Hrct iii

PRESENTED BY : DR SHAMIM

GUIDED BY : DR A PATIL (MD)

LINEAR AND RETICULAR
OPACITIES

NODULES AND NODULAR
INCREASED LUNG OPACITIES
ATTENUATION

PARENCHYMAL Consolidation
OPACIFICATION

Ground glass
HRCT PATTERN
CYSTIC
LESIONS, EMPHYSEMA, AND
BRONCHIEACTASIS

MOSAIC ATTENUATION AND
PERFUSION

DECREASED LUNG
ATTENUATION
AIR TRAPPING ON
EXPIRATORY SCANS

Thickened
Septa

Pulmonary
veins

SMOOOOTHHH...

Interlobular septal
thickening associated
with several septal
nodules giving
beaded appearance

Irregular reticular opacities
(arrows) in a patient with
idiopathic pulmonary fibrosis
shows

IS IT IN CONTACT WITH PLEURA

NO YES

CENTRILOBULAR PERILYMPHATIC RANDOM

• Random
– touch pleura
– scattered in lung

• Centrilobular
–away from pleura

• Perilymphatic
– around vessels, bronchi
– touch pleura or fissure

Consolidation

Ground-glass opacity

High attenuation
opacities & calcification

21

 what is consolidation?
Increased attenuation, which results in obscuration of the
underlying vasculature, usually producing air bronchogram.

 'what is replacing the air in the alveoli'?

Pus, edema, blood or tumor cells .
Even fibrosis as in UIP, NSIP can replace the air and cause
consolidation

24

 Pneumonias (Bacterial, mycoplasma, PCP)
 Pulmonary edema due to heart failure or ARDS
 Hemorrhage
 Acute eosinophilic pneumonia

When consolidation is evident on a CXR, HRCT does not
usually provide additional diagnostically useful information

47-year old female patient with a dry cough, slightly breathless.
The first chest film shows bilateral consolidations in the lower lobes (arrow)
After two weeks Rx with antibiotics, there is no improvement.
The differential diagnosis now includes

 Organizing Pneumonia
 Chronic eosinophilic pneumonia
 Bronchoalveolar carcinoma or lymphoma
 Fibrosis in UIP and NSIP

Low-grade
fever, progressive shortness
of breath .

We see patchy non-
segmental consolidations in
a subpleural distribution.

Low-grade
fever, progressive shortness
of breath .

We see patchy non-
segmental consolidations in
a subpleural distribution.

There was a marked
eosinophilia in the
peripheral blood.

 Idiopathic condition characterized by filling of
alveoli by an infiltrate primarily eosinophils.
 Present with fever, cough, weight loss, malaise, and
shortness of breath.
 Increased number of eosinophils in the peripheral
blood
 Patients respond promptly to steroids.

 Peripheral
consolidations with
upper lobe
predominance

(‘photo negative’ of
pulmonary edema).

 Organizing pneumonia
 Loeffler syndrome (eosinophilia and vanishing
peripheral consolidations)
 Churg-Strauss syndrome (also serum
eosinophilia, asthma, systemic vasculitis affecting
multiple organs: renal insufficiency, arthralgia and
myocarditis and pericarditis)

similarities between chronic eosinophilic pneumonia(left) and organizing pneumonia(right).
Differentiation has to be made on the basis of clinical and laboratory findings

 Aka., Bronchiolitis Obliterans with Organizing
Pneumonia (BOOP)

 An inflammatory process in which the healing
process is characterized by organization and
cicatrization of the exudate rather than by
resolution and resorption
 'unresolved pneumonia’.

 Several-months of nonproductive cough, low-grade
fever, malaise and shortness of breath.

 A great mimicker

 Actually Is a diagnosis of exclusion.

 Good response to corticosteroid therapy and a
good prognosis.

 Is mostly idiopathic and then called cryptogenic,

 Is also seen in patients with,

• Infection (bacterial, viral, PCP)
• Drugs (antibiotics, amiodarone, cocaine)
• Connective tissue disorders (SLE, RA, Sjogren
syndrome, dermatomyositis).
• Toxic-fume inhalation.
• Organ Transplantation
• Miscellaneous (inflammatory bowel dx, primary
biliary cirrhosis, lymphoma, hematologic
malignancies)

Typical :

Bilateral, patchy ground glass attenuation or
consolidation with peripheral, lower zone
distribution frequently migratory
Reversed halo sign

central ground-glass
opacity and
surrounding air-space
consolidation of
crescentic and ring
shapes

central ground-glass
opacity and
surrounding air-space
consolidation of
crescentic and ring
shapes)

Bilateral peripheral
consolidations of OP.
After exclusion of other
diseases such as
infection, lymphoma, br
onchoalveolar
carcinoma, the
diagnosis of cryptogenic
organizing pneumonia
was made.

