Computed tomography (CT) perfusion imaging provides an assessment of cerebral blood flow that may assist in the identification of ischemic regions of the brain. This technology is being evaluated in the management of acute ischemic stroke, subarachnoid hemorrhage, cerebral vasospasm, brain tumors, and head trauma. CT perfusion imaging performs by capturing images as an iodinated contrast agent bolus passes through the cerebral circulation and accumulates in the cerebral tissues. The quantitative perfusion parameters are calculated from density changes for each pixel over time with commercially available deconvolution-based software. Similar information can be provided by CT and MRI. However, CT has a short protocol time (5-6 minutes) and, because perfusion imaging can be performed with any modern CT equipment, is more widely available in the emergency department setting.
The approved therapy for stroke treatment, intravenous tissue plasminogen activator (tPA), requires only a non‒contrast CT scan to exclude the presence of hemorrhage (a contraindication to the use of the drug). Current guidelines are to administer tPA within the first 3 hours after an ischemic event, preceded by a CT scan. However, some individuals do not present within the 3-hour window. Thus, more sophisticated imaging may be needed to select the proper use of intra-arterial thrombolysis or mechanical thrombectomy.
Computed tomography perfusion imaging may be considered medically necessary if the medical appropriateness criteria are met. (See Medical Appropriateness Criteria below)
Computed tomography perfusion imaging may be considered medically appropriate if ALL of the following are met:
Individual is suspected of having an acute ischemic stroke
Individual is being evaluated for mechanical embolectomy
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American College of Radiology. (2016). ACR appropriateness criteria®cerebrovascular disease. Retrieved October 27, 2017 from https://acsearch.acr.org.
American Heart Association. American Stroke Association. (2012). Guidelines for the management of aneurysmal subarachnoid hemorrhage: A guideline for healthcare professionals from the American Heart Association/American Stroke Association. Retrieved April 26, 2013 from http://stroke.ahajournals.org.
American Heart Association. American Stroke Association. (2018). Guidelines for the early management of patients with acute ischemic stroke: A guideline for healthcare professionals from the American Heart Association/American Stroke Association. Retrieved October 18, 2018 fromhttp://stroke.ahajournals.org.
Bivard, A., Levi, C., Krishnamurthy, V., McElduff, P., Miteff, F., Spratt, N., et. al., (2015) Perfusion computed tomography to assist decision making for stroke thrombolysis. Brain, 138, 1919–1931. (Level 2 evidence)
BlueCross BlueShield Association. Evidence Positioning System. (9:2018). Computed tomography perfusion imaging of the brain (6.01.49). Retrieved October 18, 2018 from http://www.evidencepositioningsystem.com. (30 articles and/or guidelines reviewed)
Campbell, B., Mitchell, P., Kleinig, T., Dewey, H., Churilov, L., Yassi, N., et. al., (2015) Endovascular therapy for ischemic stroke with perfusion-imaging selection. New England Journal of Medicine. 372,1009-18. (Level 2 evidence)
eviCore® healthcare. (2018, May) Clinical guidelines: head imaging policy. Retrieved October 18, 2018 from www.evicore.com. (20 articles and/or guidelines reviewed)
Lansberg, M., Christensen, S., Kemp, S., Mlynash, M., Mishra, N., Federau, C., et al. (2017). Computed tomographic perfusion to presict response to recanalization in ischemic stroke. Annals of Neurology, 81 (6), 849-856. Abstract retrieved October 27, 2017 from PubMed database.
National Institute for Health and Care Excellence (2017, March) Stroke and transient ischaemic attack in over 16s: diagnosis and initial management. Retrieved October 18, 2018 from: http://www.nice.org/uk.
U. S. Food and Drug Administration. (2008, June). Center for Devices and Radiological Health. 510(k) Premarket Notification Database. K33832. Retrieved November 9, 2015 from http://www.accessdata.fda.gov.
Xin, Y. and Han, F. (2016) Diagnostic accuracy of computed tomography perfusion in patients with acute stroke: A meta-analysis. Journal of Neurological Sciences, 360, 125-130. (Level 2 evidence)
ORIGINAL EFFECTIVE DATE: 12/10/2011
MOST RECENT REVIEW DATE: 1/10/2019
Policies included in the Medical Policy Manual are not intended to certify coverage availability. They are medical determinations about a particular technology, service, drug, etc. While a policy or technology may be medically necessary, it could be excluded in a member's benefit plan. Please check with the appropriate claims department to determine if the service in question is a covered service under a particular benefit plan. Use of the Medical Policy Manual is not intended to replace independent medical judgment for treatment of individuals. The content on this Web site is not intended to be a substitute for professional medical advice in any way. Always seek the advice of your physician or other qualified health care provider if you have questions regarding a medical condition or treatment.
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