Pulmonary Radiography

Question 1

describe the lung lobes

Answer 1

1. named for the branching of the principle bronchi into the lobar bronchi
   -dogs and cats: 4 lobes on the right, 2 lobes on the left
2. left principle bronchus:
   -2 lobar bronchi: cranial and caudal
   -cranial lobar bronchus immediately divides into cranial and caudal subsegments of the cranial lobe
3. right principle bronchus:
   -3 lobar bronchi: cranial, middle, caudal
   -accessory originates from the right caudal lobar bronchus

Question 2

describe the pulmonary parenchyma

Answer 2

3 components contribute to what is seen (CT is gold standard for pulm eval)
Air within the small airways and vessels
Blood vessels
Airway walls

Question 3

describe radiographic eval of lungs

Answer 3

1. always take 3 projections of thorax
   -due to lesion conspicuity
   -both laterals (RL and LL)
   -VD or DV
2. pulmonary opacity:
   -normal, reduced, or increased
   -increased: in most diseases, where we see pulmonary patterns
   -normal: should see vessels spreading to periphery; if don’t see vessels well = something abnormal

Question 4

describe reduced pulmonary opacity

Answer 4

1. also called pulmonary (hyper) lucency
2. lungs appear darker/more black
3. increased gas opacity and decreased soft tissue opacity in the lungs
   -small vessels or no vessels

Question 5

describe 3 causes of diffuse reduced pulmonary opacity

Answer 5

1. hypovolemia:
   -small vessels, small heart, small CdVC
   -hypovolemic shock, hypoadrenocorticism
2. increased thoracic volume:
   -hyperinflation/air trapping: feline asthma
3. artifact: over exposure

Question 6

describe 3 ddx for focal reduced pulmonary opacity

Answer 6

1. (multi)focal lucency (ies)
   -bulla, bleb, pneumatocele, cavitated mass
2. regional oligemia: pulmonary thromboembolism

3, bronchial dilation: bronchiectasis

Question 7

GENERALLY describe pulmonary lung patterns

Answer 7

1. increased pulmonary opacity: lungs appear wider
   -occurs in most of the diseases
2. causes:
   -soft tissue opaque material within the air spaces: blood, pus, water, cells
   -thickening of the pulmonary interstitium/connective tissue
   -nodules/masses
   -bronchial wall thickening
   -enlarged pulmonary vessels

Question 8

what are the 4 types of lung patterns?

Answer 8

1. alveolar
2. interstitial:
   -unstructured
   -structured (miliary, nodular, masses)
3. bronchial
4. +/- vascular:
   -enlarged pulmonary arteries, veins, or both
   -small pulmonary arteries, veins, or both

first question is: can I see the vessels? if so, probs normal

many patterns are actually mixed, search for the most predominant and go from there

Question 9

describe how unstructured interstitial and alveolar patterns are related

Answer 9

a continuum! with a similar list of differential diagnoses

try to classify differentials by location:
1. cranioventral: bronchopneumonia
2. caudodorsal: pulmonary edema
3. ventral: aspiration pneumonia
4. multifocal: contusions, fungal pneumonia, metastasis
5. diffuse: lymphoma, ARDS

pattern reflects SEVERITY: progresses FROM unstructured interstitial TO alveolar, like fog is less bad closer to the ground and gets worse as move up (more opaque = worse)

use your recheck exam to determine which way you are moving on the continuum

Question 10

what are common differentials for alveolar and unstructured interstitial

Answer 10

1. atelectasis
2. aspiration pneumonia
3. bronchopneumonia
4. pneumonitis
5. pulmonary edema
   -cardiogenic
   -non-cardiogenic
6. neoplasia: lymphoma (unstructured interstitial)

Question 11

describe the alveolar lung pattern

Answer 11

VERY important!! if you miss and don’t do anything, patient will probs die overnight

4 main features: don’t need to have ALL 4 to = alveolar pattern
1. uniform grey: absent visualization of vessels (thick fog in the woods)

