USUAL INTERSTIAL PNEUMONIA.
UIP is the commonest idiopathic pulmonary fibrosis (IPF) also known as crytpogenic fibrosing alveolitis
Average age: 51 years (range 40-70 years). Shows slight male predeliction. Associated with smoking.
Patient usually complains of dry cough progressive exertional dyspnea,
Basilar dry rales, finger clubbing.
Familial pulmonary fibrosis: A form of UIP which runs in family , defined as at least two members of primary biological family having clinical features confirmed on biopsy.
Temporal heterogenecity is hallmark with variation in degree of involvement and appearance of interstitial tissue.
XRAY Findings
e/o small opacities which may be nodular , irregular or in combination
reticular/reticulonodular shadowing is usually basal
lower zone accentuation is invariable
Volume loss characterised by diaphragmatic elevation and depression of fissures.
CT findings
More reliable in diagnosis
Earliest CT feature is faint subpleural opacification in POSTEROBASAL segment
of lower zone.
The peripheral subpleural location is the characteristic of IPF on CT.
With progression of disease, faint opacification changes to RETICULAR and then to
honeycombing
Other findings include:
Irregular interfaces between lung/vessel, airways
Intralobular interstial thickening : these are areas of ground glass opacity because of
Partial volume effect.
Prominent centrilobular structure because of scarring around arteries and airway
Airway seen more peripherally than usual ; less than 3cm from pleural surface.
HRCT
Needs to be performed in PRONE position to prevent any confusion with opacification seen in the dependant posterobasal segment of many normal scan.
Characteristics:
Distinct predeliction for basilar /peripheral region
Patchy involvement with large area of spared lung
Traction bronchiectasis, bronchioloectasia
THREE MAJOR PATTERNS SEEN : Predominant pattern on HRCT may predict potential responsiveness to therapy.
1] GROUND GLASS OPACITY Usually suggests alveolar inflammation, interalveolar granulation tissue. Has good prognosis .Regresses with treatment.
2]RETICULAR PATTERN suggests fibrosis within alveolar ducts. Never regresses.
3] HONEYCOMBING PATTERN suggest irreversible destruction of alveolar walls .
CT GRADING
GRADE 1 : Ground glass opacity more than reticular pattern
GRADE 2 : Ground glass opacity pattern in equal distribution to reticular pattern .
GRADE 3 : Reticular pattern more than ground glass opacity.
Grade 1 is more likely to respond to therapy than grade 3.