Reliability of the spinal instability neoplastic scale among radiologists: an assessment of instability secondary to spinal metastases.

OBJECTIVE. The spinal instability neoplastic scale (SINS) is a new classification system for tumor-related spinal instability. The SINS may prove to be a valuable tool for radiologists to communicate with oncologists and surgeons in a standardized evidence-based manner. The objective of this study was to determine the inter- and intraobserver reliability and validity of the SINS among radiologists. MATERIALS AND METHODS. Thirty-seven radiologists from 10 international sites used the SINS to categorize the degree of spinal instability in 30 patients with spinal tumors. To assess validity, we compared the SINS scores assigned by the radiologists with the SINS scores of 11 spine oncology surgeons (reference standard). Each total SINS score (range, 0–18 points) was converted into one of the following three clinical categories: 0–6 points, stable; 7–12 points, potentially unstable; and 13–18 points, unstable. In addition, each total SINS score was converted into a binary scale: 0–6 points was defined as stable...