Radiographic Imaging of Community-Acquired Pneumonia: A Case-Based Review.

The chest radiograph is the most common imaging examination performed in most radiology departments, and one of the more common indications for these studies is suspected infection. Radiologists must therefore be aware of less common radiographic patterns of pulmonary infection if they are to add value in the interpretation of chest radiographs for this indication. This review uses a case-based format to illustrate a range of imaging findings that can be associated with acute pulmonary infection and highlight findings that should prompt investigation for diseases other than community-acquired pneumonia to prevent misdiagnosis and delays in appropriate management.

Image quality of photon counting and energy integrating chest CT - Prospective head-to-head comparison on same patients.

PURPOSE: To prospectively compare the image quality of high-resolution, low-dose photon-counting detector CT (PCD-CT) with standard energy-integrating-detector CT (EID) on the same patients. METHOD: IRB-approved, prospective study; patients received same-day non-contrast CT on EID and PCD-CT (NAEOTOM Alpha, blinded) with clinical protocols. Four blinded radiologists evaluated subsegmental bronchial wall definition, noise, and overall image quality in randomized order (0 = worst; 100 = best). Cases were quantitatively compared using the average Global-Noise-Index (GNI), Noise-Power-Spectrum average frequency (fav), NPS frequency-peak (fpeak), Task-Transfer-Function-10%-frequency (f10) an adjusted detectability index (d'adj), and applied output radiation doses (CTDIvol). RESULTS: Sixty patients were prospectively imaged (27 men, mean age 67 ± 10 years, mean BMI 27.9 ± 6.5, 15.9-49.4 kg/m2). Subsegmental wall definition was rated significantly better for PCD-CT than EID (mean 71 [56-87] vs 60 [45-76]; P < 0.001), noise was rated higher for PCD-CT (48 [26-69] vs 34 [13-56]; P < 0.001). Overall image quality was rated significantly higher for PCD-CT than EID (66 [48-85] vs 61 [42-79], P = 0.008). Automated image quality measures showed similar differences for PCD-CT vs EID (mean GNI 70 ± 19 HU vs 26 ± 8 HU, fav 0.35 ± 0.02 vs 0.25 ± 0.02 mm-1, fpeak 0.07 ± 0.01 vs 0.09 ± 0.03 mm-1, f10 0.7 ± 0.08 vs 0.6 ± 0.1 mm-1, all p-values < 0.001). PCD-CT showed a 10% average d'adj increase (-49% min, 233% max). PCD-CT studies were acquired at significantly lower radiation doses than EID (mean CTDIvol 4.5 ± 2.1 vs 7.7 ± 3.2 mGy, P < 0.01). CONCLUSION: Though PCD-CT had higher measured and perceived noise, it offered equivalent or better diagnostic quality compared to EID at lower radiation doses, due to its improved resolution.

Imaging of Smoking and Vaping Related Diffuse Lung Injury.

Lung injury associated with smoking tobacco or other substances results in a variety of clinical presentations and imaging patterns, depending on mechanism of injury and substance inhaled. Patients may present in the acute setting, as in the case of acute eosinophilic pneumonia, e-cigarette or vaping product use-associated lung injury, crack lung, or heroin inhalation. They may present with subacute shortness of breath and demonstrate findings of pulmonary Langerhans cell histiocytosis, respiratory bronchiolitis, or desquamative interstitial pneumonia. Alternatively, they may present with chronic dyspnea and demonstrate findings of emphysema or smoking-related interstitial lung fibrosis.

Radiographic Imaging of Community-Acquired Pneumonia: A Case-Based Review.

The chest radiograph is the most common imaging examination performed in most radiology departments, and one of the more common indications for these studies is suspected infection. Radiologists must therefore be aware of less common radiographic patterns of pulmonary infection if they are to add value in the interpretation of chest radiographs for this indication. This review uses a case-based format to illustrate a range of imaging findings that can be associated with acute pulmonary infection and highlight findings that should prompt investigation for diseases other than community-acquired pneumonia to prevent misdiagnosis and delays in appropriate management.

