Gd-BOPTA for assessment of myocardial viability on MRI: changes of T1 value and their impact on delayed enhancement
Gadobenate (Gd-BOPTA), injected at a dose of 0.1 mmol/kg body weight, was compared with gadopentetate (Gd-DTPA), injected at a dose of 0.2 mmol/kg body weight, for delineation of myocardial infarction interindividually in two groups of 26 patients each. Delayed enhancement images were assessed subjectively for image quality, and measured for regional T1 values before, 3 min after and 25 min after the injection of each contrast agent. In the 26 patients who received Gd-BOPTA, T1 values of remote myocardium were 1,070 ± 125 ms, 358 ± 78 ms and 562 ± 108 ms before, 3 min after and 25 min after injection, respectively. Infarcted myocardium values were 1,097 ± 148 ms, 246 ± 68 ms and 373 ± 84 ms and left ventricular blood pool 1,238 ± 95 ms, 194 ± 47 ms and 373 ± 72 ms. In the 26 patients who received Gd-DTPA, T1 values were 1,087 ± 96 ms, 325 ± 60 ms and 555 ± 108 ms for remote myocardium; 1,134 ± 109, 210 ± 43 ms and 304 ± 57 ms for infarcted myocardium; and 1,258 ± 104 ms, 166 ± 27 ms and 351 ± 73 ms for left ventricular blood pool. Delayed enhancement image quality showing myocardial infarction was rated good (54%) and excellent (46%) after Gd-BOPTA, and good (58%) and excellent (42%) after Gd-DTPA (no significant differences). A single dose of Gd-BOPTA compared with a double dose of Gd-DTPA causes similar changes of T1 values in infarcted and remote myocardium and provides fairly similar contrast between infarcted and remote myocardium (0.64 ± 14 versus 0.71 ± 11) and slightly higher contrast between left ventricular blood and infarcted myocardium (0.22 ± 17 versus 0.14 ± 6; p < 0.05). Administration of 0.1 mmol/kg body weight Gd-BOPTA can provide similar late enhancement images compared with the standard 0.2 mmol/kg body weight dose of Gd-DTPA due to the higher T1 relaxivity associated with the former.