  Purpose: To develop, optimize and implement a single shot spiral TSE-sequence
at 3 T and to demonstrate its feasibility to acquire artefact free images of
the central nervous system with 1 mm spatial resolution in < 200 ms. Theory and
Methods: Spiral TSE sequences with annulated spiral segmentation have been
implemented with different acquisition modes. In fixed mode the duration of
each spiral segment is fixed to fill the available acquisition time tacq. In
tangential mode, the beginning of each spiral segment is reached via a straight
tangential trajectory. Tangential mode allows faster transition and thus longer
tacq for a given echo spacing ESP, but less data points can be acquired per
acquisition interval. Alternating between spiral-in and spiral-out readout in
alternating echoes leads to a somewhat different point spread function for
off-resonant spins. Results: Images of the brain with 1 mm spatial resolution
acquired with a variable density spiral with ~45 % undersampling can be
acquired in a single shot. All acquisition modes produce comparable image
quality. Only mild artifacts in regions of strong susceptibility effects can be
observed for ESP of 10 ms and below. The use of variable flip angle schemes
allows seamless acquisition of consecutive slices and/or dynamic scans without
waiting time between consecutive acquisitions. Comparison with images acquired
at 1.5 T shows reduced susceptibility artifacts within the brain and facial
structures.. Conclusion: Single shot spiral TSE has been demonstrated to enable
highly efficient acquisition of high-resolution images of the brain in < 200 ms
per slice.

Medical Physics