[Semiquantitative 99mTc-HMPAO SPECT in dementia of the Alzheimer type: influence of the selection of reconstruction filter and reference region].

AIM

The aim of the study was to clarify, whether the selection of the reference-region and/or the reconstruction-filter influences the result of the semiquantitative analysis of a 99mTc-HMPAO-SPECT that was conducted to diagnose the dementia of the Alzheimer type (DAT).

METHODS

A group of 19 DAT-patients according to the criteria of NINCDS-ADRDA and DSM-III-R was examined together with a comparison group (n = 14) with normal cerebral perfusion. Three reference-regions (cerebellum, whole slice, occipital cortex) and four reconstruction-filters (Hanning fc = 0.7 and 1.0 Nyquist; Butterworth (n = 8); fc = 0.5 and 0.9 Nyquist) were applied to twelve standardized regions of interest (per patient) respectively. The data was evaluated through a ROC-analysis.

RESULTS

It has been showed, that the bilateral parieto-temporal perfusion reduction as a characteristic of DAT depends on the filters and reference-regions used. The most secure separation of both groups of patients was obtained through a Butterworth-filter (n = 8; fc = 0.5) in combination with the cerebellum as reference-region.

CONCLUSION

The selection of the reference-region and the reconstruction-filter has an important influence on the results of a semiquantitative analysis. Therefore standardisation in dependency on the actual questioning is necessary.