Misleading changes of the signal intensity on opposed-phase MRI after injection of contrast medium
- Univ. of Halle, Wittenberg (Germany); and others
The effect of opposed-phase imaging on the interpretation of MR contrast studies is highlighted. A model calculation is performed. It demonstrates the change of signal intensity of an average tumor before and after application of Gd-DTPA on an in-phase and an opposed-phase image, depending on the percentage of fat within the voxels. The effect is then demonstrated, using a small cotton stick soaked with water or a solution of contrast agent representing a tumor before and after i.v. application of Gd-DTPA. If an average enhancing tumor, which is surrounded by fat, occupies less than 50-60% of the slice thickness, it becomes undetectable on opposed-phase images. The reason is that due to signal cancellation on the the opposed image, no signal change or even signal decrease results, while signal increase is visible on the in-phase image. In those areas of the body where significant partial volume of a tumor with fat may occur (such as for breast tumors growing along ducts, which are surrounded by fat), severe errors can result. Therefore we explicitly warn from using opposed-image sequences for MR contrast studies. 14 ref.s, 4 figs.
- OSTI ID:
- 437572
- Journal Information:
- Journal of Computer Assisted Tomography, Vol. 20, Issue 2; Other Information: PBD: Mar-Apr 1996
- Country of Publication:
- United States
- Language:
- English
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