Lungs Flashcards
Causes of pulmonary granulomas?
Post-infection/inflammatory(eg TB, vasculitides, fungal disease)
Benign vs Malignant calcifications?
-benign(central, diffuse, popcorn, laminates) -malignant(eccentric, speckled, amorphous)
Typical age of round pneumonia?
Paediatric < 8 yrs
Association of multiple pulmonary AVMs?
Osler-Weber-Rendu syndrome(90%) = Hereditary hemorrhagic telangiectasia -epistaxis -telangiectasia of skin/mucous membrane -GI bleed
Communications of pulmonary AVMs?
Between pulmonary/system artery with a pulmonary vein
Acquired causes of pulmonary AVMs?
Cirrhosis, trauma, infections
Is it reliable to evaluate pulmonary harmatomas by HU?
No, as may be falsely low by averaging with air, it should instead rely on visible fat
Ddx of feeding vessel sign(a distinct vessel leading directly to a nodule or mass)?
Infarction
Embolism
Angioinvasive
pulmonary aspergillosis
Vasculitis
AVMs
Metastases
Ddx of multiple lung nodules?
metastases, lymphoma, Ca lung with synchronous primary tutors, infections, granulomatous diseases, sarcoidosis, GPA, rheumatoid lung disease, amyloidosis, septic embolism
Predilection of pulmonary metastases?
peripheral and subpleural
Associated findings of pulmonary metastases?
-surrounding haemorrhage(ill defined or halo sign) -cavitation -calcification -feeding vessel sign(reflect their embolic nature)
Prognosis of invasive mucinous adenocarcinoma(IMA)?
poor
CT features of invasive mucinous adenocarcinoma(IMA)?
-diffuse/patchy lung consolidation -GGO -multiple lung nodules in centrilobular location -CT angiogram sign(visible opacified arteries within consolidative areas on contrast-chanced CT)
Tumour behaviour of invasive mucinous adenocarcinoma(IMA)?
-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
Old terms for invasive mucinous adenoCA?
diffuse or multifocal broncioloalveolar carcinoma
Features?
- 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
Common fungal organism giving lung infection in immunocompromised patients?
Aspergillus
Differences in CT features of pulmonary infections in immunocompetent vs immunocompromised patients?
- 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
What is granulomatosis with polyangiitis?
- multisystem disease of unknown cause
associated with upper, lower resp tract and kidney
- 90% ANCA +ve
Typical locations of lung nodules in amyloidosis?
peripheral or subpleural
CT features of granulomatosis with polyangiitis?
- 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
Massive PE vs Submassive PE?
(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
What is saddle embolus?
- 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
Contrast density < ___ HU implied non-diagnostic study in CTPA?
300-350 HU
CTPA reliably detect emboli in up to _ mm in diameter(_ order vessels)?
7mm
(4th order vessels)
CXR signs of PE?
*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
Features of chronic PE?
- crescentic thrombus adherent to arterial wall(+/-calcified/recanalization)
- enlarged bronchial vessels(collateral supply)
- mosaic attenuation pattern
- right heart strain
Two vs Three Tier model in Well’s criteria for PE?
(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
What is pulmonary embolism rule-out criteria(PERC)?
***+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
Definition of pulmonary arterial hypertension?
- systolic pulmonary artery pressure > 35mmHg or
- mean pulmonary artery pressure > 25mmHg at rest or
- mean pulmonary artery pressure > 30mmHg at exercise
CT features of pulmonary infarction?
- Hampton hump(juxtapleural wedge shaped opacification without air bronchogram)
- consolidation with internal air lucencies, “bubbly consolidation”
- convex borders with halo sign secondary to adjacent haemorrhage
- decreased in normal lung enhancement
- cavitation in septic embolism and infection
In PE, what is it?
bubbly consolidation suggests pulmonary infarction
In PE, what is it? DDx?
- 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
Oxygen supply of lungs?
- 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)
causes of UIP?
- idiopathic pulmonary fibrosis
- secondary to CTD, asbestosis, chronic hypersensitivity pneumonitis, radiation, amiodarone, Hermansky-Pudlak syndrome
typical CT features of UIP?
- 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
HRCT features of honeycombing?
- 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)
pathologically what is honeycombing?
- interstitial fibrosis with lung destruction and dilatation of peripheral airspaces
- most specific HRCT sign of fibrosis
DDx of interlobular septal thickening?
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
paraseptal emphysema vs honeycombing
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
