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Brain

Introduction

  • Basic principal of identifying pathology - to differentiate between cytotoxic and vasogenic oedema.
  • Cytotoxic oedema - cellular injury + BBB intact. Most common cause: infarction.
  • Vasogenic oedema - extracellular injury + BBB disrupted. Most common causes: tumors, abscesses.

Acute stroke management

  • Note that mechanical thrombectomy within 6hrs has been shown to be better than thrombolysis, according to a landmark 2015 NJEM article.
  • CT perfusion scan is necessary to differentiate the penumbra from the clotted/necrotic region. This is because mechanical thrombectomy within 6-16 hours has also been shown to be beneficial for those with large penumbra + small clotted/nectrotic region.

CT Characteristics

  • Radiographic densities: density is directly proportional to attenuation. The more X-ray beams are attenuated > more dense is the material > the more opaque it becomes > the brighter it is on CT.
  • Cytotoxic oedema - darker region + no grey-white differentiation (cortical density is not prserved).
  • Vasogenic oedema - dark-bright region + grey-white differentiation present (cortical denisty is preserved).
  • Old infarcts approach CSF density.

Vascular Territories

Anterior circulation:

  1. ACA
  2. MCA - from the superior frontal gyrus to the inferior temporal gyrus.
  3. PCOM
  4. Anterior choroidal

Posterior circulation:

  1. PCA
  2. SCA
  3. Pontine perforators
  4. AICA - middle cerebellar peduncle.
  5. PICA


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REFERENCES

1. Goodman, L. and Felson, B. (2015). Felson's principles of chest roentgenology. 3rd ed. Philadelphia, PA: Elsevier, Saunders.
2. Dähnert W. Radiology Review Manual. LWW. (2011) ISBN:1609139437. Read it at Google Books - Find it at Amazon
3. Elizabeth Puddy, Catherine Hill; Interpretation of the chest radiograph, Continuing Education in Anaesthesia Critical Care & Pain, Volume 7, Issue 3, 1 June 2007, Pages 71–75, https://doi.org/10.1093/bjaceaccp/mkm014

Ⓒ A. Manickam 2018

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