Pulmonary Sarcoidosis: A Pictorial Review.

Sarcoidosis is a multisystem granulomatous process that most commonly involves the lungs. Radiographic findings consistent with sarcoidosis are important to the diagnosis of this disease, as no specific diagnostic test for sarcoidosis exists. The classic imaging manifestations of sarcoidosis are related to granulomatous involvement along the lymphatic pathways within the lungs, granulomatous involvement of lymph nodes, and fibrosis at the sites of previous inflammation. These findings sometimes take atypical forms. Additional manifestations of sarcoidosis are caused by involvement of the bronchi and bronchioles, the pulmonary arteries, and the heart. Fungal colonization may also occur. A range of thoracic imaging manifestations of sarcoidosis is illustrated to facilitate the diagnosis of this common, multifaceted disease.

Clinical and Radiologic Disease in Smokers With Normal Spirometry.

IMPORTANCE: Airflow obstruction on spirometry is universally used to define chronic obstructive pulmonary disease (COPD), and current or former smokers without airflow obstruction may assume that they are disease free. OBJECTIVE: To identify clinical and radiologic evidence of smoking-related disease in a cohort of current and former smokers who did not meet spirometric criteria for COPD, for whom we adopted the discarded label of Global Initiative for Obstructive Lung Disease (GOLD) 0. DESIGN, SETTING, AND PARTICIPANTS: Individuals from the Genetic Epidemiology of COPD (COPDGene) cross-sectional observational study completed spirometry, chest computed tomography (CT) scans, a 6-minute walk, and questionnaires. Participants were recruited from local communities at 21 sites across the United States. The GOLD 0 group (n = 4388) (ratio of forced expiratory volume in the first second of expiration [FEV1] to forced vital capacity >0.7 and FEV1 ≥80% predicted) from the COPDGene study was compared with a GOLD 1 group (n = 794), COPD groups (n = 3690), and a group of never smokers (n = 108). Recruitment began in January 2008 and ended in July 2011. MAIN OUTCOMES AND MEASURES: Physical function impairments, respiratory symptoms, CT abnormalities, use of respiratory medications, and reduced respiratory-specific quality of life. RESULTS: One or more respiratory-related impairments were found in 54.1% (2375 of 4388) of the GOLD 0 group. The GOLD 0 group had worse quality of life (mean [SD] St George's Respiratory Questionnaire total score, 17.0 [18.0] vs 3.8 [6.8] for the never smokers; P < .001) and a lower 6-minute walk distance, and 42.3% (127 of 300) of the GOLD 0 group had CT evidence of emphysema or airway thickening. The FEV1 percent predicted distribution and mean for the GOLD 0 group were lower but still within the normal range for the population. Current smoking was associated with more respiratory symptoms, but former smokers had greater emphysema and gas trapping. Advancing age was associated with smoking cessation and with more CT findings of disease. Individuals with respiratory impairments were more likely to use respiratory medications, and the use of these medications was associated with worse disease. CONCLUSIONS AND RELEVANCE: Lung disease and impairments were common in smokers without spirometric COPD. Based on these results, we project that there are 35 million current and former smokers older than 55 years in the United States who may have unrecognized disease or impairment. The effect of chronic smoking on the lungs and the individual is substantially underestimated when using spirometry alone.

Imaging of complications of thoracic and cardiovascular surgery.

Iatrogenic complications of thoracic and cardiovascular surgery are relatively uncommon, but contribute to potentially significant patient morbidity and mortality. The incidence of iatrogenic disease reflects the complexity of surgical procedures, including lung resection, esophagectomy, coronary artery bypass grafting, thoracic aorta repair, and cardiac valve replacement. Some iatrogenic complications are minor and common to all procedures, whereas others can be potentially devastating and are associated with precise technical components of specific surgeries. Multimodality imaging plays an important role in the diagnosis and management of operative thoracic and cardiovascular iatrogenic disease.

