Automated detection of local normalization areas for ictal-interictal subtraction brain SPECT.
J Nucl Med
; 43(11): 1419-25, 2002 Nov.
Article
em En
| MEDLINE
| ID: mdl-12411542
ABSTRACT
UNLABELLED Whole-brain activity is often chosen to quantitatively normalize peri-ictal and interictal SPECT scans before their subtraction. This use is not justified, because significant and extended modification of the cerebral blood flow can occur during a seizure. We validated and compared 2 automatic methods able to determine the optimal reference region, using simulation and clinical data. METHODS:
In the first method, the selected reference region is the intersection of peri-ictal-interictal areas with no significantly different z values. The other method relies on a 3-dimensional iterative voxel aggregation. The increase of the selected volume is stopped by using 2 different variance tests (Levene and SE). These algorithms were tested on 39 epileptic patients and were validated using 1 interictal and 10 peri-ictal scans simulated from the mean image of 22 healthy subjects.RESULTS:
In the patient studies, the mean relative activity of the selected regions, compared with whole-brain activity (classic normalization), was 122.6%. Their average relative size (compared with the size of the whole brain) was 33.2% for the z map method, 22.8% for the SE test, and 11.8% for the Levene test. After application of our automatic processes, subtraction of the simulated images revealed a recovery of abnormal regions up to 45% larger than the region obtained with classic normalization.CONCLUSION:
These results illustrate the role of normalization on the subtracted peri-ictal and interictal images. Our methods are automatic and objective and give good results on various simulated images. The z map construction is worth considering because it is simple, selects large parts of the brain, and requires little computation time.
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Base de dados:
MEDLINE
Assunto principal:
Encéfalo
/
Tomografia Computadorizada de Emissão de Fóton Único
/
Técnica de Subtração
/
Epilepsia
Tipo de estudo:
Diagnostic_studies
Limite:
Adult
/
Female
/
Humans
/
Male
Idioma:
En
Ano de publicação:
2002
Tipo de documento:
Article