Variable Gradient Delay Correction for Spiral MRI

Payal Sharad Bhavsar¹, Jim Pipe¹

A new method is proposed to estimate time varying gradient delays in spiral MRI. Gradient delays cause blurring and distortions in spiral images. Several methods have been proposed to estimate these delays. Continuous, independent delays are estimated for all three gradient channels as a function of the ADC time. This method includes gradient coupling effects and requires minimal modification of the pulse sequence design.A 3D spiral trajectory FLORET was used to estimate the gradient delays. To validate the results, a constant delay correction method was used for analysis. In-vivo and phantom experiments were reconstructed using constant and variable gradient delay correction. For in-vivo data, variable correction method showed significant reduction in the artifacts. Comparable results were obtained for constant and variable correction method for phantom simulations. The method can be applied to any stack of spirals based trajectory.