Exam IV: Thorax Imaging Flashcards
Chest X-Ray (CXR)
Frequently the first step in patient imaging
Provides information about multiple organs and body cavities
Minimally invasive and well tolerated
Commonly available
Relatively inexpensive
Previous to Looking at an Image
Check patient data (Name, age, gender)
Look for old films
Arrange films on view boxes
Be certain of the positioning: (upright vs. supine, PA vs. AP)
Check the method: (Portable vs. in department)
Then make sure images are complete, good exposure, and look for gross abnormalities
Comparison Films
Provide a wealth of information
Should be viewed whenever they are available
When using comparison films they should be arranged in order
AP vs. PA Image
Body part farthest from film is most magnified, shows the least detail
AP shows magnification of the heart and widening of the mediastinum
PA works best, AP reserved for very ill patients
Left side is against cassette holder or image intensifier
Places heart closest to film, then we turn it around to look at the image
Right Lateral Decubitus Film
Labeled as right because patient is lying with right side down
Air fluid level shows right pleural effusion
Most useful when patient is unable to stand up
Can also do decubitus films of the abdomen
To lie reclining= cubitous
Right lateral decubitous: right side down/against the table
AP Exposure
Thoracic spine disc spaces should be barely visible through the heart
Bony details of the spine are not usually seen
Penetration is sufficient that bronchovascular structures can be seen through the heart
Lateral Exposure
The sternum should be seen edge on
Posteriorly you should see two sets of ribs
The spine is lighter on top and darker at the bottom/ caudally because the amount of muscle and tissues surrounding the structures decrease inferiorly
See sternum and two ribs, one larger than the other because of magnification due to difference in distances
More magnification when farther away
In this photo the right rib is farthest
Alignment of a Chest X-Ray
Spinous processes should be centered
Clavicular heads should be symmetrical
Sometimes patients that are in too much pain, very young or old, have mental disabilities that prevent them from being compliant and being still for the image
Cardiothoracic Ratio (CTR)
The size of the heart should be ½ the width of the entire chest
Works better when image is not magnified
Checking the Pathology of a X-Ray
So, on a large scale check:
Alignment of the visible structures
Borders of the organs and cavities
Cardiothoracic ratio
Finally, carefully look at:
The entire cardiac silhouette
Each lung field in detail including hila and trachea
Everything else including bones and any “Extra” structures
Scanning Technique when Reading an X-Ray
You will see smaller details if you move your eyes and even your head to cover the entire film
Remember the human eye only focuses well on one small area at a time
Blind spot in the eye and brain fixes it so you never notice it, therefore you need to move around the x ray to see it from different angles to make sure you don’t miss any information
Pneumothorax
Lung tissue naturally want to contract to shrink, so if exposed to atmospheric air, it contracts
If air gets in the pleural space, the lung will shrink and border of lung is more medially than laterally
Tension Pneumothorax
Collapsed lung with build up of pressure from injury creating a hole like flap that moves over the wound
Causes deviation of the mediastinum and trachea to the opposite side of the injury
Impairs breathing and blood return
Surgical Emergency!
Chest tube or decompress with large bore needle in second intercostal space at the midclavicular line
Foreign Body Aspiration
If something goes into the lungs, usually through the right mainstem bronchus because straighter than left side and wants to take path of least resistance
Iatrogenic Foreign Body
Right subclavian venous catheter
Tip is in the superior vena cava (SVC) where it joins the right atrium
Chest x ray can show where catheter is and make sure no pneumothorax after catheter put in
Multiple Foreign Bodies
Cardiac pacemaker with dual wires
Wire sutures closing sternum
Chest X-Ray AP Portable
Multiple wires from cardiac telemetry
Right internal jugular catheter with kink at tip (black Arrow)
Endotracheal tube
Sternal wires
Valve replacement
Very sick patient!
