Abstract:Compared with conventional Cartesian kspace sampling, the nonCartesian sampling can enable higher coverage effeciency of kspace, more efficiently make use of the gradient system performance, and reduce dB/dt to prevent to cause the undesirable human physiological reactions. The combination of nonCartesian kspace sampling and parallel imaging can further accelerate imaging speed, however the artifact pattern in image domain would become much more complicated, which introduces a lot of technical difficulties to nonCartesian parallel MRI reconstruction. In this article, several typical nonCartesian parallel imaging reconstruction techniques including SENSE, CGSENSE, nonCartesian GRAPPA, SPIRiT and newlyemerging compressed sensing are reviewed, their technical details, advantages and disadvantages are discussed. SENSE and CGSENSE can achieve optimal reconstruction results theoretically, but both of them are restricted by the accurate measurement of coil sensitivity distribution. NonCartesian GRAPPA doesn’t rely on coil sensitivity measurement, but can only perform approximate calculation for specified nonCartesian sampling mode. SPIRiT combines the advantages of SENSE and GRAPPA, and can obtain satisfactory result by using iterative optimization algorithm. Taking the advantage of sparse transform characteristic of images, compressed sensing cooperating with existing iterative optimization parallel imaging method can further improve reconstructed image quality, and it will be a hotspot in the future study.