Preliminary evaluation of biplane correlation (BCI) stereographic imaging for lung nodule detection.

A biplane correlation (BCI) imaging system obtains images that can be viewed in stereo, thereby minimizing overlapping structures. This study investigated whether using stereoscopic visualization provides superior lung nodule detection compared to standard postero-anterior (PA) image display. Images were acquired at two oblique views of ±3° as well as at a standard PA position from 60 patients. Images were processed using optimal parameters and displayed on a stereoscopic display. The PA image was viewed in the standard format, while the oblique views were paired to provide a stereoscopic view of the subject. A preliminary observer study was performed with four radiologists who viewed and scored the PA image then viewed and scored the BCI stereoscopic image. The BCI stereoscopic viewing of lung nodules resulted in 71 % sensitivity and 0.31 positive predictive value (PPV) index compared to PA results of 86 % sensitivity and 0.26 PPV index. The sensitivity for lung nodule detection with the BCI stereoscopic system was reduced by 15 %; however, the total number of false positives reported was reduced by 35 % resulting in an improved PPV index of 20 %. The preliminary results indicate observer dependency in terms of relative advantage of either system in the detection of lung nodules, but overall equivalency of the two methods with promising potential for BCI as an adjunct diagnostic technique.

The effects of ambient lighting in chest radiology reading rooms.

Under typical dark chest radiography reading room conditions, a radiologist's pupils contract and dilate as their visual focus intermittently shifts between the high luminance monitor and the darker background wall, resulting in increased visual fatigue and degradation of diagnostic performance. A controlled increase of ambient lighting may minimize these visual adjustments and potentially improve comfort and accuracy. This study was designed to determine the effect of a controlled increase of ambient lighting on chest radiologist nodule detection performance. Four chest radiologists read 100 radiographs (50 normal and 50 containing a subtle nodule) under low (E=1 lx) and elevated (E=50 lx) ambient lighting levels on a DICOM-calibrated, medical-grade liquid crystal display. Radiologists were asked to identify nodule locations and rate their detection confidence. A receiver operating characteristic (ROC) analysis of radiologist results was performed and area under ROC curve (AUC) values calculated for each ambient lighting level. Additionally, radiologist selection times under both illuminance conditions were determined. Average AUC values did not significantly differ (p>0.05) between ambient lighting levels (estimated mean difference=-0.03; 95% CI, (-0.08, 0.03)). Average selection times decreased or remained constant with increased illuminance. The most considerable decreases occurred for false positive identification times (35.4±18.8 to 26.2±14.9 s) and true positive identification times (29.7±18.3 to 24.5±15.5 s). No performance differences were statistically significant. Study findings suggest that a controlled increase of ambient lighting within darkly lit chest radiology reading rooms, to a level more suitable for performance of common radiological tasks, does not appear to have a statistically significant effect on nodule detection performance.

Nonsurgical extracardiac vascular shunts in the thorax: clinical and imaging characteristics.

Extracardiac nonsurgical vascular shunts in the thorax are a group of well-recognized heterogeneous conditions, frequently symptomatic, in which there is diversion of blood flow from one vessel to another or from a vessel to a cardiac chamber. The authors describe and classify many of these nonsurgical extracardiac shunts or fistulas according to their source and endpoint (eg, systemic-to-systemic, systemic-to-pulmonic, pulmonic-to-systemic, and pulmonic-to-pulmonic) and to whether the oxygenated blood mixes with deoxygenated systemic venous flow (left-to-right shunts), deoxygenated blood bypasses the pulmonary capillary bed (right-to-left shunts), or oxygenated blood recirculates (left-to-left shunts). Clinical manifestations and imaging appearances of these conditions are highlighted.

ACR Appropriateness Criteria on acute respiratory illness.

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.

Imaging appearances of the sternum and sternoclavicular joints.

