15
Table 5. Chest HRCT Scan Features of the Fibrotic HP
Pattern
HRCT
Pattern Typical HP
Compatible with
GHP
Indeterminate
for HP
Relevant
radiological
findings
HRCT abnormalities
indicative of small
airway disease:
• Ill-defined,
centrilobular
nodules and/or
GGOs
• Mosaic
attenuation, three-
density pattern,
a
and/or air trapping
(often in a lobular
distribution)
• Craniocaudal: upper
lung zones
• Truly
indeterminate
HRCT pattern
HRCT abnormalities
indicative of small
airway disease:
• Ill-defined
centrilobular
nodules, or
• Three-density
pattern* and/or air
trapping
Distribution of
parenchymal
abnormalities:
• Craniocaudal:
diffuse (with or
without some basal
sparing )
• Axial: diffuse
a
e three-density pattern was formerly called the "headcheese sign." It is described in detail in Table 3.
(cont'd)
