The abnormality is on the lateral chest X-ray: What does the frontal chest radiograph look like?

The abnormality is on the lateral chest X-ray: What does the frontal chest radiograph look like? Poster No.: C-216 Congress: ECR 2009 Type: Educational Exhibit Topic: Chest Authors: D. Y. F. Chung, R. R. Misra ; Oxford/UK, High Wycombe/UK Keywords: patient dosimetry, Chest radiology, Lateral chest radigraph DOI: 10.1594/ecr2009/C-216 1 2 1 2 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. www.myesr.org Page 1 of 47

Learning objectives To present a pictorial review of 'abnormalities' present on a lateral chest xray (CXR), asking the question, 'What does the abnormality look like on the frontal radiograph?'. This is to emphasize the importance of the lateral view in problem solving without having to automatically recourse to CT, thereby minimising patient dose wherever possible. Background The frontal CXR is an extremely commonly requested investigation. By comparison, requests for lateral CXR's are in decline. The reasons can only be surmised, but rapid access to CT, for a 'CXR abnormality', is likely the main driving factor. We have a duty of care to minimize patient doses wherever possible, and the Ionizing Radiation Regulations (UK) and media attention have made patients' acutely aware of this. We present many examples where CT may be avoided, if a lateral view is initially considered. Imaging findings OR Procedure details Firstly we review the normal radiological anatomy of the lateral CXR. We then review several 'abnormal' lateral views, asking the question 'what does the abnormality look like on the frontal view?'. Finally we review the corresponding frontal CXR for each case, highlighting the lateral view appearances, thereby demonstrating why diagnostic CT may be avoided. Radiological Anatomy The normal radiological anatomy of the lateral CXR will be reviewed as follows:- 1. 2. 3. 4. Lobar and pleural anatomy Central hilar stuctures Assessment of diaphragms Assessment of normal parenchymal density Page 2 of 47

5. Mediastinal compartments Fig.: a. Diagram showing the frontal view of a chest radiograph. Fissures formed by parietal and visceral pleural coming together; these separate out the individual lobes of the lungs.b. Right lateral view showing a horizontal fissure (HF) in the right lung, in addition to an oblique fissure (OF). The upper lobe sits above the horizontal fissure, the lower lobe below the oblique fissure and the middle lobe between the two.c. Left lateral view demonstrating the oblique fissure (OF) separating the upper lobe and lower lobes. Page 3 of 47

Fig. Page 4 of 47

Fig.: Right lateral chest radiograph demonstrating the outlines of the diaphragms.red line denotes the right hemidiaphragm which extends from the posterior to the anterior chest wall and lies more superior to the left hemidiaphragm (orange line).orange line denotes the left hemidiaphragm which extends from the posterior chest wall and stops at the posterior heart border. Air is seen within the stomach fundus projected inferior to this. Page 5 of 47

Fig.: Right lateral chest radiograph demonstrating the normal reduced density as one progress from the superior to the inferior part of the posterior mediastinum. The retrosternal and the retrocardiac space should be of similar density as demonstrated on this chest radiograph. Page 6 of 47

Fig.: Right lateral chest radiograph with the three mediastinal compartments outlined. It is useful to consider the various structures contained within these thereby helping to diagnose the abnormality.anterior mediastinum: anterior to the pericardium and trachea.middle mediastinum: between the anterior and posterior mediastinum.posterior mediastinum: posterior to the pericardial surface. Case Review Section Page 7 of 47

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Fig.: What are the radiological features and what does the abnormality look like on the frontal radiograph? Fig.: The oesophagus is dilated throughout its length and of increased density due to contained debris. Additional soft tissue shadow can be seen adjacent to the right mediastinal contour on the frontal view which mimics a soft tissue mass. Note also the absence of gastric bubble. Diagnosis: Achalasia Page 9 of 47

Fig.: What are the radiological features and what does the abnormality look like on the frontal radiograph? Page 10 of 47

Fig.: There is linear opacity within the retrocardiac space with effacement of the posterior aspect of the left hemidiaphragm. This results in increased density as compared to the retrosternal air space.corresponding linear opacity can be seen in the left lower zone on the frontal view. Diagnosis: Left basal atelectasis Page 11 of 47

Fig.: What are the radiological features and what does the abnormality look like on the frontal radiograph? Page 12 of 47

