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The divided subtracted inversion recovery (dSIR) is a high T1 contrast technique that shows changes in white matter in patients with traumatic brain injury and hypoxic injury. The changes can be explained by small differences in T1; however, to date, there has been no independent validation of the technique using a standard reference. The present study develops the theory of the dSIR signal and performs validation using the NIST/ISMRM T1 phantom. Non‐idealities are explored, including the influence of noise bias and finite repetition time (TR), which leads to the introduction of an optimally efficient TR for inversion recovery acquisitions. Results show excellent agreement with theoretical calculations. [ABSTRACT FROM AUTHOR]

Purpose To compare two T1-weighted (T1W) fat-suppressed sequences for 3D breath-hold pre- and postcontrast fat-suppressed T1W imaging of the female pelvis at 3T. Materials and Methods Pelvic MRI scans of 16 female patients were retrospectively identified who were scanned with two 3D breath-hold sequences: 1) a fast spoiled gradient echo sequence with spectral inversion at lipids (SPECIAL) (called 3D FSPGR), and 2) a dual-echo two-point Dixon (DE Dixon) sequence. Contrast between soft tissue and fat, soft tissue and fluid, and fat and fluid was measured on pre- and postcontrast images. Additionally, two readers subjectively scored the images for degree and homogeneity of fat suppression plus presence and severity of artifacts. Results Contrast between muscle and myometrium to fat was improved with the Dixon technique (0.61 vs. 0.09 and 0.7 vs. 0.3, respectively, P < 0.001). Both readers agreed that fat suppression was stronger with the Dixon sequence ( P < 0.001 and P = 0.06). Artifacts were equivalent ( P = 0.53 and 0.65). Conclusion The 3D DE Dixon sequence achieved stronger fat suppression in the female pelvis when compared to a 3D FSPGR sequence with SPECIAL. J. Magn. Reson. Imaging 2008;28:121-127. © 2008 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]