The sternum and sternoclavicular joints--critical structures of the anterior chest wall--may be affected by various anatomic anomalies and pathologic processes, some of which require treatment. Pectus excavatum and pectus carinatum are common congenital anomalies that are usually benign but may warrant surgical treatment if they cause compression of vital internal structures. By contrast, developmental variants such as the sternal foramen are asymptomatic and do not require further evaluation or treatment. Arthritides of the sternoclavicular joint (osteoarthritis, septic arthritis, and seronegative arthropathies) are common and must be differentiated before an appropriate management method can be selected. The recognition of complications of sternotomy (eg, sternal dehiscence, secondary osteomyelitis) is critical to avoid life-threatening sequelae such as acute mediastinitis. Likewise, the detection of sternal fractures and sternoclavicular dislocations is important, especially where they impinge on vital structures. In addition, sternal malignancies (most commonly, metastases and chondrosarcoma) must be distinguished from benign neoplasms. To achieve accurate and timely diagnoses that facilitate appropriate treatment, radiologists must be familiar with the appearances of these normal anatomic variants and diseases of the sternum.

Design and Development of a New Multi-Projection X-Ray System for Chest Imaging.

Overlapping anatomical structures may confound the detection of abnormal pathology, including lung nodules, in conventional single-projection chest radiography. To minimize this fundamental limiting factor, a dedicated digital multi-projection system for chest imaging was recently developed at the Radiology Department of Duke University. We are reporting the design of the multi-projection imaging system and its initial performance in an ongoing clinical trial. The system is capable of acquiring multiple full-field projections of the same patient along both the horizontal and vertical axes at variable speeds and acquisition frame rates. These images acquired in rapid succession from slightly different angles about the posterior-anterior (PA) orientation can be correlated to minimize the influence of overlying anatomy. The developed system has been tested for repeatability and motion blur artifacts to investigate its robustness for clinical trials. Excellent geometrical consistency was found in the tube motion, with positional errors for clinical settings within 1%. The effect of tube-motion on the image quality measured in terms of impact on the Modulation Transfer Function (MTF) was found to be minimal. The system was deemed clinic-ready and a clinical trial was subsequently launched. The flexibility of image acquisition built into the system provides a unique opportunity to easily modify it for different clinical applications, including tomosynthesis, correlation imaging (CI), and stereoscopic imaging.

Imaging manifestations of blastomycosis: a pulmonary infection with potential dissemination.

Pulmonary blastomycosis is an uncommon pathologic condition that is endemic to Canada and the upper Midwest of the United States. Blastomycosis has a variety of radiologic manifestations, including airspace consolidation, focal masses, intermediate-sized nodules, interstitial disease, miliary disease, and cavitary lesions. Affected patients may be asymptomatic or may present with clinical manifestations ranging from mild chronic cough to acute respiratory distress syndrome-like symptoms. Patients with acute symptoms are more likely to have airspace consolidation, whereas chronic manifestations may be associated with masslike lesions. Intermediate-sized nodules with accompanying airspace consolidation, particularly in the upper lobes, should raise suspicion for fungal disease. Lymphadenopathy and pleural effusions are quite uncommon, and calcification is not often seen. Blastomycosis may be aggressive and require treatment. Dissemination from the lung is not unusual and can involve any organ. Diagnosis is often delayed because blastomycosis can mimic many other disease processes, including bacterial pneumonia, malignancy, and tuberculosis. Radiologists can best contribute to the care of patients who live or travel in endemic areas by maintaining a high degree of suspicion for blastomycosis and being familiar with its myriad manifestations.

Imaging of bacterial pulmonary infection in the immunocompetent patient.

Pulmonary infection is a common reason for imaging of the lung and a common incidental finding in immunocompetent patients. Findings on chest radiography are nonspecific in defining acute infection; however, the radiologist should be aware of classically described patterns of infection, including air space, bronchopneumonia, and interstitial patterns. The radiologist must also be aware of potential limitations of the sensitivity of chest radiography. Imaging findings at computed tomography in acute infection have been poorly studied but may be more specific. Aspiration and septic emboli are additional potential radiographic patterns of infection that may be very characteristic in appearance. In the setting of nonresolving pneumonia, the differential diagnosis includes noninfectious causes as well as a variety of atypical infectious agents, specifically, mycobacterial and fungal agents, which have overlapping but distinctive clinical and radiographic presentations.

