Selective in vivo bone imaging with long-T₂ suppressed PETRA MRI.

Area of Science:

• Magnetic Resonance Imaging (MRI)
• Biomedical Engineering
• Radiology

Background:

• Conventional MRI struggles to image bone matrix water due to interference from long-T2 signals.
• Developing advanced MRI sequences is crucial for non-invasive bone assessment.

Purpose of the Study:

• To design and evaluate an optimized point-wise encoding time reduction with radial acquisition (PETRA) sequence.
• To achieve effective long-T2 suppression at 3 Tesla for enhanced bone imaging.

Main Methods:

• Utilized an adiabatic inversion recovery scheme for long-T2 signal nulling.
• Employed variable excitation flip angles and phase-modulated pulses to maintain constant short-T2 signal amplitude and increase SNR.
• Developed a fast, noniterative reconstruction algorithm to minimize artifacts from nonuniform excitation.

Main Results:

• Achieved effective suppression of long-T2 protons and improved image SNR using phase-modulated excitation and noniterative reconstruction.
• Obtained midtibia images with SNR of 15 at 1-mm isotropic resolution in 6.5 minutes.
• Demonstrated suitability for generating multi-angle projection bone images with detailed anatomic information.

Conclusions:

• Optimized long-T2 suppressed PETRA enables imaging of bone matrix water without long-T2 soft tissue and pore water interference.
• Opens new avenues for anatomic bone imaging at isotropic resolution and quantification within practical scan times.