Observer reliability of arteriovenous malformations grading scales using current imaging modalities.

Area of Science:

• Neurosurgery
• Radiology
• Medical Imaging

Background:

• Arteriovenous malformations (AVMs) require accurate grading for treatment planning.
• Existing grading scales (Spetzler-Martin, Spetzler-Ponce, Pollock-Flickinger) are widely used but their observer reliability needs evaluation.
• Current imaging modalities and clinical practice settings are crucial for assessing scale reliability.

Purpose of the Study:

• To evaluate the observer reliability of three common arteriovenous malformation (AVM) grading scales.
• To compare the reliability of the Spetzler-Martin (5-tier), Spetzler-Ponce (3-tier), and Pollock-Flickinger scales.
• To assess reliability using current imaging techniques (MRI, CT angiography, DSA) in a clinical context.

Main Methods:

• Five experienced raters independently graded 15 MRI, 15 CT angiograms, and 15 DSA studies of AVMs.
• Intrarater reliability was assessed by repeating assessments on 5 scans per modality.
• Interrater reliability was analyzed using generalized kappa, Kendall's W, and ICC; intrarater reliability used Cohen's kappa, Kendall's tau-b, and ICC.

Main Results:

• Good to extremely strong interrater reliability was observed for Spetzler-Martin (ICC=0.69, W=0.73) and Spetzler-Ponce (ICC=0.68, W=0.70) scales, improving upon reassessment.
• Excellent to extremely strong interrater reliability was found for the Pollock-Flickinger scale (ICC=0.89, W=0.81).
• CT angiography showed the highest agreement, followed by MRI and DSA. Intrarater reliability for Spetzler-Martin was excellent in 3/5 raters.

Conclusions:

• All three AVM grading scales demonstrated high levels of agreement among observers.
• Reassessment improved reliability, likely due to a training effect and the requirement for justification.
• The need for justification in routine clinical practice may impact the utility of grades for scientific research.