2. border effacement with adjacent soft tissue/fluid opaque structures
3. air broncograms:
   -air filled bronchus surrounded by soft tissue opaque lung
4. lobar sign:
   -abnormal lung border contrasted with normal lung border; the disease is respecting the lobar border!
   -will not see if disease affecting all lung lobes

Question 12

describe the unstructured interstitial lung pattern

Answer 12

radiographic findings:

1. increased soft tissue opacity that PARTIALLY obscures pulmonary vascular margins
2. hazy
3. never mild!! always moderate or severe
   -mild = too many ddx so is artifactual essentially, only label of moderate to severe

Question 13

rank the amount of connective tissue in the lungs of different species

Answer 13

dogs and cats < horses < farm animals

can see vessels better with less CT, horses more opaque compared to dogs and cats, ruminants more opaque, alligator snapping turtle hella opaque

Question 14

describe fake outs (3) and ddx (4) for unstructured interstitial patterns

Answer 14

fake outs:
1. underexposure

2. expiratory radiographs: smaller lung lobe volume causes vessels to be closer together and look more opaque
3. large body habitus: overweight

if real: very nonspecific unless know location
1. pneumonia
2. pneumonitis
3. fibrosis: WHWT
4. lymphoma

Question 15

describe the structured interstitial lung pattern

Answer 15

1. technical name for nodules and masses
   -most commonly soft tissue opacity, but could be mineral opacity or gas opaque or mixed
2. based on difference in size
   -miliary: approx 1mm; very small nodules/pinpoint lesions

-nodule: <3cm; can be subtle; look over diaphragm and vertebrae

-mass: >3cm

Question 16

give 2 common ddx for miliary structured interstitial

Answer 16

fungal pneumonia, metastatic neoplasia

Question 17

give 3 common ddx for nodules and 5 fake outs

Answer 17

1. metastatic neoplasia
   -mammary carcinoma, hemangiosarc, thyroid carcinoma)
2. fungal pneumonia (blastomycosis, often with TB lymphadenopathy)
3. benign pulmonary osteomas (miner opaque)

-could be abscess and granuloma formation, but this is less common in small animals

fake outs:
1. end-on vessels: same or smaller size and more opaque than adjacent longitudinal (side-on) vessel, less numerous in periphery
2. cutaneous nodules
3. nipples
4. ectoparasites
5. osteomas

Question 18

give 5 common ddx for masses

Answer 18

1. primary neoplasia: more common if only see one mass (metastasis is more likely multiple masses)
   -broncheoalveolar carcinoma: usually caudal lungs
   -histiocytic sarcoma: usually mass superimposed over cardiac silhouette
   -lymphoma
2. inflammatory: usually in young dogs (young dog = less likely neoplasia initially, but are so severe could become neoplastic over time)
   -pulmonary eosinophilic granulomatosis
   -lymphatoid granulomatosis
3. abscess: migrating foreign bodies most commonly
4. granuloma
5. lung lobe torsion: not a true structured interstitial pattern but may look like a mass

Question 19

describe structured interstitial pattern of pulmonary osseous metaplasia

Answer 19

1. heterotopic bone, pulmonary osteomas, osteomata, pneumoliths
   -common in collies and shelties
2. small (<5mm), may be numerous, often more ventrally
3. MINERAL OPAQUE

Question 20

describe cutaneous nodules

Answer 20

1. skin tags, nipples, papillomas, ticks
   -distinct, sharply marginated opacity superimposed on lungs
   -surrounded by air (half of the surface)
   -but the margin in contact with the skin is ill-defined
   -a pulmonary nodule is well defined all the way around
2. careful exam of patient is critical
3. use positive contract (Barium) or a metallic marker and then re-radiograph

Question 21

describe the bronchial pattern

Answer 21

1. due to chronic inflammation;
   -many bronchi are normally visible in a centrally (hilar) position so always look in periphery = more variation and easier to tell if thickened walls
2. thickened walls are abnormal
3. RINGS and LINES: donut and tram lines
   -rings: end-on small airways
   -lines: airways moving from central to peripheral position
4. usually generalized disease
5. cats: may have concurrent mucous plugs (small nodules)

