Theoretical analysis of gadopentetate dimeglumine enhancement in T1-weighted imaging of the brain: comparison of two-dimensional spin-echo and three-dimensional gradient-echo sequences.
By using a theoretical model, the signal difference-to-noise ratios between simulated lesions and normal white matter and gray matter were calculated as a function of lesion concentration of gadopentetate dimeglumine (GD) for two-dimensional (2D) T1-weighted spin-echo (SE), three-dimensional (3D) steady-state spoiled gradient-echo (GRE) (FLASH [fast low-angle shot]), and 3D magnetization-prepared rapid gradient echo (MP-RAGE) pulse sequences. The 3D GRE sequences provided greater contrast enhancement at relatively high [GD], and the 2D SE sequence demonstrated greater enhancement and a higher rate of enhancement at low [GD]. The results predict that at low [GD], certain lesions could probably be detected with the 2D SE sequence but possibly not with one or both of the 3D GRE sequences. At high [GD], certain lesions could probably be detected with one or both of the 3D GRE sequences but possibly not with the 2D SE sequence. This provides a potential explanation for the clinical observation that certain contrast agent-enhanced lesions appear less conspicuous on 3D GRE images than on 2D SE images and vice versa. Modified parameter values were derived for the 3D FLASH and 3D MP-RAGE sequences that are predicted to produce contrast enhancement behavior equivalent or superior to that of a conventional 2D SE sequence.
Department of Radiology, University of Virginia Health Sciences Center, Charlottesville 22908.
J P
JP
Mugler
J R
JR
Brookeman
D001921:Brain / Q000473:pathology*; D003287:Contrast Media; D004338:Drug Combinations; D005682:Gadolinium; D019786:Gadolinium DTPA; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008536:Meglumine; D008962:Models, Theoretical; D009942:Organometallic Compounds; D004369:Pentetic Acid / Q000031:analogs & derivatives*
D003287:Contrast Media; D004338:Drug Combinations; D009942:Organometallic Compounds; D008536:Meglumine; D004369:Pentetic Acid; D005682:Gadolinium; D019786:Gadolinium DTPA