2D multislice and 3D MRI sequences are often equally sensitive

A simple theoretical model was developed to compare the sensitivities (i.e. , signal-to-noise ratios per unit imaging time) of two-dimensional (2D) mul tislice and 3D imaging sequences. The model shows that the sensitivities of 3D and 2D moltislice MRI sequences are usually similar. Sensitivities are identical in T-2-weighted sequences when the TRS Of the two sequences are t he same. In T-1-weighted gradient-echo sequences, sensitivities are very si milar when Ernst angle excitation is used and the T-R of the 2D sequence is less than T-1. The predictions of the model are confirmed in phantom and a nimal experiments. (C) 1999 Wiley-Liss, Inc.