The effect of Gd-DTPA on T1-weighted choline signal in human brain tumours

Gd‐enhanced MR images of substrates other than water

“…The DO3A ligand (DO3A ¼ 1,4,7,10-tetraazaciclododecane-1,4,7-triacetic acid) was kindly provided by Bracco Imaging S.p.A. (Milan, Italy). 13 C-enriched L-lactate was purchased from Isotec Inc.…”

“…Although the ability of Gd(III) chelates to act as relaxation agents for organic and inorganic molecules has been well known since the mid-1970s (10,11) (12)(13)(14). In all these studies the investigated molecules could not interact specifically with the relaxation agent and, indeed, the operating relaxation mechanism was only based on the relative diffusion between the paramagnetic agent and the molecule under investigation.…”

Effect of Gd‐DTPA‐BMA on choline signals of HT29 tumors detected by in vivo 1H MRS

“…Figure 2a-c shows the choline estimated for different echo times (analysis method 1, which uses normalized ratios of the choline and water peak areas before and after administration of Gd-DTPA-BMA), determined prior to and at 10, 22.5, and 35 minutes after 0.1 mmol/kg Gd-DTPA-BMA. A reduction in choline signal after contrast agent administration, which had been noted in some of the earlier studies, [13][14][15] was only seen at the longest echo time, 272 msec (and was not statistically significant); in contrast, at the echo times of 20 msec and 68 msec there was a significant enhancement in the choline signal. Figure 2d-f shows the effect of 0.1 mmol/kg dose of Gd-DTPA-BMA on the water peak area (analysis method 1).…”

“…It is important, therefore, to perform experiments at both doses. In addition, most of the studies mentioned above were performed using relatively long echo times (13)(14)(15), or a single short echo time (16). Therefore, the effect of variation in echo time must also be systematically investigated.…”

“…Creatine (3.03 ppm) and lipid/lactate (1.3 ppm) peaks were also included in the AMARES fitting routine, which enables an overall better time domain fit to the whole spectrum. The data were analyzed using two different approaches: 1) To enable comparison with earlier reports, the choline and water signal amplitudes were expressed as percentages of the signals before administration of contrast agent (13)(14)(15). 2) In the second approach, choline and water peak amplitudes acquired at various echo times were fitted to monoexponential curves whose extrapolation to TE ϭ 0 allowed estimation of their equilibrium magnetization (Mo).…”