#1: CT perfusion allows us to identify tissue that is irreversibly dead (infarcted core) versus that which is salvageable (ischemic penumbra) in a patient with suspected large vessel occlusion. When there is a mismatch between infarcted core and ischemic penumbra (i.e. ~ mismatch volume of 15mL or mismatch ratio > 1.8), this indicates thrombectomy may reverse some functional damage.
#2: Currently, most protocols entail scanning 1-2 slabs of the brain. The increased scan time in a short segment of the brain confers increased radiation to this tissue. Therefore it is important to choose this scan wisely.
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Outstanding review of CTP! Thank you!