Effect of imaging time in the magnetic resonance detection of intracerebral metastases using single dose gadobutrol

Objective: To compare the effect of imaging time delay on the MR detection of intracerebral metastases using single dose gadobutrol.

Materials and methods: Twenty-one patients with intracerebral metastases underwent contrast-enhanced MR with three-dimensional T1-weighted sequence at 1 minute, 5 minutes and 10 minutes after a single dose injection of gadobutrol. One hundred index metastatic lesions (1 to 30 mm; median, 7 mm) were chosen for the analysis. For the qualitative analysis, lesion conspicuity were assessed on a 1 (worst) to 5 (best) scale of the index lesions by an expert reader. For the quantitative analysis, signal intensity (SI) of enhancing lesions and normal parenchyma was measured to determine the contrast rate (CR, %) ([postcontrast SI lesion - postcontrast SI white matter] × 100 / postcontrast SI white matter) and the enhancement rate (ER, %) ([postcontrast SI lesion - baseline SI gray matter] × 100 / baseline SI gray matter). Statistical comparisons were made between three different time delays.

Results: Lesion conspicuity did not differ significantly among the three time delays (p = 0.097). Although the SI, CR and ER of lesions did not reveal any significant difference between 1 minute and 5 minutes delayed images, both the 1 minute and 5 minutes delayed images showed significantly higher CRs of lesions compared with the 10 minutes delayed images (p = 0.004 and p = 0.001, respectively).

Conclusion: With single dose gadobutrol, imaging time delay did not have an effect on lesion conspicuity. Both 1-minute and 5-minute-delayed imaging after gadobutrol injection appears to be effective for the detection of intracerebral metastases.