Comparison of Chest CT Findings of COVID-19, Influenza, and Organizing Pneumonia: A Multireader Study.

BACKGROUND. Previous studies compared CT findings of COVID-19 pneumonia with those of other infections; however, to our knowledge, no studies to date have included noninfectious organizing pneumonia (OP) for comparison. OBJECTIVE. The objectives of this study were to compare chest CT features of COVID-19, influenza, and OP using a multireader design and to assess the performance of radiologists in distinguishing between these conditions. METHODS. This retrospective study included 150 chest CT examinations in 150 patients (mean [± SD] age, 58 ± 16 years) with a diagnosis of COVID-19, influenza, or non-infectious OP (50 randomly selected abnormal CT examinations per diagnosis). Six thoracic radiologists independently assessed CT examinations for 14 individual CT findings and for Radiological Society of North America (RSNA) COVID-19 category and recorded a favored diagnosis. The CT characteristics of the three diagnoses were compared using random-effects models; the diagnostic performance of the readers was assessed. RESULTS. COVID-19 pneumonia was significantly different (p < .05) from influenza pneumonia for seven of 14 chest CT findings, although it was different (p < .05) from OP for four of 14 findings (central or diffuse distribution was seen in 10% and 7% of COVID-19 cases, respectively, vs 20% and 21% of OP cases, respectively; unilateral distribution was seen in 1% of COVID-19 cases vs 7% of OP cases; non-tree-in-bud nodules was seen in 32% of COVID-19 cases vs 53% of OP cases; tree-in-bud nodules were seen in 6% of COVID-19 cases vs 14% of OP cases). A total of 70% of cases of COVID-19, 33% of influenza cases, and 47% of OP cases had typical findings according to RSNA COVID-19 category assessment (p < .001). The mean percentage of correct favored diagnoses compared with actual diagnoses was 44% for COVID-19, 29% for influenza, and 39% for OP. The mean diagnostic accuracy of favored diagnoses was 70% for COVID-19 pneumonia and 68% for both influenza and OP. CONCLUSION. CT findings of COVID-19 substantially overlap with those of influenza and, to a greater extent, those of OP. The diagnostic accuracy of the radiologists was low in a study sample that contained equal proportions of these three types of pneumonia. CLINICAL IMPACT. Recognized challenges in diagnosing COVID-19 by CT are furthered by the strong overlap observed between the appearances of COVID-19 and OP on CT. This challenge may be particularly evident in clinical settings in which there are substantial proportions of patients with potential causes of OP such as ongoing cancer therapy or autoimmune conditions.

Comparison of Baseline, Bone-Subtracted, and Enhanced Chest Radiographs for Detection of Pneumothorax.

PURPOSE: To assess and compare detectability of pneumothorax on unprocessed baseline, single-energy, bone-subtracted, and enhanced frontal chest radiographs (chest X-ray, CXR). METHOD AND MATERIALS: Our retrospective institutional review board-approved study included 202 patients (mean age 53 ± 24 years; 132 men, 70 women) who underwent frontal CXR and had trace, moderate, large, or tension pneumothorax. All patients (except those with tension pneumothorax) had concurrent chest computed tomography (CT). Two radiologists reviewed the CXR and chest CT for pneumothorax on baseline CXR (ground truth). All baseline CXR were processed to generate bone-subtracted and enhanced images (ClearRead X-ray). Four radiologists (R1-R4) assessed the baseline, bone-subtracted, and enhanced images and recorded the presence of pneumothorax (side, size, and confidence for detection) for each image type. Area under the curve (AUC) was calculated with receiver operating characteristic analyses to determine the accuracy of pneumothorax detection. RESULTS: Bone-subtracted images (AUC: 0.89-0.97) had the lowest accuracy for detection of pneumothorax compared to the baseline (AUC: 0.94-0.97) and enhanced (AUC: 0.96-0.99) radiographs (P < .01). Most false-positive and false-negative pneumothoraces were detected on the bone-subtracted images and the least numbers on the enhanced radiographs. Highest detection rates and confidence were noted for the enhanced images (empiric AUC for R1-R4 0.96-0.99). CONCLUSION: Enhanced CXRs are superior to bone-subtracted and unprocessed radiographs for detection of pneumothorax. CLINICAL RELEVANCE/APPLICATION: Enhanced CXRs improve detection of pneumothorax over unprocessed images; bone-subtracted images must be cautiously reviewed to avoid false negatives.

