Author/Editor		Hittmair, Karl; Gomišček, Gregor; Langenberger, Karl; Recht, Michael; Imhof, Herwig; Kramer, Josef
Title		Method for the quantitative assessment of contrast agent uptake in dynamic contrast-enhanced MRI
Type		članek
Source		Magn Reson Med
Vol. and No.		Letnik 31, št. 5
Publication year		1994
Volume		str. 567-71
Language		eng
Abstract		In previous papers relative signal intensity increase was used as a quantitative assessment parameter for contrast uptake in contrast-enhanced MRI. However, relative signal intensity increase does not only reflect contrast uptake but depends also on tissue parameters (native T1 relaxation time) and sequence parameters (repetition time and flip angle); thus, the contrast uptake cannot be assessed accurately using relative signal intensity increase. Based on an analysis of the contrast behavior of spoiled gradient echo sequences, a method is described in this paper that overcomes the limitations of relative signal intensity increase measurement. A parameter, called enhancement factor" (EF) is introduced that approximates differential T1 relaxation rate. The enhancement factor scales linearly with contrast uptake and is independent of tissue and sequence parameters. The additional measurement time involved in determining the enhancement factor is less than 1 min and computation is straightforward. The practicality of the new method was confirmed by phantom measurements using T1-weighted and proton density-weighted spoiled gradient echo sequences (FLASH-2D). Enhancing tissues were simulated by water phantoms doped with increasing concentrations of Gd-DTPA.
Descriptors		CONTRAST MEDIA IMAGE ENHANCEMENT MAGNETIC RESONANCE IMAGING ALGORITHMS CALIBRATION DEUTERIUM DTPA GADOLINIUM MODELS, BIOLOGICAL MODELS, STRUCTURAL MODELS, THEORETICAL ORGANOMETALLIC COMPOUNDS PROTONS