonspecific chest radiographic findings. Literature on the indications and usefulness of radiologic studies for acute respiratory illness in different clinical settings is reviewed.

Although echocardiography remains the principal imaging technique for assessment of the cardiac valves, contrast material-enhanced electrocardiographically gated computed tomographic (CT) angiography is proving to be an increasingly valuable complementary modality in this setting. CT angiography allows excellent visualization of the morphologic features and function of the normal valves, as well as of a wide range of valve diseases, including congenital and acquired diseases, infectious endocarditis, and complications of valve replacement. The number, thickness, and opening and closing of the valve leaflets, as well as the presence of valve calcification, can be directly observed. CT angiography also permits simultaneous assessment of the valves and coronary arteries, which may prove valuable in presurgical planning. Unlike echocardiography and magnetic resonance imaging, however, CT angiography requires ionizing radiation and does not provide a direct measure of the valvular pressure gradient. Nevertheless, with further development of related imaging techniques, CT angiography can be expected to play an increasingly important role in the evaluation of the cardiac valves. Supplemental material available at http://radiographics.rsna.org/cgi/content/full/29/5/1393/DC1., ((c) RSNA, 2009.)

Purpose: To study the ability of a computer-aided detection (CAD) system to detect lung cancer overlooked at initial interpretation by the radiologist., Materials and Methods: Institutional review board approval was given for this study. Patient consent was not required; a HIPAA waiver was granted because of the retrospective nature of the data collection. In patients with lung cancer diagnosed from 1995 to 2006 at two institutions, each chest radiograph obtained prior to tumor discovery was evaluated by two radiologists for an overlooked lesion. The size and location of the nodules were documented and graded for subtlety (grades 1-4, 1 = very subtle). Each radiograph with a missed lesion was analyzed by a commercial CAD system, as was the follow-up image at diagnosis. An age- and sex-matched control group was used to assess CAD false-positive rates., Results: Missed lung cancer was found in 89 patients (age range, 51-86 years; mean age, 65 years; 80 men, nine women) on 114 radiographs. Lesion size ranged from 0.4 to 5.5 cm (mean, 1.8 cm). Lesions were most commonly peripheral (n = 63, 71%) and in upper lobes (n = 67, 75%). Lesion subtlety score was 1, 2, 3, or 4 on 43, 49, 17, and five radiographs, respectively. CAD identified 53 (47%) and 46 (52%) undetected lesions on a per-image and per-patient basis, respectively. The average size of lesions detected with CAD was 1.73 cm compared with 1.85 cm for lesions that were undetected (P = .47). A significant difference (P = .017) was found in the average subtlety score between detected lesions (score, 2.06) and undetected lesions (score, 1.68). An average of 3.9 false-positive results occurred per radiograph; an average of 2.4 false-positive results occurred per radiograph for the control group., Conclusion: CAD has the potential to detect approximately half of the lesions overlooked by human readers at chest radiography., ((c) RSNA, 2009.)

Rationale and Objective: The aim of this study was to compare image quality on dedicated and triple rule-out coronary computed tomographic (CT) angiography (CTA) with respect to motion artifacts and the quality of coronary artery opacification., Materials and Methods: Twenty dedicated coronary CT angiographic studies and 20 emergency department triple rule-out CT angiographic studies (ie, to rule out pulmonary embolism, aortic dissection, and acute coronary syndrome) performed on 64-slice CT scanner were selected. Two radiologists, blinded to type of CTA, scored coronary artery image quality. Up to 14 coronary artery segments were scored for motion artifact on a scale ranging from 1 (no motion artifact) to 4 (severe motion artifact). The radiologists also scored the quality of opacification (1 = good opacification, 2 = limited opacification, 3 = vessel not seen). The average of all segments and dedicated larger and smaller coronary artery segments was compared., Results: The average motion-artifact scores per vessel segment for dedicated and triple rule-out studies were 1.64 and 1.72, respectively (P = .6). For larger segments, the average motion-artifact score was 1.41 for dedicated CTA compared to 1.55 for triple rule-out CTA (P = .2). The average coronary artery opacification for dedicated studies was 1.05 for all segments and 1.03 for larger segments, compared to triple rule-out studies, which had scores of 1.09 (P = .5) for all segments and 1.06 (P = .5) for larger segments. No statistically significant differences in favor of dedicated CTA were identified., Conclusion: The image quality of triple rule-out CTA is comparable to that of dedicated coronary CTA, showing no statistically significant difference in motion artifacts or opacification, and therefore may be an alternative and useful diagnostic study in a select group of emergency department patients.