Multimodality Imaging of Focal and Diffuse Fibrosing Mediastinitis.

Fibrosing mediastinitis is a rare benign but potentially life-threatening process that occurs because of proliferation of fibrotic tissue in the mediastinum. The focal subtype is more common and typically is associated with an abnormal immunologic response to Histoplasma capsulatum infection. Affected patients are typically young at presentation, but a wide age range has been reported, without a predilection for either sex. The diffuse form may be idiopathic or associated with autoimmunity, usually affects middle-aged and/or elderly patients, and is more common in men. For both subtypes, patients present with signs and symptoms related to obstruction or compression of vital mediastinal structures. The most common presenting signs and symptoms are cough, dyspnea, recurrent pneumonia, hemoptysis, and pleuritic chest pain. Patients with the diffuse subtype may have additional extrathoracic symptoms depending on the other organ systems involved. Because symptom severity is variable, treatment should be individualized with therapies tailored to alleviate compression of the affected mediastinal structures. Characteristic imaging features of fibrosing mediastinitis include infiltrative mediastinal soft tissue (with or without calcification) with compression or obstruction of mediastinal vascular structures and/or the aerodigestive tract. When identified in the appropriate clinical setting, these characteristic features allow the radiologist to suggest the diagnosis of fibrosing mediastinitis. Careful assessment is crucial at initial and follow-up imaging for exclusion of underlying malignancy, assessment of disease progression, identification of complications, and evaluation of treatment response. Online supplemental material is available for this article. ©RSNA, 2019.

Head and neck skin cancer in the immunocompromised patient: a quantitative analysis.

BACKGROUND: Non-melanoma skin cancers (NMSC) are especially prone to develop in the immunosuppressed population. There is insufficient data regarding outcomes and mortality for immunosuppressed individuals with NMSC of the head and neck. CLINICAL QUESTION: What are the mortality indicators for immunosuppressed subjects with head and neck NMSC? METHODS: This retrospective chart review analyzes all immunosuppressed patients diagnosed with any stage NMSC at an academic tertiary care institution from 2006-2011. RESULTS: Thirty four patients are analyzed. Odds of mortality is significantly increased for patients who required multiple surgeries (adjusted odds ratio (aOR)=23.98, 95%CI=(1.411, 407.599)) and those who were immunocompromised secondary to leukemia (aOR=28.27, 95%CI=(1.838, 434.73)). CONCLUSION: Patients with leukemia and NMSC may have an increased risk of mortality compared to other immunocompromised patients with NMSC. Immunocompromised patients with NMSC may have a worse prognosis if multiple surgeries are required. Knowledge of mortality indicators may aid in the management of these immunocompromised patients.

Trends in coronary calcium score and coronary CT angiography imaging volume during the COVID-19 pandemic.

OBJECTIVES: The COVID-19 pandemic disrupted the delivery of preventative care and management of acute diseases. This study assesses the effect of the COVID-19 pandemic on coronary calcium score and coronary CT angiography imaging volume. MATERIALS AND METHODS: A single institution retrospective review of consecutive patients presenting for coronary calcium score or coronary CT angiography examinations between January 1, 2020 to January 4, 2022 was performed. The weekly volume of calcium score and coronary CT angiogram exams were compared. RESULTS: In total, 1,817 coronary calcium score CT and 5,895 coronary CT angiogram examinations were performed. The average weekly volume of coronary CTA and coronary calcium score CT exams decreased by up to 83% and 100%, respectively, during the COVID-19 peak period compared to baseline (P < 0.0001). The post-COVID recovery through 2020 saw weekly coronary CTA volumes rebound to 86% of baseline (P = 0.024), while coronary calcium score CT volumes remained muted at only a 53% recovery (P < 0.001). In 2021, coronary CTA imaging eclipsed pre-COVID rates (P = 0.012), however coronary calcium score CT volume only reached 67% of baseline (P < 0.001). CONCLUSIONS: A significant decrease in both coronary CTA and coronary calcium score CT volume occurred during the peak-COVID-19 period. In 2020 and 2021, coronary CTA imaging eventually superseded baseline rates, while coronary calcium score CT volumes only reached two thirds of baseline. These findings highlight the importance of resumption of screening exams and should prompt clinicians to be aware of potential undertreatment of patients with coronary artery disease.

