The need of appropriate brain SPECT templates for SPM comparisons.
OBJECTIVE
Statistical parametric mapping (SPM) is used worldwide to compare brain perfusion single photon emission computed tomography (SPECT) data. The default template within the SPM package used for SPECT image normalization includes images of a group of healthy subjects studied with [(99m)Tc]HMPAO. Since [(99m)Tc]HMPAO and [(99m)Tc]ECD have shown to distribute differently in SPECT studies, we formulated the hypothesis that comparing set of [(99m)Tc]ECD data normalized by means of a [(99m)Tc]HMPAO template may lead to incorrect results.


METHODS
A customized [(99m)Tc]ECD template was built with SPECT and magnetic resonance imaging (MRI) images of 22 neurologically healthy women. Then, two sets of subjects, i.e. a group of patients with very early Alzheimer's disease (eAD) and a matched control group, studied by means of [(99m)Tc]ECD SPECT, were chosen for comparisons. The same statistical approach (t-test between eAD patients and controls and correlation analysis between brain SPECT and a cognitive score) was applied twice, i.e. after normalization with either the default [(99m)Tc]HMPAO template or the customized [(99m)Tc]ECD template.


RESULTS
In the comparison between eAD and controls, a cluster of difference in the posterior cingulate gyrus of both hemispheres was only highlighted when using the customized [(99m)Tc]ECD template, but was missed when using the default [(99m)Tc]HMPAO template. In the correlation between brain perfusion and a cognitive score, the significant cluster was more significant and far more extended, also including the right superior temporal gyrus, using the customized [(99m)Tc]ECD template than using the default [(99m)Tc]HMPAO template.


CONCLUSIONS
These data suggest the need of customized, radiopharmaceutical-matched SPECT templates to be used within the SPM package. The present customized [(99m)Tc]ECD template is now freely available on the web.
Nuclear Medicine Unit , S. Martino University, Hospital, Genoa, Italy. s.morbe@libero.it
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S
Morbelli
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G
Rodriguez
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Mignone
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Altrinetti
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Brugnolo
A
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Piccardo
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Pupi
P M
PM
Koulibaly
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Nobili
D000293:Adolescent; D000328:Adult; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000000981:diagnostic imaging; D001921:Brain / Q000000981:diagnostic imaging* / Q000473:pathology; D001931:Brain Mapping; D003545:Cysteine / Q000031:analogs & derivatives; D005260:Female; D006179:Gyrus Cinguli / Q000000981:diagnostic imaging; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; D019690:Technetium Tc 99m Exametazime; D015899:Tomography, Emission-Computed, Single-Photon
D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; D019690:Technetium Tc 99m Exametazime; C059659:technetium Tc 99m bicisate; D003545:Cysteine