RT 120 week 4

thoracic imaging

nuclear medicine studies

V/Q (for ventilation perfusion) scans - pulmonary embolism, PET-CT (for positron emission tomography CT) - stage cancer patients

VQ scan

patients inhale isotope, can see where the isotope lit up to indicate perfusion

tissue densities visible on x ray

air, fat, water, bone

air in lung, stomach, or intestines

absorbs very few x-rays and appears virtually black (radiolucent)

fat

abosorbs a small amount of the x ray beam and is usually seen as a light gray shadow

soft tissue

absorbs a slightly greater amount of the x ray beam and is usually seen as medium gray shadow

bone

absorbs a large fraction of the x ray beam and is seen as nearly white (radiopaque) shadow

hilar region

heart, great vessels and mediastinum

chest wall and mediastinum

symmetry of chest, rib fractures, bone changes, heart size, presence of free air or fluid

lung evaluation

size, density, symmetry, lung edges in frontal and lateral films, vascular markings, presence of free air or fluid, consolidations and infiltrates

lateral neck x ray

helptul in differentiating between croup and acute apiglottitis

high resolution CT

ideal for evaluating diffuse parenchymal lung diseases like interstitial lung disease (PF), emphysema, bronchiectasis

MRI

uses radio waves to generate MRI image, no x-rays used, most often used to image mediastinum, hilar regions and large vessels in lung

ultrasound

images created by passing high frequency sound waves into the body and detecting sound waves that bounce back (echo) from the tissues of the body, ultrasonic eval of lung is rare

pleura

the thin membrane surrounding the lung parenchyma, two thin membranes - outer parietal and inner visceral

pleural effusion

hydrothorax, accumulation of excess fluid within the pleural space, best x ray for detecting is lateral, blunted costophrenic angle

transudate pleural effusion

pale or clear in color

exudate pleural effusion

cloudy, pus, clots, blood tinged, unilater, due to infection / increase in hydrostatic pressure

loculation of pleural fluid

the trapping of fluid so that it does not move freely with changing positions

empyema

infection of pleural fluid

pneumothorax

collection of air in pleural space, may occur spontaneously (bleb rupture), with trauma or invasive procedure, may occur with mechanical ventilation (barotrauma), causes lung margins to pull away from chest wall

tension pneumothorax

occurs when air within pleural space in under pressure, air accumulates in pleural space on inhalation but cannot exit on exhalation, requires immediate decompression w/ chest tube or needle aspiration, pushes organs to the other side (heart and other lung)

lung parenchyma

made up of the alveoli and interstitium, disease involves both components

pulmonary edema

alveoli are filled with a watery fluid that contains few cells, parenchymal disease, pink, frothy secretions, BiPAP

bacterial pneumonia

alveoli are filled with an exudative fluid containing numerous white blood cells (pus), parenchymal disease

pulmonary hemorrhage

alveoli fill with blood, parenchymal disease, ICU patients mechanically ventilated → given herparin on high FiO2 breaking down alveolar capillary membrane → frank blood exits membranes into lungs

airspace opacity or infiltrates

indentical-appear patchy, increased density shadows that tend to coalesce over time on chest radiograph, infiltrates → fluid filling of alveolus (pneumonia, pus)

air bronchograms

the lucent tubular structures that course through dense airspace opacities or infiltrates on both chest radiographs and chest CT images, air filled airways surrounded by infiltrates will cause these, hallmark of infiltrates that fill alveoli (air space disease)

pulmonary edema

due to left heart failure usually, kerley B lines-thin lines seen near pleural edge on a chest film as a result of increased pulmonary capillary pressures, bat wing appearance-applied to predominance of edema in the hilar regions of both lungs

radiograph signs of cardiac decomp

(pulmonary edema) cardiac enlargement, pleural effusions - bilateral, redistribution of blood flow to upper lobes, poor definition of the central blood vessels, kerley B lines, alveolar filling

interstitial lung disease

(idiopathic pulmonary fibrosis, sarcoidosis) radiograph shows diffuse, bilateral infiltrates, opacities may resemble scattered, poorly defined nodules, HRCT important tool in establishing specific form of disease, low lung volumes and elevated diaphragms

plate atelectasis

when atelectasis is localized to subsegmental portion of lung, makes a plate shape where good lung function remains in center

radiographic signs of volume loss

unilateral diaphragmatic elevation, mediastinal shift towards atelectasis, narrowing of the space between ribs, hilar displacement towards atelectasis

hyperinflation

commonly seen with emphysema, more than seven anterior ribs are seen above diaphragm, flattening of hemidiaphragms, large retrosternal airspace, narrowed mediastinum, increased AP diameter

solitary pulmonary nodules

can only be seen via CT, benign - smooth edge, malignant - star, jagged edge, parenchymal opacity smaller than 3cm in diameter surrounded by aerated lung

mediastinum

consists of heart, great vessels, trachea, and other soft tissue structures that lie between the lungs (hilar region)

pneumomediastinum

a form of barotrauma, may result from movement of air into mediastinum, esophageal rupture - occurs in distal esophagus, chest trauma - may cause rupture of trachea or a mainstem bronchus

central line

main hazard is a pneumothorax, central venous catheter, catheter tip in superior vena cava

PICC line

peripherally inserted central venous catheter, alternative to central line, no pneumothorax risk, long term use, lower infection rate than central line

pulmonary artery (swan-ganz) catheter

used to measure hemodynamic and central pressure variables, floated into position using inflatable baloon on catheter tip, usually in right pulm artery

chest tube

small bore to large bore tubes placed into pleural space from outside the chest wall, drains blood, fluid or air