Supine Anteroposterior Chest Radiograph Research Articles

The Utility of Special Radiological Signs on Routinely Obtained Supine Anteroposterior Chest Radiographs for the Early Recognition of Neonatal Pneumothorax

Background: Bedside chest radiographs used for the confirmation of diagnosis of pneumothorax in the neonatal intensive care unit (NICU) are routinely obtained in the supine position. However, pneumothoraces may not appear in the classically described forms on these radiographs, resulting in a delayed diagnosis. Objective: To assess the utility of special radiological signs in the neonatal population for the early recognition of pneumothorax. Methods: A case-control study was conducted at a level III referral center from January 2006 to December 2012. For each neonate with pneumothorax, one infant was selected for the control group. A senior radiologist and neonatologist experienced in reading chest radiographs evaluated each radiograph for the presence of special radiological signs. Results: Of the 1,375 infants admitted to the NICU during the study period, 39 had a pneumothorax. A total of 223 radiographs were scored and 46% of the neonates were found to have occult pneumothoraces before they were clinically diagnosed. Twenty-six percent had a single sign detected on a radiograph, whereas 20% had multiple signs. The time interval between the appearance of these signs and clinical diagnosis ranged between 0.5 and 27 h. Conclusions: The present study shows that the recognition of these signs would assist the physician in identifying occult pneumothorax earlier in its course. Physicians dealing with critically ill infants should ensure that they can recognize these radiological signs.

A Porcine Pneumothorax Model for Teaching Ultrasound Diagnostics

Objectives: Ultrasound (US) is a sensitive diagnostic tool for detecting pneumothorax (PTX), but methods are needed to optimally teach this technique outside of direct patient care. In training and research settings, porcine PTX models are sometimes used, but the description of the PTX topography in these models is lacking. The study purpose was to define the distribution of air using the reference imaging standard computed tomography (CT), to see if pleural insufflation of air into a live anaesthetized pig truly imitates a PTX in an injured patient.Methods: A unilateral catheter was inserted into one pleural cavity of each of 20 pigs, and 500 mL of air was insufflated. After a complete thoracic CT scan, the anterior, lateral, medial, basal, apical, and posterior components of the PTXs were compared. The amount of air in each location was quantified by measuring the distance from the lung edge to the chest wall (LE-CW). A supine anteroposterior chest radiograph (CXR) was taken from each model and interpreted by a senior radiologist, and the image results were compared to CT.Results: All 20 hemithoraces with PTX were correctly identified by CT, while six remained occult after interpreting the CXRs. The PTXs were anterior (100%), lateral (95%), medial (80%), basal (60%), apical (45%), and posterior (15%). The major proportion of the insufflated 500-mL volume was found in the anterior, medial, and basal recesses.Conclusions: The authors found the distribution of the intrathoracic air to be similar between a porcine model and that to be expected in human trauma patients, all having predominantly anterior PTX topographies. In a training facility, the model is easy to set up and can be scanned by the participants multiple times. To acquire the necessary skills to perform thoracic US examinations for PTX, the porcine models could be useful.

A computerized method for automated identification of erect posteroanterior and supine anteroposterior chest radiographs

A computerized scheme was developed for automated identification of erect posteroanterior (PA) and supine anteroposterior (AP) chest radiographs. The method was based on three features, the tilt angle of the scapula superior border, the tilt angle of the clavicle and the extent of radiolucence in lung fields, to identify the view of a chest radiograph. The three indices Ascapula, Aclavicle and Clung were determined from a chest image for the three features. Linear discriminant analysis was used to classify PA and AP chest images based on the three indices. The performance of the method was evaluated by receiver operating characteristic analysis. The proposed method was evaluated using a database of 600 PA and 600 AP chest radiographs. The discriminant performances Az of Ascapula, Aclavicle and Clung were 0.878 ± 0.010, 0.683 ± 0.015 and 0.962 ± 0.006, respectively. The combination of the three indices obtained an Az value of 0.979 ± 0.004. The results indicate that the combination of the three indices could yield high discriminant performance. The proposed method could provide radiologists with information about the view of chest radiographs for interpretation or could be used as a preprocessing step for analyzing chest images.

Can cervical spine computed tomography assist in detecting occult pneumothoraces?

