Rads Review of the Week – Week 5 Answers

1. Which of the following is NOT a disadvantage of obtaining an AP Portable CXR?

• A. Falsely enlarged mediastinum
• B. Inability to see good lung fields
• C. Frequent poor inspiratory effort
• D. Frequent rotational malalignment

ANSWER: B

When lying supine a patient is often unable to take a full inspiration. Also,
he may be rotated because of difficulty in cooperating. Therefore some
AP CXRs are of inferior quality in comparison with a departmental PA
radiograph and often lead to magnified of falsely enlarged mediastinum and vessels.

Be careful of making a major diagnosis (e.g. hilar mass) too readily. But don’t be
too gloomy. Many AP radiographs, even if not meeting the quality expected of a
PA CXR, will usually conÄ rm whether or not the lungs are clear.

2. Which of the following is correct in regards to a good inspiratory film?

• A. The anterior end of the left sixth rib should reach or project above the level of the dome of the diaphragm
• B. The anterior end of the left fifth rib should reach or project above the level of the dome of the diaphragm
• C. The inferior end of the right fifth rib should touch the distal aspect of the diaphragm
• D. Both domes of the diaphragm are clearly seen and well-defined

ANSWER: A

If the anterior end of the left sixth rib reaches or is projected above the level of the dome of the diaphragm—then a good inspiration is likely.
Pitfall. A small inspiration can cause: (a) the heart to appear enlarged; and (b) vessel crowding at the bases mimicking infection.

3. In an adult, what cardiac-thoracic ratio would be considered normal on a PA CXR?

• A. < 75%
• B. < 70%
• C. < 60%
• D. < 50%

ANSWER: D

Normal adult cardiac-thoracic ratio should be < 50%

4. 22 y/o male patient presents with chest pain after a party on Saturday night. No recollection of injury. What is the diagnosis?

• A. Pneumothorax
• B. Normal CXR
• C. Multiple Rib Fractures
• D. Pericardial Effusion

ANSWER: C

If you do not use a systematic approach and remember to check the bones you will miss several right sided posterior rib fractures. Bonus there appears to be a pneumomediastinum as well.

5. Which of the following is true regarding rotation on PA or AP CXR?

• A. AP CXR is less likely to have rotational malialignment than a PA CXR
• B. The patient is NOT rotated if a vertical line drawn through the center of the vertebral bodies (T1-T5) is equidistant from the medial end of each clavicle
• C. The patient is NOT rotated if the right lung appears more black then the left lung
• D. The patient is NOT rotated if vessels arising from the arch of the aorta are much more prominent on the right

ANSWER B:

The patient is not rotated if a vertical line drawn through the centre of the vertebral bodies (T1–T5) is equidistant from the medial end of each clavicle. Rotation is present when one of the clavicles is further away from this vertical line.
A rotated CXR will cause various structures to be projected towards the right or
left side. Potential problems:

• Rotation to the right on a PA CXR…the manubrium and / or superior vena cava and / or vessels arising from the arch of the aorta may become unusually prominent on the right. This can simulate a mediastinal mass.
• Rotation to the left on an AP CXR…the aortic arch may appear enlarged.
• Rotation is a common cause for one lung appearing blacker than the opposite side.