Interobserver agreement in perfusion computed tomography evaluation in acute ischaemic stroke

Area of Science:

• Neuroradiology
• Neurology
• Medical Imaging

Background:

• Semiquantitative assessment of perfusion computed tomography (PCT) shows prognostic value in acute ischemic stroke.
• The Alberta Stroke Program Early CT Score (ASPECTS) quantifies ischemic changes on CT scans.

Purpose of the Study:

• To investigate the agreement of ASPECTS analysis between neuroradiologists and stroke neurologists.
• To compare the agreement of ASPECTS on non-contrast CT (NCCT) versus PCT in acute stroke patients.

Main Methods:

• 34 acute ischemic stroke patients underwent NCCT and PCT within 12 hours of onset.
• Two reviewer pairs independently assessed NCCT and PCT (CBF, CBV, TTP maps) using ASPECTS with dichotomized scores (e.g., 7 vs. <7).
• Agreement was determined using kappa statistics.

Main Results:

• PCT maps demonstrated better agreement than NCCT scans.
• Agreement for NCCT was fair (k=0.27).
• Agreement for PCT maps was moderate for cerebral blood flow (CBF) (k=0.46) and cerebral blood volume (CBV) (k=0.57), and substantial for time-to-peak (TTP) (k=0.77), particularly at a cut-off of 7 vs. <7.

Conclusions:

• Semiquantitative assessment of PCT using ASPECTS shows good agreement.
• PCT is a reliable tool for analyzing acute ischemic stroke patients.
• PCT is superior to NCCT for ASPECTS analysis in this patient group.