Increasing sampling interval in cerebral perfusion CT: limitation for the maximum slope model.

Area of Science:

• Radiology and Imaging Science
• Neurology
• Medical Physics

Background:

• Dynamic perfusion computed tomographic (PCT) imaging is crucial for assessing acute stroke.
• Accurate quantification of cerebral blood flow (CBF), cerebral blood volume, and time to peak (TTP) relies on optimal sampling intervals.
• Software utilizing the maximum slope model is commonly employed for PCT data analysis.

Purpose of the Study:

• To evaluate the impact of increased sampling intervals on dynamic PCT imaging.
• To assess the reliability of cerebral perfusion parameters calculated using the maximum slope model with extended sampling intervals.
• To determine if longer sampling intervals are suitable for clinical use in acute stroke evaluation.

Main Methods:

• Perfusion computed tomographic (PCT) data from 32 acute stroke patients were analyzed.
• Simulated sampling intervals of 2, 3, and 4 seconds were created from original 1-second interval data.
• Cerebral blood flow (CBF), cerebral blood volume, and time to peak (TTP) maps were generated using maximum slope model software.
• Key perfusion parameters and ischemic areas were measured and compared across different sampling intervals.

Main Results:

• Increased sampling intervals (>1 second) significantly decreased parenchymal peak enhancement in the nonischemic hemisphere.
• Absolute CBF and TTP values in the nonischemic hemisphere were significantly increased with longer sampling intervals.
• The size of ischemic areas was significantly underestimated for both CBF and TTP with sampling intervals greater than 1 second.

Conclusions:

• Sampling intervals exceeding 1 second significantly alter absolute CBF and TTP values when using the maximum slope model.
• Increased sampling intervals lead to a significant underestimation of ischemic regions on perfusion maps.
• Extending the sampling interval in dynamic PCT imaging is not recommended with the maximum slope model algorithm due to altered perfusion quantification and ischemia assessment.