HRCT

HRCT is a chest CT tuned to its sharpest setting. Instead of ordinary slices, it reconstructs very thin cross-sections (around one millimetre) with a high-detail algorithm, so the fine internal architecture of the lung comes into focus. If a standard CT shows the streets of a city, HRCT lets you see the individual houses — the small airways, the delicate walls between air sacs, and the lacy framework that holds the lung together.

This makes HRCT the workhorse for diffuse, widespread lung disease — conditions that subtly change the lung's texture everywhere rather than forming a single lump. Radiologists look for recognisable patterns: ground-glass haze, fine reticular (net-like) lines, honeycomb cysts, nodules along certain structures, or traction bronchiectasis. The distribution and combination of these patterns often points strongly to a specific diagnosis such as idiopathic pulmonary fibrosis or hypersensitivity pneumonitis.

Because it is so sensitive to texture, HRCT is also valuable in bronchiectasis and early interstitial change that a plain film would miss. It is a reading-intensive study: the same images can support different interpretations, so the findings are best discussed alongside the patient's history, lung function and sometimes a multidisciplinary team rather than read in isolation.