Introduction Screening CT often detects posttraumatic pneumothoraces that were not diagnosed on a preceding supine anteroposterior chest radiograph (occult pneumothoraces (OPTXs)). Because abdominal CT imaging misses OPTXs in the upper thorax, the objective of this study was to evaluate the utility of cervical spine (C-spine) CT screening for diagnosing OPTXs. Methods A dual-institution (Foothills Medical Centre and Grady Memorial Hospital) retrospective review of consecutive OPTXs was performed. The accuracy of various CT screening protocols in detecting OPTXs was compared. Results OPTXs were detected in 75 patients. Patient demographics and injury characteristics were similar between centres (65% male; 97% blunt mechanism; 29% hemodynamically unstable; mean ISS = 27; mean length of stay = 22 days; mortality = 9%)( p > 0.05). Patients received either abdominal (41%) or thoraco-abdominal (59%) CT imaging. Most patients (89%) also underwent C-spine CT imaging. OPTXs were evident on thoracic CT in 100% (44/44), abdominal CT in 83% (62/75), and C-spine CT in 82% (55/67) of cases. All patients with OPTXs identified solely on thoracic CT (i.e. not abdominal) who also underwent imaging of their C-spine could have had their OTPXs diagnosed by using the pulmonary windows setting of their C-spine CT series. Combining C-spine and abdominal CT screening diagnosed all OPTXs (67/67) detected on thoracic CT, for patients who also underwent these investigations. Conclusions OPTXs were evident on thoracic (and not abdominal) CT in 17% of severely injured patients. For patients who also underwent C-spine imaging, all OPTXs isolated to thoracic CT could be diagnosed by using the pulmonary windows setting of their C-spine CT imaging protocol. All OPTXs, regardless of intra-thoracic location, could also be detected by combining C-spine and abdominal CT screening.

Pericardial Cyst: Unexpected Finding on a Chest Radiograph

A 32-year-old female presented to the emergency department after a motor vehicle collision with complaints of thoracic back pain. Further history was not obtainable owing to marked ethanol intoxication. Vital signs and physical examination were unremarkable except for a mild tachycardia, which resolved with intravenous fluids. A chest radiograph was obtained (Figure 1). Medical records' review revealed that the same abnormality had been noted 17 months earlier (Figure 2). Figure 1. Supine anteroposterior chest radiograph showing (arrow) a 6 × 8-cm focal mass in the left lung base. Figure 2. Chest computed tomographic scan with intravenous contrast obtained 17 months previously and showing (arrow) a 4.5 × 2.8-cm, well-defined, encapsulated fluid collection contiguous with the left heart border.

Sensitivity of Bedside Ultrasound and Supine Anteroposterior Chest Radiographs for the Identification of Pneumothorax After Blunt Trauma

Supine anteroposterior (AP) chest radiographs in patients with blunt trauma have poor sensitivity for the identification of pneumothorax. Ultrasound (US) has been proposed as an alternative screening test for pneumothorax in this population. The authors conducted an evidence-based review of the medical literature to compare sensitivity of bedside US and AP chest radiographs in identifying pneumothorax after blunt trauma. MEDLINE and EMBASE databases were searched for trials from 1965 through June 2009 using a search strategy derived from the following PICO formulation of our clinical question: patients included adult (18 + years) emergency department (ED) patients in whom pneumothorax was suspected after blunt trauma. The intervention was thoracic ultrasonography for the detection of pneumothorax. The comparator was the supine AP chest radiograph during the initial evaluation of the patient. The outcome was the diagnostic performance of US in identifying the presence of pneumothorax in the study population. The criterion standard for the presence or absence of pneumothorax was computed tomography (CT) of the chest or a rush of air during thoracostomy tube placement (in unstable patients). Prospective, observational trials of emergency physician (EP)-performed thoracic US were included. Trials in which the exams were performed by radiologists or surgeons, or trials that investigated patients suffering penetrating trauma or with spontaneous or iatrogenic pneumothoraces, were excluded. The methodologic quality of the studies was assessed. Qualitative methods were used to summarize the study results. Data analysis consisted of test performance (sensitivity and specificity, with 95% confidence intervals [CIs]) of thoracic US and supine AP chest radiography. Four prospective observational studies were identified, with a total of 606 subjects who met the inclusion and exclusion criteria. The sensitivity and specificity of US for the detection of pneumothorax ranged from 86% to 98% and 97% to 100%, respectively. The sensitivity of supine AP chest radiographs for the detection of pneumothorax ranged from 28% to 75%. The specificity of supine AP chest radiographs was 100% in all included studies. This evidence-based review suggests that bedside thoracic US is a more sensitive screening test than supine AP chest radiography for the detection of pneumothorax in adult patients with blunt chest trauma.

