الفهرس 
AcknowledgmentOnly 14 pages are availabe for public view
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Abstract
The current study aims to evaluate the role of non- contrast MSCT in detection of thrombopulmonary embolism through detection the direct and indirect sign, and its sensitivity and specificity,. Also evaluate those patients by the revised Geneva scoring system.. This study was conducted in radiology Department, in Assiut University Hospital during the period from 1stJanuary to 30thJune 2017.Clinical classification of those patients has very important role and helps us in selection of the suspected cases and decreases the unnecessary and expensive investigations. So we evaluated the patients in our study by the revised Geneva score that include groups of symptoms and signs and risk factors as age, malignancy, previous pulmonary embolism and recent surgery or fracture. Symptoms as heamptosis and unilateral lower limb pain and signs as; unilateral lower limb edema and tachycardia above 75 beet /minute or 95 beet/ minute. Through these items we could evaluate patients into low, moderate, and high risk for pulmonary embolism. Revised Geneva scoring system has good sensitivity and specificity for suspicion the positive and exclusion the low risk cases.As the unenhanced CT of the chest is performed for evaluation of patients with nonspecific cardiopulmonary symptoms and for the patients with limitations to contrast as patients who have allergy to the contrast material or others with raised renal chemistry, so awareness of these signs may be useful in the detection of acute pulmonary thromboembolism even if it is not clinically suspected. Such detection can determine further imaging needed and allows the timely initiation of appropriate therapy. Hyper-attenuating clot is a sign of current acute pulmonary embolism particularly in cases involving the central pulmonary arteries , so when the intravenous contrast material is contraindicated (e.g. in patients with impaired renal functions and hypersensitivity to the contrast agent), detection of this sign in non-contrast chest CT scans may still allow the diagnosis of acute pulmonary thromboembolism. However, since the sensitivity of this sign is modest, its absence does not exclude the presence of acute pulmonary thromboembolism. Knowing the attenuation range for acute pulmonary thromboembolism may also be useful in the incremental evaluation of pulmonary artery filling defects and may aid in differentiating acute from chronic thrombi.
Also the indirect signs as pulmonary artery dilatation, right ventricular dilatation, and peripheral wedge shaped opacity that considered the most important useful sign and can help in the diagnosis other indirect signs had insignificant value in diagnosis.
Pulmonary embolism may exaggerate symptoms and signs of some diseases as COPD so we should exclude it in those patients also some diseases have symptoms and signs may similar to those with pulmonary embolism as pneumonia, pneumothorax, some of cardiac disorders, and interstitial lung diseases but with insignificant values.