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AJNR - American Journal of Neuroradiology

Published ahead of print on January 9, 2008
doi: 10.3174/ajnr.A0905

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A Serial Dilution Study of Gadolinium-Based MR Imaging Contrast Agents

A.G. Bleicher^a and E. Kanal^a

^a From the Department of Radiology, Division of Neuroradiology, the University of Pittsburgh Medical Center, Pittsburgh, Pa

View larger version (30K): [in this window] [in a new window]   Fig 1. Sample image demonstrates the phantom at 3T, by using spin-echo technique (TR = 100, TE = 14).

View larger version (19K): [in this window] [in a new window]   Fig 2. Measured signal intensity (SI) as a function of the dilution factor for TR = 100 and TE = 14 msec. At 1.5T (A) and at 3T (B), there are low signal intensities measured at low dilution factors/high concentrations, reflecting R2 relaxivity and T2(*) effects of contrast. At higher dilution factors/lower concentrations, T1 shortening effects predominate. Physiologic concentrations for T1WI range between the 2 dashed lines, 1:000–1:4000. Concentrations for PWI range below the dotted line, 1:200.

View larger version (14K): [in this window] [in a new window]   Fig 3. Measured signal intensity (SIs) as a function of TR for TE = 14 ms and a dilution factor of 1:2048. At 1.5T (A) and at 3T (B), there is an increase in signal intensity with progressively longer TRs until full longitudinal magnetization recovery of the solution is reached, at approximately 2000 ms, for all agents.

View larger version (13K): [in this window] [in a new window]   Fig 4. Measured signal intensities (SIs) as a function of TE for TR = 8000 ms and a dilution factor of 1:2048. At 1.5T (A) and 3T (B), measured signal intensities are closely plotted at shorter TE values. With longer TE and greater T2-weighting, T2(*) effects of contrast predominate, and there is a decrease in measured signal intensity. The greatest signal intensity loss per TE is demonstrated for gadobenate.

View larger version (9K): [in this window] [in a new window]   Fig 5. Measured signal intensities (SI) at 1.5 and 3T for TR = 250 ms, TE = 14 ms; 1:2048 dilution factor demonstrates globally increased SIs at a higher field strength.