ct chest part 1

1. Computed Tomography in
Chest Diseases
Dr. Rikin Hasnani

2. • Developmental Anomalies
• Airway Diseases
• Pulmonary infection & Pneumonias
• Neoplastic diseases
• Diffuse Lung Diseases
• Disease of mediastinum , Pleura & Chest Wall

3. Developmental Anomalies of
Lung

4. Tracheal bronchus
• Also known as “pig bronchus” or “bronchus suis.
• Incidental finding
• Usually arise from lateral wall of trachea.
• Other type of anomalous bronchus – pre and post eparterial
bronchus, accessory cardiac bronchus, pre and post hyparterial
bronchus.
• Displaced v/s supernumery bronchus

5. Anomalous bronchi

6. Etiology
• Tracheobronchial development occurs during the early embryonic
period (26 days to six weeks).
• Precise etiology of tracheal (and other anomalous) bronchi is not
known,
• regression of anomalous bronchial buds,
• migration of primitive bronchi to anomalous positions, and
• induction of anomalous bronchial branches by surrounding primitive
mesenchyme have all been suggested as possible mechanisms.

7. Development of lung

8. Imaging
• Visualization of anomalous bronchus originating from lateral tracheal wall
or proximal mainstem bronchus
• Multiplanar reformations, shaded surface displays , volume rendering, and
virtual bronchoscopy techniques useful in anatomic characterization and
classification
• D/D
• Tracheobronchial diverticula are blind-ending airways that often arise
from the mainstem bronchi.
• Tracheal air cysts are tracheal diverticula manifesting as air-filled thin-
walled blind-ending structures at the thoracic inlet. These exhibit a normal
mucosal lining and cartilage within their walls.

10. ???

11. Tracheal Air Cyst

12. Bronchial Atresia
• Bronchial atresia is a rare congenital anomaly that typically affects
segmental bronchi, although lobar and subsegmental bronchi may also be
involved.
• The left upper lobe bronchus (apical-posterior segment) is affected in
approximately 64% of cases.
• The surrounding alveoli may fail to develop normally and may overinflate
because of collateral air drift through pores of Kohn, canals of Lambert, or
other communications.
• Endoluminal debris accumulating
distal to the atresia may form a mucocele.
• Symptoms

13. Imaging
Radiography
• Focal overinflation surrounding mucocele (Rounded, tubular, or branching opacity)
• Expiratory air trapping surrounding mucocele
• Air-fluid level within mucocele (with superimposed infection)
MDct
• Rounded , branching , or tubular typically central opacity; low attenuation (–5 to 25 HU))
• Absence of contrast enhancement within bronchus or mucocele
• Overinflated lung surrounding mucocele
Mri
• Visualization of mucocele with high signal intensity on T1- and T2-weighted images
Management :
D/D – vascular abnormalities , endobronchial growth

17. Pulmonary Sequesterations
• It is abnormal unventilated lung tissue that has no normal communication
with the bronchial system and derives its blood supply from systemic ,
rather than pulmonary circulation.
• Intralobar sequestrations are four times more frequent than extralobar
sequestrations and occur almost exclusively in the lower lobes, slightly
more frequently on the left.
• The systemic arterial supply to the lesion often courses within the
pulmonary ligament and originates from the descending aorta. The venous
drainage is into the pulmonary veins.
• The lesion is often heterogeneous due to acute and chronic inflammation
and bronchopneumonia with resultant bronchiectasis, fibrosis, and cystic
change.
• The lesion typically abuts adjacent normal (nonsequestered) lung.

18. • Extralobar sequestrations represent accessory pulmonary lobes that
result from abnormal foregut budding and are located outside the
confines of normal lung.
• They may occur in the thorax, diaphragm, or abdomen; are
characteristically supplied and drained by the systemic circulation;
and represent true congenital anomalies.
• Affected patients are diagnosed within the first 6 months of life, but a
small number of lesions (10%) are diagnosed in asymptomatic adults.

