Chest Imaging (Chapter 10) PDF

Clinical Application of the Chest Radiograph  Indications for Chest Radiograph Detecting abnormal pulmonary conditions. Determining appropriate therapy. Evaluating effectiveness of treatment. Determining position of invasive devices (tubes, catheters, etc). Observin...

Clinical Application of the Chest Radiograph  Indications for Chest Radiograph Detecting abnormal pulmonary conditions. Determining appropriate therapy. Evaluating effectiveness of treatment. Determining position of invasive devices (tubes, catheters, etc). Observing progression of lung disease. Brightness Comparison on Chest X-ray  Radiopaque vs. Radiolucid Appearance Dense objects absorb more x-rays-opacity – Bone/tissue. – Less penetration – Radiopaque: less darkening/white shadows. Air-filled objects absorb less x-rays- lucencies – Lung tissue. – More penetration. – Radiolucid: more darkening/black  PA View Posteroanterior View (PA) – Patient instructed to take a deep breath before exposure. Patient upright with back to x- ray source, anterior chest against metal cassette containing the film, and arms out of the way. This helps move scapulae out of the way. PA Chest Radiograph Lateral Chest X-Ray  Compartments/Main Structures of the Lateral Chest X-Ray Middle compartment Anterior Compartment Trachea, bronchi, lymph Fat, lymph nodes, nodes, esophagus, thymus, heart, descending aorta ascending aorta. Posterior Compartment Vertebral column and soft tissue Lateral Chest X-ray RUL LUL RLL ML LLL  Lateral View Preferred to avoid cardiac magnification  Portable CXR (AP view) Typically obtained in critically ill patients. X-ray source is placed in front of the patient and film behind patient’s back. Interpretation of the film: – AP film is usually not centered. – Overexposed or underexposed. – Full vs partial inspiration. – Extrathoracic shadows: bedding, gowns, ECG leads, tubing. Evaluate placement of tubes and lines. Portable Chest X-ray: AP View  Anteroposterior (AP) View Heart Size: PA vs. AP Anterior Ribs and Posterior Ribs Lung Fissures Lobe Opacity Lobe Anatomy  Special Radiographic Views Lateral Decubitus – Patient laying down one of the sides to see free fluid in the chest. – As little as 25-50 ml of pleural fluid could be detected with this view. – Also useful in identifying pneumothorax (air tends to raise). Lateral Decubitus Position Lateral Decubitus  Evaluation of Lines and Tubes ORAL AND NASAL TRACHEAL TUBES – Inferior tip should be 3-5 cm above the carina, or between the clavicles. – R or L mainstem intubation should be recognized. CVP and Swan-Ganz Placement – Assess proper placement of the tip of the catheter. – Usually placed through subclavian or jugular vein. – Should rest into SVC or R atrium/ Pulmonary artery. – A CXR is required immediately after catheter insertion to confirm placement and rule out complications. NG Tubes Chest Tubes Evaluation of line and tubes  Nasogastric Tube Proper position Improper position-tube to high Rib Fracture Right Main Stem Intubation Right Main Stem Intubation ETT Placement Too high RULE OF THUMB ETT positioned properly at the Good Position medial ends of the clavicles (T5-T7) or 3-5 cm above the carina Too low  ETT and Rotation Pt. rotated to the left. Notice the No patient rotation Ribs are longer on the side of Rotation. Newborn Right Main Stem Intubation Right Main stem Intubation ETT positioned too low entering right main stem bronchus. Left lung collapsed. RULE of THUMB Flex the neck causes the tube to move downward by 1.9 cm Extending the neck causes the tube to move upward by 1.9 cm Rotating the neck causes the tube to move upward by 0.7 cm. Esophageal Intubation Tracheostomy Evaluation of Lines-CVP Pulmonary Artery Catheter  Pacemaker Pacemaker implanted in a subcutaneous pocket over the pectoralis Muscle. Electrodes are then placed in the right ventricle or atria Central Venous Catheter (CVC)  Central Venous Pressure Catheter A B A. CVP line in internal jugular and B. Left subclavian insertion.  Tomography Special type of x-ray examination in which the x-ray tube is rotated in a chamber above patient and rays are focused into a central point or “cut”. Cuts are 1cm wide. Useful in pinpointing chest lesions, their size and shape. Replaced by computerized tomography (CT) and magnetic resonant imaging (MRI)  Computerized Tomography Computerized axial tomography (CAT) SCAN Computed enhancement of x-rays shadows. Application: – Lung Tumors: Evaluation of metastasis to the lung from extrathoracic cancer. Detection of nodules as small as 2-3mm. Placement of biopsy needle into the lesion. Computerized Tomography – Interstitial Lung Disease: CT scan demonstrates changes even when conventional chest film is reported to be normal. – Bronchiectasis Replaced bronchogram. CT Heart and Lung  Ventilation/Perfusion Scan (V/Q) Dx: Pulmonary Embolism but