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Updated: Mar 19, 2026
A Magnetic Resonance Imaging Protocol for Stroke Onset Time Estimation in Permanent Cerebral Ischemia
Published on: September 16, 2017
Inter-Observer Agreement on Diffusion-Weighted Magnetic Resonance Imaging Interpretation for Diagnosis of Acute
Deniz Oray1, Onder Limon1, Cem Ertan1
1Department of Emergency Medicine, Izmir University School of Medicine, Izmir, Turkey.
Objectives:
Diffusion-weighted magnetic resonance imaging (DW-MRI) is a highly sensitive tool for the detection of early ischemic stroke and is excellent at detecting small and early infarcts. Nevertheless, conflict may arise and judgments may differ among different interpreters. Inter-observer variability shows the systematic difference among different observers and is expressed as the kappa (Κ) coefficient. In this study, we aimed to determinate the inter-observer variability among emergency physicians in the use of DW-MRI for the diagnosis of acute ischemic stroke.
Methods:
Cranial DW-MRI images of 50 patients were interpreted in this retrospective observational cross-sectional study. Patients who were submitted to DW-MRI imaging for a suspected acute ischemic stroke were included in the study, unless the scans were ordered by any of the reviewers or they were absent in the system. The scans were blindly and randomly interpreted by four emergency physicians. Inter-observer agreement between reviewers was evaluated using Fleiss' Κ statistics.
Results:
The mean kappa value for high signal on diffusion-weighted images (DWI) and for reduction on apparent diffusion coefficient (ADC) were substantial (k=0.67) and moderate (k=0.60) respectively. The correlation for detection of the presence of ischemia and location was substantial (k: 0.67). There were 18 false-positive and 4 false-negative evaluations of DWI, 15 false positive and 8 false-negative evaluations of ADC.
Conclusions:
Our data suggest that DW-MRI is reliable in screening for ischemic stroke when interpreted by emergency physicians in the emergency department. The levels of stroke identification and variability show that emergency physicians may have an acceptable level of agreement.
Insights
Diffusion-weighted MRI (DW-MRI) shows substantial agreement among emergency physicians for diagnosing acute ischemic stroke. This imaging technique is reliable for emergency department stroke screening.
Area of Science:
- Neurology
- Radiology
- Emergency Medicine
Background:
- Diffusion-weighted magnetic resonance imaging (DW-MRI) is highly sensitive for detecting early ischemic stroke.
- Inter-observer variability can affect diagnostic accuracy, measured by the kappa (Κ) coefficient.
Purpose of the Study:
- To determine the inter-observer variability among emergency physicians using DW-MRI for acute ischemic stroke diagnosis.
Main Methods:
- Retrospective analysis of cranial DW-MRI scans from 50 patients suspected of acute ischemic stroke.
- Blind and random interpretation of scans by four emergency physicians.
- Evaluation of inter-observer agreement using Fleiss' Κ statistics.
Main Results:
- Substantial agreement (k=0.67) for high signal on diffusion-weighted images (DWI) and moderate agreement (k=0.60) for apparent diffusion coefficient (ADC) reduction.
- Substantial agreement (k=0.67) for detecting the presence and location of ischemia.
- Reported false-positive and false-negative evaluations for DWI and ADC.
Conclusions:
- DW-MRI is a reliable screening tool for ischemic stroke when interpreted by emergency physicians.
- Emergency physicians demonstrate an acceptable level of agreement in stroke identification using DW-MRI.
