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High-Resolution Computed Tomography (HRCT)

High-Resolution Computed Tomography (HRCT)

Why in news?

  • An Intervention Application has been moved before the Allahabad High Court in the COVID Management matter wherein the High Court is taking stock of the surge in COVID-19 cases in the state of Uttar Pradesh.
  • The Application has been moved for directions to State Government to pass appropriate orders to regulate and cap the prices of CT scan and blood test and other ancillary tests which are required and warranted for detection of Corona Virus in the body, in the State of U.P.

About High-Resolution Computed Tomography (HRCT)

  • ‘High Resolution Computed Tomography’ (HRCT) is a type of CT scan with specific techniques to enhance image resolution.
  • It is used in the diagnosis of various health problems, most commonly lung diseases.
  • The technique of HRCT was developed with relatively slow CT scanners, which didn’t make use of multi-detector technology.
  • High Resolution Computed Tomography is used for diagnosis and assessment of interstitial lung disease such as pulmonary fibrosis, and other generalized lung diseases such as emphysema and bronchiectasis. These are the airways diseases.
  • HRCT is used for diagnosis and assessment of interstitial lung disease, such as pulmonary fibrosis, and other
  • generalized lung diseases such as emphysema and bronchiectasis.
  • Where HRCT is unable to reach a definitive diagnosis, it helps locate an abnormality, and so helps planning a biopsy, which may provide the final diagnosis.

About CT scan 

  • It is also known as computed tomography scan.
  • It is a medical imaging technique used in radiology to get detailed images of the body noninvasively for diagnostic purposes.
  • CT scanners use a rotating x-ray tube and a row of detectors placed in the gantry to measure X-ray attenuations by different tissues inside the body.
  • The multiple X-ray measurements taken from different angles are then processed on a computer using reconstruction algorithms to produce tomographic (cross-sectional) images (virtual “slices”) of a body.
  • The use of ionizing radiations sometimes restricts its use owing to its adverse effects.

CT versus HRCT

  • HRCT (high resolution computed tomography) scans of the chest are crucial in the evaluation of idiopathic pulmonary fibrosis.
  • A CT scan of the chest uses X-rays to obtain images of the lung tissue.
  • The images are obtained in “slices” or thin views that are put together to form a picture.
  • The slices of an HRCT are much thinner than with a standard CT scan giving a more detailed picture.
  • One easy comparison is the difference between regular sliced bread and thinly sliced bread.
  • Normal CT scans of the lungs create three to five millimeter slices of the lung tissue for evaluation.
  • These slices are great for looking at the lung tissue for nodules or masses but not for appreciating the fine details.
  • HRCT scans take one millimeter slices.  The thinner slices allow for a much more detailed analysis.


  • HRCT is particularly useful in the assessment of diffuse lung conditions involving the interstitium such as:
    • Interstitial Lung Disease
    • Cystic Lung Disease
    • Small Airways Disease
    • Pulmonary Micronodules
    • Bronchiectasis
  • HRCT may be used to evaluate extent of disease, monitor treatment response, and select biopsy sites in the setting of diffuse interstitial lung disease.
  • Uninformed referrals commonly request for a “high-resolution” CT of the chest with the notion that HRCT represents a better version of a “standard” CT chest, however this is a misconception.


  • The term ”high-resolution computed tomography” was first used by Todo et al. in 1982.
  • He also described the usefulness of HRCT imaging in pulmonary diseases.
  • In 1985, Naidich et al., Nakata et al., and Zerhouni et al. described the fundamental technique of HRCT and published the first report on HRCT.



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