cardiac radiography

Question 1

what are the indications for taking thoracic radiographs

Answer 1

• identification, location and quantification of lesions producing respiratory signs (typically dyspnoea/cough
• identification of lesions too small to produce clinical signs (mets of a mass we are removing elsewhere -> check to make sure doesnt have long metastasis first)
• assess effectiveness of treatment

Question 2

what factors make generating radiogrpahs of diagnostic quality difficult

Answer 2

• movement blur
• wide radiographic contrast (bone, soft tissue air)
• hard to interpret
• breen normals/age normals vary
• should be taken on inspiration (hard to do)

Question 3

do we want to take thoracic radiographs on inspiration or expiration

Answer 3

inspiration

Question 4

how do you minimise movement blur

Answer 4

• careful handling
• sedation/GA
• reduce exposure time (sedation helps do this)

Question 5

what radiographic positions should you take to evaluate the heart

Answer 5

lateral (right and/or left)
dorsoventral

Question 6

what radiographic positions should you take to assess the lungs

Answer 6

right and left lateral
ventrodorsal

Question 7

list artefacts commonly seen in thoracic radiographs

Answer 7

• skin folds
• nipples
• cartilage mineralisation
• size and shape of cardiac silhouette (breed variance)
• “collapse of dependent lung when you do lateral first –> to DV first to avoid. shows up radioopaque)

Question 8

what else should you assess when taking thoracic rads (not heart and lungs)

Answer 8

• peripheral soft tissue structures
• anterior abdominal contents
• thoracic skeleton
• cranial mediastinum
• caudal mediastinum
• diaphragm
• pleural space

Question 9

what are the rules of thumb for assessing cardiac silhouette size

Answer 9

• lateral should not exceed 3.5 rib spaces (tnercostal) in dogs (cranio caudal dimension)
• DV should not exceed 2/3 f the width of the thorax at rib six

Question 10

label

Answer 10

Question 11

describe how to measure the cardiac silhouette using the vertebral heart score

Answer 11

length is measured on lateral and compared to number of vertebral bodies (starting with the cranial edge of T4)
width is measured similarly
vertebral heart score = L+W
average in dogs is 9.7 (range is 8.5-10.5), 8 in cats

Question 12

how do you differentiate if the cardiac silhouette is enlarged because the pericardium is full of fluid or if the heart itself is enlarged (L vs R)

Answer 12

based on clinical findings
if pericardium is filled with fluid (pericardial effusion), will be hard to hear heart sounds, will be muffled
confirm if fluid with U/s
- whole silhouette will be greatly enlarged
- globular appearance
- outline will be distinct as no movement blurring from heartbeat
- secondary signs of right sided heart failure
- U/s very sensitive indicator

if heart enlarged (L):
- caudal border will straighten trachea
- height will increase
- pulmonary veins will be enlarged due to increase pressure
- left atrium enlarged, tenting appearance

R enlargement
- lots more sternal contact
- reverse D shape on right side in DV

Question 13

assess heart

Answer 13

left sided heart enlargement

Question 14

assess this heart

Answer 14

right sided enlargement

Question 15

what condition does this image depict

Answer 15

pericardial effusion

Question 16

what are the dimensions of a normal feline heart

Answer 16

width should be 2 intercohondral spaces
in DV: width should be 2/3 width of thorax at 5 rib