Imaging Patterns of Pneumonia.

Imaging findings of pneumonia are diverse, with frequent overlap between the various infectious etiologies of pneumonia, as well as various other disease conditions, including inflammatory conditions, vasculitis, and malignancy. In the appropriate clinical context, a number of imaging findings and the patterns that they form on imaging may provide clues that enable radiologists and clinicians to narrow the differential diagnostic considerations. Although a definite diagnosis can rarely be provided based on imaging findings alone, the combination of clinical, imaging, and laboratory findings are usually sufficient for accurate diagnosis and management decisions. It is important for radiologists to recognize the wide variety of imaging patterns that occur with different causes of pneumonia, and recognize specific imaging signs of certain infections when present, thereby facilitating diagnosis and optimizing patient care.

Imaging of the Anterior/Prevascular Mediastinum.

Prevascular mediastinal masses include a wide range of benign and malignant entities. Localization of mediastinal masses to specific compartments together with characteristic imaging findings and demographic and clinical information allows formulation of a focused differential diagnosis. Radiologists may use these methods to distinguish between surgical and nonsurgical cases and thus inform patient management and have an impact on outcomes. Treatment of choice varies based on the pathology, ranging from no intervention or serial imaging follow-up to surgical excision, chemotherapy, and/or radiation.

Coronary Artery Disease Reporting and Data System (CAD-RADS) Adoption: Analysis of Local Trends in a Large Academic Medical Center.

PURPOSE: To perform a retrospective review of Coronary Artery Disease Reporting and Data System (CAD-RADS) adoption at a high-volume cardiac CT service. MATERIALS AND METHODS: In this retrospective study, the adoption of CAD-RADS in 6562 coronary CT angiography (CTA) reports from January 1, 2017, to February 13, 2020, was evaluated. Reports without CAD-RADS were classified as opt-outs or exceptions to CAD-RADS. CAD-RADS classifications were retrospectively assigned to the opt-outs and the clinical indications for coronary CTA. RESULTS: CAD-RADS scores were reported in 95% (6264 of 6562) of cases. Among the 5% (n = 298) of reports not reported according to CAD-RADS, 58% (n = 172) were considered opt-outs and 42% (n = 126) were exceptions. Cases with higher degree of stenosis, stents, and coronary artery bypass grafts (CABGs) occurred more often in opt-outs versus reports with CAD-RADS (odds ratio [OR], 8.3 [95% CI: 1.6, 42.1]; P < .001). The quarterly opt-out rate decreased over consecutive quarters in the 1st year (OR, 0.77 [95% CI: 0.61, 0.96]; P = .01), then stabilized. Quarterly opt-out rate for patients with stents decreased over time (OR, 0.82 [95% CI: 0.73, 0.92]; P = .008), as did the opt-out rates in patients with CABG (OR, 0.83 [95% CI: 0.76, 0.91]; P < .001). Exceptions (n = 126) included coronary dissections (44%), anomalous coronary arteries (41%), coronary artery aneurysms or pseudoaneurysms (10%), vasculitis (2%), stent complications (2%), and extrinsic compression of grafts (2%). CONCLUSION: CAD-RADS was adopted rapidly and widely. Readers opted out of its use most often in complex cases of CAD, and the most common exceptions were coronary dissections and anomalous coronary artery.Keywords: Coronary Arteries, CT Angiography© RSNA, 2021.

Clinical and Imaging Features of Non-Small-Cell Lung Cancer in Young Patients.