19. Feature Intralobar Extralobar
Frequency More common Less common
Male : female 1:1 4:1
Most common site Within Posterior basal
segment
Between lower lobe and
diaphragm
Side of thorax 60% left sided 90% left sided
Arterial supply 70% thoracic aorta 45% thoracic aorta
Venous drainage Usually pulmonary vein Often systemic vein
Diagnosed in neonates Rarely Commonly
Other cong. defects Uncommon Frequent

21. Clinical features
• Extralobar are frequently diagnosed in 1st year of life.
• Intralobar may present with LRTI, recurrent pneumonic episode or
massive hemoptysis.
• Extralobar sequestraaions are less liable to infections

22. Imaging
• Radiography
• • Typical location: posterior basal segment of a lower lobe.
• • Consolidation or mass; may contain air, fluid, and/or air-fluid levels and
multilocular cystic areas, irregular margins typical,
• • Predominantly cystic lesions; exhibit a single cyst or multiple cysts of
variable sizes
• • Rarely, branching tubular opacities representing mucoid impacted
bronchi
• • Surrounding lung may be hyperlucent
• • May produce mass effect on adjacent structures

23. • MDCT
• Heterogeneous enhancement
• Hyperlucent or predominantly cystic lesion with single or multiple thin-walled cysts; may contain
air and/or fluid
• Demonstration of anomalous systemic arterial supply (usually from descending aorta) in up to
80% of cases; CT angiography with multiplanar reformatted images may enhance visualization of
anomalous vessel
• MRI
• Heterogeneous intrapulmonary lower lobe lesion; may exhibit cystic areas • Gradient-echo
sequences may demonstrate systemic blood supply and pulmonary venous drainage
• Angiography
• Aortography for demonstration of anomalous systemic arterial supply arising from descending
aorta in up to 73% of cases, or other systemic abdominal arteries
• Selective angiography of anomalous systemic artery may allow demonstration of pulmonary
venous drainage

25. Pulmonary Arteriovenous Malformation
• It is an abnormal communication between a pulmonary artery and a
pulmonary vein without an intervening capillary bed, and results in a
right-to-left shunt.
• It is of two types
• Simple PAVMs (90%) are defined as single or multiple feeding arteries
originating from a single segmental pulmonary artery.
• Complex PAVMs (10%) are characterized by feeding arteries
originating from two or more segmental pulmonary arteries.

26. Etiology
• Congenital
• Acquired
• Rendu-Osler-Weber syndrome or hereditary hemorrhagic
telangiectasia (HHT) is an autosomal dominant disorder characterized
by recurrent epistaxis, mucocutaneous telangiectasias, and
arteriovenous malformations, with an estimated prevalence of one in
5,000 to 10,000 persons.
• c/f – asymptomataic, dyspnea, paradoxical emboli

27. • Radiography
• Lobular well-defined non-calcified nodule/mass
• Typically in peripheral lower lobe; often projects below dome of diaphragm.
• Associated tortuous tubular opacities coursing to and from ipsilateral hilum representing feeding
and draining vessels
• Rarely, multiple pulmonary nodules/masses
• CT
• PAVM manifests as nodule with feeding and draining vessels
• Evaluation of origin, number, length, and diameter of feeding vessels and internal structure of
vascular sac
• CECT shows Enhancing mass with vascular connections, Rapid contrast enhancement and
washout
• Unenhanced or enhanced multidetector CT imaging for screening , characterization, and
quantification of PAVM

29. • Mri
• Low-signal flow void in PAVM; low to intermediate signal in PAVM with internal thrombus
• Three-dimensional contrast-enhanced MR angiography for non-invasive diagnosis of PAVM larger
than 3 mm in size, it shows high-signal-intensity nodule and associated vessels
• Evaluation of size and number of feeding vessels prior to embolotherapy
• Angiography
• Opacification of feeding vessels and draining veins
• It is useful in confirmation of diagnosis, documentation of multiple lesions, and evaluation of
origin, number, length, and diameter of the feeding vessel for coil embolization therapy planning.
• Contrast-enhanced two-dimensional echocardiography for screening (90% sensitivity for
detection of intrapulmonary shunts)
• Lung perfusion scintigraphy for determination of shunt size

32. Scimitar Syndrome
• Scimitar syndrome, also known as pulmonary venolobar syndrome or
hypogenetic lung syndrome, is characterised by a hypoplastic lung
that is drained by an anomalous vein into the systemic venous
system. It is a type of partial anomalous pulmonary venous return.

