Contrast Bolus Interference in a Multimodal CT Stroke Protocol.

Area of Science:

• Neuroradiology
• Medical Imaging
• Stroke Imaging

Background:

• Multimodal CT stroke protocols vary in the sequence of CT Perfusion (CTP) and CT Angiography (CTA).
• Performing CTA before CTP may introduce artifacts like venous filling or alter CTP metrics.
• Potential interferences of the CTA contrast bolus with CTP measurements require investigation.

Purpose of the Study:

• To compare CTP metrics when performed before versus after CTA in a large stroke patient cohort.
• To analyze interferences of the CTA contrast bolus with CTP measurements.
• To evaluate the impact of CTA sequence on stroke imaging analysis.

Main Methods:

• Retrospective analysis of 1980 stroke patients (368 CTP-before-CTA, 1612 CTP-after-CTA).
• Calculation of CTP parameters including baseline HU, CBF, CBV, Tmax, hypoperfusion, and core volumes using VEOcore software.
• Analysis of CTA and CTP interferences and proposal of a detection and correction method.

Main Results:

• Mean CTP baseline HU differed significantly between groups (41 vs 45 HU).
• Perfusion metrics, hypoperfusion, and core volumes showed no significant differences between groups.
• CTA bolus interference caused erroneously low CBV in 49 patients, which was corrected by the proposed method.

Conclusions:

• CTP can be reliably performed after CTA without significant impact on perfusion metrics.
• A 30-second pause or a correction method is recommended when performing CTP after CTA.
• Accurate CTP measurements avoid overestimation of infarct core, potentially preventing exclusion from mechanical thrombectomy.