A Relative Noncontrast CT Map to Detect Early Ischemic Changes in Acute Stroke

Area of Science:

• Neurology
• Radiology
• Medical Imaging

Background:

• Early ischemic changes on noncontrast computed tomography (NCCT) are often subtle and difficult to detect.
• Accurate and timely detection of ischemic changes is crucial for effective stroke management.

Purpose of the Study:

• To develop and evaluate a novel postprocessing technique, ratio maps of the NCCT (rNCCT), for improved detection of early ischemic changes.
• To assess the efficacy of rNCCT in quantifying infarct volume compared to standard NCCT and CT perfusion (CTP).

Main Methods:

• Generated rNCCT maps by comparing voxel density differences between contralateral hemispheres.
• Defined infarct voxels with a relative density difference below 0.95.
• Pilot tested rNCCT on six stroke patients, comparing segmentation with baseline NCCT, CTP, and day-5 FLAIR imaging.

Main Results:

• rNCCT identified early ischemic changes in all five eligible cases, while standard NCCT detected them in only three.
• rNCCT infarct segmentation showed a trend towards better estimation of day-5 FLAIR volume compared to baseline CTP core volumes.
• The median difference between rNCCT and day-5 FLAIR volume was 6.2 mL, versus 51.7 mL for CTP.

Conclusions:

• The rNCCT technique shows promise as a tool for detecting and quantifying early ischemic changes in acute stroke.
• Further validation in a larger patient cohort is warranted to confirm these preliminary findings.