Does the location of the arterial input function affect quantitative CTP in patients with vasospasm?

Area of Science:

• Neuroradiology
• Cerebrovascular Imaging
• Medical Physics

Background:

• CT Perfusion (CTP) is increasingly used for evaluating vasospasm in aneurysmal subarachnoid hemorrhage (SAH).
• Accurate CTP data relies on precise arterial input function (AIF) localization.
• Previous studies explored AIF placement effects in acute stroke, but its impact in SAH with vasospasm is less understood.

Purpose of the Study:

• To investigate the impact of AIF location distal to significant vasospasm on quantitative CTP metrics.
• To determine if AIF placement affects cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT) calculations in aneurysmal SAH.

Main Methods:

• Retrospective analysis of 28 aneurysmal SAH patients (2005-2011) with and without vasospasm in anterior cerebral artery (ACA) or MCA.
• CTP datasets were postprocessed four times, varying AIF location in ACA and MCA vessels.
• Quantitative CBF, CBV, and MTT were calculated using region-of-interest sampling for each processed examination.

Main Results:

• Analysis included 112 processed CTP studies.
• No significant differences were observed in quantitative CBF, CBV, and MTT.
• These results held true for AIF locations distal to vasospasm compared to non-vasospasm vessels across all analyzed vascular territories (ACA, MCA, PCA).

Conclusions:

• Arterial input function placement distal to significant vasospasm does not significantly alter quantitative CTP data.
• This finding applies to the affected vascular territory and other territories in aneurysmal SAH patients.
• Standardized AIF selection in CTP may be robust even in the presence of vasospasm.