BOLD MRI is well implanted in clinical practice and remains the reference technique for activation mapping in surgical planning for primitive brain tumor. Our goal was to perform qualitative and quantitative evaluation of fASL and BOLD in Primitive Motor Area (PMA) detection in this clinical context.

BOLD and pseudo-continuous ASL with Post Labeling Delay of 1500ms (pCASL1500) and 1000ms (pCASL1000) acquisitions were performed on 21 subjects (4 healthy volunteers and 17 patients scheduled to neurosurgery), at 3T, using a block-design motor paradigm. Motor maps (Fig. 1) were produced using General Linear Model with a massively univariate analysis and a 5% Family Wise Error Rate. Visual detection rate was defined by the rate of subjects, whose motor maps visually matched the PMA defined by anatomical landmarks. PMA detection sensitivity and specificity were computed using manual segmentation of PMA as a reference Region Of Interest (ROI) and inside an analysis ROI (Fig. 2) to overcome inter-patient variability in other motor area activation. Activation volumes obtained from BOLD and fASL were also compared.

Visual detection rates were 47,6% for pCASL1500, 85,7% for pCASL1000 and 95,2% for BOLD. Detection sensitivity of PMA was significantly higher in BOLD (80,6±26%) compared to pCASL1500 (19±32%, P<0,001) and pCASL1000 (50,5±36%, P=0,013). Detection specificity was significantly higher in pCASL1500 (94±8%, P=0,001) and pCASL1000 (93,2±6%, P=0,01) compared to BOLD (73,1±16%). However, activation volumes were higher in BOLD (11,81±8ml, P<0,0001) compared to pCASL1500 (1,25±2ml) and pCASL1000 (2,74±2ml). Considering a reference ROI volume of 1,14±0,5ml, the PMA's volume estimation error would be higher in BOLD (P<0,001).

fASL is able to detect PMA in pre-neurosurgical context. Despite a lower PMA detection sensitivity than BOLD, fASL offered a higher specificity. pCASL1500 had a low visual detection rate of PMA while pCASL1000 should be further explored for a potential clinical use.