Cardiac DTI using short-axis PROPELLER: A feasibility study.

Area of Science:

• Cardiovascular MRI
• Diffusion Tensor Imaging
• Medical Imaging Techniques

Background:

• Cardiac diffusion tensor imaging (cDTI) is crucial for assessing myocardial microstructure.
• Traditional methods often suffer from geometric distortion and aliasing, especially in free-breathing scans and individuals with higher body mass index (BMI).
• Mitigating these artifacts is essential for accurate quantitative analysis of the myocardium.

Purpose of the Study:

• To develop and evaluate a novel free-breathing (FB) cDTI method, termed SAP-M2-EPI.
• This method utilizes short-axis PROPELLER (SAP) and M2 motion-compensated spin-echo EPI (SAP-M2-EPI) to address geometric distortion and aliasing.
• The goal is to improve image quality and quantitative accuracy in cDTI, particularly for patients with higher BMI.

Main Methods:

• The study included 10 healthy volunteers with varying BMIs (<25, 25-28, >30).
• Cardiac DTI parameters (FA, MD, HAT) were compared between the novel SAP-M2-EPI and a standard M2-ssEPI sequence.
• Geometric distortion was quantified using the DICE similarity coefficient (DSC) and misregistration area, comparing SAP-M2-EPI to CINE and M2-ssEPI.

Main Results:

• SAP-M2-EPI successfully produced high-quality, aliasing-free LV DWIs in all volunteers.
• Significantly reduced geometric distortion was observed with SAP-M2-EPI (average DSC 0.92, average misregistration 90 mm²), outperforming M2-ssEPI.
• Reduced signal loss due to bulk motion and consistent DTI parameter maps without motion artifacts were noted.

Conclusions:

• SAP-M2-EPI enables high-fidelity, free-breathing cDTI of the entire left ventricle.
• The method effectively eliminates aliasing and minimizes geometric distortion compared to M2-ssEPI.
• Accurate quantification of myocardial microstructure is preserved, offering a significant advancement in cardiac MRI.