Traumatic Pulmonary Pseudocysts

Traumatic pulmonary pseudocyst constitutes an uncommon, though well recognized, manifestation of closed chest trauma. It is usually encountered in young patients, whose compliant chest wall permits the transmission of great compressive forces to the lung parenchyma and the laceration of the latter. Traumatic pulmonary pseudocyst is usually detected during the imaging evaluation of multi-injured patients with the use of computed tomography, as it is often not apparent in the initial supine anteroposterior chest radiographs. We present 5 cases of trauma patients, in whom we detected the presence of multiple traumatic pulmonary pseudocysts during the imaging evaluation of blunt chest trauma with the use of computed tomography.

Incidence, Risk Factors, and Outcomes for Occult Pneumothoraces in Victims of Major Trauma

The supine anteroposterior chest radiograph (CXR) is an insensitive test for posttraumatic pneumothoraces (PTXs). Computed tomographic (CT) scanning often detects PTXs that were not diagnosed on CXR (occult PTXs [OPTXs]). The purpose of this study was to define the incidence, predictors, and outcomes for OPTXs after trauma. Thoracoabdominal CT scans and corresponding CXRs of all trauma patients entered into a regional database were reviewed. Patients with OPTXs were compared with those with overt, residual, and no PTXs regarding incidence, demographics, associated injuries, early resuscitative predictors, treatment, and outcomes. Paired CXRs and CT scans were available for 338 of 761 (44%) patients (98.5% blunt trauma). One hundred three PTXs were present in 89 patients, 57 (55%) of which were occult; 6 (11%) were seen only on thoracic CT scan. Age, sex, length of stay, and survival were similar between all groups. OPTXs and PTXs were similar in comparative size index and number of images. Subcutaneous emphysema, pulmonary contusion, rib fracture(s), and female sex were independent predictors of OPTXs. Seventeen (35%) patients with OPTXs were ventilated, of whom 13 (76%) underwent thoracostomy. No complications resulted from observation, although 23% of patients with thoracostomy had tube-related complications or required repositioning. OPTXs are commonly missed both by CXR and even abdominal CT scanning in seriously injured patients. Basic markers available early in resuscitation are highly predictive for OPTXs and may guide management before CT scanning. Further study of OPTX detection and management is required.

A Prospective Comparison of Supine Chest Radiography and Bedside Ultrasound for the Diagnosis of Traumatic Pneumothorax

Background: Supine anteroposterior (AP) chest radiography may not detect the presence of a small or medium pneumothorax (PTX) in trauma patients. Objectives: To compare the sensitivity and specificity of bedside ultrasound (US) in the emergency department (ED) with supine portable AP chest radiography for the detection of PTX in trauma patients, and to determine whether US can grade the size of the PTX. Methods: This was a prospective, single-blinded study with convenience sampling, based on researcher availability, of blunt trauma patients at a Level 1 trauma center with an annual census of 75,000 patients. Enrollment criteria were adult trauma patients receiving computed tomography (CT) of the abdomen and pelvis (which includes lung windows at the authors' institution). Patients in whom the examination could not be completed were excluded. During the initial evaluation, attending emergency physicians performed bedside trauma US examinations to determine the presence of a sliding lung sign to rule out PTX. Portable, supine AP chest radiographs were evaluated by an attending trauma physician, blinded to the results of the thoracic US. The CT results (used as the criterion standard), or air release on chest tube placement, were compared with US and chest radiograph findings. Sensitivities and specificities with 95% confidence intervals (95% CIs) were calculated for US and AP chest radiography for the detection of PTX, and Spearman's rank correlation was used to evaluate for the ability of US to predict the size of the PTX on CT. Results: A total of 176 patients were enrolled in the study over an eight-month period. Twelve patients had a chest tube placed prior to CT. Pneumothorax was detected in 53 (30%) patients by US, and 40 (23%) by chest radiography. There were 53 (30%) true positives by CT or on chest tube placement. The sensitivity for chest radiography was 75.5% (95% CI = 61.7% to 86.2%) and the specificity was 100% (95% CI = 97.1% to 100%). The sensitivity for US was 98.1% (95% CI = 89.9% to 99.9%) and the specificity was 99.2% (95% CI = 95.6% to 99.9%). The positive likelihood ratio for a PTX was 121. Spearman's rank correlation showed at ρ of 0.82. Conclusions: With CT as the criterion standard, US is more sensitive than flat AP chest radiography in the diagnosis of traumatic PTX. Furthermore, US allowed sonologists to differentiate between small, medium, and large PTXs with good agreement with CT results.