Figure out wires and tubes first, then look for pathology
Free Air Under the Diaphragm
If air outside of tube outside of GI tract= indicates leak in GI tract
Area underneath of the diaphragm- bad and needs to go to OR
Orienting Yourself in Chest CT
Pt’s right side is on your left, their left on your right (Correct Anatomical Position)
Look at easy to recognize structures to calibrate your eye
The layer just deep to the thin skin shows how bright fat is
Vertebral column to see how bright bone is
Muscles behind the vertebral column to see how bright it is
The aorta to see how bright blood is (it will be bright if contrast dye was used)
Air is always black.
Different “windows” allow viewing of different tissues
Image is looking up shirt
Pulmonary Embolus
Clot from a deep vein thrombosis (DVT) breaks free and goes to the lungs
Variable size and severity
Initially treated with anti-coagulants
If severe may require surgery to remove clot
André Frédéric Cournand,Werner Forssmann, and Dickson W. Richards
Were awarded the Nobel Prize in Physiology or Medicine for the development of cardiac catheterization
Werner Forssmann
1929 credited with the first human cardiac catheterization – on himself
While still a surgical resident, he incised his arm and fed a urinary catheter into the right atrium of his heart
Walked down a flight of stairs to the radiology department to x-ray it – he was later fired
Won the Nobel Prize in Physiology or Medicine in 1956 – 37 years later
Echocardiogram
Ultrasound study
Performed through anterior chest wall
US probe on chest, avoid bones of chest by going between the ribs
Can show: wall thickness and movement, ejection fraction, valvular function, vegetations
Minimal complications associated with ECG
Transesophageal Echocardiogram(TEE)
Similar information as ECG but probe is closer to heart, allows more detail
Patient must be sedated
Get a probe down the throat to see behind the heart (heart is closer to esophagus) and see individual structures and get better calculations of function of the heart
Myriad potential complications: risk of aspiration, may react to sedation, never wake up…
Mammogram
Becomes technical in interpretation
Place all images in the same order every time to be able to know what and where you are looking
Craniocaudal images (CC): head to tail (look down shirt)
Medial Lateral Oblique (MLO): “short person dancing with lady and look side to side”
White dense material: pectoralis major
US of Breast Cyst
Smooth margins
No internal echoes (anechoic)
Enhanced through transmission of sound
Ultrasound is the test of choice for a suspected cyst
MRI of Breast
Gives excellent detail
At present quite expensive
May be too sensitive for screening test- many false positives
Is currently an “emerging technology”
Seldinger Technique
It is named after Dr. Sven-Ivar Seldinger (1921-1998), a Swedish radiologist who introduced the procedure in 1953
A vessel or cavity is punctured with a sharp hollow needle
A round-tipped guide wire is then advanced through the lumen of the needle which is then withdrawn
A “sheath” or blunt cannula can now be passed over the guide wire into the cavity or vessel
Drainage tubes or indwelling catheters can also be passed over the guide wire and left in place while removing the wire
Basic Seldinger Technique
Steps:
- Insert guide wire through needle in vein
- Remove needle
- Pass catheter over wire
- Remove wire
Example: this is how stent is placed in ureters
Various Guide Wires
J tip guide wire
Have many sizes, textures, and shapes of guide wires
Angiography
Guide wire is inserted into vessel, maneuvered to a specific location in the circulatory system
Catheter is passed over the guide wire to deliver contrast media to desired site for imaging
Also allows for angioplasty, chemoembolization or thrombolysis
Balloon Angioplasty
Guide wire is passed beyond narrowing, inflate balloon when in place to increase blood flow of that vessel
Special balloon catheter is placed for maximum effectiveness
Diagram makes the lumen look perfectly smooth afterward – not really true
Opens up the lumen and increases blood flow
Vertebral Artery Stent
Metallic stent is wrapped around balloon
Locks into open position after balloon is expanded, provides structural support to newly re-opened vessel
Treated as a foreign body by the surrounding tissues
Wire cage and expand it and open the artery
Stenting of an artery, works but will not last indefinitely
Stent Grafting of Abdominal Aortic Aneurysm
Graft tube is attached to the stent
Performed through a femoral arteriotomy by an interventional radiologist
Less pain, quicker recovery
Unless the vessel ruptures
