Background:
Preoperative embolization is based on the preoperative digital subtraction angiography (DSA) tumor blush, and as such is considered the “gold standard” for determining tumor vascularity. However, to our knowledge reliability studies evaluating vascularity ratings of DSA tumor blush in spinal metastases have not been published previously.

Purpose:
To evaluate inter- and intra-rater agreement in the assessment of the vascularity of spinal metastases using DSA tumor blush.

Material and Methods:
This reliability study included 46 patients with symptomatic metastatic spinal cord compression requiring surgery. DSA data stored in the hospital picture archiving and communication system (PACS) from the participants of a randomized controlled trial were used. Inter- and intra-rater agreement on vascularity assessment using DSA tumor blush according to a three-step ordinal scale was evaluated: no hypervascularity; moderate hypervascularity; and pronounced hypervascularity. The statistical analysis was based on the linear weighted kappa’s for multiple raters that extend Cohen’s κ. Three raters and κ = 0.2 in the null hypothesis implied that the power of the study was 0.96.

Results:
Inter- and intra-rater agreements were moderate in rating the vascularity of spinal metastases and the agreements were significantly higher than the κ = 0.20 in the null hypothesis (P = 0.0002 and P = 0.0001). The κ value for inter-rater agreement was 0.57 (95% confidence interval [CI], 0.41–0.72) and for intra-rater agreement 0.55 (95% CI, 0.38–0.71).

Conclusion:
There is moderate inter-rater and intra-rater agreement in classifying the vascularity of spinal metastases on a three-step ordinal scale for DSA tumor blush.