Cardio/mediastinal radiographs

Question 1

what is VHS? what is the mean?

Answer 1

used to evaluate cardiac size, compares heart to mid-thoracic vertebrae (ID enlargement, monitoring change)
place length of both short and long axes along vertebrae, starting at T4 and going caudally. number of vertebrae along measurement (add together short and long axes) –> VHS

mean: 9.7 ± 0.5 (dogs), <8 (cats)

short axis: middle 3rd of heart (incl. R atrium & L chambers)
long axis: tracheal carina to cardiac apex (incl. L atrium + ventricle)

Question 2

what are the 25-50-25 and the 2/3:1/3 rules?

Answer 2

25-50-25: in VD/DV view, heart should be 50% of mediastinum, and the L and R space between body wall and heart should each be 25%

2/3:1/3: in lateral view, heart should be 2/3 of mediastinum, and there should be 1/3 of space above heart to body wall

Question 3

what is hypertrophy vs dilation in the context of radiography?

Answer 3

hypertrophy: maintains overall vol w/ loss of luminal vol (increase wall thickness) – difficult to visualize
dilation: increases overall vol v/ increase in intraluminal vol, similar to decreased wall thickness – visible radiographically

Question 4

left-sided cardiac enlargement – what conditions cause this?

Answer 4

myxomatous mitral valve disease (most common!)
aortic stenosis
hypertrophic cardiomyopathy
restrictive cardiomyopathy
patent ductus arteriosus
ventricular septal defect

Question 5

how can you see left ventricular cardiac enlargement on radiograph?

Answer 5

lateral view: “taller” heart, rounding of L ventricular border, dorsal elevation of trachea

VD: “taller” heart, difficult to evaluate

Question 6

how can you see left atrial/auricular cardiac enlargement in radiograph?

Answer 6

lateral: loss of cardiac waist, rounding of atrial border
VD: auricle often displaced laterally by enlarged atrium, atrium causes lat. displacement of primary bronchi

Question 7

how can you see right sided cardiac enlargement on radiograph?

Answer 7

widened heart on DV/VD, rounding of right ventricular border, increased sternal contact (variable w/ breed/species)

Question 8

what conditions cause right sided cardiac enlargement?

Answer 8

pulmonic stenosis
tricuspid dysplasia
heartworm
pulmonary hypertension

Question 9

tell me about looking at pulmonary vessels sizes on radiographs and what they mean

Answer 9

V>A: venous hypertension –> mitral valve disease
A >V: pulmonary hypertension –> heartworm, pulmonary fibrosis
A&V increase: shunt (L to R), fluid overload, fluid retention
A&V decrease: dehydration, decrease right ventricle output

Question 10

what does a globoid heart mean on radiograph? what are the ddx’s?

Answer 10

generalized cardiac enlargement
pericardial effusion, DCM, end-stage mitral valve disease

Question 11

you have a patient with potential heart failure. What should you do to assess?

Answer 11

consider DV view, corroborate with 2 views (if only on 1, then likely not edema)

right-sided HF: pleural effusion present
left-sided HF: pulmonary edema present, perihilar distribution, tends to be patchy alveolar to interstitial patterns - look at vessels, should be enlarged (may not be if treated)
the above is for dogs only

Question 12

what is pectus excavatum?

Answer 12

sternum sunken into chest, commonly incidental

Question 13

thoracic masses – origin? how to discern from pulmonary masses?

Answer 13

often rib origin (chondrosarcoma, osteosarcoma)
difficult to differentiate from pulmonary masses
but! can use extra pleural signs – well-circumscribed, cranial and caudal edges taper to thoracic wall rather than circular appearance of pulmonary mass

Question 14

tell me about visibility of pleural space on radiographs

Answer 14

not usually visible bc silhouetting with adjacent ST
if tangential, may become mildly apparent
if widened with other ST/fluid in b/t, may become visible
if thickened (age, pleuritis)

fissure lines indicate pleura

Question 15

when should you examine the pleural space on radiograph? what are the 3 main categories of disease?