A patient with rheumatoid arthritis and bilateral peripheral consolidations

 Chronic eosinophilic pneumonia

 Bronchoalveolar cell carcinoma

 Lymphoma

 Aspiration pneumonia

 Pulmonary infarction

Chronic eosinophilic pneumonia (left) versus Organizing pneumonia (right)

Ground glass Consolidation

•Hazy attenuation •Denser attenuation
•Vessels seen •Obscuration of vessels
•'dark bronchus' sign •'air bronchogram‘.

 Hazy increased attenuation of lung,
 Preservation of vascular margins
 Result of replacement of air in the alveoli by
fluid, cells or fibrosis
 May also be due to volume averaging of
morphological abnormality too small to be resolved

NB :: Ground Glass opacity should be diagnosed only on
scans obtained with thin sections : with thicker sections
volume averaging is more - leading to spurious GGO,

Decreased air content without totally obliterating the
alveoli # Normal expiration
# Partial collapse of alveoli

Filling of the alveolar spaces with
pus, edema, hemorrhage, inflammation or tumor cells.
# Partial filling of air spaces
Thickening of the interstitium or alveolar walls below the
spatial resolution of the HRCT as seen in fibrosis.
# interstitial thickening
# Increased capillary blood volume

So, ground-glass opacification may either
be the result of
 air space disease (filling of the alveoli)
or
 interstitial lung disease (i.e. fibrosis).

 Nonspecific but important finding since,
 60-80% of patients with ground-glass opacity have active
potentially treatable disease
 20-40% of cases, disease is not treatable and pattern is
the result of fibrosis

In the absence of fibrosis, mostly indicates the presence of
an ongoing, active, potentially treatable process

Pneumonia
Edema Hemorrhage

Organising pneumonias

Hypersensitivity pneumonia

Non specific pneumonia (NSIP)

Pulmonary alveolar proteinosis

 Immune reaction to
inhaled antigens in dust
 Clue—exposure history
 HRCT-ground glass
opacity

 Subacute:
 Ill-defined Centrilobular Micronodules (reflecting
the bronchiolocentric nature of inflammation),
 Diffuse Bilateral Ground-glass Opacification (due
to the lymphoplasmacytic inflammatory infiltrate)
 Air- Trapping (because of small airways
obstruction).
 Mosaic Pattern : combination of patchy ground-
glass opacity due to lung infiltration and patchy
lucency due to bronchiolitis with air trapping

 Chronic :
 Reticular Pattern with parenchymal distortion
(indicating lung fibrosis) intermingled with areas of
decreased attenuation; sometimes called the
“head-cheese” sign.
 Occasionally indistinguishable from UIP.
Fibrosis of HP does not have a predilection for the
periphery and lower zones and is often associated with
ground-glass opacification, micronodules and air-
trapping.

Subacute hypersensitivity pneumonitis with ill-defined centrilobular nodules

Mosaic Pattern.
Some lobules demonstrate ground-glass opacity due to lung infiltration, while
others are more lucent due to bronchiolitis with air trapping

Homogeneous, uniform pattern of cellular interstitial inflammation
Associated with variable degrees of fibrosis.

 Associated with,
collagen vascular disease, drug reaction
 Good response to steroids, ( unlike UIP)
 As in UIP mainly involves the dependent regions of
the lower lobes, but NSIP lacks the extensive
fibrosis with honeycombing.
 In contrast, UIP is associated with extensive fibrosis
which is temporally inhomogeneous (i.e. various lesions
are of different ages).

 specific entity or

 'wastebasket' diagnosis

 very inhomogeneous group

 type I :cellular pattern seen as ground glass opacity

 type IV :fibrotic pattern, indistinguishable from UIP.

Known case of dermatomyositis with breatlessness.

 The predominant finding is ground glass opacity
(GGO).

 There is very subtle traction
bronchiectasis, indicating that the GGO is the result
of fibrosis and therefore irreversible.

NSIP is by far the most common
interstitial lung disease in patients
with connective tissue disease.

Areas of ground-glass and traction bronchiectases
More extensive abnormalities in the lower lung
But honeycombing is typically lacking.
Mildly dilated esophagus,

 Not a diagnosis on it's own , is a pattern of lung
damage.
 The diagnosis of NSIP requires histological proof.
 For the pathologist the key feature is the uniformity
of the abnormality within the lung.
 The role of the radiologist is more to ‘exclude UIP
pattern’ rather than to make the diagnosis of NSIP.
 In all patients with a NSIP , the clinician should be
advised to look for connective tissue
diseases, hypersensitivity pneumonitis or drugs

 Heterogenous group of disorders represent
fundamental responses of the lung to injury and do not
represent 'diseases' per se.
 These diseases have specific patterns of morphologic
findings on HRCT and histology.
 These patterns are also common findings in collagen
vascular diseases (e.g., sclerodermia, rheumatoid
arthritis) and drug-related lung diseases.
For instance in patients with rheumatoid arthritis
findings of NSIP, UIP, OP and LIP have been reported.
 IIPs include seven entities in order of relative frequency.