Question 22

describe the common differentials for the bronchial pattern

Answer 22

1. bronchial wall mineralization (dogs) is NOT a bronchial pattern, just happens
2. chronic bronchitis: infectious, allergic, irritant
3. asthma: cats
4. eosinophilic bronchopneumopathy: dogs
5. heartworm disease: in combo with other findings

Question 23

describe the bronchial pattern with bronchiectasis

Answer 23

1. abnormal and PERMANENT bronchial dilation secondary to chronic airway disease
2. rad findings:
   -increased bronchial lumen diameter: failure to taper peripherally
   -thickened bronchial wall

Question 24

what are the ways to describe distribution of pulmonary changes?

Answer 24

1. cranial or caudal, dorsal or ventral
2. focal (lobar), multifocal, or diffuse
3. hilar, mid-zone, peripheral

Question 25

give the common differentials for variable location lung patterns, also where cardiogenic edema, pulmonary pneumonia, and aspiration and bronchopneumonia usually life

Answer 25

1.variable locations:
-hemorrhage/trauma or diffuse coagulopathy

-PTE (pulmonary thromboembolism: peripheral to diffuse

-ARDS: usually diffuse
(acute respiratory distress syndrome)

3. cardiogenic edema: usually caudodorsal, perihilar
4. caudodorsal: pulmonary edema usually affects here
5. cranioventral: aspiration pneumonia and bronchopneumonia usually live here

Question 26

describe consolidation

Answer 26

-increased opacity with NORMAL TO INCREASED lung volume

-lungs are filled with something other than air (blood, pus, water, cells)

-will result in an unstructured interstitial to alveolar pattern

Question 27

describe atelectasis/collapse

Answer 27

1. lungs are collapsed
2. increased opacity with DECREASED lung volume
   -usually see shift of cardiac silhouette to fill the gap (ipsilateral mediastinal shift)
3. possible underlying disease
4. will result in an unstructured interstitial to alveolar pattern

Question 28

describe bullas/blebs

Answer 28

gas filled structures with a thin soft tissue opaque wall!

diff from masses (thick, ill-defined walls)

Question 29

describe lung lobe torsion

Answer 29

1. uncommon
2. important ddx for lobar consolidation
   - +/- vesicular pattern: pathognomonic of lung lobe torsion (gas trapped and forms bubbles inside torsed lobe initially, rabsorbed later on)
   -abnormal lobar bronchial path: easier to see on CT; may see interruption of lung lobe lumen (CT is gold standard to eval for lung lobe torsion)
3. concurrent pleural effusion is very common
4. caudal lobes rarely torsion
   -pugs: left cranial LL
   -afghan hounds: right middle LL
   -rare in cats

Question 30

describe the vascular pattern

Answer 30

any changes along pulmonary lobar vessels:

-enlarged
-small
-tortuous

Question 31

describe ddx for enlarged arteries and veins

Answer 31

1. fluid overload
2. left sided cardiac failure: esp cats

Question 32

describe ddx for enlarged arteries with normal veins

Answer 32

1. pulmonary hypertension
   -due to heartworm disease or important pulmonary fibrosis

Question 33

describe didx for small arteries and veins

Answer 33

1. hypovolemia
2. addison’s disease

Question 34

describe ddx for enlarged veins with normal arteries

Answer 34

left-sided heart failure

Question 35

describe equine pulmonary disease

Answer 35

1. same pulmonary patterns as SA
   -just need craniodorsal, cranioventral, caudodorsal, and caudoventral views
2. associate predominant pulmonary pattern and location for ddx
   -ddx may differ from SA though
3. cavitated structured interstitial pattern: pulmonary abscesses
4. caudodorsal peripheral unstructured interstitial: exercise-induced pulmonary hemorrhage
   -diff from SA!
5. caudodorsal alveolar, esp with dorsal tracheal displacement: pulmonary edema