Utilization of MR angiography in perfusion imaging for identifying arterial input function

Area of Science:

• Neuroimaging
• Medical Physics
• Radiology

Background:

• Accurate arterial input function (AIF) is crucial for quantitative perfusion imaging.
• Shape distortions in concentration time curves (CTCs) can lead to inaccurate cerebral blood flow (CBF) calculations.
• Identifying correct arterial locations is essential for reliable AIF extraction.

Purpose of the Study:

• To utilize magnetic resonance angiography (MRA) for precise arterial localization during parametric evaluation of CTCs.
• To prevent shape distortions in the AIF, thereby improving the accuracy of CBF measurements.
• To refine cluster analysis methods for AIF selection in perfusion imaging.

Main Methods:

• Cluster analysis of CTC parameters within and around the middle cerebral artery (MCA).
• MRA-guided identification of voxels meeting AIF criteria and those with distorted CTCs.
• Rescaling CTCs by the venous output function (VOF) to minimize partial volume effects.
• Using the steady-state value to area under curve ratio (SS:AUC) of VOF as a reference for AIF selection.

Main Results:

• Selected AIFs were located superior, inferior, posterior, or anterior to the MCA.
• Eliminated AIFs were predominantly on or anterior to the MCA.
• Significant under- or over-estimation of CBF (up to 41.1% and 36.6%, respectively) occurred when AIF SS:AUC deviated from the reference value.

Conclusions:

• MRA effectively aids in excluding voxels on the MCA during cluster analysis.
• This method prevents shape distortions in the AIF, enhancing the reliability of perfusion parameters.
• Improved AIF selection using MRA leads to more accurate CBF quantification.