Assessment of tumor blood flow in breast tumors with T1-dynamic contrast-enhanced MR imaging: impact of dose reduction and the use of a prebolus technique on diagnostic efficacy.

PURPOSE

To prospectively evaluate whether dose reduction and the application of a prebolus technique can effectively alleviate signal saturation effects in T1 dynamic contrast enhanced (T1-DCE) magnetic resonance imaging (MRI) data in breast tumors and lead to increased diagnostic efficacy of the regional tumor blood flow (TBF) values obtained with deconvolution of T1-DCE MRI data.

MATERIALS AND METHODS

After obtaining informed consent, 23 women (32-80 years) with histologically proven breast tumors underwent MR mammography that included a whole-breast T1 DCE sequence. In the slice where the tumor enhanced maximally, a prebolus protocol was applied. One mL of Gd-DTPA solution at 2 mL/s was injected at the beginning of a dynamic axial single slice inversion-prepared turbo field echo acquisition. At the 400th dynamic, a high dose of either 20 mL (15 patients) or 10 mL (8 patients) of contrast agent was injected at 2 mL/s and a further 400 dynamics were acquired. From the aortic prebolus curve an arterial input function (AIF) was reconstructed by time-shifting and adding the prebolus data. The relative enhancement time course from the tumor region of interest was deconvolved with the reconstructed AIF to generate the impulse response function, the maximum of which yielded the TBF. The institutional ethical committee approved the study.

RESULTS

Reducing the contrast dose by a factor of 2 led to an increase in diagnostic contrast for the TBF values of malignant and benign tumors by a factor of slightly more than 2. Addition of the prebolus technique improved this further by 45%. receiver operating characteristic analysis showed a significant increase of diagnostic yield related to the combined use of a prebolus and minimal dose.

CONCLUSION

Using a prebolus approach provides an estimate of the unsaturated AIF, while reduction of the high-dose bolus minimizes possible saturation effects in the tumor time course.