title: Effects of inversion and saturation times on relationships between contrast agent concentrations and signal intensities of T1-weighted magnetic resonance images.
abstract: The present study was an attempt to investigate the effect of variation of inversion time (T (I)) and saturation time (T (S)) on the linear relationship between contrast agent concentration and signal intensity (SI) on Turbo Fast Low Angle Shot (TurboFLASH) T (1)-weighted images in MRI. For this purpose, inversion recovery (IR) and saturation recovery (SR) sequences (Center out Phase-Encoding acquisition) were used. A phantom was designed to hold 25 vials which contained either different (between 0 and 19.77 mmol/L) or constant (1.20 mmol/L) concentrations of contrast agent. The vials of constant concentration were used for the measurement of coil non-uniformity, which was normalized to give a correction factor. The vials of different concentrations were used to measure the SI by using different sequences and different T (I) and T (S) values. To calculate the corrected SI for different concentrations, we multiplied the SI of each vial by its correction factor. The relationships between the corrected SI and the concentration [were evaluated], where the threshold of (R (2) = 0.95 and 0.99) was maintained. This study shows that different sequences and different T (I) and T (S) values can have an effect on the correlation between the SI and concentration. Regardless of the values of T (I), T (S), and the different IR and SR sequences chosen, the linear relationship between the SI and concentration was about twice that previously reported (i.e., 0.8 mmol/L, R (2) = 0.95).
authors.affiliation: Department of Radiology, Faculty of Paramedicine, Tabriz University of Medical Sciences, Tabriz, Iran. mnazarpoor@yahoo.co.uk
authors.forename: Mahmood
authors.initials: M
authors.lastname: Nazarpoor
mesh_terms: D003287:Contrast Media; D007091:Image Processing, Computer-Assisted; D016014:Linear Models; D008279:Magnetic Resonance Imaging / Q000379:methods*; D013997:Time Factors
chemical_list: D003287:Contrast Media
references.citation: Magn Reson Imaging. 2007 Jun;25(5):641-51
references.pmid: 17540275
references.citation: Invest Radiol. 2000 Jul;35(7):401-11
references.pmid: 10901101
references.citation: Eur J Radiol. 2009 Jun;70(3):465-74
references.pmid: 18359598
references.citation: AJNR Am J Neuroradiol. 1992 Jan-Feb;13(1):39-48
references.pmid: 1595482
references.citation: Invest Radiol. 2005 Nov;40(11):715-24
references.pmid: 16230904
references.citation: J Magn Reson Imaging. 1995 Jul-Aug;5(4):411-5
references.pmid: 7549202
references.citation: Magn Reson Imaging. 1994;12(3):421-7
references.pmid: 8007771
references.citation: J Magn Reson Imaging. 1999 Feb;9(2):197-203
references.pmid: 10077013
references.citation: J Magn Reson Imaging. 1994 May-Jun;4(3):235-42
references.pmid: 8061420
references.citation: Magn Reson Imaging. 2003 Jul;21(6):637-43
references.pmid: 12915195
references.citation: Magn Reson Med. 1994 Jul;32(1):121-8
references.pmid: 8084227
references.citation: J Magn Reson Imaging. 1997 Jan-Feb;7(1):82-90
references.pmid: 9039597
references.citation: Eur J Radiol. 2008 May;66(2):160-7
references.pmid: 18358659
references.citation: Magn Reson Imaging. 1998 Oct;16(8):893-9
references.pmid: 9814771