Brain tumours at 7T MRI compared to 3T—contrast effect after half and full standard contrast agent dose: initial results

Objectives To compare the contrast agent effect of a full dose and half the dose of gadobenate dimeglumine in brain tumours at 7 Tesla (7T) MR versus 3 Tesla (3T). Methods Ten patients with primary brain tumours or metastases were examined. Signal intensities were assessed in the lesion and normal brain. Tumour-to-brain contrast and lesion enhancement were calculated. Additionally, two independent readers subjectively graded the image quality and artefacts. Results The enhanced mean tumour-to-brain contrast and lesion enhancement were significantly higher at 7T than at 3T for both half the dose (91.8 ± 45.8 vs. 43.9 ± 25.3 [ p = 0.010], 128.1 ± 53.7 vs. 75.5 ± 32.4 [ p = 0.004]) and the full dose (129.2 ± 50.9 vs. 66.6 ± 33.1 [ p = 0.002], 165.4 ± 54.2 vs. 102.6 ± 45.4 [ p = 0.004]). Differences between dosages at each field strength were also significant. Lesion enhancement was higher with half the dose at 7T than with the full dose at 3T ( p = .037), while the tumour-to-brain contrast was not significantly different. Subjectively, contrast enhancement, visibility, and lesion delineation were better at 7T and with the full dose. All parameters were rated as good, at the least. Conclusion Half the routine contrast agent dose at 7T provided higher lesion enhancement than the full dose at 3T which indicates the possibility of dose reduction at 7T. Key Points • The contrast effect of gadobenate dimeglumine was assessed at 7T and 3T. • In brain tumours, contrast effect was higher at 7T than at 3T. • Tumour-to-brain contrast at 7T half dose and 3T full dose were comparable. • 7T half dose lesion enhancement was higher than 3T full dose enhancement. • Our results indicate the possibility of contrast agent dose reduction at 7T.