Phantom Validation of DCE-MRI Magnitude and Phase-Based Vascular Input Function Measurements

Area of Science:

• Medical Imaging
• Biophysics
• Radiology

Background:

• Accurate patient-specific arterial input functions (AIF) are crucial for model-based analysis of vascular permeability.
• Magnetic resonance imaging (MRI) offers potential for AIF measurement, but its accuracy is affected by various factors.

Purpose of the Study:

• To investigate factors influencing AIF measurements from MRI magnitude (AIF_MAGN) and phase (AIF_PHA) signals.
• To compare MRI-derived AIFs against computed tomography (CT) AIFs (AIF_CT) under controlled conditions.

Main Methods:

• A multimodality flow phantom was used with varying flip angles, flow rates, and contrast agent concentrations.
• MRI 3D-FLASH signals and variable flip angle T1 profiles were measured to assess in-flow and radiofrequency biases.
• Gd-DTPA concentrations derived from MRI magnitude and phase signals were compared to AIF_CT using Pearson correlation.

Main Results:

• AIF_MAGN was sensitive to imaging orientation, spatial location, flip angle, and flow rate, significantly underestimating AIF_CT peak concentrations.
• Converting AIF_MAGN to Gd-DTPA concentration using orientation- and flow-matched T1 improved accuracy but remained variable above 2.5 mM.
• AIF_PHA performed equivalently to AIF_CT within 1 mM across all tested conditions, demonstrating superior robustness.

Conclusions:

• MRI phase-derived arterial input functions (AIF_PHA) provide a more robust and accurate measurement compared to magnitude-derived AIFs (AIF_MAGN).
• AIF_PHA demonstrates reliable performance equivalent to AIF_CT across a wide range of physiological conditions.
• AIF_PHA shows significant promise for accurate patient-specific AIF quantification in clinical settings.