TY - JOUR
T1 - BOLD signal and vessel dynamics
T2 - a hierarchical cluster analysis
AU - Garreffa, Girolamo
AU - Ken, Soléakhéna
AU - Macrì, Maria Antonietta
AU - Giulietti, Giovanni
AU - Giove, Federico
AU - Colonnese, Claudio
AU - Venditti, Eugenio
AU - De Cesare, Emilio
AU - Galasso, Vittorio
AU - Maraviglia, Bruno
PY - 2006/5
Y1 - 2006/5
N2 - The aim of the present study was to analyze blood oxygenation level-dependent (BOLD) signal variation during an apnea-based task in order to assess the capability of a functional magnetic resonance imaging (fMRI) procedure to estimate cerebral vascular dynamic effects. We measured BOLD contrast by hierarchical cluster analysis in healthy subjects undergoing an fMRI experiment, in which the task paradigm was one phase of inspirational apnea (IA). By processing the time courses of the fMRI experiment, analysis was performed only on a subclass of all the possible signal patterns; basically, root mean square and absolute variation differences have been calculated. Considering the baseline value obtained by computing the mean value of the initial rest period as reference, particular voxels showed relative important variations during the IA task and during the recovery phase following the IA. We focused our interest on the signal response of voxels that would correspond mainly to white and gray matter regions and that also may be affected by the proximity of large venous vessels. The results are presented as maps of space-temporal distribution of time series variations with two levels of hierarchical clustering among voxels with low to high initial response. Furthermore, we have presented a clustering of the signal response delay, conducting to a partition and identification of specified brain sites.
AB - The aim of the present study was to analyze blood oxygenation level-dependent (BOLD) signal variation during an apnea-based task in order to assess the capability of a functional magnetic resonance imaging (fMRI) procedure to estimate cerebral vascular dynamic effects. We measured BOLD contrast by hierarchical cluster analysis in healthy subjects undergoing an fMRI experiment, in which the task paradigm was one phase of inspirational apnea (IA). By processing the time courses of the fMRI experiment, analysis was performed only on a subclass of all the possible signal patterns; basically, root mean square and absolute variation differences have been calculated. Considering the baseline value obtained by computing the mean value of the initial rest period as reference, particular voxels showed relative important variations during the IA task and during the recovery phase following the IA. We focused our interest on the signal response of voxels that would correspond mainly to white and gray matter regions and that also may be affected by the proximity of large venous vessels. The results are presented as maps of space-temporal distribution of time series variations with two levels of hierarchical clustering among voxels with low to high initial response. Furthermore, we have presented a clustering of the signal response delay, conducting to a partition and identification of specified brain sites.
KW - Apnea
KW - BOLD contrast
KW - Cluster analysis
KW - fMRI
KW - Venous blood flow
UR - http://www.scopus.com/inward/record.url?scp=33748140318&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=33748140318&partnerID=8YFLogxK
U2 - 10.1016/j.mri.2005.11.004
DO - 10.1016/j.mri.2005.11.004
M3 - Article
C2 - 16677947
AN - SCOPUS:33748140318
VL - 24
SP - 411
EP - 418
JO - Magnetic Resonance Imaging
JF - Magnetic Resonance Imaging
SN - 0730-725X
IS - 4
ER -