الفهرس 
AnatomyOnly 14 pages are availabe for public view
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Abstract
Blunt polytrauma remains a leading cause of death and disability worldwide. With the major advances in computed tomography (CT) technology over the past decade, whole-body CT is increasingly rec¬ognized as the emerging standard for providing rapid and accurate diagnoses within the narrow therapeutic window afforded to trauma victims with multiple severe injuries(Dreizin and Munera, 2012).
The examination of CT scans is extremely useful for the evaluation of blunt abdominal injuries in haemodynamically stable patients. CT scans can reveal a wide variety of injuries.In addition, CT examination is fast and widely available. With appropriate scanning protocol, CT can provide good resolution images with MPR(Hassan and Abd Aziz,2010).
In the setting of blunt abdominal trauma, active arterial extravasation can be clinically challenging and thus, close cooperation between the various multidisciplinary teams is critical to a successful clinical outcome. Establishing the source of active arterial extravasation is important, because morbidity and mortality rates are high(Ryan et al.,2004).
Several reports have described the appearances and accuracy of post traumatic emergent contrast-enhanced CT in the diagnosis of active arterial extravasation of contrast agent. The role of contrast-enhanced CT is to promptly identify the presence and sources of active arterial extravasation, particularly in those patients who could benefit from life-saving arterial embolization. Knowledge of vascular anatomy is thus mandatory in both deciding the source of hemorrhage and directing subsequent angiographic intervention(Ryan et al.,2004).
Hemodynamic stability is a prerequisite before CT imaging. However, hemodynamic status may deteriorate during or immediately after the examination because of continuous life threatening hemorrhage. It is certain that prompt resuscitation by highly experienced trauma teams played a major role. It is also likely in several cases that spontaneous thrombosis of arterial bleeding occurs(Ryan et al.,2004).
In a study by Ryan et al (2004), he stated that active arterial bleeding appears as focal areas of high attenuation contrast blush surrounded by a hematoma of high attenuation and fluid-fluid levels. The range and mean attenuation values for vascular extravasation of arterial contrast agent representing active arterial bleeding were higher than both the mean attenuation unit values of clotted blood and the nearest arterial vessel, but were only slightly greater than the mean attenuation unit values of the nearest arterial vessel. Furthermore, the attenuation unit values of the surrounding hematoma were also significantly lower (p< 0.001) than the attenuation values of adjacent arterial structures.
Multidetector CT with dual phase protocol is an important part of the patient work-up for blunt abdominal trauma. Timely diagnosis, differentiation of vascular injuries from other findings of trauma, signs of depleted intravascular volume, and localization of vascular injury are important to convey to the interventional radiologist or surgeons. More accurate diagnosis can be accomplished through attention to shape, attenuation, and evolution over time of areas of high attenuation, in addition to high quality injections of contrast material and display techniques. Understanding the physical properties ofbleeding may help radiologists predict those circumstances that put patients at significant riskfor re-bleeding after vessel injury and thus aid in determining the necessity for interventional orsurgical procedures (Hamilton et al.,2008).
Although familiarity with the American Association for the Surgery of Trauma (AAST) solid organ injury scoring systems is important, they may not be used to accurately predict whether non-surgical treatment will succeed because they do not take active extravasation into account (Dreizin and Munera, 2012).
In conclusion, the ability of CT to depict and characterize solid organ injuries and exclude major vascular and bowel injuries that require immediate intervention is primarily responsible for the paradigm shift toward non-surgical treatment (Dreizin and Munera, 2012).