not conclusive Breath in a radioactive gas (ex;xenon-133) Radioisotopes are injected in the circulation Ventilation is normal and perfusion is abnormal  Magnetic Resonance Imaging Better than CT in identifying hilar region lesions. – Lymph nodes vs blood vessel enlargement. – Crucial in cancer management. Allows better determination of precise position of the tumor and the involvement of surrounding structures. Not used as often as CT scan MRI  Pulmonary Angiography Gold-standard diagnostic method for pulmonary embolism. Indicated when inconclusive V/Q scan findings or CT findings. Dye injected into blood stream to help blood vessels show up clearly Series of x-rays taken  Positron Emission Tomography (PET/CT) A compound injected into the vein Cancer cells “pick up” this compound Area will light up and produce a bright spot on the film. Used to target cancer cells and avoid healthy cells Positron Emission Tomography (PET/CT)  Systematic Review Sequence is not important as long as all structures are included. First: – F - film placement -digital – I -inspiratory effort – R -rotation – E - exposure Next – A: airways – B: bones/skin – C: cardiac  Viewing Film Film placed as if patient were facing the clinician. L side of the patient’s chest = cardiac shadow. L and/or R letters may be visible on the film to assist with orientation. Verify that name matches the patient in question. On computer it will always come up correct. F- film placement Since most x-rays are on computer they come up correct but look at the upper left hand corner should see and L for correct placement. Also look to see if the larger part of the heart is on the left hand side (left ventricle) I =Inspiratory Effort INSPIRATORY EFFORT Count posterior ribs above the diaphragm. – On PA film ≥ 8 ribs indicate good effort. I-Inspiratory Effort: ≥8ribs Lung Anatomy  Inspiratory Film Same patient taken within a short time of one another. Left is good Inspiration. B. Is poor inspiration. Note the size of the heart which may fool you to believe there is heart enlargement  R=Rotation Centered film = uniform exposure of both lung fields. Assessed by identifying spinal processes, tracheal air shadow, interclavicular space on midline.  R-rotation Notice the left clavicle is higher than th Notice the clavicles are adjacent to right indicating rotation. ne another. EXPOSURE Look at vertebral bodies. – They should be visualized through the cardiac shadow. – Overexposed = they are easily seen and lung fields are black/hyperlucid. – Underexposed= difficult to identify and lung fields are white/radiopaque lungs. Under or overexposure could cause misinterpretation of pulmonary abnormalities.  E-exposure Underexposed-unable to see vertebral column and trachealNormal-loose vertebral Overexposed-difficult air column. column through heart and To see underlying Good tracheal air column. Structures in lungs. Airways/Lungs and Bones Trachea Costophrenic angles Diaphragm Bones – Clavicles – Ribs – Spine Rib Fractures Skin  C=Heart 1-superior vena cava 2-right atrium 3-location of inferior vena cava 4-aortic knob/arch of aorta 5-left pulmonary trunk 6-left pulmonary artery 7-left atrium 8-left ventricle 9-left cardiophrenic angle Normal size heart-right side 1/3, left side 2/3 Hilar Point and Shadow of Hilum x Heart Size Cardiac Thoracic Ratio (CTR) should be no greater than 50% of the width of the thorax. Enlarged Heart: CHF Effect of Age on the Heart 20 yr old female 30 year female 60 yr old female This is normal change of the heart, no disease Radiographic Findings in Lung Disease Silhouette Sign Useful in determining where the pulmonary infiltrate is located. Presence of infiltrates in contact with cardiac border cause this border to be blurred or obliterated. Rule of Thumb – If a boundary line can be seen between the lung opacity and the heart, the opacity is located posterior in the lower lobe. – If a boundary line cannot be identified, the opacity must have a more anterior location in the middle lobe. Figure 28.1a - shows infiltrate at the level of the right middle lobe(37) and is in Contact with the right atrium (2) no boundary line between the heart and opacity Figure 28.2. Figure 28.1b – shows infiltrate (37) not in contact with the heart and is further back In the lower lobe thus a boundary line is seen preserving the outline of the heart. From The Chest X-ray. A Systematic Teaching Atlas. Matthias Hofer (editor) Thieme Publishers, New York. 2007 To use silouhette sign you need to know what structures are adjacent to each silouhette. Silhouette Sign A. Pneumonia left lower lobe B. Lingular segment of upper lobe C. Right middle lobe D. Right lower lobe  Air Bronchogram Intrapulmonary bronchial tree is radiolucid on the chest film because surrounding alveoli and bronchi are air- filled structures. If surrounded by consolidated alveoli they will be appear as linear branching air shadows. Often seen in pneumonia and pulmonary edema. Air Bronchograms  ATELECTASIS Compressive – Pleural effusion. – Pneumothorax. – Hemothorax. – Any space-occupying lesion. Obstructive – Ventilation to the area is absent leading to collapse. – Usually entire lobes or segments are involved. – Tumor, aspiration, mucus plugging, mechanical obstruction, fibrosis. – Complete vs partial obstruction, one-way valve mechanism.  