First-pass myocardial perfusion MRI with reduced subendocardial dark-rim artifact using optimized Cartesian sampling

Area of Science:

• Cardiovascular Imaging
• Medical Physics
• Radiology

Background:

• Subendocardial dark-rim artifact (DRA) poses a significant challenge in first-pass perfusion (FPP) cardiac magnetic resonance imaging (MRI).
• Gibbs ringing effects are a primary contributor to DRA, impacting image quality and diagnostic interpretation.
• Existing FPP techniques often struggle to mitigate these artifacts effectively.

Purpose of the Study:

• To develop and validate a novel free-breathing FPP imaging scheme using Cartesian sampling to minimize DRA.
• To enable near-instantaneous image reconstruction for improved clinical workflow.
• To assess the efficacy of the proposed method in reducing DRA compared to conventional techniques.

Main Methods:

• A two-step k-space manipulation strategy was employed: undersampled Cartesian acquisition to widen k-space coverage and a modified parallel imaging scheme with optimized apodization.
• The method suppresses Gibbs ringing by shaping the point spread function.
• Studies were conducted on healthy volunteers (n=10) and infarcted canines (n=3), along with two patients with suspected coronary microvascular dysfunction, comparing the proposed method against conventional Cartesian FPP at 3T.

Main Results:

• The proposed method significantly reduced DRA width (1.3 vs. 2.9 mm, P < 0.001) and the number of affected myocardial segments (2.6 vs. 8.7, P < 0.0001).
• Severe DRA prevalence decreased by 10-fold.
• Image quality scores were comparable (P=0.2), though signal-to-noise ratio was slightly lower (P < 0.05).
• Animal studies successfully detected subendocardial perfusion defects, and patient results correlated with invasive tests.

Conclusions:

• The developed free-breathing Cartesian FPP imaging method effectively reduces severe DRAs.
• The technique maintains comparable image resolution and quality to conventional methods.
• This advancement offers improved diagnostic potential for myocardial perfusion assessment using cardiac MRI.