TRUE PROTON DENSITY AND T2-WEIGHTED TURBO SPIN-ECHO SEQUENCES FOR ROUTINE MRI OF THE BRAIN

Our aim was to evaluate the diagnostic reliability of turbo spin-echo (TSE) sequences compared to a conventional dual-echo spin-echo (SE) se quence in routine brain MRI at 1.0 T. The following demands were made on TSE sequences: acquisition time-reduction of at least 50% and true proton density (PD) contrast (low-signal cerebrospinal fluid). A conve ntional spin-echo and two single-echo TSE sequences were used in 150 p atients, a dual-echo TSE sequence in addition in 50 patients. Demonstr ation of most anatomical structures and disorders was equivalent with TSE and SE sequences. Advantages of TSE were reduced flow artefacts on T2-weighted images, better lesion contrast on PD-weighted TSE images (especially in the dual-echo sequence) and acquisition time reduction to about 5 min (single-echo TSE) and 3:35 min (dual-echo TSE). Disadva ntages of TSE were: reduced contrast of iron-containing substances suc h as haemosiderin and of areas of calcification. By virtue of the shor ter acquisition time and diagnostic reliability dual-echo TSE proved t he best sequence. If it is used with only one acquisition - whereby im age quality but not diagnostic reliability is slightly decreased - acq uisition time can be further reduced to 1:48 min. Application of a sus ceptibility-sensitive gradient-echo sequence, such as FLASH, compensat es for the disadvantages mentioned above.