Imaging of Pleural Effusion: Comparing Ultrasound, X-Ray and CT findings

Transcription

1 Imaging of Pleural Effusion: Comparing Ultrasound, X-Ray and CT findings Poster No.: C-2067 Congress: ECR 2017 Type: Educational Exhibit Authors: J. M. Almeida, N. Antunes, C. Leal, L. Figueiredo ; Lisboa/PT, Lisbon/PT Keywords: Thorax, Lung, CT, Conventional radiography, Ultrasound, Diagnostic procedure, Education and training DOI: /ecr2017/C-2067 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. Page 1 of 18

2 Learning objectives The purpose of our educational exhibit is to review the role of noninvasive imaging modalities for the diagnosis and assessment of pleural effusion. We will compare x-ray, ultrasound (US) and CT findings, illustrating the pros and cons of each modality. Page 2 of 18

3 Background A pleural effusion is an accumulation of fluid in the pleural space, as a consequence of an imbalance between the formation and reabsorption of such fluid. A wide range of diseases may be the cause of a pleural effusion, with different pathogenic mechanisms: elevated hydrostatic pressure gradient (transudation); increased extravasation of the pleural vessels (exudation); due to local inflammatory process; decrease in lymphatic drainage caused by a mechanical obstruction, and decreased oncotic pressure. Diagnostic evaluation of pleural effusion begins by obtaining a clinical history and doing physical examination, followed usually by chest radiography, and analysis of pleural fluid in specific situations. In addition to the chest radiography, US and CT have an important role in some cases. Page 3 of 18

4 Findings and procedure details Chest Radiograph: It is usually the first imaging approach regarding a pleural effusion. The chest posteroanterior (PA) view shows an abnormal blunting of lateral costophrenic angle when pleural fluid is over 200 ml. In the anteroposterior (AP) view, blunting only occurs over 300 ml. In addition, the lateral radiography may show earlier signs, with blunting of the sharp posterior costophrenic angle when fluid exceeds 50 ml. In the lateral decubitus view, pleural effusion is easily detected by free pleural fluids shifting between the dependent chest wall and the lower border of the lung. Fig. 1: Postero-anterior and lateral chest radiography showing a blunt of lateral and posterior costophrenic angle, suggestive of a small pleural effusion. References: - Lisboa/PT Page 4 of 18

5 Fig. 2: Moderate left pleural effusion with the classic meniscus sign. References: - Lisboa/PT Fig. 3: Left hemithorax is opacified by a large pleural effusion. Trachea is pushed towards the right side. References: - Lisboa/PT On the semi-full upright radiograph, increasing amounts of the effusion form a meniscus, opacify the lung and silhouette the diaphragmatic margin. If the effusion is very large, then the entire hemithorax may be opaque and the heart may be pushed towards the normal side. There are other patterns: Page 5 of 18

6 Lamellar: A linear shadow paralleling the lateral aspect of the lung. Encysted: Loculation within a fissure or elsewhere. Subpulmonary: Pooling within the pleural space below the lung. It is usually easier to detect on the left side, where the effusion can cause the gastric air bubble to appear widely separated from the (apparent) superior margin of the diaphragm (>2cm). In addition, it may show displacement of the apex of the apparent diaphragm more laterally. The supine radiograph is relatively insensitive in the detection of pleural fluid, and often underestimates the amount of pleural fluid. The costophrenic angle is often not blunted, and the supine radiograph may only demonstrate hazy "veil-like" opacification caused by layering pleural fluid. Chest radiography may show additional lesions, either pleural (pleural thickening, plaques, masses), pulmonary parenchymal (consolidation, atelectasis, tumor, diffuse reticulo-nodular) or mediastinal, that will direct diagnosis. Ultrasound: Thoracic ultrasonography (TUS) has a higher accuracy in detecting pleural effusion in comparison with bedside chest x-rays, detecting as little as 3mL. It has a sensitivity of 100% for detecting pleural effusion. Ultrasonography can be used under several different situations: Determining the presence of pleural fluid and semiquantification on the amount of pleural fluid. Identification of the appropriate locations for an attempted thoracocentesis, pleural biopsy or chest tube placement. Identification of pleural fluid loculations. Distinction of pleural fluids from thickening The aspect of pleural effusion can suggest the nature of the fluid. It can appear either as echo free (anechoic),, complex septated (fibrin strands or septa), complex nonseptated (heterogeneous echogenic material) or homogeneously echogenic. Page 6 of 18

7 Fig. 4: Different aspects of pleural effusion: anechoic/free (upper left image), complex non septated (upper right), complex septated (lower left) and homogeneously echogenic (lower right). References: - Lisboa/PT Transudative pleural effusions are typically anechoic, and exudative effusions usually have a complex/ecogenic appearance. Although this is generally applied, we should have in mind that 55% of proven transudative pleural effusions have a complex/non septated appearance and up to 27% of exudative effusions are anechoic. Homogenously echogenic collections typically contain blood or debris and almost invariably suggest the presence of empyema. Page 7 of 18

