Breuer Felix A, Blaimer Martin, Mueller Matthias F, Seiberlich Nicole, Heidemann Robin M, Griswold Mark A, Jakob Peter M
University of Würzburg, Department of Experimental Physics 5, Würzburg, Germany.
Magn Reson Med. 2006 Mar;55(3):549-56. doi: 10.1002/mrm.20787.
The CAIPIRINHA (Controlled Aliasing In Parallel Imaging Results IN Higher Acceleration) concept in parallel imaging has recently been introduced, which modifies the appearance of aliasing artifacts during data acquisition in order to improve the subsequent parallel imaging reconstruction procedure. This concept has been successfully applied to simultaneous multi-slice imaging (MS CAIPIRINHA). In this work, we demonstrate that the concept of CAIPIRINHA can also be transferred to 3D imaging, where data reduction can be performed in two spatial dimensions simultaneously. In MS CAIPIRINHA, aliasing is controlled by providing individual slices with different phase cycles by means of alternating multi-band radio frequency (RF) pulses. In contrast to MS CAIPIRINHA, 2D CAIPIRINHA does not require special RF pulses. Instead, aliasing in 2D parallel imaging can be controlled by modifying the phase encoding sampling strategy. This is done by shifting sampling positions from their normal positions in the under-sampled 2D phase encoding scheme. Using this modified sampling strategy, coil sensitivity variations can be exploited more efficiently in multiple dimensions, resulting in a more robust parallel imaging reconstruction.
并行成像中的CAIPIRINHA（并行成像中控制混叠实现更高加速率）概念最近被提出，它在数据采集过程中改变混叠伪影的表现形式，以改进后续的并行成像重建过程。这一概念已成功应用于同时多层成像（MS CAIPIRINHA）。在这项工作中，我们证明CAIPIRINHA概念也可应用于三维成像，在三维成像中可以同时在两个空间维度上进行数据缩减。在MS CAIPIRINHA中，通过交替多波段射频（RF）脉冲为各个层面提供不同的相位周期来控制混叠。与MS CAIPIRINHA不同，二维CAIPIRINHA不需要特殊的RF脉冲。相反，二维并行成像中的混叠可以通过修改相位编码采样策略来控制。这是通过在欠采样二维相位编码方案中将采样位置从其正常位置进行偏移来实现的。使用这种修改后的采样策略，可以在多个维度上更有效地利用线圈灵敏度变化，从而实现更稳健的并行成像重建。
