Basic elements Appearance pattern DistributionPatient data pattern Ct interpretation
Normal HRCT Findings airwaysNormal airways are visible only towithin 3 cm of the pleura.The centrilobular bronchiole, with a diameter of 1mm and a wall thickness of 0.15 mm, is notnormally visible on HRCT.
Normal HRCT Findingssmall pulmonary arteries and veins More peripherally, numerous small "dots" and a few branching lines represent small pulmonary arteries and veins. Throughout, arteries branch at acute angles, and veins branch at 90° angles Centrilobular arteries (1 mm in diameter) are V- or Y-shaped structures on HRCT seen within 5 to 10 mm of the pleural surface. Pulmonary veins (0.5 cm) are occasionally seen as linear or dotlike structures within 1 to 2 cm of the pleura and, when visible, indicate the locations of interlobular septa
Ground-glass opacity(GGO)• GGO: • hazy increase in lung density, • with preservation of airway vessel margins. • The density of the intra-bronchial air appears darker as the air in the surrounding alveoli. This is called the dark bronchus sign• Occurs when: • there is mild decrease in the amount of air in air- spaces(Air space disease ) • when there is mild increase in size andor amount of soft tissue structures (Interstitial lung disease ). • two phenomena that often occur simultaneously.
High Attenuation pattern1. Ground-glass- opacity (GGO)2. Consolidation High Attenuation
Crazy Paving in a patient with Alveolar proteinosis Linear Crazy- GGO pattern paving• Crazy Paving is a combination of ground glass opacity with superimposed septal thickening
Consolidation• Defined as: • Increased in lung density • with obscuration of underlying vessels and airway walls, – an air-bronchogram may be present.• Air-space nodules, focal area of GGO are often seen in association with consolidation.
Increased lung attenuation Preservation of B-V Obscuration of vascular marking=GGO marking=consolidation Symptoms course Symptoms course(acute,sub-acute,chronic) (acute,sub-acute,chronic) Centri-lobularLinear pattern sub-pleural Other pattern No linear patternsuperimposed patchy diffuse also lobar Centri-lobular DD for otherCRAZY PAVING Sub-pleural pattern Patchy,diffuse
Increased lung attenuation Appearance pattern GGO Cosolidation Patient data(symptoms course) Acute Sub-acute Chronic Distribution patternother patternCentri-lobular Sub-pleural Patchy Diffuse Lobar Regional lung distribution Upper lowerdiffuse Central peripheral