Improved post-processing strategy for MOLLI based tissue characterization allows application in patients with dyspnoe...

Area of Science:

• Cardiovascular Imaging
• Magnetic Resonance Imaging (MRI)
• Biomarker Discovery

Background:

• T₁-mapping using Modified Look-Locker Inversion Recovery (MOLLI) is crucial for identifying myocardial fibrosis and assessing heart failure risk.
• Standard MOLLI T₁-mapping sacrifices accuracy for reduced scan times, which is problematic for heart failure patients.
• Inversion Group Fitting (IGF) offers improved accuracy for long T₁ values but less precision for short T₁ values.

Purpose of the Study:

• To develop and evaluate a novel conditional fitting routine for T₁-mapping.
• To combine the accuracy of IGF for long T₁ values and the precision of standard MOLLI for short T₁ values.
• To shorten acquisition time for T₁-mapping in cardiac patients.

Main Methods:

• Measurements were conducted on a 1.5T clinical MRI scanner using a MOLLI 5(n)3(n)3 prototype.
• Phantom experiments covered a wide range of T₁ times, waiting times, and heart rates, with saturation recovery as the gold standard.
• Data were analyzed using standard MOLLI, IGF, and the proposed conditional fitting routine, with in vivo validation in healthy volunteers and patients with dilated cardiomyopathy and amyloidosis.

Main Results:

• A threshold value was established to determine whether to use IGF or standard MOLLI post-processing, validated in phantoms and patients.
• Reducing the waiting time between inversion experiments to 1 heart beat yielded reliable results, shortening acquisition time from 17 to 13 heart beats.
• In vivo extracellular volume (ECV) values showed expected trends across healthy subjects, dilated cardiomyopathy, and amyloidosis patients.

Conclusions:

• The conditional fitting algorithm accurately determines long T₁ values and maintains high precision for short T₁ values.
• Reduced waiting times and heart rate independence enable shorter breath-hold durations for fast T₁-mapping.
• This technique is highly beneficial for patients with cardiac diseases requiring rapid imaging.