High-resolution computed tomography

High-resolution computed tomography (HRCT) is a CT technique using thin image sections and high spatial resolution to depict fine lung structures, especially the pulmonary interstitium and small airways.

Computed tomography: An imaging method that reconstructs cross-sectional images from measurements of X-ray attenuation at multiple angles. HRCT is a specialized way of acquiring and reconstructing CT images.
Interstitial lung disease: A broad group of disorders involving the lung interstitium and often producing inflammation or fibrosis. HRCT is central to evaluating many disorders in this disease group.
Pulmonary acinus: The portion of lung supplied by a terminal bronchiole, containing respiratory bronchioles, ducts, and alveoli. HRCT abnormalities can be localized to this small functional unit.
Routine computed tomography: Standard CT acquisition and reconstruction protocols designed for general diagnostic imaging. Compared with routine CT, HRCT prioritizes fine lung detail through thinner sections and sharper reconstruction.
Idiopathic pulmonary fibrosis: A chronic fibrosing interstitial pneumonia of unknown cause, typically progressing over time. HRCT can show a usual interstitial pneumonia pattern that supports its diagnosis.
Spatial resolution: The ability of an imaging system to distinguish small, closely spaced structures as separate. It sets the smallest lung structures that HRCT can depict distinctly.
Usual interstitial pneumonia: A characteristic pattern of lung injury and fibrosis associated with idiopathic pulmonary fibrosis and other conditions. HRCT can show the basal, subpleural fibrosis and honeycombing that define its imaging pattern.
Secondary pulmonary lobule: The smallest lung unit surrounded by connective-tissue septa and supplied by a small bronchiole and pulmonary artery. Its anatomy provides a framework for describing the location of HRCT findings.
Low-dose computed tomography: CT performed with reduced radiation exposure, commonly for screening or repeated imaging. Dose reduction and HRCT detail are distinct protocol goals, though they can overlap.
Radiation dose: A measure of the energy deposited by ionizing radiation in matter or tissue. Repeated CT examinations make exposure a practical consideration in HRCT use.

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