206 S
Subsequently, the spatial transformer obtained for the TACs corresponded to the mean radioactivity concen-
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summed PET image normalization was applied to each tration on the defined VOI corrected for
C decay. For frame of the kinetic PET study. Since MRI was not
each VOI, the BZR density B and the four rate constants
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available for one of the control subjects, a FMZ template were obtained by fitting the kinetic model to the ex-
was obtained by averaging the normalized PET images of perimental TACs.
the four other control subjects. This template was then used to normalize the summed and kinetic PET images in
the Talairach and Tournoux coordinate system. Using the image analysis program Mediman [10], ROIs
3. Results
were delineated by taking in consideration the activity on the normalized static PET image and anatomical landmarks
The fitting of the compartmental model to the ex- on the MRI. ROIs were named following the Talairach and
perimental TACs allowed the estimation of the five Tournoux nomenclature [56]. For all subjects, volumes of
compartmental parameters for all the brain regions consid- interest VOIs were subsequently obtained from several
ered in all subjects. For B and K , the standard
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ROIs drawn on consecutive planes all over the cerebral variations obtained from the covariance matrix for all
cortex and on the cerebellum. Special attention was made subjects were mostly below 12 and 25, respectively.
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on the ROIs in the occipital region where the primary and The overall distribution of [ C]FMZ in the brain of EB
associative visual cortices were considered separately. subjects appeared qualitatively similar to that of SC
Since the spatial resolution of PET and MRI images does subjects. For all subjects, the highest B
value was
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not allow to distinguish the exact border between the observed in region BA 17-18, and the lowest values were
striate cortex and the visual areas surrounding it, the found in the cerebellum. Fig. 2 shows the mean B
in
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primary visual cortex included BA-17 and part of BA-18. visual areas, parietal, temporal, frontal cortices and cere-
In addition to the occipital regions in the cerebral cortex, bellum for the EB and SC groups.
VOIs were obtained in the parietal, temporal and frontal An ANOVA showed no significant main effect for the
regions. The template of VOIs was subsequently projected type of subject factor, F1,853.2, P.0.05; no significant
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on each normalized kinetic study and the [ C]FMZ time main effect for the side factor, F1,851.1, P.0.05; but a
activity curves TACs were obtained by using Mediman. significant main effect for VOI factor, F6,48577, P,
Fig. 2. B mean values in visual areas BA 17-18 and BA 19, parietal, temporal, frontal cortices and cerebellum of EB s and SC h subjects. Brain
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distribution of BZR in cortical areas is qualitatively and quantitatively similar for all subjects. However, B estimates in the cerebellum is significantly
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´ lower P ,0.05, Scheffe criterion for EB subjects. Error bars correspond to the standard deviation of the group mean values. Units are in pmol ml.
S .M. Sanabria-Bohorquez et al. Brain Research 888 2001 203 –211
207
0.05. Similarly, the interaction between type of subject and was significantly higher than the K value in all cerebral
d
VOI was significant, F6,4853.6, P,0.05. B estimates
cortex VOIs P,0.05.
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for all the regions considered in the cerebral cortex were similar in both groups of subjects P.0.05 as shown by
´ post-hoc comparisons using a Scheffe criterion. However,
4. Discussion
