Subarachnoid hemorrhage

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[edit] Discussion of Subarachnoid hemorrhage

[edit] Imaging Findings for Subarachnoid hemorrhage

[edit] CT

  • SAH appears as a high-attenuating, amorphous substance that fills the normally dark CSF-filled subarachnoid spaces.
  • These findings are most evident in the largest subarachnoid spaces, such as the suprasellar cistern and Sylvian fissures.
  • Acute SAH is typically 50-60 HU.
  • When CT scanning is performed several days to weeks after the initial bleed, the findings are more subtle.
    • The initial high-attenuation of blood and clot tend to decrease, and these appear as intermediate gray.
    • These findings can be isointense relative to normal brain parenchyma.
  • In addition to detecting SAH, CT is useful in localizing the source of bleeding.

[edit] MRI

  • Fluid-attenuated inversion recovery (FLAIR) is the most sensitive MRI pulse sequence for the detection of SAH. SAH appears as high-intensity signal in normally low signal CSF spaces.
  • T2- and T2*-weighted images can potentially demonstrate SAH as low signal intensity in normally high-signal subarachnoid spaces.
  • On T1-weighted images, acute SAH may appear as intermediate- or high-intensity signal in the subarachnoid space.
  • MR angiography may be useful in the evaluation of aneurysms and other vascular lesions that cause SAH.

[edit] Images

Patient #1: CT images demonstrate diffuse subarachnoid hemorrhage

[edit] See Also

[edit] External Links

[edit] References for Subarachnoid hemorrhage