Correlation between bone density measurements on CT or MRI versus DEXA scan: A systematic review

Area of Science:

• Radiology and Imaging Science
• Orthopedic Surgery and Spine Research
• Bone Densitometry and Osteoporosis Research

Background:

• Emerging computed tomography (CT) and magnetic resonance imaging (MRI) techniques for bone density assessment are increasingly discussed in spine surgery literature.
• The correlation between these novel imaging-derived bone mineral density (BMD) measurements and traditional Dual-Energy X-ray Absorptiometry (DEXA) remains incompletely understood.

Purpose of the Study:

• To conduct an updated systematic review evaluating the correlations between bone mineral density (BMD) assessed via CT or MRI and DEXA measurements.

Main Methods:

• Systematic review of studies published between 2011 and 2021.
• Inclusion criteria focused on studies reporting correlations between CT-Hounsfield Units (HU) or MRI measurements and DEXA t-scores or BMD of the lumbar spine or hip.

Main Results:

• Twenty-five studies (15 CT, 10 MRI) involving 2,745 patients were analyzed.
• Pooled correlation coefficients indicated moderate agreement: CT-HU versus spine DEXA (r²=0.60), CT-HU versus hip DEXA (r²=0.50), and MRI versus spine/hip DEXA (r²≈-0.41 to -0.44).
• In spine surgery cohorts, pooled correlations between CT and DEXA were r²=0.64.

Conclusions:

• Computed tomography (CT) Hounsfield Units (HU) demonstrate stronger correlations with Dual-Energy X-ray Absorptiometry (DEXA) compared to magnetic resonance imaging (MRI) measurements.
• Both CT and MRI provide only moderate correlations with DEXA, necessitating cautious interpretation for bone mineral density (BMD) evaluation.
• The predictive value of CT and MRI for mechanical complications and clinical outcomes in spine surgery patients requires further investigation, especially in degenerative spine populations.