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Everything you need to know about Computed Tomography (CT) & CT Scanning


MDCT of the Spleen:  Splenic Trauma

Article

The spleen is the most frequently injured organ with blunt abdominal trauma. Detection of splenic injury approaches close to 100% with contrast enhanced CT. While this exam can be performed quickly, only stable patients should be scanned in this setting. During early arterial phase imaging, the spleen normally enhances with a mottled appearance. The heterogeneous enhancement typically does not pose a problem with diagnosing splenic injury, however if there remains any question, delayed phase images should be acquired. On delayed images the spleen should be enhanced homogeneously and any defect would be abnormal.

Splenic lacerations appear as linear or geographic regions of relatively decreased attenuation compared to the normal, brightly enhancing spleen. When a laceration crosses two capsules it is called a splenic fracture. Lacerations should still be suspected, even when not visualized, if there are ancillary findings of bright (hyperdense) perisplenic fluid, as this represents clotted blood in the trauma patient. This clotted blood, also known as the "sentinel-clot" sign, has Hounsfield units great than 60 HU.

Hyperdense, clotted blood represents a hematoma and is often the result of trauma. The density of blood parallels the age of the bleed. Increased density reflects older blood that has coagulated. Fresh hematomas may initially be isodense to spleen on noncontrast scans when the blood has not had enough time to coagulate. Fresh hematomas should be discernable following contrast injection and appear as darker regions of the spleen that enhance less than the adjacent normal parenchyma. Developing hematomas may have regions that are hypo, iso or hyper dense to normal spleen reflecting the age of blood. Hematomas may be subcapsular and collect in a cresentic pattern, flattening the normally convex margin of the spleen or may be intraparenchymal. Intraparenchymal hematomas may be focal, round areas or more frequently, irregular in shape.

As hematomas evolve over weeks to months, the appearance progressively becomes less dense. Sequela may persist long after the initial event resulting is pseudocyst formation. Often this cystic degeneration of a hematoma appears centrally water density, but often has a calcified wall.

Patients who have small or non-visible splenic lacerations, typically without associated hematoma, are prone to delayed splenic rupture. This event may occur later than 48 hours after injury and happens in 0.3 - 20% of patients. If a small or subtle laceration is detected, judicious hemodynamic monitoring is essential.

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