Sources of variability in computed tomography perfusion: implications for acute stroke management

Abstract

<jats:sec> <jats:title>Object</jats:title> <jats:p>Although dynamic, first-pass cerebral CT perfusion is used in the evaluation of acute ischemic stroke, a lack of standardization restricts the value of this imaging modality in clinical decision-making. The purpose of this study was to comprehensively review the reported sources of variability and error in cerebral CT perfusion results.</jats:p></jats:sec> <jats:sec> <jats:title>Methods</jats:title> <jats:p>A systematic literature review was conducted, 120 articles were reviewed, and 23 published original research articles were included. Sources of variability and error were thematically categorized and presented within the context of the 3 stages of a typical CT perfusion study: data acquisition, postprocessing, and results interpretation.</jats:p></jats:sec> <jats:sec> <jats:title>Results</jats:title> <jats:p>Seven factors that caused variability were identified and described in detail: 1) contrast media, the iodinated compound injected intravascularly to permit imaging of the cerebral vessels; 2) data acquisition rate, the number of images obtained by CT scan per unit time; 3) user inputs, the subjective selections that operators make; 4) observer variation, the failure of operators to repeatedly measure a perfusion parameter with precision; 5) software operational mode, manual, semiautomatic, or automatic; 6) software design, the mathematical algorithms used to perform postprocessing; and 7) value type, absolute versus relative values.</jats:p></jats:sec> <jats:sec> <jats:title>Conclusions</jats:title> <jats:p>Standardization at all 3 stages of the CT perfusion study cycle is warranted. At present, caution should be exercised when interpreting CT perfusion results as these values may vary considerably depending on a variety of factors. Future research is needed to define the role of CT perfusion in clinical decision-making for acute stroke patients and to determine the clinically acceptable limits of variability in CT perfusion results.</jats:p></jats:sec>

A robust noise reduction technique for time resolved CT

“…12 Previous published studies showed that even minor variations in the user-defined inputs in venous ROI placement or in pre-and postenhancement cutoff values significantly changed quantitative perfusion parameter values. [45][46][47] This may cause variability of perfusion results, even when the same data are repetitively processed by the same observer. Using custom-designed perfusion analysis software in which the users have full control may reduce these variations and their influence on differences in the resulting perfusion parameters.…”

Pre-intervention cerebral blood volume predicts outcomes in patients undergoing endovascular therapy for acute ischemic stroke

“…One reason could be the lack of a standardized imaging approach. Variation in the imaging technique as well as vendor software highlights this limitation 20 21. Second, imaging represents a snapshot in time in an otherwise complicated and rapidly evolving process.…”

Pretreatment Advanced Imaging in Patients with Stroke Treated with IV Thrombolysis: Evaluation of a Multihospital Data Base

“…[16][17][18][19][20][21][22] While advanced imaging techniques hold promise for the evaluation of patients with acute ischemic stroke, there is variation in techniques and definitions of parameters that limit wide application and acceptance of these techniques. 4,[23][24][25] There is currently no consensus on a standard imaging approach for acute ischemic stroke. We studied a large data base of hospitals in the United States to assess the recent use of advanced imaging in patients with acute ischemic stroke treated with intravenous thrombolysis, including an evaluation of the use of advanced imaging, with respect to patient outcome.…”