A Comparative Study of Selection of Different Reference Areas in SPECT Image of OCD Compulsive Disorder Using SPM Analyses

Objective To study the distribution variations of regional cerebral blood flow (rCBF) in obsessive compulsive disorder (OCD) patients by alternation of designating the cerebellum and the global brain as normalizing reference. Methods The rCBF measurements using 99m Tc-ethyl cysteinate dimer (ECD) SPECT were performed on 13 OCD patients and 23 age-matched healthy volunteers. The rCBF distribution (including increased and decreased) was compared between these group samples using SPM and MRIcro software after normalization by designating the cerebellum and the glo bal brain as reference separately. ResultsThere were seven clusters in the OCD patients brain showing difference in the rCBF from the volunteers when the cerebellum was designated as normalizing reference. While the global brain was chosen as reference, OCD showed 24 clusters of regional distribution variations, including all the clusters found using the solution one normalization. Further more, SPM showed the rCBF of the cerebellum itself was different from the normal group. Conclusion For distribution variations of the rCBF in the cerebellum, designating the cerebrum as normalizing reference will not only overlook the change of the rCBF itself but also mask those brain regions in relation with the cerebellum.