ATELECTASIS Radiological Findings – Radiopacity of entire segments or lobes. – Shift of the trachea, heart, and great vessels – Shift of the fissure lines toward the collapsed area. – Movement of hilar structures toward the area of collapse. – Loss of volume in lung affected. – Hemidiaphragm elevation. – Microatelectasis, or plate-like atelectasis when lesion causing the compression is not large enough to cause obstruction. Appear as diffuse linear radiopaque densities. Atelectasis-AP Atelectasis Mediastinal shift to the right from hypoventilation and compensatory hyperinflation of the left lung. 21 represents right middle lobe atelectasis. 36 raised diaphragm. Right Upper Lobe Atelectasis  PNEUMOTHORAX Extreme form of atelectasis. Air in pleural space from a hole in the chest wall or from a hole in the lung. Causes loss of negative pleural pressure. Tension Pneumothorax: – Stab wounds, rib fractures, central lines placement, positive pressure ventilation,etc. – One-way valve mechanism allows air into pleural space resulting in positive pressure. – Positive pressure shifts structures away from affected side. – Pressure affects ability of contralateral lung to expand, affects venous return, and cardiac contractility. Pneumothorax  Pneumothorax and Pneumomediastinum B C A red alveoli has caused a leak and air now is routed through the lung to (B). C. The air now enters the mediastinum and the parietal pleura and into the pace. Non-tension Pneumothorax-AP Tension Pneumothorax-AP view Subcutaneous Emphysema and Spontaneous pneumo- thorax. AP view  Pneumothorax Supine CXR showing air in pleural space. This position causes air to rise to the highest point with patient laying flat. Erect CXR showing air in pleural space. This position causes air to rise. Supine CXR showing pneumothorax in left base.  Small vs. Large Pneumothorax A B Small pneumothorax is one where the distance between the pleura is < cm. B. Large pneumothorax is > 2 cm distance.  Hyperinflation Most common cause: COPD. Radiological changes: – Large lung volumes. – Increased retrosternal and retrocardiac spaces. – Depressed diaphragms. – Small narrow heart. – Enlarged intercostal spaces. Hyperinflated Lung-AP Retrosternal and Retrocardiac Air Normal Hyperinflation from COPD  Pleural Fluid Free fluid in the intrapleural space. If PA/AP film questionable = lateral decubitus. Radiological changes depend on the volume of fluid in the pleural space. – Blunting of the costophrenic angle. – Small meniscus sign on side of the chest wall. – Partially obscured diaphragm with elevation from its normal position. – Complete “whiteout” of involved side when large volume is present. Pleural Effusion-AP  Pleural Effusion Fluid volume-to be seen on x-ray – Upright PA-175-500 mL – Lateral-150 mL – Supine-500-1000mL  Pleural Effusion eural effusion of approximately 200 mL, B. Approximately 2L, C. Approximately 5  Pleural Effusion with Mediastinal Shift Massive left pleural effusion causing mediastinal shift away from the effusion.  CONSOLIDATION Fluid-filled lung parenchyma. Pneumonia. Radiographic signs: – Minimal loss of volume. – Usually lobar distribution. – Homogeneous density. – Air bronchogram if airway leading to consolidated area is open. Effusion vs. Consolidation Effusion vs. Infiltrate CONSOLIDATION-AP  Congestive Heart Failure Pulmonary edema. Redistribution of pulmonary vasculature to the upper lobes. – Lower lobes congested. – Upper lobes are relatively fluid-free areas. C/T ratio is increased > 0.50 – Normal: ≤ 0.5 Kerley B lines (interstitial edema) – Typically seen in R base. – 1mm thick and 1-2 cm long. – Start at the periphery and follow the line toward the heart. Butter fly or batwing outline Congestive Heart Failure Arrow is pointing to Kerley B line Congestive Heart Failure-AP  CHF The cardiac silhouette is enlarged. The pulmonary hilar are prominent. The pulmonary vasculature is engorged. Peri-hilar infiltrates are present in a "bat-wing" distribution. Upright or decubitus films may demonstrate pleural fluid (R > L). Case Report 1 One lung is darker than the other (left greater than right) Any thoughts?? Case Report 1 Patient plays tennis and has a well developed right pectoral muscle. More of the x-ray beam is absorbed by the well developed muscle. Case Report 2 Right lung completely whited out as compared to the left lung. Any guesses as to why? Case Report 2 Right sided pneumonectomy