Lungs

Question 1

Causes of pulmonary granulomas?

Answer 1

Post-infection/inflammatory(eg TB, vasculitides, fungal disease)

Question 2

Benign vs Malignant calcifications?

Answer 2

-benign(central, diffuse, popcorn, laminates) -malignant(eccentric, speckled, amorphous)

Question 3

Typical age of round pneumonia?

Answer 3

Paediatric < 8 yrs

Question 4

Association of multiple pulmonary AVMs?

Answer 4

Osler-Weber-Rendu syndrome(90%) = Hereditary hemorrhagic telangiectasia -epistaxis -telangiectasia of skin/mucous membrane -GI bleed

Question 5

Communications of pulmonary AVMs?

Answer 5

Between pulmonary/system artery with a pulmonary vein

Question 6

Acquired causes of pulmonary AVMs?

Answer 6

Cirrhosis, trauma, infections

Question 7

Is it reliable to evaluate pulmonary harmatomas by HU?

Answer 7

No, as may be falsely low by averaging with air, it should instead rely on visible fat

Question 8

Ddx of feeding vessel sign(a distinct vessel leading directly to a nodule or mass)?

Answer 8

Infarction

Embolism

Angioinvasive

pulmonary aspergillosis

Vasculitis

AVMs

Metastases

Question 9

Ddx of multiple lung nodules?

Answer 9

metastases, lymphoma, Ca lung with synchronous primary tutors, infections, granulomatous diseases, sarcoidosis, GPA, rheumatoid lung disease, amyloidosis, septic embolism

Question 10

Predilection of pulmonary metastases?

Answer 10

peripheral and subpleural

Question 11

Associated findings of pulmonary metastases?

Answer 11

-surrounding haemorrhage(ill defined or halo sign) -cavitation -calcification -feeding vessel sign(reflect their embolic nature)

Question 12

Prognosis of invasive mucinous adenocarcinoma(IMA)?

Answer 12

poor

Question 13

CT features of invasive mucinous adenocarcinoma(IMA)?

Answer 13

-diffuse/patchy lung consolidation -GGO -multiple lung nodules in centrilobular location -CT angiogram sign(visible opacified arteries within consolidative areas on contrast-chanced CT)

Question 14

Tumour behaviour of invasive mucinous adenocarcinoma(IMA)?

Answer 14

-lepidic growth(tumor cells proliferating along the surface of intact alveolar walls without stromal or vascular invasion pathologically) -they secrete mucin to fill the alveoli so consolidation can be seen as well

Question 15

Old terms for invasive mucinous adenoCA?

Answer 15

diffuse or multifocal broncioloalveolar carcinoma

Question 16

Features?

Answer 16

• Large arrows: focal areas of consolidation
• Small arrows: multiple nodules in centri-lobular location reflecting endobronchial spread of tumour
• Dx: invasive IMA with consolidaiotn and multiple nodules

Question 17

Common fungal organism giving lung infection in immunocompromised patients?

Answer 17

Aspergillus

Question 18

Differences in CT features of pulmonary infections in immunocompetent vs immunocompromised patients?

Answer 18

• Immunocompetent: focal consolidation/solitary nodule/solitary mass more common except massive inoculation of organism(e.g. histoplasmosis in a cave explorer)
• Immunocompromised: multiple nodules +/- halo sign +/- cavitation

Question 19

What is granulomatosis with polyangiitis?

Answer 19

• multisystem disease of unknown cause

associated with upper, lower resp tract and kidney

• 90% ANCA +ve

Question 20

Typical locations of lung nodules in amyloidosis?

Answer 20

peripheral or subpleural

Question 21

CT features of granulomatosis with polyangiitis?

Answer 21

• typical multiple lung masses/cavities 2-4cm
• less commonly solitary nodule/mass
• +/- pulmonary hemorrhage
• with treatment, cavitatory nodules and masses become thin walled and decrease in size/complete resolution

Question 22

Massive PE vs Submassive PE?

Answer 22

(1) Massive PE
- systemic hypotension
- drop in systolic arterial pressure >= 40mmHg for at leasts 15 minutes not caused by new-onset arrhythmias
- shock
(2) Submassive PE
- haemodymically stable but with RV dysfunction or hypokinesis confirmed by echocardiography

Question 23

What is saddle embolus?

Answer 23

• large pulmonary embolism that straddles the birfurcation of the pulmonary trunk extending into left and right pulmonary arteries
• right heart strain signs usually present
  (1) RV width > LV width
  (2) straightening/leftward bulging of IV septum
  (3) enlarged pulmonary trunk
• contrast reflux into azygos vein(via SVC)/hepatic veins(via IVC) is controversial as it often occurs in the absence of raised RV pressure

Question 24

Contrast density < ___ HU implied non-diagnostic study in CTPA?

Answer 24

300-350 HU

Question 25

CTPA reliably detect emboli in up to _ mm in diameter(\_ order vessels)?

Answer 25

7mm | (4th order vessels)

Question 26

CXR signs of PE?

