CooperativeT1 andT2 effects on contrast using a new driven inversion spin-echo (DISE) MRI pulse sequence

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Abstract
A pulse sequence is presented for obtaining a single image with combined T1/T2 weighting. T2 relaxation is made to increase intensity, in cooperation with the effect of T1 relaxation, by providing T2 weighting with a 90°‐180°‐90° driven inversion pulse triplet in an inversion recovery method. Unlike the inversion spin‐echo method having a short inversion time (TI), signals in the new driven inversion spin‐echo (DISE) method need not be negative and the most T1‐sensitive region of the recovery curve can be used. Selecting sensitivity to one relaxation time does not degrade the sensitivity to the other relaxation time. T1 sensitivity is thus extended to longer echo times (TE intervals), T2 sensitivity is extended to longer TI intervals, and the combined Tl / T2‐weighted technique with intermediate TE and T1 has highly cooperative and near‐maximal T1 and T2 effects on contrast. Intensity is not multiplicatively degraded by T1 and T2weighting so that the signal‐to‐noise of the combined T1/T2 ‐weighted method is high. High intensity and TI and T2 cooperatively occur for a much wider range of relaxation times, and especially for images heavily weighted to the pathologic intermediate and long T1 and T2 Rgime. © 1990 Academic Press, Inc.