Fig.: Homogenous soft tissue density mass is seen herniating through the posterior aspect of the right hemidiaphragm. An apparent mass can be seen at the right lung base on the frontal projection. This would often warrant further investigation with CT; however the features described (indicated by the arrows on the lateral chest radiograph) are consistent with a Bochdalek hernia (15% occurs on the right), a benign finding. Diagnosis: Bochdalek hernia Page 13 of 47

Fig.: What are the radiological features and what does the abnormality look like on the frontal radiograph? Page 14 of 47

Fig.: Multiple rounded homogenous soft density lesions seen throughout the lungs.density of the posterior mediastinum does not progressively reduce inferiorly. Increased density is also seen within the retrosternal space.corresponding multiple rounded soft tissue opacities within both lungs on the frontal view. The appearance is consistent with multiple parenchymal masses. Diagnosis: Cannon ball metastasis Page 15 of 47

Fig.: What are the radiological features and what does the abnormality look like on the frontal radiograph? Page 16 of 47

Fig.: Right lateral projection demonstrates a rounded opacity projected over several thoracic vertebralbodies. The opacity has central lucent area consistent with cavitation, and lies inferior to theoblique fissure. The appearances are consistent with a cavitating mass within the right lower lobe.this can be seen on the frontal projection in the right lower zone adjacent to a crisp right heartborder i.e. the mass does not involve the middle lobe. This correlates with the lateral projectionwhere the mass lies in the lower posterior mediastinum within the lower lobe. Despite confirmingthe location of the mass, further investigation would still be warranted in this case. Diagnosis: Cavitating mass Page 17 of 47

Fig.: What are the radiological features and what does the abnormality look like on the frontal radiograph? Page 18 of 47

Fig.: Increase AP diameter of the chest with an increase in the retro-sternal airspace causing a 'barrel-shaped' appearance. The frontal projection demonstrates hyperinflation of the lungs with flattening of the diaphragms, and correlates with the findings on the lateral projection. Diagnosis: Chronic obstructive pulmonary disease Page 19 of 47

Fig.: What are the radiological features and what does the abnormality look like on the frontal radiograph? Page 20 of 47

Fig.: Dense opacity seen lying superior to the oblique and horizontal fissure. Corresponding homogenous dense opacity within the right upper zone seen on the frontal projection. This correlates with features on the lateral projection. Diagnosis: Right upper lobe collapse Page 21 of 47

Fig.: What are the radiological features and what does the abnormality look like on the frontal radiograph? Page 22 of 47

Fig.: There is increase opacification in the anterior mediastinum and the retro-sternal space. The oblique fissure lies in a more vertical and anterior position. On the frontal view, increased opacification is seen in the left lung, especially the upper zone, with a veiling density below. Appearances are consistent with left upper lobe collapse. The anteriorly displaced oblique fissure (yellow line) results from volume loss from the collapsed upper lobe and compensatory hyperexpansion of the left lower lobe (asterix). Diagnosis: Left upper lobe collapse Page 23 of 47

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Fig.: What are the radiological features and what does the abnormality look like on the frontal radiograph? Fig.: There is increase opacification anterior to the oblique fissure on this right lateral projection. Dense opacification involves most of the left hemithorax obscuring the left heart border but not the left hemidiaphragm. This correlates with the finding on the lateral projection and the features are consistent with left upper lobe consolidation. The oblique fissure in this case is not displaced as seen in the case of collapse as there is no loss of volume from the consolidation. Diagnosis: Left upper lobe consolidation Page 25 of 47

Fig.: What are the radiological features and what does the abnormality look like on the frontal radiograph? Page 26 of 47

Fig.: Dense opacification lies between the oblique and horizontal fissures. Dense opacification is seen in the right mid zone on the frontal projection which abuts the horizontal fissure and obscure the right heart border. Diagnosis: Right middle lobe consolidation Page 27 of 47

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Fig.: What are the radiological features and what does the abnormality look like on the frontal radiograph? Fig.: Progressive increased density is seen within the inferior aspect of the posterior mediastinum, towards the right base. The density of the retrocardiac space should be similar to retrosternal space. On the frontal view, patchy opacification is seen in the right lower zone with preservation of the right heart border and, in this case, the right hemidiaphragm. This correlates with the features on the lateral projection and is consistent with right lower lobe consolidation. Diagnosis: Right lower lobe consolidation Page 29 of 47

Fig.: What are the radiological features and what does the abnormality look like on the frontal radiograph? Page 30 of 47

