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Brain MR imaging is an important adjunct to CT in the context of trauma, especially regarding early detection of focal intra-axial primary or secondary injuries, such as diffuse axonal injury, edema, infarction, or fat emboli, which can have little to no correlation on CT in the acute phase.
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Although most extra-axial injuries are readily detectable on CT, MR imaging shows similar versus slightly higher sensitivity for some extra-axial hemorrhages, especially in the subacute and chronic phases.
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Conventional MR Imaging in Trauma Management in Adults
Section snippets
Key points
Imaging findings/pathology
Contusions are the most common form of intra-axial injury. They are most often due to blunt closed head trauma, which causes brain tissue to impact against the skull or dural reflections (falx cerebri and tentorium cerebelli).13 Rarely, open head trauma, such as depressed skull fractures, may also result in contusions of the impacted brain parenchyma. Hemorrhagic components are common and the MR signal depends on timing of injury (Table 1).14
Contusions always involve the superficial areas of
Imaging findings/pathology
Epidural hematomas (EDHs) consist of hemorrhagic collections between cranial bones and their periosteum (or outer layer of the dura). As such, they are usually limited by cranial sutures, where the periosteum typically folds around the bone, except in rare anatomical variants. If significant in size, as can be the case when the cause of hemorrhage is arterial, EDH may distend the periosteum enough to appear biconvex or lentiform (Fig. 4). However, in the minority of cases where the cause of
Imaging findings/pathology
In TBI, any focal or diffuse mass effect (brain swelling, intra-axial /extra-axial collections) may lead to herniation phenomenon. Multiple types of non-mutually exclusive herniation phenomenon can occur.
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Subfalcine:
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Herniation of the ipsilateral ventricle and cingulate gyrus across the midline
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May be associated with foramen of Monroe obstruction (with associated hydrocephalus) and wedging of the anterior cerebral artery (ACA) against the falx cerebri with possible ACA territory infarction.
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Imaging findings/pathology
Dissections are characterized by a tear of one or more layers of the blood vessels, allowing blood to dissect in between said layers, which may stenose or occlude the vessel lumen, or even result in outpouchings called pseudoaneurysms, which can rupture. Imaging on MR imaging may show pathognomonic collection of blood product of various age along the afflicted blood vessel (classically crescent-shaped in appearance, as shown in Figs. 10 and 11), which may only appear as a vague vessel wall
Summary
MR imaging has been shown to have higher sensitivity than CT for traumatic intracranial soft tissue injuries, as well as most cases of intracranial hemorrhage, thus making it a significant adjunct to CT in the management of TBI, mostly in the subacute to chronic phase, but also in the acute phase, when there are persistent neurologic symptoms unexplained by CT imaging. Although CT remains the modality of choice in most cases of acute TBI because of ease of access, faster imaging time, lower
Disclosure
The Authors have nothing to disclose.
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