Stroke Imaging Guidelines

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

Guidelines Summary

American College of Radiology

The ACR Appropriateness Criteria for Cerebrovascular Disease includes the following key recommendations for stroke imaging [133] :

  • Screening for carotid artery stenosis can be performed noninvasively with duplex ultrasound, contrast-enhanced MRA, or CTA.  
  • Digital Subtraction Angiography (DSA) is the gold standard for carotid artery evaluation and should be performed if noninvasive imaging is inconclusive or contradictory.
  • Evaluation of cerebrovascular reserve with CT or MR perfusion with acetazolamide challenge may identify patients at higher risk for stroke due to poor collateral circulation.
  • Imaging evaluation of TIA should be performed as soon as possible and is ideally performed with contrast-enhanced brain MRI along with 3-D time-of-flight (TOF) MRA of the circle of Willis and contrast-enhanced MRA of the neck vasculature.
  • Noncontrast head CT is the first-line imaging test for acute stroke patients to rule out intracranial hemorrhage and large infarct.
  • When possible, CTA should be the next imaging study after intravenous tissue plasminogen activator (IV-tPA) administration in acute stroke patients to evaluate for large-vessel occlusion as a target for intra-arterial therapy
  • Patients presenting with acute stroke beyond the 6-hour treatment window are ideally evaluated with contrast-enhanced brain MRI along with 3-D TOF-MRA of the circle of Willis and CE-MRA of the neck vasculature. Age of the infarct can be determined with contrast-enhanced brain MRI.
  • Patients with risk factors for cerebral aneurysms can undergo noninvasive screening with TOF-MRA or CTA. 
  • The initial imaging study in patients presenting with suspected nontraumatic intracranial hemorrhage, whether SAH or intraparenchymal hemorrhage, should be noncontrast head CT.
  • Initial evaluation in patients with acute nontraumatic SAH could start with DSA or noninvasive imaging with CTA or MRA. If the initial DSA is negative, then CTA or MRA should subsequently be performed. If CTA or MRA was performed as the initial imaging test and was negative, then DSA should be performed for further evaluation. If both initial DSA and noninvasive studies are negative, DSA should be repeated in 1–2 weeks.
  • Unruptured aneurysms that are incidentally discovered on noninvasive imaging should be followed using the same noninvasive imaging modality on which the initial diagnosis was made. 
  • Definitive diagnosis of cerebral vasospasm after SAH is made with catheter angiography.
  • Screening for vasospasm is performed with transcranial Doppler (TCD) ultrasound. CTA or MRA may be useful in the setting of indeterminate TCD ultrasound results. 
  • Intraparenchymal cerebral hemorrhages that have the classic clinical history and imaging appearance indicative of hypertensive hemorrhage usually do not require further imaging workup other than follow-up noncontrast head CT to evaluate for hemorrhage evolution and complications.
  • Intraparenchymal cerebral hemorrhages that do not have the classic clinical history and imaging appearance for hypertensive hemorrhage should undergo further parenchymal and vascular imaging with contrast-enhanced brain MRI, MRA, and sometimes MRV. CT, CTA, and sometimes CTV are imaging alternatives.