Answer 26

\*low sensitivity and specificity (1) Most common signs - Watermark's sign(localized peripheral ligaemia secondary to embolus lodging in peripheral artery) +/- proximal arterial dilatation - peripheral airspace opacification(pulmonary haemorrhage) - linar atelectasis(ischemic injury leading to surfactant deficiency) - pleural effusions - central pulmonary arterial enlargement (2) signs associated with infarction - Hampton's hump(rare, non-specific) - consolidation may be multifocal - cavittion follows secondary infection - haemorrhagic pleural effusions in 50% of patients

Question 27

Features of chronic PE?

Answer 27

- crescentic thrombus adherent to arterial wall(+/-calcified/recanalization) - enlarged bronchial vessels(collateral supply) - mosaic attenuation pattern - right heart strain

Question 28

Two vs Three Tier model in Well's criteria for PE?

Answer 28

(1)Two tier \<= 4 unlikely -\> D-dimer \>= 4.5 likely -\> CTPA (2)Three tier 0-1 low risk -\> PERC and D-dimer 2-6 moderate risk -\> D-dimer/CTPA \>6 high risk -\> D-dimer not recommended

Question 29

What is pulmonary embolism rule-out criteria(PERC)?

Answer 29

\*\*\*+ve if for any of the followings, D-dimer sould be considered - age \<50 - pulse \<100 bpm - oxygen saturation \>95% on room air - absence of unilateral leg swelling - absence of haemoptysis - no recent trauma or surgery - no prior history of venous thromboembolism - no exogenous oestrogen use

Question 30

Definition of pulmonary arterial hypertension?

Answer 30

- systolic pulmonary artery pressure \> 35mmHg or - mean pulmonary artery pressure \> 25mmHg at rest or - mean pulmonary artery pressure \> 30mmHg at exercise

Question 31

CT features of pulmonary infarction?

Answer 31

- Hampton hump(**juxtapleural** **wedge** shaped opacification **without air bronchogram**) - consolidation with internal air lucencies, "**bubbly consolidatio**n" - convex borders with **halo sign** secondary to adjacent haemorrhage - decreased in normal lung enhancement - cavitation in septic embolism and infection

Question 32

In PE, what is it?

Answer 32

bubbly consolidation suggests pulmonary infarction

Question 33

In PE, what is it? DDx?

Answer 33

- juxtapleural wedge shape opacification without air bronchogram(Hampton hump) suggests pulmonary infarction - DDx of peripheral wedge-shaped lesion: pulmonary haemorrhage(ischemic chnge without infarction), septic pulmonary emboli

Question 34

Oxygen supply of lungs?

Answer 34

- pulmonary vascular system - bronchial vascular system - directly from inspired air \*\*following occlusive pulmonary embolus, bronchial arteries are recruited as primary source of perfusion, leading to higher pressure of bronchial arteries(prone to haemorrhage)

Question 35

causes of UIP?

Answer 35

- idiopathic pulmonary fibrosis - secondary to CTD, asbestosis, chronic hypersensitivity pneumonitis, radiation, amiodarone, Hermansky-Pudlak syndrome

Question 36

typical CT features of UIP?

Answer 36

- honeycombing (if \>8% of lung vol then highly specific) - reticular opacities in the immediate subpleural lung often associated with honeycombing and traction bronchiectasis with peripheral, posterior and lower lobe predominance (apicobasal gradient), posterior costophrenic angles are almost always involved - reticular opacity-to-GGO ratio: \>= 1; GGO less extensive and almost never seen in isolation - lung architectural distortion reflecting lung fibrosis - lobar volume loss predominantly lower lobes in advanced fibrosis - absence of upper or mid-lung or peribronchovascular predominance - absence of extensive GGO - absence of discrete bilateral cysts - absence of significant mosaic perfusion or air trapping - absence of profuse micronodules

Question 37

HRCT features of honeycombing?

Answer 37

- subpleural in location - 3 to 10mm - thick easily seen walls - cysts in cluster or layer and share walls - air attenuation - empty without "anatomy" within; complete black hole - do not branch - associated with other signs of fibrosis(traction bronchiectasis and irregular reticulation)

Question 38

pathologically what is honeycombing?

Answer 38

- interstitial fibrosis with lung destruction and dilatation of peripheral airspaces - most specific HRCT sign of fibrosis

Question 39

DDx of interlobular septal thickening?

Answer 39

1) smooth: pulmonary edema, lymphangitis carcinomatosis, lymphproliferative disease, amyloidosis(rare), pulmonary veno-occlusive disease(rare), Erdheim-Chester diseaes(rare) 2) nodular: sarcoidosis, lymphangitic carcinomatosis, lymphoproliferative disease, amyloidosis (rare) 3) irregular: fibrotic lung disease

Question 40

paraseptal emphysema vs honeycombing

Answer 40

1) paraseptal emphysema: always one layer; very thin wall; upper lobes predominance; large size; increased overall lung vol; absent associated reticulation or traction bronchiectasis; +/- associated with centrilobular emphysema 2) honeycombing: one/more layers; thick walled; traction bronchiectasis; irregular reticulation; lower lobes predominance; small size; decreased overall lung volume