BSAVA Thorax Flashcards
What kV & mAs settings are best for thorax?
High kV, Low mAs (high mA, short exposure time)
- High kV –> low contrast image w/ wide range of grey tones
On which image is the sternal node more easily identified?
Right Lateral
What are 4 reasons why a right lateral image preferable over a left if only a single lateral can be obtained?
1) Sternal node more easily identified
2) Diaphragm obscures less of caudodorsal lungs
3) Heart in a more consistent position (due to R side cardiac notch)
4) R middle lung lobe superimposed over heart & sternum –> better cardiac detail
What are DV and VD views preferred for, respectively?
DV = cardiac related disorders (more standard heart appearance b/c less magnified & caudal vasculature more easily identified)
VD = pulmonary parenchyma
What is an extra pleural sign?
Where a lung margin is locally deviated from a mass arising from the chest wall
What disease process may cause septal flattening in a RPS short axis view?
Pulmonic stenosis (secondary to increased RV pressure)
MPA diameter should be _____ or ______ than the Ao.
Equal to or smaller than
(Increased diameter w/ normal pulmonic valves may suggest PH)
What are two disease processes that cause decrease radionuclide clearance from pulmonary circulation?
L to R shunt & L CHF (If bolus too slow, iatrogenic slow pulmonary clearance can also be simulated)
In a R to L shunt, what two structures fill with radionuclide simultaneously?
Aorta & pulmonary arteries
What is the embryological origin of the heart?
Paired endocardial tubes that arise from splanchnic mesoderm
The L and R main coronary arteries arise from where?
Root of the aorta
In terms of L, R, cranial, & caudal where are the LA, LV, RA, & RV located in a dog?
LV and LA = L and caudal aspects
RV and RA = R & cranial aspects
At what intercostal space is the carina normally located?
4th - 5th
What is the pericardial fat stripe?
Fat present between the fibrous pericardium & pericardial mediastinal pleura that may remain visible on a lateral view in patients w/ pleural effusion
T or F, aortic size alters in association w/ hypovolemia or volume overload?
False
What are the terminal abdominal tributaries of the CVC?
Hepatic veins
Within what structure does the CVC cross the diaphragm?
W/in plica vena cava on R side
What vessels unite to form the CrVC?
Axillary veins join w/ internal & external jugular veins to form the R & L brachiocephalic veins which then unite to form CrVC
What 3 vessels join the CrVC in the cranial mediastinum before it empties into the RA?
Costocervical veins
Internal thoracic veins
Azygous vein
What does the azygous vein form from?
1st lumbar veins
What is the location of origin & course of the thoracic duct?
Origin = between diaphragmatic crura
Courses cranially along right dorsal Ao border & usually enters CrVC or L jugular vein
Cranial pulmonary arteries and veins are best separated on which lateral projection?
Left lateral
Explain concentric versus eccentric cardiac hypertrophy?
Concentric hypertrophy results from inc systolic pressure (pressure overload) –> thickened ventricular wall w/ normal or reduced luminal size
Eccentric hypertrophy results from increased diastolic pressure & volume (volume overload) –> normal ventricular wall six w/ inc luminal size
Rotation of the cardiac apex caudodorsally away from sternum is a sensitive sign of what?
RV enlargement
Enlargement of which structures cause ventral and dorsal displacement of the caudal mainstream bronchi, respectively?
Ventral = tracheobronchial lymphadenopathy
Dorsal = LAE
What are 2 ddx for enlargement of the entire aortic arch?
SAS & age-related changes in cats
What disease causes enlargement of the descending portion of the aortic arch?
PDA
What are 3 things that can cause a redundant aorta?
Aged related changes in cats
Brachycephalic dogs
Congenital hypothyroidism
What are 6 disease processes that can cause calcification/mineralization of the Ao?
Primary or secondary hyperparathyroidism
Lymphoma
Spirocera lupi
Hypervitaminosis D
Hyperadrenocorticism
Arteriosclerosis
What vascular dissension occurs secondary to segmental aplasia of the CVC?
Marked enlargement of the azygous vein
What are 4 causes of an enlarged MPA?
Pulmonic stenosis (post-stenotic dilation)
Inc circulating volume (PDA, ASD, VSD_
Pulmonary hypertension
Severe HWD or Angiostrongylosis
T or F, R CHF is a rare cause of feline pleural effusion?
True
Screens increase or decrease patient dose? Explain the mechanism.
Decrease. Ability to convert few absorbed xray photons into light.
What screen is the most efficient type?
Rare earth screens
The faster the screen has what effect of exposure and detail?
Faster exposure, but less detail.
What are the 3 effects of high kV that lead to it’s contrast level? And what sort of contrast on the image does it result in?
High kV –> low contrast with many grey tones
3 factors that cause low contrast =
1) high amount of undesirable scatter
2) Predominance of Compton effects
3) High penetration of beam energy
What are two benefits and one negative of grids?
Benefits:
- Decrease scatter
- Improve contrast
Con:
- Increase patient dose (because must use higher exposure factors since some of primary beam absorbed)
To better assess for small volumes of pleural effusion or gas, radiographs should be taken at what point during the respiratory cycle?
End of expiration
What are 2 advantages of a DV projection?
1) Cardiac silhouette is less magnified & adopts a more standard appearance
2) Caudal pulmonary arteries & veins better identified due to surrounding gas-filled lung
What are 3 scenarios to consider a decubitus/horizontal beam VD/DV?
1) Small volume pleural effusion
2) Small volume pneumothorax
3) Skyline view for thoracic wall lesions
Film-screen radiographs have better ________ _________ than digital images?
Spatial resolution
What weight/volume percentage of barium sulphate suspension should be administered for esophageal studies?
60%
What are 3 cons of barium sulphate suspension in esophageal studies?
1) May not distend a dilated esophagus
2) May not show a stricture
3) Does not adhere well to mucosa
True or false, barium aspiration will result in permanently altered lung function ?
False, but may result in permanent visualization
What are 2 rare complications of barium aspiration?
Granulomatous pulmonary reactions and aspiration pneumonia
If you are suspicious for what 2 disease processes/lesions then barium should NOT be orally administered?
Esophageal perforation or bronchoesophageal fistula (may result in mediastinal granuloma & adhesion formation)
If you cannot use orally administered barium due to concern for esophageal perforation, then what medium should be used?
What are the potential negative side effects of this contrast media?
Non-ionic iodinated contrast
2 possible S/E:
1) Pulmonary edema
2) Death
How can you improve visibility of the thoracic inlet on a lateral projection?
Move one thoracic limb cranially & the other caudally
At what age does the thymus reach its maximal size?
4 mos
What effect does emaciation have on the opacity of the lung fields?
Makes them hyperlucent. (Decrease exposure factors to compensate for this)
A sharply marginated cardiac silhouette may be indicative of what disease process?
Pericardial effusion. (Normally the margins should be slightly hazy from respiratory motion)
Caudal vena cava merges with which crus of the diaphragm?
Right crus
On which lateral view is it easier to distinguish between cranial pulmonary arteries & veins?
Left lateral
Which view gives a “3 humped” appearance to the diaphragm?
VD
Discuss the differences between VD and DV projections for the assessment of pulmonary parenchyma?
VD - ventral lung fields better evaluated & accessory lobe better visualized (due to cranial position of the heart)
DV - dorsal lung fields better evaluated & accessory lobe LESS aerated due to cranial position of mid-diaphragm
