COMPARISON BETWEEN CONVENTIONAL AND FAST SPIN-ECHO STIR SEQUENCES

Purpose: To evaluate the common characteristics and differences in con trast behavior of short-TI-inversion-recovery (STIR) and short-TI-inve rsion-recovery fast spin echo(TurboSTIR) sequences. Material and Metho ds: Phantoms doped with increasing doses of Gd-DTPA and a pork-fat pha ntom were used to evaluate the dependence of the STIR and TurboSTIR si gnals on the T1 relaxation time. Clinical TurboSTIR images were obtain ed from 30 patients with musculoskeletal abnormalities and compared to conventional STIR images in 15 cases and to postcontrast TurboSTIR im ages in another 15 cases. Results: In the phantom measurements, a sign ificantly shorter inversion time (TI) was needed to achieve fat suppre ssion on TurboSTIR images, and, with an identical number of signal ave rages, contrast-to-noise ratios were lower on TurboSTIR images. These differences between STIR and TurboSTIR can be attributed to the contri bution of stimulated echoes to overall TurboSTIR signal and can be com pensated by a shorter TI and a higher number of signal averages for Tu rboSTIR, respectively. With these adaptations, clinical TurboSTIR and STIR images showed an identical contrast behavior with fat suppression and a high sensitivity to pathological lesions but TurboSTIR saved a significant amount of scan time and reduced some types of artifacts. C ontrast uptake impaired lesion conspicuity on TurboSTIR images. Conclu sion: TurboSTIR sequences should replace conventional STIR sequences a nd should be performed before contrast administration.