B-0118 Determination of the vascular input function using magnitude or phase-based MRI: influence on dynamic contrast-enhanced MRI model parameters in carotid plaques

 R.H.M. van Hoof, M.T.B. Truijman, E. Hermeling, R.J. van Oostenbrugge, R.J. van der Geest, M.J.A.P. Daemen, J.E. Wildberger, W.H. Backes, M.E. Kooi | Thursday, March 7, 10:30 – 12:00 / Room N/O

Purpose: A reliable vascular input function (VIF) is important for quantitative analysis of atherosclerotic carotid plaque microvasculature using dynamic contrast-enhanced (DCE) MRI. In tumour imaging and brain perfusion studies, it has been demonstrated that a phase-based VIF (ph-VIF) is less sensitive to flow artefacts compared to magnitude-based VIF (m-VIF). The purpose is (1) to compare m-VIF and ph-VIF and (2) to investigate the influence of different VIFs on DCE MRI model parameters in carotid plaques.
Methods and Materials: 21 patients with 30-99% carotid stenosis underwent 3 T DCE MRI. Data from four patients, scanned with a high temporal resolution were used to construct group-averaged m-VIF and ph-VIF of the jugular vein. The other 17 patients were used for calculating K^trans (measure of plaque microvasculature) using m-VIF and ph-VIF. The effect of neglecting flow on the m-VIF was estimated using the Bloch equations.
Results: Peak concentrations of m-VIFs were on average 4-fold lower than for ph-VIFs (p<0.001). Despite these differences, strong and significant correlation between K^trans determined using group averaged m-VIF and ph-VIF was found (Pearson’s correlation 0.91, p<0.001). Taking into account a theoretical flow of 8 cm/sec, the discrepancy in peak concentration of m-VIF and ph-VIF disappeared.
Conclusion: Our data suggest a strong influence of flow when calculating m-VIF of the jugular vein. Despite this, strong correlation between K^transparameters determined using m-VIF and ph-VIF was found. It is expected that a phase-based VIF results in a quantitative more realistic value of K^trans.

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