http://www.nitrc.org/forum/forum.php?forum_id=6466 <table border="0" width="100%"><tr><td align="left"/></tr></table> <p><b>Calibrated bold fMRI with an optimized ASL-BOLD dual-acquisition sequence.</b></p> <p>Neuroimage. 2016 Aug 5;</p> <p>Authors: Fernández-Seara MA, Rodgers ZB, Englund EK, Wehrli FW</p> <p>Abstract<br/> Calibrated fMRI techniques estimate task-induced changes in the cerebral metabolic rate of oxygen (CMRO2) based on simultaneous measurements of cerebral blood flow (CBF) and blood-oxygen-level-dependent (BOLD) signal changes evoked by stimulation. To determine the calibration factor M (corresponding to the maximum possible BOLD signal increase), BOLD signal and CBF are measured in response to a gas breathing challenge (usually CO2 or O2). Here we describe an ASL dual-acquisition sequence that combines a background-suppressed 3D-GRASE readout with 2D multi-slice EPI. The concatenation of these two imaging sequences allowed separate optimization of the acquisition for CBF and BOLD data. The dual-acquisition sequence was validated by comparison to an ASL sequence with a dual-echo EPI readout, using a visual fMRI paradigm. Results showed a 3-fold increase in temporal signal-to-noise ratio (tSNR) of the ASL time-series data while BOLD tSNR was similar to that obtained with the dual-echo sequence. The longer TR of the proposed dual-acquisition sequence, however, resulted in slightly lower T-scores (by 30%) in the BOLD activation maps. Further, the potential of the dual-acquisition sequence for M-mapping on the basis of a hypercapnia gas breathing challenge and for quantification of CMRO2 changes in response to a motor activation task was assessed. In five subjects, an average gray matter M-value of 8.71±1.03 and fractional changes of CMRO2 of 12.5±5% were found. The new sequence remedies the deficiencies of prior combined BOLD-ASL acquisition strategies by substantially enhancing perfusion tSNR, which is essential for accurate BOLD calibration.<br/> </p><p>PMID: 27502047 [PubMed - as supplied by publisher]</p> en-us Copyright 2000-2026 NITRC OSI Tue, 05 May 2026 4:33:06 GMT http://blogs.law.harvard.edu/tech/rss NITRC RSS generator