CT Hounsfield Unit Measurements Around the Hip and Their Utility for Opportunistic Screening: A Systematic Review

Area of Science:

• Orthopedic Surgery
• Radiology
• Bone Metabolism

Background:

• Computed tomography (CT) scans are standard for hip preservation surgery and fracture evaluation.
• Assessing bone mineral density (BMD) via CT Hounsfield units (HU) may enhance surgical planning.
• Current literature on CT HU reliability for BMD assessment in the hip and pelvis is reviewed.

Purpose of the Study:

• To systematically review the literature on the reliability and placement of regions of interest (ROIs) for CT HU measurements.
• To evaluate the correlation of CT HU with local and systemic BMD.
• To determine the potential of CT scans for opportunistic BMD screening.

Main Methods:

• A systematic review of PubMed, Scopus, and Web of Science was conducted.
• Twenty-four studies were included, analyzing intraclass correlation coefficients (ICCs) of HU measurements.
• CT HU values were compared with DXA t-scores for predicting regional BMD.

Main Results:

• Twenty-four studies involving 7,035 patients were analyzed.
• Femoral neck was the most common ROI for HU measurement (n=10).
• Moderate to excellent intrarater and interrater reliability was found for femur and pelvis HU measurements.
• Moderate to strong correlations were observed between femoral head/neck CT HU and DXA; correlations were poor to moderate for the pelvis.

Conclusions:

• Various ROIs around the pelvis and proximal femur demonstrate reasonable reliability for CT HU measurement.
• The strongest correlation between CT HU and DXA was found for the femoral neck.
• Preoperative hip/pelvis CT scans may be utilized for opportunistic BMD screening by measuring femoral neck HU.