Thoracic Imaging Flashcards
Define attenuation (x-rays).
reduction of x-ray beams through different substances
Define scatter (x-ray)
Reflection of radiation beam
What are the key differences between antero-posterior (AP) CXR & postero-anterior (PA) CXR & lateral CXR?
- AP: is bedside & sloppy
- PA: pt erect & controlled environment
- Lateral is similar to PA (adds second dimension)
(PA + lateral = PA Lateral best view of chest)
AP films make the heart look _____.
bigger
(casts wider shadow on film; important structures further from “camera”)
In PA films, the heart should be < 50% total _______.
(shot through the back; most important structures are closer to “camera”)
transthoracic diameter
(AP it is >50%)
Pulmonary Surface Anatomy. Name the structures.
Right lateral pulmonary surface anatomy. Name the structures.
Left lateral pulmonary surface anatomy. Name the structures.
List the order of evaluation on PA Chest films (10).
- Patient data (name, hx, age, sex)
- Clavicles, sternum, vertebrae, shoulders and rib fx
- trachea, carina, R & L bronchi
- Hila
- Mediastinum
- Heart
- Lungs
- Pleura
- Diaphragms
- Stomach
List the order of evaluation for lateral chest films (6).
- Clavicles
- Trachea/mainstem bronchi
- Heart
- Lung fields
- Retrosternal space
- Diaphragms
PA CXR is done from ______ inches away. AP is done from _____ inches away.
- 72
- 40
Diaphragm is found at the ______ level of the posterior ribs or the ______ level of the anterior ribs.
- 8-10th
- 5-6th
In a PA CXR, why is the left side of the chest against the film?
minimizes LV enlargement
Why is it important for the patient to take a deep inhale and hold it for a CXR?
loss of R heart border silhouette looks like pneumonia
(left: poor inspiration looks like pneumothorax, but its just overpenetrated; right: same pt done correctly)
What are signs of adequate penetration on PA CXR?
- T spine discs barely visible
- vertebrae details not visible
- bronchovascular structures seen through heart
What are signs of adequate penetration on lateral CXR?
spine appears to darken as you move caudally
(more air in lower lobes of lungs)
What do these XR represent
Left: underpenetrated PA film
Right: overpenetrated PA film
What is the consequence of rotated clavicular heads on CXR?
mediastinum appears wider
(if rotated, the heads will not be equidistant from the spinous process)
Lateral CXR shows right ribs that appear larger due to magnification (red arrow); left ribs more prominent and anterior
Define Silhouette sign
elimination of the silhouette (loss of lung/soft tissue interface) due to mass or fluid in the normally air-filled lung
silhouette sign: left lingular lobe
(lingula apples to the anatomical equivalent: portion of L upper lobe that borders the heart and has superior & inferior segments)
Air Bronchogram: tubular outline of airway
(visible due to fluid/infiltrates)
6 causes of air bronchograms
- lung consolidation
- pulmonary edema
- nonobstructive pulmonary atelectasis
- severe interstitial disease
- neoplasm
- normal expiration
What is this called? What would make these suspicious for cancer?
solitary pulmonary nodule: irregular (stippled, spiculated) calcifications
(if unchanged for 2 years → benign ; < 1 cm benign; make note of the “bamboo” spine: fused by autoimmune condition)
Retrocardiac pulmonary tumor on lateral CXR
One of the MC findings on CXR which is most often benign secondary to prolonged bed rest/post surgical
atelectasis
Kerley B Lines: upward sloping horizontal lines < 2 cm long; thickened, edematous interlobular septa
(atelectasis is downward sloping)
Causes of Kerley B lines (7)
(white dashed lines)
- pulmonary edema
- lymphangitis carcinomatosis
- malignant lymphoma
- viral & mycoplasma pneumonia
- interstitial pulmonary fibrosis
- pneumonoconiosis
- sarcoidosis
What are the causes of this?
pneumonia: virus, bacteria, fungus, mycoplasma
(airspace consolidation disease; filled w/pus & microorganisms)
How many ounces of fluid are needed to visualize this on CXR?
- pleural effusion
- 200 mL
When are decubitus CXR films taken?
detects pleural effusion
(infiltrates won’t move with gravity; they’re “loculated”)
Define pneumothorax
air inside the thoracic cavity but outside the lung
Define tension pneumothorax
air enters pleural cavity & is trapped during expiration → increases intrathoracic pressure
(this can compromise venous filling of heart → death)
Pneumothorax is best demonstrated by _____.
full expiration of breath
(note the lack of lung markings at the apex)
interstitial pulmonary fibrosis: hazy “ground glass” opacification early; late: volume loss w/linear opacities bilaterally & honeycomb lung
(restrictive)
Prognosis?
3-6 years to live unless lung transplant
Emphysema: loss of elastic recoil
Describe the common visual keys to emphysema on CXR (7)
- diffuse hyperinflation w/flattening/tenting of diaphragms
- increased retrosternal space
- thoracic kyphosis
- elongated lung fields past the 10th rib
- bullae
- vertical elongation of the heart
- RA/RV enlargement
make note of pulmonary edema and interstitial fibrosis differentiate the two.
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