A Prospective Comparison of Supine Chest Radiography and Bedside Ultrasound for the Diagnosis of Traumatic Pneumothorax

Supine anteroposterior (AP) chest radiography may not detect the presence of a small or medium pneumothorax (PTX) in trauma patients. To compare the sensitivity and specificity of bedside ultrasound (US) in the emergency department (ED) with supine portable AP chest radiography for the detection of PTX in trauma patients, and to determine whether US can grade the size of the PTX. This was a prospective, single-blinded study with convenience sampling, based on researcher availability, of blunt trauma patients at a Level 1 trauma center with an annual census of 75,000 patients. Enrollment criteria were adult trauma patients receiving computed tomography (CT) of the abdomen and pelvis (which includes lung windows at the authors' institution). Patients in whom the examination could not be completed were excluded. During the initial evaluation, attending emergency physicians performed bedside trauma US examinations to determine the presence of a sliding lung sign to rule out PTX. Portable, supine AP chest radiographs were evaluated by an attending trauma physician, blinded to the results of the thoracic US. The CT results (used as the criterion standard), or air release on chest tube placement, were compared with US and chest radiograph findings. Sensitivities and specificities with 95% confidence intervals (95% CIs) were calculated for US and AP chest radiography for the detection of PTX, and Spearman's rank correlation was used to evaluate for the ability of US to predict the size of the PTX on CT. A total of 176 patients were enrolled in the study over an eight-month period. Twelve patients had a chest tube placed prior to CT. Pneumothorax was detected in 53 (30%) patients by US, and 40 (23%) by chest radiography. There were 53 (30%) true positives by CT or on chest tube placement. The sensitivity for chest radiography was 75.5% (95% CI = 61.7% to 86.2%) and the specificity was 100% (95% CI = 97.1% to 100%). The sensitivity for US was 98.1% (95% CI = 89.9% to 99.9%) and the specificity was 99.2% (95% CI = 95.6% to 99.9%). The positive likelihood ratio for a PTX was 121. Spearman's rank correlation showed at rho of 0.82. With CT as the criterion standard, US is more sensitive than flat AP chest radiography in the diagnosis of traumatic PTX. Furthermore, US allowed sonologists to differentiate between small, medium, and large PTXs with good agreement with CT results.

Ultrasound Better Than AP Chest X-Ray for Traumatic Pneumothorax?

Pneumothorax can be difficult to discern on supine anteroposterior chest radiographs (APCXR), in part because gravity prompts air to collect anteromedially, and a visible pleural stripe can be absent. Extended focused assessment with sonography for trauma (EFAST) detects gliding of the parietal and visceropleural surfaces over one another and comet-tail, a hyperechoic reverberation artifact that is present in normally opposed pleural surfaces. In the appropriate clinical context, an absence of …

Mediastinal Evaluation Utilizing the Reverse Trendelenburg Radiograph

When thoracic aortic rupture is suspected, a 45-degree reverse Trendelenburg (RT) anteroposterior (AP) chest radiograph should place the mediastinal structures in a more appropriate position and allow a more accurate evaluation than a supine AP radiograph. One hundred ninety-one consecutive hemodynamically stable adult patients with major blunt thoracic trauma were initially evaluated for mediastinal abnormalities associated with aortic disruption by both supine AP chest radiograph and an AP chest radiograph with the patient in 45-degree RT position. One hundred four patients underwent contrast aortography based on mediastinal abnormalities detected on the supine AP chest radiograph. Twenty of these patients had abnormal aortograms demonstrating traumatic aortic disruption confirmed at surgery. Supine and RT chest radiographs were retrospectively compared in a blinded fashion to evaluate their specificity and positive predictive value for detection of traumatic thoracic aortic rupture. If RT chest radiographic findings had been used to determine the need for further assessment, 29 angiograms (26%) would have been eliminated, specificity would have increased from 52 per cent to 69 per cent, and positive predictive value would have increased from 19 per cent to 27 per cent. Both supine and RT chest radiographs demonstrated mediastinal widening in all 20 patients with abnormal aortograms, with no missed thoracic aortic disruptions (100% sensitivity). This study indicated that the RT chest radiograph may be used instead of the standard supine radiograph as the initial screen for mediastinal evaluation, maintaining a high sensitivity and eliminating the cost and morbidity of many unnecessary aortograms.

Pneumothorax size: correlation of supine anteroposterior with erect posteroanterior chest radiographs.

Findings in 30 consecutive patients with pneumothorax were prospectively analyzed. All patients underwent supine anteroposterior (AP) and erect posteroanterior (PA) chest radiography. The interpleural distances were measured at three locations. Average interpleural distances on supine AP and erect PA radiographs were analyzed by means of correlation and linear regression analysis. The authors developed a formula that can be used to estimate the size of a pneumothorax on a supine AP chest radiograph.