A simplified spin and gradient echo approach for brain tumor perfusion imaging.

Area of Science:

• Magnetic Resonance Imaging
• Medical Physics
• Radiology

Background:

• Dynamic susceptibility-contrast MRI (DSC-MRI) is crucial for assessing brain perfusion.
• Contrast agent T1 leakage effects can confound DSC-MRI analysis, leading to inaccurate hemodynamic parameter estimation.
• Existing methods for correcting T1 leakage often involve complex acquisition or analysis protocols.

Purpose of the Study:

• To introduce a simplified acquisition and analysis approach for SAGE-based DSC-MRI.
• To develop a method that is free of contrast agent T1 leakage effects.
• To validate the simplified approach against a more complex multi-echo SAGE technique.

Main Methods:

• Acquisition of DSC-MRI data using a five-echo SAGE sequence in rat C6 tumors.
• Nonlinear fitting of all echoes to obtain T1-insensitive ΔR2* and ΔR2 time series.
• Application of a simplified SAGE approach (two gradient echoes, one spin echo) for analytical computation of T1-insensitive ΔR2* and ΔR2.

Main Results:

• Excellent agreement between the five-echo and simplified SAGE methods for ΔR2* and ΔR2 time series.
• Significant T1 leakage correction achieved by both methods compared to uncorrected data.
• No significant differences in derived hemodynamic parameters (blood volume, blood flow, vessel size) between the two SAGE methods.

Conclusions:

• The simplified SAGE technique effectively corrects for T1 leakage effects in DSC-MRI.
• This simplified approach yields hemodynamic parameters comparable to the multi-echo SAGE method.
• The technique eliminates the need for nonlinear fitting, streamlining DSC-MRI data analysis.