Simultaneous Acquisition of Water, Fat, and Velocity Images Using a Phase‐Contrast T2*‐IDEAL Method

Water-fat separation MRI techniques use frequency differences between water and fat encoded in the phase of the MR signal. Similarly, phase-contrast MRI (2D PC-MRI) uses phase differences to estimate blood flow velocity. This study proposes to enhance efficiency by acquiring both images in a single scan, resulting in co-registered images of water-fat species and velocity. This work introduces a method that combines phase-contrast with T2*-IDEAL to acquire water-fat components and velocity images in a single MR acquisition. We developed a phase-contrast multi-echo (PCME-MRI) acquisition to obtain IDEAL MR images with velocity encoding. Our T2*-IDEAL method estimates velocity and separates water-fat components by considering three chemical species: fat concentration and two water components with velocity information. The proposed PC T2*-IDEAL method was validated with a numerical phantom and 2D MR axial images of the neck in 14 healthy volunteers, measuring blood flow in the carotid arteries and water-fat components around the region of interest. In volunteers, the median and range MAE when comparing PC T2*-IDEAL and standard T2*-IDEAL fat fraction was 0.06 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:semantics><mml:mrow><mml:mo>±</mml:mo></mml:mrow> <mml:annotation>$$ \pm $$</mml:annotation></mml:semantics> </mml:math> 0.02. The median and range of velocity for PC T2*-IDEAL were 8.44 and [6.23, 10.6] mL, compared to 7.16 and [4.79, 8.78] mL obtained by 2D PC-MRI. Numerical phantom simulations demonstrated similar results in water-fat components and velocity information compared to standard T2*-IDEAL and 2D PC-MRI methods. Volunteer images showed accurate estimations of water-fat components and differences in velocity information using PC T2*-IDEAL in comparison with standard 2D PC-MRI.