CT Protocol for Acute Stroke: Tips and Tricks for General Radiologists

Abstract

Acute stroke services have been installed in most hospitals in the industrialized world, and dealing with hyperacute stroke has become one of the most frequently performed tasks of the on-call radiologist. Imaging plays a key role in current guidelines for thrombolysis, and knowledge of classic early ischemic signs or depiction of hemorrhage at nonenhanced computed tomography (CT) is necessary (although not sufficient) for a satisfactory imaging study. A modern CT examination must also include perfusion CT and CT angiography. Perfusion CT delineates the ischemic tissue (penumbra) by showing increased mean transit time with decreased cerebral blood flow (CBF) and normal or increased cerebral blood volume (CBV), whereas infarcted tissue manifests with markedly decreased CBF and decreased CBV. CT angiography can depict the occlusion site, help grade collateral blood flow, and help characterize carotid atherosclerotic disease. A complete CT study (nonenhanced CT, perfusion CT, and CT angiography) may be performed and analyzed rapidly and easily by general radiologists using a simple standardized protocol and may even facilitate diagnosis by less experienced radiologists in affected patients.

Multidetector computed tomography angiography in clinically suspected hyperacute ischemic stroke in the anterior circulation: an etiological workup in a cohort of Brazilian patients

“…Several studies have highlighted that MDCTA findings closely correlate with those from digital angiography for the degree of stenosis, which suggests that the sensitivity of MDCTA in evaluating the degree of stenosis may be comparable to that of angiography but with a lower level of risk 22,23,24,25 . The majority of the patients from our series demonstrated some degree of cervical artery abnormalities that were detected on MDCTA (64.0% in both groups).…”

Differences in CT Perfusion Summary Maps for Patients with Acute Ischemic Stroke Generated by 2 Software Packages

“…It has been shown that differences in CTP hardware and software can affect the results. [4][5][6] Additional known pitfalls of CTP analysis include incorrect placement of the perfusion volume, incorrect selection and variability of the AIF and VOF, chance of missing small infarcts due to the low resolution of CTP analysis, and changes in perfusion due to extracranial and intracranial stenosis. 7 On the other hand, it has recently been shown that despite the general belief, the order of scanning (CTA before or after CTP) has no significant influence on quantitative CTP parameters.…”

Modern Imaging Modalities in the Assessment of Acute Stroke

“…5,[8][9] A non-enhanced CT scan is needed to detect hemorrhage or early ischemic signs. 10 CT angiography can show intravascular thrombi and signifi cant stenoses, and CT perfusion demonstrates the cerebral tissue at risk of irreversible changes, which may be salvageable by therapy.…”