33. Imaging
• Chest radiographic findings are that of a
• decreased lung volume with ipsilateral mediastinal shift,
• Diminished right pulmonary vascularity
• Broad retrosternal band-like opacity on lateral radiography
• Blunt costophrenic angle
• Vertically oriented curved tubular opacity (anomalous draining vein)
in right inferior hemithorax coursing toward right cardiophrenic angle
scimitar sign.

36. Pulmonary stenosis

38. Airway Diseases

39. Tracheal Stenosis
Tracheal stenosis is defined as narrowing
of the tracheal lumen by more than 10%
of its normal diameter.
Etiology – cong, acquired
Clinical features – dyspnea , wheezing ,
stridor
Imaging –
Management - Surgical excision of
stenotic segment and reconstruction
Endoscopic mechanical dilatation
Tracheal stenting
Laser photoablation for focal mucosal
lesions

40. Saber sheath trachea
• Saber sheath trachea is defined
as a tracheal deformity in which
the transverse tracheal
diameter is equal to or less than
one-half the AP diameter,
measured 1 cm above the
superior aspect of the aortic
arch.
• The deformity begins at the
thoracic inlet, affects only the
intrathoracic trachea, and is a
manifestation of chronic
obstructive pulmonary disease.

41. Tracheobronchomegaly; Mounier-Kuhn
Syndrome
• It is also known as
tracheal diverticulosis
and
tracheobronchiectasis.
• It is diagnose when
diameter of trachea ,
right main bronchus or
left main bronchus size
greater than 3.0 cm;
2.4cm ; 2.3 cm
respectively.

42. Tracheobronchomalacia
• It is characterised by excessive expiratory collapse of the tracheal
walls and/or supporting cartilage and is an important cause of airway
obstruction, chronic cough, recurrent lung infection, and other
respiratory symptoms.
• Percentage of luminal collapse between end inspiration and
expiration is calculated as follows:
• LC = 100 · [1 – (LAee/LAei)]
• LC = percentage of luminal collapse
• LAee = luminal area at end expiration (mm2)
• LAei = luminal area at end inspiration (mm2)
• ≥70% luminal narrowing on forced expiration is the diagnostic
threshold for TM

44. Tracheoesophageal Fistula
• TEF may occur as a complication of intrathoracic malignancy (60%),
prolonged tracheal intubation, esophageal instrumentation, infection,
or trauma.
• TEF occurs in 5–10% of patients with advanced esophageal cancer
and is more prevalent in those who have had prior irradiation.
• The diagnosis is usually made with a fluoroscopic contrast
esophagogram.
• CT may demonstrate an occult TEF in patients at risk who have a
normal esophagogram.

45. Chest radiography
• Normal chest radiographs
• Pneumomediastinum (common)
• Pneumothorax
• Consolidation related to aspiration
• Air-distended esophagus
• Airway opacification on contrast esophagography
MDct/3-D.reformations
• Direct visualization of fistula
• Assessment of fistula size and location

46. Bronchiectasis
• It is defined as abnormal,
irreversibly dilated and
thick-walled bronchi.
• It is typically graded
according to its severity as
mild, moderate, and severe
forms, respectively termed
cylindrical, varicose, and
saccular (cystic)

47. Imaging
• Radiography
Visible bronchial walls –
• Single or parallel “tram track” lines (thickened airway walls seen
longitudinally) ◦
• Poorly defined ring-like/curvilinear opacities (thickened airway walls seen
on-end or obliquely)
Variable lung volume (atelectasis or hyperinflation) ◦
Round, oval, or tubular Y- or V-shaped opacities (dilated airways filled with
secretions, mucoid impaction)
Multiple thin-walled ring-like opacities in cystic bronchiectasis, often with
air-fluid levels
Normal chest radiograph in 7% of affected patients

48. • MDCT/HRCT
• Absence of normal distal tapering of bronchial lumen
• Internal diameter of bronchial lumen greater than that of adjacent
pulmonary artery (i.e., signet ring sign)
• Visible bronchi within 1.0 cm of costal pleura or abutting mediastinal
pleura
• Mucus-filled dilated bronchi
• Associated bronchiolitis in 75% of patients (decreased lung
attenuation and vascularity, bronchiolectasis, and centrilobular tree-
in-bud opacities)

51. ???

