Accuracy and repeatability of QRAPMASTER and MRF-vFA.

Area of Science:

• Magnetic Resonance Imaging
• Quantitative Imaging
• Biomedical Engineering

Background:

• Quantitative magnetic resonance imaging (qMRI) provides essential tissue-specific information.
• Assessing the bias and repeatability of qMRI sequences is crucial for clinical translation.
• QRAPMASTER and MRF-VFA are two distinct qMRI techniques with differing underlying principles.

Purpose of the Study:

• To evaluate the bias and repeatability of QRAPMASTER and MRF-VFA quantitative MRI sequences.
• To compare these techniques across different magnetic field strengths (1.5T and 3T) and in both phantom and volunteer studies.
• To determine the suitability of these methods for reliable quantitative relaxometry.

Main Methods:

• Standardized phantom and volunteer studies were conducted on 1.5T and 3T scanners.
• Both QRAPMASTER (steady-state) and MRF-VFA (transient response) sequences were repeated eight times over consecutive weeks.
• Bias and coefficients of variation (CoV) for T1 and T2 values were calculated and analyzed using GLM.

Main Results:

• Both QRAPMASTER and MRF-VFA demonstrated high repeatability with low CoV in phantom and in-vivo measurements.
• QRAPMASTER showed lower bias for T1 and T2 values compared to MRF-VFA across both field strengths.
• In-vivo T1 and T2 values were within previously reported ranges, with variations primarily dependent on field strength and subject, not repetition.
• MRF-VFA was found to be 4.77 times faster than QRAPMASTER.

Conclusions:

• QRAPMASTER and MRF-VFA are highly repeatable quantitative MRI methods suitable for relaxometry.
• QRAPMASTER exhibits superior accuracy compared to MRF-VFA, while MRF-VFA offers a significant speed advantage.
• The choice between methods may depend on the balance between accuracy requirements and the need for faster scan times.