The differentiation between NSIP and UIP has
tremendous prognostic implication for the
patient.
UIP is more progressive and more than 50%
of patients with UIP die within 3 years.

 Honeycombing consisting of multilayered thick-
walled cysts.
 Architectural distortion with traction bronchiectasis
due to fibrosis.
 Predominance in basal and subpleural region.
 Mild mediastinal lymphadenopathy

layered peripheral cysts, stacked one
on top of the other

 Is a pathology diagnosis at lungbiopsy, when
honeycombing is visible.
 If the UIP pattern is of unknown cause (i.e.
idiopathic), the disease is called Idiopathic pulmonary
fibrosis (IPF).
IPF accounts for more than 60% of the cases of UIP.
 Diagnosis of IPF requires exclusion of other known
causes of UIP including drug toxicities, environmental
exposures (asbest), and collagen vascular diseases like
RA, SLE, polyarteritis nodosa and sclerodermia.

Photomicrograph of histopathologic specimen
(low-power view) shows typical patchy
interstitial fibrosis and areas of microscopic
honeycombing (arrows)

57-year-old man with biopsy-proven
idiopathic pulmonary fibrosis. Gross
pathologic specimen from autopsy
shows predominantly lower
lobe, peripheral, and subpleural
fibrotic lesions that alternate with
areas of normal lung (asterisks).
Honeycombing cysts are seen in
subpleural regions (arrow).

Honeycombing Cystic lung disease

Reticular pattern – no honeycombing Reticular pattern - honeycombing

• Reticular abnormality
• Honeycombing with or without
traction bronchiectasis
• Subpleural basal predominance
• Absence of features
inconsistent with these

Lower zone – UIP pattern Upper zone - chronic
hypersensitivity pneumonitis

Long standing sarcoidosis with fibrosis – upper and mid-zone fibrosis

emphysema in the upper lobes and a UIP pattern in the lower lobes

UIP NSIP
• Honeycombing • Ground glass
• Subpleural • Septal lines
• Lower lungs • Lower lungs
• Clinical- • Clinical-better
fibrosis, poor prognosis
prognosis

 ‘Crazy Paving' is a combination of ground glass
opacity with superimposed septal thickening in a
patchy distribution. Some lobules are affected and
others are not.

 It was first thought to be specific for alveolar
proteinosis,.

Combination of ground glass opacity and
septal thickening : Alveolar proteinosis.

 Abnormal surfactant metabolism Filling of the
alveolar spaces with PAS positive material
 30 - 50 years old.
 Nonproductive cough, fever, and mild dyspnea
 The diagnosis is based on the suggestive HRCT
pattern (crazy paving) and the characteristic
features of BAL fluid (Broncho Alveolar Lavage)

Accumulation of PAS positive material within
the alveoli and thickening of the interstitium.

 Patchy but geographical ground-glass opacification,
 With a network of smoothly thickened interlobular
septa (termed the “crazy paving” pattern).

the proteinacious material, which is removed from the
alveolar space by macrophages is transported to the
interstitium and thus leads to thickening of septa

the appearances are not pathognomonic of the disease

“Crazy-paving” in a patient with alveolar proteinosis.
There is ground-glass opacification in a patchy but
geographical distribution on which a network of smoothly-
thickened interlobular septa is superimposed.

 Alveolar proteinosis
 Infection (PCP, viral, Mycoplasma, bacterial)
 NSIP
 Organizing pneumonia (COP/BOOP)
 Neoplasm (Bronchoalveolar Ca)
 Pulmonary hemorrhage
 Edema (heart failure, ARDS, AIP)
 Sarcoid

 Pneumocystis jiroveci

 Opportumistic infection in immunocompromised

 Nowadays PCP is seen more in immunosuppressed
patients, i.e. transplant recipients and patients on
chemotherapy.

 Perihilar or diffuse ground-glass opacification.
 Thickened septal lines with areas of ground-glass (
Crazy Paving )
 Later, cysts (or pneumatoceles) in 10-35% , typically
involving upper lobes ; bizarre shapes, thick walls
 Pneumothorax in 35% of patients with cysts
 Following therapy : complete disappearance, or
residual nodules or scars

Immunocompromised patient with PCP.
The CT findings are diffuse ground-glass opacification.
The findings are not specific for PCP, but in this clinical setting PCP is
the most likely diagnosis.