BACKGROUND: Non-small-cell lung cancer (NSCLC) in young adult patients is rare, with scarce data available in patients aged < 40 years and even less in those aged < 35 years. Our goal was to determine the presenting symptoms, clinicopathologic characteristics, and imaging features of young patients with NSCLC at time of diagnosis and compare them to those of older adults. PATIENTS AND METHODS: We retrospectively analyzed the medical records and imaging of young patients (≤ 40 years old) with NSCLC treated at our institution between 1998 and 2018. Patients < 35 years old were compared to those between 35 and 40 years old. Characteristics of patients ≤ 40 years old were compared to older patients (> 40 years) from publicly available data sets. RESULTS: We identified 166 young patients with NSCLC (median age, 36.6 years; range, 18-40 years). Most presented with nonspecific respiratory symptoms and were diagnosed with pneumonia (84/136, 62%). Compared to patients < 35 years old, patients 35-40 years old were more likely to have malignancy detected incidentally (15% vs. 5%, P = .04). Patients < 35 years old were more likely to have central tumors (55% vs. 33%, P = .02) and to have bone (38% vs. 19%, P = .007) and lung (39% vs. 24%, P = .03) metastases. Compared to older patients (> 40 years), young patients were more likely to be never smokers (65.0% vs. 14.7%, P < .001) and to have advanced disease (88% vs. 66%, P < .001). CONCLUSION: Young patients with NSCLC often present with nonspecific symptoms and have advanced disease at diagnosis, often mimicking other pathologies. Awareness of the clinical presentation and imaging features of NSCLC in young patients may help minimize delays in diagnoses.

Implementation of the Radiological Society of North America Expert Consensus Guidelines on Reporting Chest CT Findings Related to COVID-19: A Multireader Performance Study.

BACKGROUND: RSNA expert consensus guidelines provide a framework for reporting CT findings related to COVID-19, but have had limited multireader validation. PURPOSE: To assess the performance of the RSNA guidelines and quantify interobserver variability in application of the guidelines in patients undergoing chest CT for suspected COVID-19 pneumonia. MATERIALS AND METHODS: A retrospective search from 1/15/20 to 3/30/20 identified 89 consecutive CT scans whose radiological report mentioned COVID-19. One positive or two negative RT-PCR tests for COVID-19 were considered the gold standard for diagnosis. Each chest CT scan was evaluated using RSNA guidelines by 9 readers (6 fellowship trained thoracic radiologists and 3 radiology resident trainees). Clinical information was obtained from the electronic medical record. RESULTS: There was strong concordance of findings between radiology training levels with agreement ranging from 60 to 86% among attendings and trainees (kappa 0.43 to 0.86). Sensitivity and specificity of "typical" CT findings for COVID-19 per the RSNA guidelines were on average 86% (range 72%-94%) and 80.2% (range 75-93%), respectively. Combined "typical" and "indeterminate" findings had a sensitivity of 97.5% (range 94-100%) and specificity of 54.7% (range 37-62%). A total of 163 disagreements were seen out of 801 observations (79.6% total agreement). Uncertainty in classification primarily derived from difficulty in ascertaining peripheral distribution, multiple dominant disease processes, or minimal disease. CONCLUSION: The "typical appearance" category for COVID-19 CT reporting has an average sensitivity of 86% and specificity rate of 80%. There is reasonable interreader agreement and good reproducibility across various levels of experience.

Postcardiovascular Surgery Findings of the Thoracic Aorta.

Various disease processes may affect the ascending thoracic aorta, aortic arch, and/or descending thoracic aorta, including aneurysms, dissections, intramural hematomas, penetrating atherosclerotic ulcers, and aortic transection/rupture. Many of those conditions require surgical intervention for repair. Multiple open and endovascular techniques are used for treatment of thoracic aortic pathology. It is imperative that the cardiothoracic radiologist have a thorough knowledge of the surgical techniques available, the expected postoperative imaging findings, and the complications that may occur to accurately diagnose life-threatening pathology when present, and avoid common pitfalls of misinterpreting normal postoperative findings as pathologic conditions.