2D multislice MP2RAGE sequence for fast T₁ mapping at 7 T: Application to mouse imaging and MR thermometry

Area of Science:

• Magnetic Resonance Imaging
• Medical Physics
• Animal Research

Background:

• T1 mapping is crucial for quantitative MRI.
• High-field (7T) MRI offers improved signal-to-noise ratio but requires optimized sequences.
• MR thermometry is valuable for monitoring temperature during interventions.

Purpose of the Study:

• To develop a 2D radial multislice MP2RAGE sequence for rapid and accurate T1 mapping at 7T in mice.
• To evaluate the sequence's utility for MR thermometry.

Main Methods:

• A 2D multislice MP2RAGE sequence was implemented with optimized parameters (TI1-TI2-TR: 1000-3000-9000 ms).
• Interleaved multislice acquisition allowed for six slices in 9 seconds.
• In vitro T1 measurements and temperature dependence were assessed; in vivo studies were performed on mouse brain and abdomen.

Main Results:

• Optimized pulse shape and slice parameters yielded T1 measurement SD and bias below 1% and 2%, respectively.
• A linear T1-temperature relationship was observed between 10°C and 60°C.
• In vivo mouse brain T1 maps showed <1% variation; abdominal imaging revealed 6% T1 underestimation due to respiratory motion.

Conclusions:

• The developed multislice MP2RAGE sequence enables fast, whole-body T1 mapping and MR thermometry at 7T.
• The sequence's reconstruction method supports on-the-fly processing.
• This technique holds promise for advanced in vivo quantitative MRI applications in small animals.