MOSAIC ATTENUATION
AND PERFUSION

• Definition: Heterogeneous lung density having a
zonal or geographic pattern of distribution with

areas of “groundglass attenuation”
alternating with
areas of “decreased” lung density

 Lung density and attenuation depends partially on
amount of blood in lung tissue.

 Mosaic perfusion refers to areas of decreased
attenuation which results from regional differences
in lung perfusion secondary to airway disease or
pulmonary vascular disease.

May be due to ,

vascular obstruction,

abnormal ventilation or

airway disease

131

 The pulmonary arteries will be reduced in size in
the lucent lung fields thus allowing mosaic
perfusion to be distinguished from ground-glass
opacities.

 Patchy ground glass infiltrates
resulting from airspace/interstitial
disease: eg PCP
 Air-trapping resulting from airway
obstruction: eg constrictive
bronchiolitis
 Vascular disease: eg. chronic
embolic PHT

 Parenchymal disease: high attenuation regions are
abnormal and represent ground-glass opacity
 Obstructive small airways disease: low attenuation
regions are abnormal and reflect decreased
perfusion of the poorly ventilated regions, e.g.
bronchiectasis, cystic fibrosis, constrictive
bronchiolitis
 Occlusive vascular disease: low attenuation regions
are abnormal and reflect relative oligaemia
e.g. Chronic pulmonary embolism

 Peripheral Vessels : if vessels in hypoattenuated
regions of the lung are smaller than in the other
regions, the pattern is due to mosaic perfusion (i.e.
airways or vascular disease rather than ground-
glass)
 Central Vessels : pulmonary hypertension, reflected
as dilatation of the central pulmonary
arteries, suggests a vascular cause
 Small Airways : the presence of abnormally dilated
or thick walled airways in the relatively lucent lung
confirms underlying airway disease

 Parenchymal Changes : ground glass opacity is the
likely cause if other features of infiltrative disease
are present,
 Air Trapping : refers to regions of lung which
following expiration do not show the normal
increase in attenuation. The presence of air
trapping suggests airway disease

# Areas of increased attenuation have relatively large
vessels, while areas of decreased attenuation have
small vessels.
# Air trapping and bronchial dilatation commonly
seen.
# Causes include: Bronchiectasis, cystic fibrosis and
bronchiolitis obliterans.

138

# Decreased vessel size in less opaque regions is often
visible
# Dilatation of the central pulmonary arteries
# common in patients with acute or chronic
pulmonary embolism (CPE),

MOSIAC PATTERN

DEPENDENT LUNG ONLY NONDEPENDENT LUNG

EXPIRATION
PRONE
POSITION

NO AIR
TRAPPING
NOT AIR TRAPPING
RESOLVE
RESOLVE

VESSEL SIZE

PLATE GROUND
ATELECTASIS GLASS
AIRWAYS
DECREASED NORMAL DISEASE

GROUND
VASCULAR GLASS
140

The vessels within the areas of abnormally low attenuation are
smaller than their counterparts in areas of normal lung
attenuation.
142

 Air-space Disease
 Pcp, Edema
 Interstitial Disease
 Fibrosis/Microscopic
 Honeycombing

 Combined Air-space / Interstitial Disease

 Large airway disease
 Bronchiectasis
 Small airway disease
 Constrictive bronchiolitis
 Asthma

Air trapping on expiratory imaging in the absence of inspiratory
scan findings in a patient with bronchiolitis obliterans.

 Chronic pulmonary embolism
 Pulmonary hypertension
 2° increased pulmonary pressure

Mosaic perfusion pattern with marked regional variations in attenuation of the lung
parenchyma and disparity in the size of the segmental vessels, with larger-diameter
vessels in regions of increased attenuation (arrows). A peripheral parenchymal band
or scar (arrowhead) from infarction also is depicted.

mosaic lung attenuation, with segmental and subsegmental
perfusion defects. A small pleura-based opacity (arrowhead)
caused by previous infarction is seen in the apical segment of the
right lower lobe.

Mosaic Algorithm

Air trapping

Small Small
Airways Vessel

 It refers to mixed densities
# Consolidation
# Ground Glass Opacities
# Normal Lung
# Mosaic Perfusion

• Signifies mixed infiltrative
and obstructive disease

HRCT scan shows lung
with a geographic
appearance, which
represents a
combination of patchy
or lobular ground-
glass opacity (small
arrows) and mosaic
perfusion (large
arrows).

Common cause are :

1. Hypersensitive pneumonitis

2. Sarcoidosis

3. DIP

166

A patient with hypersensitivity pneumonitis shows a
combination of ground-glass opacity, normal lung, and
mosaic perfusion (arrow) on the same inspiratory image.
167

Bilateral multiple centrilobular nodules

Ground-glass opacification in a geographical distribution
with smoothly-thickened interlobular septa

Bilateral peripheral consolidations with reverse halo

Air trapping on expiratory imaging

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