53. Emphysema
• Emphysema is defined as abnormal permanent enlargement of the
airspaces distal to the terminal bronchiole accompanied by
destruction of their walls with minimal or absent fibrosis.
• Emphysema is categorized according to the affected part of the
pulmonary acinus.
• Proximal acinar (syn. centrilobular, centriacinar)
emphysema involves the proximal aspect
of the acinus with distension and destruction
that primarily affects the respiratory bronchioles

54. Imaging
• Radiography
• Increased lung volumes or lung height (measured ≥30 cm from right first
rib tubercle to diaphragm dome)
• Diaphragmatic flattening (highest level of diaphragmatic contour is <1.5 cm
above a line connecting the costophrenic and vertebrophrenic junctions on
PA view or a line connecting the sternophrenic and posterior costophrenic
angles on lateral view)
• Enlarged retrosternal clear space (horizontal distance between sternum
and anterior margin ascending aorta >2.5 cm on lateral view)
• Abnormal lucency in the upper lung zones
• Reduction in number and caliber of pulmonary vessels; vessels may be
displaced by bullae or emphysematous spaces; may exhibit widened
branching angles with loss of side branches
• Crowding of vessels in mid and lower lungs in moderate and severe
emphysema
• Normal in mild cases

55. MDCT
• Focal areas (3–10 mm) of centrilobular low attenuation with
imperceptible walls .
• Central nodular opacity (centrilobular arteriole) within an area of low
attenuation.
• More severe involvement of upper lobes and superior segments of
lower lobes.
• Large confluent areas of emphysema may progress to panlobular
involvement
• Associated paraseptal emphysema and/or bullae

57. Panacinar emphysema
Panacinar (syn. panlobular)
emphysema affects each
acinus in its entirety and all
acini within the secondary
pulmonary lobule.
It is the characteristic finding
in patients with α-1-
antiprotease deficiency. While
panacinar emphysema may
involve the lung diffusely,
predominant lower lung
involvement is characteristic.

58. Radiology –
Large lung volumes
Decreased pulmonary vascularity
Predominant lower lobe
involvement
MDct/hrct
• Extensive areas of abnormal low
attenuation
• Paucity of vasculature •
Involvement of entire secondary
pulmonary lobule
• Diffuse or lower lobe
predominance
• Absence of focal lucencies or
bullae

60. • Distal acinar (paraseptal) emphysema is the least common type of
emphysema and, together with proximal acinar emphysema, is frequently
associated with the formation of bullae.
• It affects the periphery of the acinus.
• Adjacent foci of paraseptal emphysema may coalesce to form bullae.
• A bulla is defined as a sharply demarcated air-containing space measuring
1.0 cm in diameter or more in the distended state. Bullae are
characteristically thin-walled (1 mm) and may be unilocular or
compartmentalized by thin septa.
• The term giant bullous emphysema refers to bullae that occupy at least
one-third of a hemithorax.

61. Imaging Features
Chest.radiography
• Thin-walled, well-defined
avascular areas in lung
parenchyma (bullae)
• Mass effect on adjacent lung
• Air-fluid levels within
secondarily infected bullae
• Associated pneumothorax

62. MDCT/HRCT
• Many of the same features
seen on chest radiography
• Focal subpleural cystic areas
near interlobular septa, large
vessels, and bronchi
• Frequent associated
proximal acinar emphysema
• Large bullae, usually
between 2–8 cm in diameter
(giant bullous emphysema)

63. Thank You