الفهرس 
Basic Anatomical ConsiderationsOnly 14 pages are availabe for public view
 |  | from | 205 |  |  |
| | | from | 205 | | |
Abstract
A cavity is an air containing area within the lung surrounded by definitive wall which is at least 4 mm in thickness. Cavity may also contain blood, pus, fluid or debris. Cavities are commonly encountered lesions in the lung discovered during chest radiography and chest CT. the cavitary lung lesions include wide variety of pulmonary diseases such as infection (bacterial, fungal, parasitic), neoplastic, congenital, airways and collagen diseases.
Computed tomography provides a useful diagnostic information in the evaluation of cavitary lung diseases as it can define the distribution of the cavities, characterization of the cavity wall and abnormalities in the surrounding lung parenchyma. In many cases, CT allows a confident specific diagnosis of the cavitary lung lesions.
Recently, CT technology has undergone a major evolution with the introduction of multislice technology. With the advent of MDCT, we have the possibility to acquire submillimetre slice data over the whole thorax (up to 1000 slices) within a single breath-hold with advantage of shorter acquisition times, greater coverage, and superior image resolution along the z-axis enabling one to obtain contiguous thin sections on the order of 0.5 to 1 mm while minimizing respiratory and cardiac motion artifact.
Multi-slice or multidetector CT allows larger volumes to be scanned with thinner sections, and yet shorter scan times. The speed of scanning makes multislice CT well suited to the demonstration of thoracic vasculature, including pulmonary arteries, and permits a shorter contrast medium injection, thus reducing contrast usage.
Reading should be performed on a workstation. To avoid reading of an excessive number of individual axial slices image by image, a thin sliding MIP, MPR or VRT reconstruction can be used for more effective reading. Thin sliding MIPs have already proven to be the most suitable visualization method of all secondary reconstruction techniques. Volume-rendering techniques are anticipated to enable improved three-dimensional contour evaluation of cavities.
MDCT has proved to be an indispensable modality in studying and assessing air and fluid filled cavitary lesions. It can assess the size, number, location, wall thickness and surrounding parenchyma to limit the differential diagnosis.
In conclusion, CT is essential diagnostic tool for diagnosis of cavitary lung lesions in addition to other radiological investigation. CT is superior to plain X-ray in demonstrating the cavitary lung lesions with higher degree of clarity. It can define the exact anatomical site of the cavity, characterization of the cavity wall and abnormalities in the surrounding lung parenchyma. It is reliable in detecting lesions in areas difficult to visualize by plain X- ray.