Radiology

Question 1

which trimester of pregnancy is mri completely contraindicated?

Answer 1

1st

Question 2

what is the main absolute contraindication to an mri?

Answer 2

pacemaker

Question 3

name a few other contraindications to mri

Answer 3

intracranial clips/ electronics/ need to check prosthetic cardiac valves before mri/ metal in eye/ claustrophobia/ recent prosthetic joint

Question 4

first thing to check on cxr is

Answer 4

confirm patients name and dob

check date and time taken

Question 5

what are the 4 main things to check on a cxr?

Answer 5

side marker
projection
direction of inspiration
centering

Question 6

how do you check the side marker and why is this important?

Answer 6

check whether it has been correctly placed and you are looking at the side the patient complained of - does the patient have dextrocardia?
check by palpating the apex

Question 7

why in resp do you have to ensure if there is true dextrocardia?

Answer 7

it would affect the position of the picc line

Question 8

what is the projection?

Answer 8

most commonly PA projection (can assume this is what is taken unless stated otherwise)

Question 9

why is pa projection best?

Answer 9

well imspired scapulae minimally overlap and heart size can be reliably assessed

Question 10

why would you need another projection?

Answer 10

sick patients may not be able to stand so require ap projection
some are too sick to sit up so are taken supine
lateral

Question 11

what are the problems with ap projection

Answer 11

exaggerate heart size

scapulae overlap the lungs which can simulate or mask disease there

Question 12

what are the problems with supine projections?

Answer 12

do not show pneumoperitneum due to bowel perforation as gas would not move to the diaphram

Question 13

how do you check for adequate inspiration?

Answer 13

6 anterior rib ends should be visible above the left diaphragm (costal cartilages are not visible on cxr)

Question 14

what is wrong with poorly inspired cxrs?

Answer 14

they exaggerate heart size and basal lung markings simulating heart disease or lung base infection

Question 15

how do you check if the cxr is rotated ?

Answer 15

measure the distances from the medial ends of the clavicles to a thoracic spinous process (the distance should eb the same on both sides - if not its rotated)

Question 16

what is wrong with grossly rotated cxrs?

Answer 16

exaggerate heart size
and can simulate a hilar or mediastinal mass
misdiagnosis of lung disease

Question 17

how do you technically assess a cxr?

Answer 17

examine the heart 
examine the hila
examine the mediastinum 
 examine the 4 regions of both lungs
examine the diaphrams
examine the review areas

Question 18

what is the normal heart size on a cxr?

Answer 18

50% or less of the cardiothoracic ratio

Question 19

what is the normal heart position?

Answer 19

one third of the heart should lie to the right of the midline and two thirds to the left

Question 20

why do you need to know the hearts position?

Answer 20

pneumothorax would shift the position

Question 21

the normal right hilum lies about …….. ……. the left hilum

Answer 21

1.5cm below

Question 22

why look at the hila ?

Answer 22

any increase in density should raise suspicion of hilar lymph node enlargement or cancer

Question 23

where should the normal trachea be

Answer 23

superimposed on te thoracic spine

Question 24

the normal aortic arch

Answer 24

protrudes above the left hilum

Question 25

the aortic arch merges inferiorly with the

Answer 25

descending aorta

Question 26

why check if the descending aorta is visible?

Answer 26

it would be obscured when the left lower lobe is diseased

Question 27

why is diaphragmatic position important?

Answer 27

chest diseases that alter the thoracic volume may cause a shift in diaphragmatic position - eg lef lower collapse where reduced lung volume has caused left diaphragm to rise above that on the right (the heart may also shift to the left)

Question 28

why check the costophrenic recess?

Answer 28

pleural fluid gravitates to the lung bases - the earliest sign of pleural effusion is obliteration of the normally sharp costophrenic angle

Question 29

why check for gas under the diaphrams?

Answer 29

gas under the right hemidiaphragm should raise suspicion of bowel perforation and pneumoperitoneum

Question 30

how should you split the lungs into zones?

Answer 30

apices

upper mid and lower zone

Question 31

what is the silhouette sign?

Answer 31

On a CXR, the outline of a structure like the heart is visible because adjacent lung has a different density.
•Most lung diseases cause an increase in lung density. If the dense diseased lung abuts the heart or diaphragm, the outline (or silhouette) of that structure becomes obscured, because it shares the same density as the diseased lung.
•The pulmonary lobes abut predictable parts of the heart or diaphragm, so loss of that part

Question 32

what is a useful way of diagnosing a right upper/middle lobe pneumonia?

Answer 32

horizontal fissure leads to sharply defined area of opacity either above or below this

Question 33

what devices can be assessed for correct placement using a cxr?

Answer 33

et tube 
bg tube 
central venous line
intercostal chest drain 
pacemaker

Question 34

what is the correct central venous line position?

Answer 34

within the SVC, just proximal to the right atrium.

Question 35

what is the correct ng tube position?

Answer 35

below the diaphragm, projected within the stomach