Table 1.
Properties of the two gadolinium contrast agents used in this study.
| Gd-DTPA | Gd-DO3A-butrol | |
|---|---|---|
| Chemical properties | ||
| Molecular structure | Linear, ionic | Macrocyclic, non-ionic |
| Concentration (mol/L) | 0.5 | 1.0 |
| Thermodynamic stability constant (log Keq) | 22.1 | 21.8 |
| Conditional stability constant at pH 7.4 | 18.1 | 14.7 |
| Osmolality (Osm/kg) | 1.96 | 1.6 |
| Viscosity (mPa·s at 37°C) | 2.9 | 5.0 |
| T1 relaxivity (L/mmol·s−1) 1.5 T, plasma | 4.1 | 5.2 |
| T1 relaxivity (L/mmol·s−1) 3 T, plasma | 3.7 | 5.0 |
| Metal chelate (mg/ml) | 469 | 605 |
| Excess chelate (mg/ml) | 0.4 | 0.5 |
| Signal intensity in the cochlea after intratympanic Gd delivery | ||
| Apical turn, SV (after 1 and 4 h) | 1.71 and 2.22 | 0.98 and 1.74 |
| Middle turn, SV (after 1 and 4 h) | 2.60 and 2.21 | 2.02 and 1.95 |
| Basal turn, SV (after 1 and 4 h) | 2.02 and 2.18 | 2.54 and 2.38 |
Gd, gadolinium; SV, scala vestibule.