Purpose: To compare a low-dose dynamic contrast-enhanced breast MRI protocol (LITE) to standard-dosage using a dual-dose injection technique.
Methods: Eight women with a total of ten lesions with imaging features most compatible with fibroadenoma were imaged. Each patient underwent a DCE-MRI scan using a dual-dose technique on a 3T scanner. After pre-contrast scans, 15% of a standard dose of a contrast media (gadobenate dimeglumine) was administered (0.015mM/kg); approximately 10 minutes after the first dose the remaining 85% of the standard dose was administered (0.085mM/kg), followed by the same post-contrast imaging protocol, including interleaved ultrafast (3.2s-3.6s temporal resolution) and high-spatial-resolution sequences. Mean signal enhancement from each lesion was fit to an empirical model. Enhancement kinetic parameters, conspicuity and signal-to-noise ratio were measured quantitatively for all lesions.
Results: One lesion showed no enhancement in either DCE series. In all of the nine enhancing lesions there was concordance between the LITE and standard-dose images in terms of lesion visualization. While the (low-to-standard) ratio of contrast doses was roughly 0.18, this did not match the ratios of kinetic parameters. The signal enhancement rate was higher in the LITE images, 3.7%/s Â± 2.5%/s, compared to 2.8%/s Â± 1.5%/s, a (low-to-standard) ratio of 1.3 Â± 0.4. Lesion conspicuity was also higher in LITE, with a ratio of 1.5 Â± 0.1. The upper limit of enhancement and SNR were higher in the standard-dose images, with ratios 0.3 Â±0.1 and 0.5 Â± 0.1, respectively. However these values were not as high as would be expected based on the ratio of the doses.
Conclusion: This preliminary study suggests that LITE MRI has the potential to match standard DCE-MRI in the detection of enhancing lesions. Additionally, LITE may enhance sensitivity to contrast media dynamics. Growing concern related to gadolinium deposition may be addressed with low-dose contrast administration, increasing screening compliance.