Comparison between cortical distribution of I-123 iomazenil and Tc-99m HMPAO in patients with Alzheimer's disease using SPECT.

Abstract

PURPOSE:

To compare brain perfusion and synaptic density in Alzheimer's disease assessed using I-123 iomazenil SPECT with brain perfusion assessed using Tc-99m HMPAO SPECT.

MATERIALS AND METHODS:

Early and delayed I-123 iomazenil SPECT images acquired 20 and 180 minutes after injection were compared with Tc-99m HMPAO SPECT studies acquired 15 to 20 minutes after injection in five patients with Alzheimer's disease.

RESULTS:

Visual analysis of I-123 iomazenil images showed more severe (n = 4) and extensive (n = 3) defects than did Tc-99m HMPAO. Semiquantitative analysis was performed by normalizing the uptake of Tc-99m HMPAO and I-123 iomazenil in individual brain regions in the cerebellum and expressing these values as a ratio of the occipital regions. The analysis of brain regional ratios in Tc-99m HMPAO studies showed a low but significant correlation with ratios of delayed (r = 0.325, P < 0.05) images in the I-123 iomazenil studies. Furthermore, when compared with Tc-99m HMPAO, early (P < 0.01) and delayed mean ratios (P < 0.05) were significantly less in the frontal regions; early mean ratios were significantly less in the temporal regions (P < 0.05), and delayed (P < 0.05) mean ratios were significantly less in the parietal regions.

CONCLUSIONS:

Tc-99m HMPAO images were better correlated with I-123 iomazenil images, indicating cortical synaptic density (delayed images). I-123 iomazenil SPECT in patients with Alzheimer's disease provided more sensitive information than Tc-99m HMPAO, allowing evaluation of brain perfusion and synaptic density.

• Authors: A Varrone, A Soricelli, A Postiglione, M Salvatore
• Journal: Clinical nuclear medicine (Clin Nucl Med) Vol. 24 Issue 9 Pg. 660-5 (Sep 1999) ISSN: 0363-9762 [Print] United States
• PMID: 10478740 (Publication Type: Comparative Study, Journal Article)

Chemical References

• Iodine Radioisotopes
• Technetium Tc 99m Exametazime
• Flumazenil
• iomazenil

Topics

• Alzheimer Disease (diagnostic imaging, metabolism)
• Brain (metabolism)
• Female
• Flumazenil (analogs & derivatives, pharmacokinetics)
• Humans
• Iodine Radioisotopes (pharmacokinetics)
• Male
• Middle Aged
• Technetium Tc 99m Exametazime (pharmacokinetics)
• Tomography, Emission-Computed, Single-Photon