Do Hounsfield Units From Intraoperative CT Scans Correlate With Preoperative Values?

Area of Science:

• Spine surgery
• Medical imaging
• Bone density assessment

Background:

• Increasing interest in forecasting postoperative complications using bone density metrics.
• Vertebral Hounsfield units from opportunistic CT scans show promise for bone density assessment.
• Intraoperative advanced imaging is increasingly adopted in spine surgery.

Purpose of the Study:

• Assess the reliability of measuring vertebral Hounsfield units from intraoperative CT scans.
• Determine if intraoperative Hounsfield unit measurements correlate with preoperative CT scan values.

Main Methods:

• Retrospective study of 81 patients undergoing instrumented spinal fusion with intraoperative CT.
• Two physician reviewers measured vertebral Hounsfield units from preoperative and intraoperative CT scans.
• Interrater reliability, intraclass correlation, repeated measures correlation, and linear mixed models were used for analysis.

Main Results:

• Vertebral Hounsfield units can be reliably measured from intraoperative CT scans with good interrater concordance (correlation=0.82).
• No correlation was found between Hounsfield units measured from intraoperative CT scans and preoperative CT scans (r=0.01).
• This lack of correlation persisted even after controlling for patient and clinical factors.

Conclusions:

• Measuring Hounsfield units from intraoperative CT scans is feasible and reliable.
• Intraoperative Hounsfield unit measurements do not correlate with preoperative values and should not be used interchangeably.
• Future research should investigate the prognostic value of intraoperative Hounsfield units as a distinct metric.