Answer 15

dyspnea, thoracic distension, asynchronous breathing, muffled heart sounds on auscultation

pleural effusion
pneumothorax
diaphragmatic hernia

Question 16

what does pleural effusion look like on radiograph? what do these signs depend on? what positioning?

Answer 16

fluid opacity in pleural space, retraction and rounding of lung lobes, scalloping, effacement of heart/diaphragm, widening pleural space filled with fluid

depend on vol of fluid (100ml needed to see widening of pleural fisures)

VD more sensitive (fluid accumulates dorsally, lungs retract better, but more dangerous for patient)
(DV safer for patient, but fluid accumulates ventrally and silhouettes the heart)

Question 17

if pleural effusion is severe and effacing all thoracic contents what should you do?

Answer 17

thoracocentesis to drain and then re-take images

Question 18

tell me about the categories of pneumothorax

Answer 18

open: free passage of air from environment
closed: air leakage from lungs, trachea, bronchi, esophagus, mediastinum
tension: valve effect, air drawn in doesn’t escape
normotensive: pleural pressure is same as atm

Question 19

what are the radiographic signs of pneumothorax?

Answer 19

gas in pleural space, retraction of lung lobes (truncated normal pulmonary vasculature), elevation of cardiac silhouette

Question 20

tension pneumothorax – is it serious? what does it cause radiographically?

Answer 20

emergency!
displacement of lung and mediastinal shift away from side of tension pneumothorax

Question 21

what is included in the cranial, middle, and caudal mediastinum?

Answer 21

cranial: great vessels, esophagus, trachea, lymph nodes, thymus, fat
middle: heart
caudal: esophagus, aorta, vena cava

Question 22

tell me about the normal proportions of the cranial mediastinum

Answer 22

normal thickness is apex 2x width of vertebral bodies in dogs, 1x in cats
variation w/I breed and BCS

Question 23

what are the 4 general classifications of mediastinal abnormalities?

Answer 23

mediastinal shift
mediastinal masses
mediastinal fluid
pneumomediastinum

Question 24

what is mediastinal shift? what are the causes? how to evaluate/views?

Answer 24

deviation of mediastinal structures towards 1 side of the chest cavity

causes: unilateral increase/decrease in lung vol, presence of intrathoracic mass with secondary deviation

best evaluated on VD and DV

Question 25

mediastinal masses – where? what to look for radiographically?

Answer 25

ventral and dorsal aspects
differentials based on location
look for deviation of trachea

Question 26

mediastinal fluid is often accompanied by ____?

Answer 26

pleural effusion

Question 27

pneumomediastinum – provides ____ contrast? what is the consequence? how does it relate to pneumothorax?

Answer 27

good contrast, which makes structures previously not visible, visible
pneumomediastinum may progress to pneumothorax but not vice versa

Question 28

what are the 6 causes of pneumomediastinum?

Answer 28

1. trauma to lung interstitium with gas dissection adjacent to bronchi into the mediastinum (Macklin effect) – most common
2. extension of gas from the fascial planes of neck
3. tracheal perforation
4. esophageal perforation
5. extension of retroperitoneal gas into the mediastinum
6. gas producing organism

Question 29

what is a tracheal stripe sign? what does it indicate?

Answer 29

tissue band b/t the tracheal and the esophagus

indicates esophageal gas

Question 30

broad strokes, how do you do an esophagram?

Answer 30

oral admin of barium paste, which outlines any defect in mucosa and will coat any intraluminal structure

serial radiographs taken during swallowing and post swallowing

Question 31

what are the radiographic signs of a peritoneal pleural diaphragmatic hernia?

Answer 31

gas viscous in thorax
ST summating with cardiac silhouette
displacement of cardiac silhouette
loss of diaphragmatic margination

Question 32

what are the radiographic signs of a pericardial peritoneal diaphragmatic hernia?

Answer 32

huge ass heart

Question 33

what are the 3 types of hiatal diaphragmatic hernias?

Answer 33

esophageal, paraesophageal, mixed