Excitation of Complicated Shapes in Three Dimensions
- 作者：Ser&scaron ; a ; Igor ; Macura ; Slobodan
- 刊名：Journal of Magnetic Resonance
- 出版年：1998
- 期刊代码：126_10907807
- 类别：ch
- 出版时间：December, 1998
- 卷：135
- 期：2
- 页码：466-477
- 文件大小：1.53 M
摘要
We experimentally verified a recently proposed technique for the excitation of a complicated three-dimensional profile (CARVE,completelyarbitraryregionalvolumeexcitation). CARVE is based on a generalized DANTE RF pulse sequence and a synchronous string of gradient steps. Provided there is no limitation in the number of pulses, CARVE can generate an excitation profile of any shape with any resolution. However, hardware limitations and sample properties restrict the number of RF pulses and gradient steps and, thus, limit attainable resolution of the excitation profile. We theoretically and experimentally showed that spatial resolution can be increased by distributing a long sequence among several CARVE experiments and summing up their signals. This is particularly important for three-dimensional excitation profiles where ann-fold increase in resolution requires ann3-fold increase of the number of events in the sequence. The potential use of three-dimensional CARVE might be in spectroscopic imaging where the excitation profile can be tailored to match the shape of a selected organ or body part.