Recent advancement in computed tomography angiography (CTA) has enabled the noninvasive delineation of cardiac valves using this method. Although echocardiography is the current standard, CTA is a valuable complementary imaging method to evaluate valvular morphology and function. In addition, CTA may contribute to the assessment of both congenital and acquired valvular heart disease, infectious endocarditis, and postsurgical complications of valve replacement.

Purpose: To prospectively determine management strategies used by international thoracic radiologists in evaluation of small (3-5-mm) pulmonary nodules at chest computed tomography (CT)., Materials and Methods: Institutional review board exemption was granted for this study, which included consenting participants. An electronic survey was sent to members of major thoracic radiology societies in North America, Europe, and Asia. The main part of the survey consisted of four management questions with clinical scenarios. Associations between recommendations and years of experience, location in a region endemic for granulomatous disease, country, and practice type were assessed. Univariate analysis was performed to determine differences in follow-up recommendations on the basis of patient characteristics, percentage of chest CT scans obtained at follow-up, years of experience in radiology, and professional society affiliation of respondents. Differences in categorical variables were examined by using Pearson chi(2) and Fisher exact tests., Results: Two hundred two (25%) of approximately 800 online surveys were completed. Surveys from respondents from the United States comprised 61% of completed surveys. Median experience of respondents was 11-20 years. Fifty-two percent practice in an area endemic for granulomatous disease. Only 35% of practices have a policy in place for nodule management. In scenarios in which patients had a low likelihood of malignancy, respondents' preferential recommendation was short-term CT follow-up (3-6 months) rather than intermediate-term CT follow-up (12 months) for patients older than 40 years compared with their recommendation in patients younger than 40 years, in whom recommendations for short- or intermediate-term follow-up were roughly equal. In scenarios in which patients had a high risk of malignancy, follow-up was also strongly favored instead of biopsy, with short-term follow-up more commonly advocated. Location in an area endemic for granulomatous disease and years of experience also influenced recommendations., Conclusion: Globally, the most common recommendation for CT evaluation of nodules is short-term follow-up, with a tendency toward less aggressiveness in scenarios in which patients had lower risk of malignancy and increased aggressiveness in scenarios in which patients had higher risk of malignancy., ((c) RSNA, 2008.)

Objectives: This study sought to assess the feasibility of deriving 3-dimensional (3D) scar maps from positron emission tomography (PET)/computed tomography (CT) hybrid imaging and to integrate those into clinical mapping systems to assist in ventricular tachycardia (VT) ablations., Background: Ablation strategies for nonidiopathic VT are increasingly based on the anatomic information of the scar and its border zone. However, the current "gold standard" of voltage mapping is limited by its inability to accurately describe a complex 3D scar morphology, its imperfect spatial resolution, and prolonged procedure times., Methods: Fourteen patients underwent PET/CT multimodality imaging before the VT ablation. We used PET/CT-derived scar maps to characterize myocardial scar using a 17-segment analysis and surface reconstruction. In 10 patients, reconstructed 3D metabolic scar maps were integrated into a clinical mapping system and compared with high-resolution voltage maps., Results: A good correlation was found between the voltage maps and PET/CT-derived scar maps (r = 0.89; r < 0.05). In addition, 3D metabolic scar maps accurately displayed endocardial and epicardial surface and could be successfully integrated with a registration error of 3.7 +/- 0.7 mm. A combination of visual alignment and surface registration was most accurate for myocardial scar accounting for

