What is the role of PET scanning in stroke imaging?

Updated: Nov 30, 2018
  • Author: Andrew Danziger; Chief Editor: L Gill Naul, MD  more...
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Answer

PET imaging can be used to quantify areas of altered cerebral blood flow and abnormal glucose and oxygen metabolism. This can be used to elucidate areas of ischemic penumbra and infarcted tissue, as follows:

  • Regional blood flow, oxidative metabolism, and relative oxygen extraction and cerebral metabolic rate for oxygen (CMRO2) can be measured after infusion of15 O bound to water to detect areas of ongoing ischemia and necrosis.

  • Areas of ischemic penumbra correspond to regions where cerebral blood flow is decreased but oxygen extraction is increased.

  • Necrotic areas may be seen when CMRO2 falls below 65 μmol/100 gm/min. [106]

Reduced vascular reserve can also be measured with SPECT using an acetazolamide challenge. Reactivity in patients with carotid stenosis is related to stroke risk [105, 107] and can predict development of ischemic lesions in patients undergoing carotid endarterectomy.

The vulnerability of a carotid plaque to rupture can be detected by using18 F-fluorodeoxyglucose (FDG) PET. FDG is known to accumulate in inflammatory lesions with inflammation being a key feature of atherosclerosis. [105]

Other specific features of the vulnerable plaque, such as oxidized LDL accumulation and apoptosis, can be detected with radiolabeled cytokines and lipids using SPECT. [105]

PET has been described as the criterion standard for quantifying oxygen and glucose metabolism in the brain and for identify the penumbra in humans. [105] SPECT is also useful in detecting areas of abnormal blood flow. However, PET is costly and neither modality is routinely available for use in most acute clinical settings.


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