Observer Agreement on Computed Tomography Perfusion Imaging in Acute Ischemic Stroke

Area of Science:

• Neurology
• Radiology
• Medical Imaging

Background:

• Computed tomography perfusion (CTP) offers valuable data for acute stroke treatment guidance.
• Previous assessments of CTP interobserver reliability were limited in scope.
• This study addresses the need for large-scale reliability assessment of CTP interpretation.

Purpose of the Study:

• To evaluate the interobserver and intraobserver reliability of computed tomography perfusion (CTP) interpretation in acute stroke.
• To assess the agreement among observers in identifying perfusion abnormalities and quantifying stroke extent using CTP.

Main Methods:

• A large, internet-based study involving 57 observers interpreting 24 diverse acute stroke cases.
• Observers analyzed noncontrast CT, CTP maps (CBV, CBF, MTT, delay time, penumbra), and clinical vignettes.
• Interobserver and intraobserver agreement were quantified using Krippendorff-α.

Main Results:

• High interobserver agreement was observed for all CTP parameters, particularly mean transit time (α=0.77), delay time (α=0.79), and penumbra maps (α=0.81).
• Agreement was higher for perfusion maps than noncontrast CT.
• Intraobserver agreement ranged from fair to substantial (α=0.29–0.80).

Conclusions:

• CTP interpretation in acute stroke demonstrates high interobserver and intraobserver reliability.
• Mean transit time, delay time, and penumbra maps show particularly strong agreement.
• These findings support the routine use of CTP for guiding acute stroke management.