PFT's and Thoracic Imaging Flashcards
Four tissue densities seen on chest radiographs and whether they appear more radiolucent or radiopaque
Radiolucent (appears black on film, absorbs the least)
-Air
-Fat
-Soft tissue
-Bone
Radiopaque (appears white on film, absorbs the most)
Clinical indications for chest radiographs (outpatient and inpatient)
Outpatient: Unexplained dyspnea, severe persistent cough, hemoptysis, fever and sputum production, acute severe chest pain, positive TB skin test
Inpatient: Placement of endotracheal tube, placement of pulmonary artery catheter, sudden onset of dyspnea or chest pain, elevated or changing plateau pressure during MV, sudden decline in oxygenation
Technical quality assessment of a chest film
- Is the film appropriately labeled?
- Is the film PA with a lateral view or AP portable film?
- Is the entire chest image on the film?
- Was the patient properly positioned
- Were optimal settings for x-ray selected (penetration)?
PA vs AP chest film
PA (Posteroanterior)- x-ray beam passes through patients posterior side and then through the patients anterior side and then to the film
AP (Anteroposterior)- x-ray beam in front of patient, passes through patients anterior side then posterior side and then to the film. May cause the heart to appear enlarged.
Steps of interpreting thoracic imaging studies (4 steps)
- Evaluation of technical quality and adequacy of film
- Normal anatomic structures
- more sophisticated imaging techniques
- major anatomic components seen
CT scan
Computed Tomography- visualization of thorax in cross section, great detail and minuscule structures (~2mm). performed lying on a gantry, spiral and helical moving x-ray images taken.
CT Angiography
-A large amount of contrast dye is injected into the patient’s vein. Used to identify pulmonary thromboemboli, and to provide an alternative to routine coronary angiography of the coronary artery in many patients.
MRI
-Magnetic Resonance Imaging- Uses the radio waves of realigning nuclei to generate an image, strength of these waves is s bring metal equipment like gas cylinders or ventilators near the MRI machine. Most common uses are for imaging the mediastinum, large vessels, or hilar regions of the lungs.
Ultrasound
Imaging created by passing high-frequency sound waves into the body and detecting sounds waves that bounce back from the tissues of the body. Excellent for evaluating the heart or pleural fluid. Does not transmit through the air filled lungs very well. Used to guide placement of arterial and central catheters.
Pleural abnormalities
Hydrothorax (pleural effusion)- accumulation of excess fluid within the pleural space. Costophrenic angle appears rounded rather than sharp.
Hydropneumothorax- both air and fluid accumulation in the same space.
Empyema- Infected pleural fluid, presence of gas bubble in fluid
Pneumothorax- collection of air in pleural space (appears dark)
Tension pneumothorax- tear in pleura allowing air into pleural space open on inspiration but closes on expiration, causes displacement of mediastinum (opposite of the involved side) and depression of hemidiaphram (involved side)
Parenchyma abnormalities
Alveolar disease- seen as dense shadows that tend to coalesce over time know as infiltrates. Often have lucent and tubular visible structures through them known as air bronchograms. Also fluffy opacities, rapid coalescence, acinar nodules, segmental/lobar distribution.
Pulmonary edema- first seen as enlarging blood vessels to the apices of the lungs due to increased pressure (cephalization). As fluid builds thickening septa are seen as thin lines against the pleural edge that run perpendicularly away from it, known as Kerley-B lines
Interstitial lung disease- causes edema of intralobular septa. X-ray usually has bilateral infiltrates. appear as nodules and lines (honeycombing, represent scaring and end-stage lung disease), cysts, or septal lines.
Radiographic signs of volume loss
(LETS)lobar collapse, (USE)unilateral diaphragmatic elevation, (MUSIC)mediastinal shift, (NOW)narrowing of space between ribs, and (HANK)hilar displacement.
Radiographic signs of cardiac decompensation
CPRPKA
-(CAN)cardiac enlargement, (POLICE)pleural effusion, (REALLY) redistribution of blood flow to upper lobes, (PUT)poor definition to central vessels (perihilar haze), (KIDS) Kerley-B lines, (AWAY)alveolar filling.
Mediastinum abnormalities
Mediastinal mass
Pneumomediastinum- air in mediastinum, visible as linear lucencies
Positioning of ET tube, central line, trach-tubes, pulmonary artery catheters or intraaortic balloon pump.
