C-DIR: Double Inversion Recovery with Controlled Artifact Suppression in Brain MRI

Area of Science:

• Magnetic Resonance Imaging (MRI)
• Medical Physics
• Neuroimaging

Background:

• Double Inversion Recovery (DIR) MRI suppresses cerebrospinal fluid (CSF) and white matter (WM) using two inversion pulses.
• Field inhomogeneities (B0 and RF) can cause inadequate inversion, leading to artifacts and reduced image quality.
• Existing DIR techniques are susceptible to these artifacts, limiting diagnostic accuracy.

Purpose of the Study:

• To develop a DIR MRI sequence with inversion pulses robust against B0 and RF field inhomogeneities.
• To improve the reliability and quality of DIR imaging in the presence of magnetic field variations.

Main Methods:

• Developed Controlled DIR (C-DIR) using optimal control theory for inversion pulse design.
• Incorporated robustness against field inhomogeneities into the pulse optimization cost functional.
• Acquired 3T MRI images in 14 participants (healthy, MS, concussion, WMH) and assessed artifacts and lesion visibility.

Main Results:

• C-DIR demonstrated improved inversion and artifact removal in the presence of field inhomogeneities.
• Significant increases in Contrast-to-Noise Ratio (CNR) were observed (e.g., 102% between brainstem and CSF, p<0.001).
• Signal-to-Noise Ratio (SNR) in cortical gray matter showed a trend towards improvement with C-DIR (p=0.07).

Conclusions:

• Robust RF pulse design in C-DIR significantly enhances DIR MRI quality.
• The technique effectively reduces artifacts and improves CNR, leading to better tissue contrast.
• C-DIR offers a more reliable method for DIR imaging, especially in challenging magnetic field conditions.