Objective: Cardiac CT angiography (CTA) is commonly performed after coronary artery bypass grafting surgery (CABG) to assess graft patency, but the images also include parts of the lungs, abdomen, and mediastinum. The purpose of our study was to retrospectively assess the prevalence of unsuspected disease identified on cardiac CTA examinations after CABG and to determine their potential clinical significance., Materials and Methods: CTA was performed postoperatively in 259 patients (mean, 5.2 days), and 40 patients underwent a follow-up CT scan (mean, 12.7 months). Cardiac CTA was acquired using a 16-MDCT scanner with ECG-gating and bolus timing with a small field of view centered on the heart. Two thoracic radiologists assessed each examination in consensus. The prevalence of graft disease and incidental findings (cardiac and noncardiac) was established. The electronic medical record was reviewed. A finding was judged potentially significant if a therapeutic intervention or radiologic follow-up was deemed advisable on the basis of the cardiac CTA. Bypass graft occlusions were analyzed separately., Results: In the immediate postoperative period, 51 patients (19.7%) had at least one unsuspected, potentially significant finding. Twenty-four patients (9.3%) had a cardiac finding such as a ventricular pseudoaneurysm, ventricular perfusion deficit, or intracardiac thrombus, and 34 patients (13.1%) had a noncardiac finding including pulmonary embolism, lung cancer, or pneumonia. At least one bypass graft was occluded in 17 patients (6.6%) in the immediate postoperative period. In the later postoperative period, seven patients (17.5%) had a potentially significant unsuspected finding. Four patients (10.0%) had at least one graft occlusion., Conclusion: Cardiac CTA after CABG revealed a high prevalence of unsuspected cardiac and noncardiac findings with potential clinical significance. Interpreters of these studies should be familiar with the spectrum of these abnormalities.

Distinguishing insignificant from life-threatening causes of acute chest pain in patients who present to the emergency department remains a major challenge. Initial evaluation with history, electrocardiography, and biochemical markers is often unrevealing leading to additional workup. Radionuclide perfusion and echocardiography may be diagnostic but provide only indirect assessment of coronary status. The development of multidetector computed tomography (MDCT) and its increasingly frequent placement near the emergency suite has facilitated its use for the evaluation of serious noncardiac diagnoses such as pulmonary embolism and aortic dissection. Recent innovations in MDCT technology have facilitated the depiction of coronary arteries. These advances have led to the possibility of using CT to evaluate cardiac etiologies of chest pain, using either a comprehensive or triple rule out protocol to assess both cardiac and noncardiac causes or a dedicated coronary protocol. This article will review both options and describes our preliminary experience with the first of these protocols. The article also reviews the potential value of an acute chest pain CT protocol and the considerable challenges that remain prior to its implementation for routine clinical use.

Object: Aortic valve bypass is a technique used in high-risk patients with critical aortic stenosis that consists of placement of a conduit from the left ventricular apex to descending aorta. We describe the imaging appearances of this apicoaortic conduit on multidetector CT (MDCT)., Methods: Each patient underwent retrospective ECG-gated MDCT using a 16-detector-row scanner several days after placement of an apicoaortic conduit. All images were assessed by two radiologists who reviewed the appearance of the apicoaortic conduit and any post-operative complications. Follow-up studies were available for several patients., Results: Twelve patients (9 men, 3 women, mean age - 78 years) underwent evaluation and the conduit was visible in each. The valve within the conduit was visible in ten (91%) of the 11 patients who received intravenous contrast material. Common findings were periconduit outpouching and hypoperfusion involving the left ventricle. Complications included pericardial hemorrhage, hemothorax and ventricular pseudoaneurysm. Mild to moderate increase in wall thinning was identified in the three patients who underwent follow-up imaging., Conclusion: Aortic valve bypass with an apicoaortic conduit appears to be a feasible alternative to aortic valve replacement in high-risk patients. MDCT is an excellent method to assess the imaging features of such conduits.