MRCP: technical improvements with parallel imaging technique.

Learning objectives: To review the current state-of-the-art MRCP sequences. To describe the distinct parallel imaging (PI) algorithms that can be applied to MRCP sequences. To understand the technical advances and improvements with PI with respect to the image acquisition and image quality of MRCP in diagnosing pancreatico- biliary pathologies. Background: PI techniques use the spatial sensitivity information inherent in an array of multiple receiver surface coils to partially replace time-consuming spatial encoding usually performed by switching magnetic field gradients. The reduction of the number of phase-encoding steps allows decreasing the acquisition time and, in single-shot sequences, the length of the echo train (ETL) and thus the duration of the readout period. Imaging findings OR Procedure details: Standard MRCP sequences described will include the following T2-weighted sequences: 1) projection technique, 2D thick slab half-Fourier-acquired single-shot turbo-spin echo (HASTE); 2) 2D multi-slice HASTE; and 3) 3D turbo-spin-echo (TSE). The distinct effects of PI on standard MRCP sequences will be described in detail: When applied to HASTE sequences, PI technique shortens the ETL and thus reduces the blurring of the image. When applied to 3D TSE sequence, PI reduces the acquisition time and allows obtaining of high resolution imaging with isotropic voxel size. Conclusion: PI increases quality and performance of MRCP sequences. Ultimately, these improvements in image quality may manifest better diagnostic accuracy.