J Korean Med Assoc JKMA Journal of the Korean Medical Association 1975-8456 Korean Medical Association 10.5124/jkma.2009.52.1.14 Focused Issue of This Month Interstitial Lung Diseases Radiologic Diagnosis of Interstitial Lung Diseases Yi Chin A MD Lee Kyung Soo MD Department of Radiology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Korea. kyungs.lee@samsung.com 01 2009 31 01 2009 52 1 14 21 Copyright © 2009 Korean Medical Association 2009

Diffuse interstitial lung diseases (DILD) are a group of chronic disorders showing varying degrees of active inflammation and established fibrosis mainly involving the interstitium of the lungs. DILD can be classified into two groups in an etiologic aspect; idiopathic and DILD with known-cause, such as connective tissue diseases associated with DILD. Although there had been complexity and variability in the classification of idiopathic interstitial pneumonia (IIP), an international standard was established for the classification of IIPs including seven clinical-radiologic-pathologic entities; idiopathic pulmonary fibrosis (IPF), nonspecific interstitial pneumonia (NSIP), cryptogenic organizing pneumonia (COP), acute interstitial pneumonia (AIP), respiratory bronchiolitis-associated interstitial lung disease (RB-ILD), desquamative interstitial pneumonia (DIP), and lymphoid interstitial pneumonia (LIP). The prognosis of fibrotic NSIP and IPF is much poorer compared to those of other spectrum of IIPs, such as COP, RB-ILD, DIP, and LIP. Therefore, fibrotic NSIP and IPF can be considered separately as a group of fibrotic IIPs. Trying to predict the prognosis of IIPs, there has been an effort to differentiate inflammation-predominant lesions from fibrosis-predominant lesions in patients with fibrotic IIPs. Radiologic features of low fibrotic scores at high-resolution CT and early enhancement patterns at dynamic enhancement of MRI can be useful prognostic determinants for the prediction of disease improvement in patients with fibrotic IIPs.

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Stable UIP (concordant diagnosis in all three pathologists) in a 67-year-old woman.

(A) Transverse thin-section (1.0-mm section thickness) CT scan obtained at the level of liver dome shows bilateral subpleural distribution of reticulation and ground glass attenuation. Total extent of parenchymal abnormalities on CT scans was 15% and fibrotic score (reticulation plus HC) was 10%.

(B) Seven-year follow-up CT scan obtained at the similar level shows no progression of disease (total extent of parenchymal abnormalities; 15%, fibrotic score; 10%).

Progressive UIP (concordant diagnosis in all three pathologists) in a 63-year-old man.

(A) Transverse thin-section (1.0-mm section thickness) CT scan obtained at the level of liver dome shows bilateral subpleural distribution of reticulation, honeycombing, and ground glass attenuation. Total extent of parenchymal abnormalities on CT scans was 35% and fibrotic score (reticulation plus HC) was 30%.

(B) One-year follow-up CT scan obtained at the similar level shows progression of disease (total extent of parenchymal abnormalities; 50%, fibrotic score; 35%).

A 55-year-old woman with nonspecific interstitial pneumonia (group 1, cellular) exhibiting early enhancement.

(A) Transverse high-resolution CT scan (1.25-mm section thickness) at level of liver dome shows subpleural patchy parenchymal opacities in both lungs.

(B) Serial dynamic MR images show early enhancement with peak enhancement at 3 minutes. Biopsy was performed on lesions in left upper and lower lobes. Pathologic specimens disclosed inflammation-predominant nonspecific interstitial pneumonia (group 1, cellular).

A 78-year-old man with interstitial pneumonia (group 3, fibrotic) exhibiting slight enhancement.

(A) Coronal thin-section (2.5-mm section thickness) CT scan shows subpleural reticulation and traction bronchiectasis in both lungs.

(B) Serial dynamic MR images show no significant enhancement. Biopsy was performed on lesions in left lower lobe. Pathologic specimens disclosed fibrosis-predominant nonspecific interstitial pneumonia (group 3).

Typical CT findings and differential diagnosis of idiopathic interstitial pneumonias (1)