Incidence and management of occult hemothoraces.

BACKGROUND: Little is known about the incidence of and associated management outcomes of occult hemothorax in blunt trauma patients. The increased use of computed thoracic tomography for the evaluation of the multiply injured blunt trauma patient has led to an increase in the identification of these hemothoraces and management dilemmas. METHODS: A retrospective review of blunt trauma patients with occult hemothoraces was performed. Patients were divided into 2 groups: chest tube versus no chest tube. Outcomes and complications for the 2 groups were defined. Data included demographics, Injury Severity Score, length of stay, need for mechanical ventilation and thoracic consult, pneumonia, and empyema. The size of the occult hemothorax was measured on the computed thoracic tomography. RESULTS: Eighty-eight patients (21.4%) had a total of 107 occult hemothoraces. Patients in the chest tube group were more likely to have a higher Injury Severity Score and an associated occult pneumothorax and to have smaller hemothoraces. CONCLUSIONS: Occult pneumothoraces occur in a significant proportion of the multiply injured blunt trauma population. Small, isolated, occult hemothoraces can be managed safely in the stable patient.

Inherent variability of CT lung nodule measurements in vivo using semiautomated volumetric measurements.

OBJECTIVE: The objective of our study was to evaluate repeatability and reproducibility of lung nodule volume measurements using volumetric nodule-sizing software. MATERIALS AND METHODS: Fifty nodules, less than 20 mm in diameter, in 29 patients were scanned with 1.25-mm collimation using MDCT (time 1 = T1). During the same session, two additional scans, using identical technique, were obtained through each nodule (T2, T3). Three observers working independently then obtained volumetric measurements using a semiautomated volumetric nodule-sizing software package. Qualitative nodule characterization was also performed. The Bland-Altman method for assessing measurement agreement was used to calculate the 95% limits for agreement for nodule volumes at T1, T2, and T3. RESULTS: Automated nodule segmentation was successful in 438 (97%) of 450 measurements. Forty-three nodules were available for final evaluation. Twenty-six nodules had well-defined edges, and 17 had irregular or spiculated margins. Seventeen were freestanding, 16 were juxtapleural, and 10 were juxtavascular in location. Average nodule volume was 345.5 mm(3) (range, 49.3-1,434 mm(3)). The mean interobserver variability (repeatability) was 0.018% (SD = 0.73%), and the SD of the mean for the three contemporaneous scans (reproducibility) was 13.1% (confidence limits, +/- 25.6%). SD and confidence limits narrowed as volumes increased. CONCLUSION: Volumetric measurements show minimal interobserver variability (0.018%) but an interscan SEM of 13.1% (confidence limits, +/- 25.6%). Repeatability and reproducibility of volumetric measurements are better than those of linear measurements reported in the literature.

Clinicians' response to radiologists' reports of isolated subsegmental pulmonary embolism or inconclusive interpretation of pulmonary embolism using MDCT.

