Assessment of Arterial Spin Labeling for functional localization of active and passive motor tasks.

Purpose/Introduction: Functional magnetic resonance imaging (fMRI) us- ing Arterial Spin Labeling (ASL) is emerging as a useful technique for spatial mapping of brain activity. It allows to localize and also estimate cerebral blood flow (CBF) changes induced by different tasks[1]. The purpose of this study was to assess the applicability of ASL to detect brain activations during active and passive movements compared to the gold standard, i.e. fMRI based on the blood-oxygenation-level-dependent (BOLD) contrast[2]. Subjects and Methods: Eight healthy volunteers were studied on a Siemens Allegra 3T. A pulsed Q2TIPS-PICORE sequence was used for the ASL ac- quisition in a block design with eight cycles of rest/task of 30s each (TR/TE/ TI2=3000/16/1400ms).The BOLD fMRI protocol consisted of six 30s cycles of task alternated to rest (TR/TE=3000/30ms). During active movement, they flexed and released their right hand, while passive movement was applied by one investigator by repeating the same task. The fMRI data were analyzed with a General Linear Model approach, using a design matrix with 2 covariates for BOLD, while 4 covariates were assumed to model ASL data[3]. Since the low signal-to-noise-ratio (SNR) of the ASL technique[1], two different thresholds for ASL and BOLD data were chosen for the statistical significance. Results: In the group analysis, for active-movement task, ASL showed activa- tions in the contralateral sensorimotor cortex (SMI), supplementary motor area (SMA), ipsilateral cerebellum, inferior parietal lobe and thalamus (p < 0.01 uncorrected). BOLD also showed the same network of areas, but with more consistent activations (p < 0.005 Bonferroni)(Fig.1).