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High-resolution CT of thorax
Last reviewed: 23.04.2024
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Principles of high-resolution computed tomography (BPKT)
To construct an image of a computer tomography of high resolution, thin sections and an algorithm for reconstructing sections with high spatial resolution are used. Traditional CT scanners are also capable of performing thinner slices than standard 5-8 mm. If necessary, change the parameters of the image formation by setting the working console to a thickness of cuts of 1-2 mm.
With helical computed tomography, the thickness of the slices can also be adjusted after scanning, with a spiral pitch of 1: 1. However, slices thinner than 1 mm are not informative, because the quality of the image deteriorates significantly.
High-resolution computed tomography is not a method of choice for routine chest examination due to a significant increase in the radiation dose. The increased research time and the high cost of printing a large number of sections on the printer are additional arguments against the widespread use of high-resolution computed tomography. It is much better to visualize only structures with a high natural density difference, for example, bone and nearby soft tissue.
Indications for use in high-resolution computed tomography
One of the important advantages of high-resolution computed tomography is the ability to distinguish old scar tissue changes from acute inflammation, for example, in patients with immunodeficiency or in patients who underwent bone marrow transplantation. Cicatricial changes always have clear boundaries, whereas an acute inflammatory process is surrounded by an edema zone. Computed tomography of high resolution is often the only method by which it is possible to continue chemotherapy in patients with lymphoma in the aplastic phase (with the development of fungal pneumonia, chemotherapy is discontinued). Acute inflammatory infiltration can sometimes be found alongside old cicatricial changes.
Due to the fact that the slices are extremely thin, a horizontal interlobar slot in the form of a ring of irregular shape or a half moon can appear on the scans.
Small areas of collapse of lung tissue, which are usually adjacent to the posterior pleura, must be distinguished from the plane sections of the interlobar gaps. In doubtful cases, repeated scanning in the position of the patient on the abdomen helps. In this case, the collapse or hypoventilation zones disappear or appear in front. If the changes in lung tissue are preserved, one should think about the presence of infiltration or pneumoconiosis.
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