FRCR -----Ground-glass pattern on HRCT

Ground-glass pattern on HRCT

• A ground-glass pattern on HRCT is defined as a generalized increase in opacity that does not obscure pulmonary vessels. 

• At a microscopic level, the changes responsible for ground-glass opacity are complex and include partial filling of the airspaces, considerable thickening of the interstitium, or a combination of the two. Ultimately, the pattern of ground-glass opacity on HRCT results from displacement of air from the lungs. 
• Many conditions result in the non-specific pattern of ground-glass opacity but the most common causes include:

1. subacute hypersensitivity pneumonitis, 
2.acute respiratory distress syndrome (ARDS),
3. acute interstitial pneumonia (AIP), 
4.non-specific interstitial pneumonia (NSIP) and 
5.diffuse pneumonias, particularly Pneumocystis jirovecii (carinii) pneumonia in patients with acquired immune deficiency syndrome (AIDS). 

• The definite identification of dilated airways within areas of ground glass is usually an indication of fine fibrosis and thus usually indicates irreversible disease. 
• In organizing pneumonia,dilated airways that are present within areas of ground glass in the acute setting may completely resolve following successful treatment.