8 Fig. 7: US evaluation of a pleural effusion with patient sitting: very small pleural effusion, unsafe for thoracocentesis. References: - Lisboa/PT The superiority of TUS over chest radiography is particularly evident for small or loculated effusions, because they may appear as mass lesions on the chest radiograph. TUS may also detect tumors in relation with the parietal pleura and the chest wall, guiding biopsy with significant diagnostic yield, low complication rate and cost. Chest Computer Tomography: CT is more sensitive than both conventional chest radiography and US for differentiating pleural fluid from pleural thickening and for identification of focal masses involving the pleura or the chest wall. CT detects small pleural effusions with less than 10 ml and possibly as little as 2 ml of liquid in the pleural space. Thickening of the visceral and parietal pleura as Page 8 of 18

9 well as enhancement of the visceral and parietal pleura after injection of intravenous contrast material (the split pleura sign) suggest the presence of inflammation and thus an exudative, rather than transudative, effusion. The administration of intravenous contrast material in patients with pleural abnormalities helps the differential diagnosis of pleural effusions. Pathological findings: Free flowing pleural effusion: sickle-shaped or crescentic opacity in the most dependent part of the pleural cavity, typically with HU. Page 9 of 18

10 Fig. 5: Free pleural effusion on CT (sickle-shaped or crescentic shape) References: - Lisboa/PT Loculated effusions: Lenticular shape with smooth margins and relatively homogeneous attenuation. Hemothorax is suggested by relatively high attenuation of pleural fluid, commonly 35 to 70 HU. Page 10 of 18

11 Fig. 6: Loculated pleural effusion on CT (Lenticular shape with smooth margins and relatively homogeneous attenuation). References: - Lisboa/PT Other uses of CT scanning in the evaluation of pleural disease includes: Facilitating measurement of pleural thickness. Distinguishing an empyema from a lung abscess. Visualization of small pneumothoraces in supine patients. Visualization of underlying lung parenchymal processes that are obscured on the chest radiograph by a large pleural effusion. Determination of the exact location of pleural masses and characterization of their composition. Occasionally identifying peripheral bronchopleural fistulae. Identification of lung parenchymal or upper abdominal abnormalities that may provide a clue to the etiology of the pleural effusion (eg, lung mass, apical cavities, aortic dissection, subdiaphragmatic abscess, liver cirrhosis with ascites leading to hepatic hydrothorax). Guidance for thoracentesis and tube thoracostomy of loculated empyemas Page 11 of 18

12 Images for this section: Fig. 8: Large pleural effusion that was homogeneously echogenic on US. Thoracocentesis was performed and lab results revealed positive malignant lung cells on pleural effusion. - Lisboa/PT Page 12 of 18

13 Fig. 9: X-ray and CT showing a moderate left pleural effusion. US evaluation revealed a septated pleural effusion. Septae wasn't clearly demonstrated on X-ray or CT. - Lisboa/PT Fig. 10: Right free pleural effusion, before (upper images and lower left) and after thoracocentesis (lower right). Page 13 of 18

14 - Lisboa/PT Fig. 11: Imaging evaluation of a pleural effusion: CT shows a central mass occluding left lower lobar bronchus with atelectasis of left lower lobe. CT allows visualization of underlying lung parenchymal processes that are obscured on the chest radiograph/ ultrasound by a large pleural effusion. - Lisboa/PT Page 14 of 18

15 Fig Lisboa/PT Page 15 of 18

16 Conclusion Chest x-ray and CT are the standard imaging modalities in evaluation of a pleural effusion. US has an important role in small or loculated pleural effusions and guiding interventional procedures. Page 16 of 18

17 Personal information J. M. Almeida, N. Antunes, C. Leal, L. Figueiredo; Lisboa/PT Page 17 of 18

18 References 1. Marios E. Froudarakis MD, PhD; et all - Diagnostic Work-Up of Pleural Effusions; Respiration 2008;75: Moon Jun Na, M.D., Ph.D. ; Diagnostic Tools of Pleural Effusion; Tuberc Respir Dis 2014;76: Mohammad Esmadi et all; Multiloculated pleural effusion detected by ultrasound only in a critically-ill patient; Am J Case Rep, 2013; 14: Matthew P.Moy, MD et all; A New, Simple Method for Estimating Pleural Effusion Size on CT Scans - CHEST / 143 / 4 / APRIL Lynch, David; Chung, Jonathan - Chest imaging: Clinics in Chest medicine volume 36 number 2. Page 18 of 18