SU-G-IeP1-03: Comparing Arterial Input Function Measurements in DCE-MRI Using MOLLI and Phase

Authors


Abstract

Purpose:

To compare two different methods for measuring the arterial input function (AIF) in dynamic contrast-enhanced (DCE)-MRI.

Methods:

Five DCE-MRI experiments were performed on an aqueous DCE-MRI phantom (Shelley Medical) in a Siemens 3T Trio MRI scanner with 32 channel head coil and clinical DCE-MRI protocol. MRI signal phase (φ) data were saved for offline processing. T1 relaxation measurements, using a Modified Look- Locker Inversion Recovery (MOLLI) pulse sequence, were performed preand post-DCE. The input flow rate was set to 200 mL/min to mimic blood flow in the human body. The AIF of Gd injection was determined with two different methods. 1. “Phase-only”: Pre-injection baseline phase (φ0) was subtracted from phase-vs-time [φ(t)]. This quantity, φ(t) – φ0, was then used to compute the AIF. 2. “Phase+MOLLI”: The AIF value during the post-injection steady-state washout, denoted AIF(w), was calculated from MOLLI T1s and known relaxivity. Phase during washout was denoted φ(w). The quantity φ(t) – φ(w) was used to compute AIF – AIF(w). The final Phase+MOLLI AIF was then calculated by adding the MOLLI AIF(w). A “gold-standard” AIF(w) was also obtained by sampling liquid in the input tube port of the phantom post-DCE, then later measuring T1 with standard inversion recovery (IR). AIF(w) values from Phase-only, MOLLI, and IR were compared using a two-tailed paired t-test.

Results:

AIF(w) from Phase-only and MOLLI were significantly different (p = 0.04). AIF(w) from MOLLI and IR were the same (p = 0.89). The Phase-only curve therefore incorrectly estimated AIF(w).

Conclusion:

There is currently no standard method for determining the AIF in DCE-MRI. This work has shown that a Phase-only AIF returns incorrect values for the washout portion of the curve. The Phase+MOLLI method could provide a more accurate and reproducible AIF in clinical DCE-MRI, which could lead to better diagnoses.

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