Diseases Characterised by Parenchymal Opacification

Diseases characterised by Parenchymal opacification

Shivaprakash B Hiremath DNB Resident

Normal lung density Slightly higher than air

Vs Air in airspaces Interstitial lung and small airways tissues Wall of the alveoli Small airways Capillaries, blood in these

Increased lung opacity< in the amount of air > size / volume of soft tissues

Reduction in the volume (expansion) of the airspaces Partial or total replacement of the air in the airspaces by fluid or cells

Increase in blood flow and blood volume in vessels Thickening of the interstitial tissues and of the alveolar wall

Degree of Opacification Ground-glass opacity - hazy increase in lung opacity that does not obscure the underlying vessels and bronchi Lung consolidation or consolidation - vessels and bronchial walls are obscured

Increased lung attenuation that have a density that is greater than soft tissue density Development of calcifications within existing lesions Deposition of calcium within the lung parenchyma Diffuse or multifocal pulmonary ossification

Ground Glass OpacityFocal Vs Diffuse

Patchy distribution of ground-glass opacity Pneumocystis jiroveci pneumonia

Ground Glass OpacityFocal Vs Diffuse

Diffuse ground-glass opacity Hypersensitivity pneumonitis

Pulmonary haemorrhage in the right middle lobe Ill-defined GGO

Sharply defined area of GGO in RUL Pulmonary haemorrhage

GGO located near centre of the secondary pulmonary lobules and then look like ill-defined nodules

Reduction of Air in the Airspaces Volume Loss of the Alveoli Physiological phenomenon development of ground-glass opacity Increase in density in dependent lung regions Lower lung > Middle and upper zones Greater diaphragmatic movement Gravitational effect

Prone scans Dependent density is no longer visible against the posterior chest wall and may appear against the anterior chest wall

Volume Loss of the Alveoli Pathological changes in the lung and pleura Fibrotic scarring in the lung Pleural thickening Restrict lung expansion Ground-glass opacity

Decreased expansion right lung due to Right-sided malignant mesothelioma

Replacement of Alveolar Air Partial filling of the alveolar spaces by fluid or cells Alveolar proteinosis Respiratory bronchiolitis, bronchiolitis Interstitial lung disease Alveolar haemorrhage Bronchioloalveolar cell carcinoma

Partial filling of the alveolar spaces + Thickening of the interstitium, alveolar walls = Crazy paving

Alveolar proteinosis Areas of ground-glass opacity with intralobular reticular pattern superimposed creating the crazy-paving pattern

Increase in Parenchymal Perfusion > in capillary blood volume = > in lung density Mosaic perfusion = Areas with > attenuation (GGO) + < attenuation

Mosaic perfusionDecreased attenuation Increased lung attenuation

Narrowing or obstruction of the blood vessels Small airways narrowing Reflex vasoconstriction

Redistribution of blood flow

GGO Vs Mosaic perfusion Calibre of the blood vessels Delineation of the ground-glass opacity Density changes after deep expiration

Mosaic perfusion secondary to recurrent pulmonary embolism

Thickening of Parenchymal Interstitium / Alveolar Wall Minimal thickening of the alveolar wall, parenchymal interstitium = groundglass opacity Inflammation or infiltration Intraalveolar cellular infiltrate, filling the airspaces Acute inflammation i.e indicating active disease or reactivation of disease

GGO Fibrosis and result from fibrotic thickening of the alveolar wall and interstitium

Be careful to diagnose GGO as an active process Traction bronchiectasis or honeycombing

Usual interstitial pneumonia in Systemic sclerosis GGO in the dorsal and basal subpleural region of both lungs, i.e active lung disease

When a lung biopsy is performed, areas of ground-glass opacity are the best locations to be targeted, especially when no signs of fibrosis are present

Diffuse ground-glass opacity in chronic hypersensitivity pneumonitis Bronchial deformation indicates pulmonary fibrosis

Acute Versus Subacute or Chronic Disease

Crazy-Paving Pattern Superposition of a linear pattern on groundglass opacity = Crazy paving Pulmonary alveolar proteinosis

Acute radiation pneumonitis in a patient treated for leftsided breast cancer Ground-glass opacity and consolidation Faint intralobular reticular pattern Crazy-paving pattern

Lung Consolidation Increase in lung density with obscuration of the underlying vessels & bronchial walls Bronchi can be recognised as an air bronchogram, i.e. low-density branching tubular structures Lung consolidation are similar to the lung changes that are responsible for ground-glass opacity

Most frequent cause is a decrease in the amount of air in the airspaces Replacement of this air by fluid, cells, tissue or other substances Interstitial pneumonia (UIP) Sarcoidosis

Subpleural areas of lung consolidation Eosinophilic pneumonia

Consolidation margins Consolidation has one or more sharply defined borders because the pathology reaches an anatomic structure such as a fissure Borders of consolidation that are not adjacent to the fissure may be, Sharply defined Irregular and blurred Possibly surrounded with ground-glass opacity

Sharp delineation by major fissure

Lung consolidation and ground-glass opacity in a patient with overwhelming pneumonia

Pulmonary infection with lung consolidation and GGO

Airspace filling is the most frequent cause of consolidation, this pattern is often associated with, presence of centrilobular airspace nodules - early airspace filling, i.e bronchial distribution

Diseases producing ID-GGO: Diffuse pneumonias Primarily opportunistic infections Chronic interstitial diseases Acute alveolar diseases Unusual miscellaneous disorders

Increased Lung Attenuation more than Soft Tissue Density Multifocal lung calcification Granulomatous diseases Tuberculosis Silicosis Sarcoidosis Amyloidosis Associated with lung nodules

Metastatic calcification Deposition of calcium typically within the parenchymal, peribronchovascular interstitium Hypercalcaemia abnormal calcium and phosphate metabolism Chronic renal failure Secondary hyperparathyroidism

Areas of GGO with calcification that may be inconspicuous or very dense or present as patchy areas of consolidation Consolidated lung parenchyma appears abnormally dense

Metastatic calcification Dense centrilobular ground-glass opacities

Metastatic calcification in consolidated lung in chronic renal failure and secondary hyperparathyroidism

Disseminated pulmonary ossification Small deposits of mature bone form within the lung parenchyma Chronic heart disease (mitral stenosis) Idiopathic pulmonary fibrosis (IPF) Asbestosis

Amiodarone lung toxicity Pulmonary toxic reaction with interstitial pneumonia and fibrosis Consolidated lung parenchyma may appear abnormally dense Liver and spleen appear abnormally dense as drug accumulates in the organs