QUANTITATIVE PERFUSION CHANGES IN FUNCTIONAL ARTERIAL SPIN LABELING MR IMAGING DURING LANGUAGE AND MOTOR TASKS

Purpose: This study compares functional arterial spin labeling (fASL) to the standard of blood oxygen level dependent (BOLD) imaging in classic language and motor tasks and provides normative data regarding quantitative cerebral blood flow (CBF) changes within the motor cortex and Broca’s area.

Materials and Methods: The study was approved by the hospital IRB and all participants provided informed consent. Thirty healthy adult volunteers performed word generation and finger tapping tasks with a simple two-condition block design. For each functional task, traditional BOLD images were acquired followed by a pseudo-continuous arterial spin labeling acquisition. The BOLD activation maps were used to generate masks over the hand motor cortex and Broca’s area for the finger tapping and word generation tasks, respectively. The masks were then mapped into the ASL scan space and quantitative changes in CBF calculated within the masked regions of interest.

Results: During the finger-tapping task, the increase in CBF in the hand motor cortex ranged from 8.27% to 90.12% with a mean of 44.37% (+/- 16.13 SD). During the word generation task, the increase in CBF in Broca’s area ranged from 7.08% to 41.26% with a mean of 23.09% (+/- 8.14% SD).

Conclusion: Perfusion-based functional imaging using ASL provides robust and consistent quantitative perfusion information when used for functional activation mapping in motor and language paradigms when compared to BOLD MRI. This technique may allow for the application of functional MRI across differing populations to a greater degree than achievable with BOLD imaging.