Fig.: The right hemidiaphragm is clearly visible from the anterior to posterior chest wall. The anterior aspect is markedly elevated. Corresponding elevation of the right hemidiaphragm is seen on the frontal projection which could be mistaken for a mass in the right lower zone. However the lateral view confirms this as a diaphragmatic contour abnormality. Diagnosis: Elevated hemidiaphragm Page 31 of 47

Fig.: What are the radiological features and what does the abnormality look like on the frontal radiograph? Page 32 of 47

Fig.: An air-fluid level can be seen in the middle mediastinum (arrows). There is the suggestion of a retrocardiac mass on the frontal projection which may be a hiatus hernia or a cavitating mass. However the lateral projection confirms the presence of a hiatus hernia. Diagnosis: Hiatus hernia Page 33 of 47

Fig.: What are the radiological features and what does the abnormality look like on the frontal radiograph? Page 34 of 47

Fig.: There is a round density projected over the retrocardiac space on the lateral view. The frontal projection demonstrates the presence of a mass within in the right lower zone, which could be interpreted as parenchymal or extra parenchymal in nature. However the lateral projection confirms that the lesion is within the lung parenchyma and provides justification for further investigation with CT. Diagnosis: Right lower zone mass Page 35 of 47

Fig.: What are the radiological features and what does the abnormality look like on the frontal radiograph? Page 36 of 47

Fig.: Increased density is seen within the subcutaneous soft tissue of the anterior chest wall. Rounded opacity with well defined edges is seen in the right lower zone, not abutting the horizontal fissure or the right heart border. A pulmonary nodule could be suspected, but on the lateral view, the density is seen within soft tissue and is consistent with a nipple shadow and further imaging is not required. Diagnosis: Nipple shadow Page 37 of 47

Fig.: What are the radiological features and what does the abnormality look like on the frontal radiograph? Page 38 of 47

Fig.: A large confluent mass, with a well defined superior and inferior margin, is seen obscuring the cardiac density on the lateral view. On the frontal view a sharply marginated mass lesion is seen extending towards the right costo-phrenic angle, and is inseparable from the right heart border. This could be mistaken for a parenchymal soft tissue mass. However the lateral view confirms this as pericardial in origin. Diagnosis: Pericardial cyst Page 39 of 47

Fig.: What are the radiological features and what does the abnormality look like on the frontal radiograph? Page 40 of 47

Fig.: The arch and descending aorta are tortuous, with a focal saccular projection seen arising from the proximal descending aorta on the lateral view. On the frontal view a soft tissue density mass is seen in the region of the left hilum. The exact nature of this mass may require further imaging, if a carcinoma is suspected. However the lateral projection confirms this to be aortic in origin. Diagnosis: Thoracic aortic aneurysm Page 41 of 47

Fig.: What are the radiological features and what does the abnormality look like on the frontal radiograph? Page 42 of 47

Fig.: Large volume soft tissue opacification is projected over the left hilar area on the lateral projection. Corresponding left mid zone consolidation seen on the lateral view. Diagnosis: Left mid zone consolidation Page 43 of 47

Fig.: What are the radiological features and what does the abnormality look like on the frontal radiograph? Page 44 of 47

Fig.: Deformity of the sternum, with reduction in the AP diameter of the thorax, is seen on the lateral view. On the frontal view this correlates with the posterior ribs adopting a more horizontal position, and the anterior ribs a more vertical position than usual; the so called 'seven, reverse seven' orientation. The deformity causes displacement of the mediastinum to the left, creating the false impression of right middle lobe pathology. Diagnosis: Pectus excavatum Images for this section: Page 45 of 47

Fig. 1: a. Diagram showing the frontal view of a chest radiograph. Fissures formed by parietal and visceral pleural coming together; these separate out the individual lobes of the lungs.b. Right lateral view showing a horizontal fissure (HF) in the right lung, in addition to an oblique fissure (OF). The upper lobe sits above the horizontal fissure, the lower lobe below the oblique fissure and the middle lobe between the two.c. Left lateral view demonstrating the oblique fissure (OF) separating the upper lobe and lower lobes. Page 46 of 47

Conclusion This review should help the viewers reacquaint themselves with the clinical usefulness of the lateral CXR, and to appreciate its value in dealing with an 'abnormal' frontal radiograph, thus avoiding unnecessary CT radiation exposure. Conversely, the lateral CXR can also be used to provide further justification for radiation exposure when CT imaging is being considered. Personal Information References Page 47 of 47