OBJECTIVE: The purpose of our study was to investigate clinician response and patient outcome associated with the radiologist's report of isolated subsegmental pulmonary emboli (ISSPE) or indeterminate or inconclusive results on MDCT for venous thromboembolism. MATERIALS AND METHODS: All patients were examined using 8- or 16-MDCT. Reported findings on combined CT pulmonary angiography and CT venography of 1,435 consecutive patients were analyzed retrospectively. The charts of patients of interest with ISSPE or with indeterminate or inconclusive pulmonary embolism results were analyzed for clinician response and recurrent symptoms of venous thromboembolism in both treated and untreated patients during the following 3 months. RESULTS: We studied 207 patients of interest, and follow-up was available on 192 (92.8%) (67 ISSPEs, 125 inconclusive). Of the 192 patients, 25 (37%) of 67 patients with ISSPE and 108 (86%) of 125 patients with inconclusive results did not receive anticoagulation. Two patients with ISSPE and two patients with inconclusive results returned with new symptoms suggesting recurrent venous thromboembolism, but no venous thromboembolism was found. Thirteen (10%) of 133 untreated patients died without clinical evidence of recurrent venous thromboembolism. In 61 patients who received anticoagulation (42/67 [63%] ISSPE and 17/125 [14%] inconclusive), five patients returned with venous thromboembolism symptoms. None had recurrent emboli. Two (3%) of 61 patients who received anticoagulation died of other diseases. CONCLUSION: Patients with ISSPE more commonly received anticoagulation than not. In the patients who did not receive anticoagulation, no recurrent pulmonary embolism was identified on follow-up. In most patients with inconclusive findings on CT pulmonary angiography, clinicians chose to withhold anticoagulation without additional imaging workup. No adverse effects of this clinical decision were uncovered.

CT of deep venous thrombosis and pulmonary embolus: does iso-osmolar contrast agent improve vascular opacification?

PURPOSE: To prospectively compare the vascular attenuation achieved with the iso-osmolar dimeric contrast agent iodixanol with that achieved with the nonionic monomeric contrast agent iohexol for computed tomographic (CT) venography after CT pulmonary angiography. MATERIALS AND METHODS: Institutional review board approval and informed consent were obtained, and 51 consecutive patients undergoing CT pulmonary angiography and CT venography were recruited. A 130-mL dose of iodixanol 320 was injected intravenously at a rate of 4 mL/sec and followed by injection of 50 mL of saline. CT venography was performed after 3.5 minutes. From prior studies, 51 patients of similar weight were picked as control subjects. They received a similar iodine load with iohexol 300 and were studied with a similar technique. Section thickness was 1.25 mm for pulmonary emboli and 5 mm for deep venous thrombosis. Test and control group characteristics (ie, sex, age, and weight) were not significantly different (P >.05). Additionally, in test patients who had undergone CT pulmonary angiography and CT venography during the two preceding years, current and previously obtained CT scans were compared (ie, paired studies). Regions of interest were measured in four pulmonary artery and four lower extremity vein locations by two independent observers. RESULTS: Iodixanol increased average attenuation by 7 HU (P <.05) in the lower extremities and decreased average attenuation by 42 HU (P <.05) in the pulmonary arteries. In the 11 paired studies, similar results were obtained. CONCLUSION: Iodixanol caused a modest but statistically significant improvement in venous attenuation and a decrease in arterial attenuation. The diagnostic importance of this small increase in venous attenuation is not clear.

Incidence of asymptomatic pulmonary embolism in moderately to severely injured trauma patients.

BACKGROUND: Chest computed tomographic (CT) scanning is used frequently to evaluate symptomatic patients for pulmonary embolus (PE). The incidence of PE diagnosed by helical CT scanning in asymptomatic patients is unknown. METHODS: Asymptomatic trauma patients with an Injury Severity Score > or = 9 were studied with contrast-enhanced helical CT images of the chest, pelvis, and lower extremities. Clot burden was assessed using an anatomic scoring system. Patients not receiving anticoagulation were followed. RESULTS: Twenty-two of 90 patients had a PE. Four had major clot burden, including one patient with a saddle embolus. Risk factors for asymptomatic PE include age (odds ratio [OR], 1.04), head injury (OR, 6.78), chest injury (OR, 4.51), lower extremity injury (OR, 5.03), and transfusion (OR, 3.42). Thirty percent of patients receiving pharmacologic prophylaxis had a PE. CONCLUSION: Asymptomatic PE occur in 24% of moderately to severely injured patients. Age, head, chest, and lower extremity injury are associated with an increased risk. Standard thromboembolic prophylaxis is not reliably protective.