2 types (a) cellular NSIP (b) Fibrotic NSIP (more common) Fibrosis may involve alveolar septa, peribronchivascular interstitium, interlobular septa and visceral pleura. Prognosis of fibrotic NSIP is worse , cellular NSIP has good prognosis. HRCT finding may show both, airspace and interstitial patterns

1. Dr. Vrishit Saraswat
Resident
Department of Radiodiagnosis

2. Homogenous expansion of alveolar walls
by varying amounts of interstitial
inflammation and fibrosis.
Relative temporal and geographical
homogenicity.
Women
Non smoker
Age less than 50 yrs
Honeycombing is uncommon

3. 2 types (a) cellular NSIP
(b) Fibrotic NSIP (more
common)
Fibrosis may involve alveolar septa,
peribronchivascular interstitium,
interlobular septa and visceral pleura.
Prognosis of fibrotic NSIP is worse ,
cellular NSIP has good prognosis.
HRCT finding may show both, airspace
and interstitial patterns.

4.  Typical HRCT findings- GGO , irregular linear
opacity ( reticulations ), traction bronchietasis.
 GGO found in patients , changed into reticular
opacity after few years.
 Honeycombing id present, tends to be mild
 Lower lobe predominance is common. Upper
lobe is uncommon in NSIP and should
suggest another diagnosis (chronic HP,
sarcoidosis)

5.  Characteristic finding of NSIP is relative
sparing of the immediate subpleural lung
in dorsal region of lower lobe.
 CT findings tend to improve with treatment in
pts who mainly have GGO predominance (cellular;
airspace) than pts who have predominant fibrosis
on previous scans.
 The majority of patients who show
progression of fibrosis on follow up ; a
significant minority progress to UIP pattern.

6.  Abnormalities seen on HRCT in NSIP can mimic
with :-
(a) UIP (predominantly lower lobe reticulations)
(b) HP, RB-ILD (predominantly GGO)
(c) BOOP(when there is extensive consolidation)
 Multivariate logistic regression analysis showed
that the most useful finding for distinguishing IPF
from NSIP was the extent of honeycombing. The
average extent of honeycombing was 4.4% of
parenchyma in IPF and less than 1% in NSIP.

7.  Various studies demonstrate that HRCT allows
distinction of NSIP from IPF and chronic HP in
many patients. However, although the presence of
predominantly peripheral and basal honeycombing
in the appropriate clinical setting often allows a
confident diagnosis of IPF on HRCT, a confident
diagnosis of NSIP requires surgical biopsy and a
dynamic multidisciplinary approach with input from
clinicians, radiologists, and pathologists . It is
important to note that even a histologic diagnosis
of NSIP does not establish a final diagnosis.

8. HRCT finding of patchy or subpleural
ground-glass opacity, with or without
reticulation, should suggest a likely
diagnosis of NSIP rather than UIP.
Generally, lung biopsy is recommended in
this setting.

9.  In cases where diagnosis cannot be made
because of overlap of CT and histological findings;
Chrug & Muller proposed a three seperations on
HRCT for chronic interstitial diseases.
(A) Air space opacification(GGO or consolidation) –
COP / Cellular NSIP/DIP / Sub acute HP – good
prognosis.
(B) Diseases manifesting extensive GGO with mild
reticulation(>25% of lung parenchyma)- mixed
NSIP / Chronic HP.
(C) Predominant Reticulations – fibrotic NSIP/ UIP.