الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Pulmonary nodule is a round or oval opacity smaller than 3 cm in diameter that is completely surrounded by pulmonary parenchyma and is not associated with lymphadenopathy, atelectasis, or pneumonia.The pulmonary nodule is a common finding at computed tomography (CT) that may be due to primary or secondary malignancy but also to benign conditions, including granulomatous diseases and other infectious processes. The morphologic imaging diagnosis of a pulmonary nodule can be performed, with special attention paid to the nodule’s margin or internal structure and to its relationships to surrounding structures. In addition, the degree of enhancement or the pattern of enhancement seen with administration of contrast medium at CT is useful for differentiating malignant from benign nodules.
A pulmonary nodule may be a precursor for the possible presence of lung cancer. Its early detection with the subsequent down staging will provide earlier diagnosis, thus raising survival rates. Also in patients with underlying malignancies it might be the proof that the cancer has spread into the lung. This makes the detection of lung nodules essential in terms of staging cancer disease and for evaluation of the success of therapy; hence, in cases of known pulmonary proliferation, it is important to know whether the number of pulmonary metastases is increasing, stable or decreasing to assess treatment response.
Multidetector CT has dramatically improved pulmonary nodule evaluation in terms of detection and characterization. With MDCT capabilities, thin section imaging can be performed rapidly through the thorax, and therefore high-quality image data can be obtained. Since its introduction, MDCT technology has continued to advance with an increasing number of detector rows and more rapid scan times. Such technology enables improved spatial and temporal resolution while increasing coverage in the craniocaudal z- axis.
Multidetector CT allows larger volumes to be scanned with thinner sections, and yet shorter scan times. The speed of scanning makes multidetector CT well suited to the demonstration of thoracic vasculature, including pulmonary arteries, and permits a shorter contrast medium injection, thus reducing contrast usage.The advantages of MDCT also include both improved nodule detection and nodule characterization on lung cancer screening programs, because the entire lung can be scanned with thin slice in a single breath-hold without an intersection gap. In the evaluation of lung cancer, MDCT will allow improved detection of pleural dissemination and hilar lymph node adenopathy because of the continuous and narrow scan collimation.
Recent advances in MDCT technology and post processing software have brought excellent post processing of axial images into superior quality non axial images. Commonly performed post processing techniques produce two dimensional images using multiplanar reformation (MPR) and maximum intensity projection (MIP), or three dimensional images using various types of volume rendering (VR).