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Published on: January 31, 2025
Optimization of MR-Relaxometry for BMD-measurements and its Correlation with DEXA
N Riyahi Alam1, M Bakhtiary, M Oghabian
1Medical Physics Department and Research Center for Science and Technology in Medicine (RCSTIM), School of Medicine, Tehran University of Medical Sciences (TUMS), Tehran-Iran. (email: riahinad@sina.tums.ac.ir).
Summary
This study optimized MRI protocols for bone density measurements using MR-Relaxometry, showing it correlates with BMD and can complement DEXA scans, especially for femoral neck assessment.
Area of Science:
- Medical Imaging
- Biophysics
- Radiology
Background:
- Dual-energy X-ray absorptiometry (DEXA) can misinterpret bone mineral density (BMD) due to inability to separate cortical and trabecular bone.
- MR-Relaxometry offers a method for bone quality assessment by deriving relaxation rates (R2, R2*, R2').
Purpose of the Study:
- To optimize conventional MRI protocols for BMD measurements using MR-Relaxometry on systems without specialized multi-echo capabilities.
- To evaluate the efficacy of MR-Relaxometry in measuring BMD, particularly in the femoral neck, and compare it with DEXA.
Main Methods:
- Utilized a 1.5T MRI system and a uniformity phantom for calibration.
- Employed multi-echo Gradient Echo (GE) and Spin Echo (SE) protocols with varying echo times (TE) and repetition times (TR) to determine R2* and R2.
- Optimized GE and SE parameters for phantom calibration and subsequently applied them to 21 volunteers (normal, osteopenia, osteoporosis).
- Compared MR-derived relaxation rates with BMD measurements obtained from a Lunar DEXA system.
Main Results:
- Optimized GE parameters (TE=13.42/18/26.8 ms, TR=800ms, ST=8mm) and SE parameters (TE=30/60/90/120ms, TR=800ms, ST=8mm) were established for phantom calibration.
- Achieved coefficients of variation (CV) of 2.96% for R2* and 3% for R2.
- Demonstrated a significant positive correlation between R2* and R2' with BMD (r=0.62, p<0.05).
Conclusions:
- MR-Relaxometry, using optimized conventional MRI protocols, is a viable tool for BMD measurements in the femoral neck.
- MR-Relaxometry can serve as a complementary method to DEXA, particularly in cases where DEXA assessments may be limited or prone to erroneous interpretation.
