How much are clinical fMRI reports influenced by standard postprocessing methods? An investigation of normalization and region of interest effects in the medial temporal lobe.
Recent evidence has indicated that standard postprocessing methods such as template-based region of interest (ROI) definition and normalization of individual brains to a standard template may influence final outcome of functional magnetic resonance imaging investigations. Here, we provide the first comprehensive investigation into whether ROI definition and normalization may also change the clinical interpretation of patient data. A series of medial temporal lobe epilepsy patients were investigated with a clinical memory paradigm and individually delineated as well as template-based ROIs. Different metrics for activation quantification were applied. Results show that the application of template-based ROIs can significantly change the clinical interpretation of individual patient data. This relates to sensitivity for brain activation and hemispheric dominance. We conclude that individual ROIs should be defined on nontransformed functional data and that use of more than one metric for activation quantification is beneficial.
Beisteiner
Roland
R
Study Group Clinical fMRI, Department of Neurology, Medical University of Vienna, Vienna, Austria. roland.beisteiner@meduniwien.ac.at
Klinger
Nicolaus
N
Höllinger
Ilse
I
Rath
Jakob
J
Gruber
Susanne
S
Steinkellner
Thomas
T
Foki
Thomas
T
Geissler
Alexander
A
D000293:Adolescent; D000328:Adult; D000368:Aged; D001931:Brain Mapping / Q000379:methods; D004833:Epilepsy, Temporal Lobe / Q000378:metabolism / Q000503:physiopathology*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D013702:Temporal Lobe / Q000033:anatomy & histology / Q000378:metabolism / Q000503:physiopathology*; D055815:Young Adult