UNLABELLED:In this study, we assessed the accuracy and reliability of MRI-guided SPECT measurements of medial temporal lobe blood flow in Alzheimer's disease (AD).
METHODS:Interactively aligned three-dimensional MP-RAGE MRI and 99mTc-HMPAO SPECT images were used for MRI-guided measurement of medial temporal lobe CBF in eight control subjects and eight patients with probable AD. Intraoperator reliability was assessed by repeated alignment and measurement by one experienced operator. Accuracy was assessed by examining two subjects with fiducial markers.
RESULTS:The alignment error was less than 1 SPECT pixel size (3.5 mm) and the coefficient of variation in repeated measures of medial temporal-to-cerebellar CBF ratios was 3.2%. The difference in mean medial temporal-to-cerebellar CBF ratios between eight control subjects and eight AD patients was 12%. Also by using three-dimensional seed-grow defined healthy brain reference regions, there were significant differences between control subjects and AD patients in medial temporal blood flow. Furthermore, the volumes of the MRI-defined medial temporal ROIs were smaller in the AD patients. The best separation between AD patients and control subjects was achieved by combining MRI measurements of atrophy and SPECT measurements of CBF.
CONCLUSION:These data show that the accuracy and reliability of MRI-guided SPECT measurements of medial temporal CBF clearly allow the detection of changes in AD. Also, a direct comparison of structural and functional changes is possible by this methodology, which might improve the early diagnosis of AD.
METHODS:Interactively aligned three-dimensional MP-RAGE MRI and 99mTc-HMPAO SPECT images were used for MRI-guided measurement of medial temporal lobe CBF in eight control subjects and eight patients with probable AD. Intraoperator reliability was assessed by repeated alignment and measurement by one experienced operator. Accuracy was assessed by examining two subjects with fiducial markers.
RESULTS:The alignment error was less than 1 SPECT pixel size (3.5 mm) and the coefficient of variation in repeated measures of medial temporal-to-cerebellar CBF ratios was 3.2%. The difference in mean medial temporal-to-cerebellar CBF ratios between eight control subjects and eight AD patients was 12%. Also by using three-dimensional seed-grow defined healthy brain reference regions, there were significant differences between control subjects and AD patients in medial temporal blood flow. Furthermore, the volumes of the MRI-defined medial temporal ROIs were smaller in the AD patients. The best separation between AD patients and control subjects was achieved by combining MRI measurements of atrophy and SPECT measurements of CBF.
CONCLUSION:These data show that the accuracy and reliability of MRI-guided SPECT measurements of medial temporal CBF clearly allow the detection of changes in AD. Also, a direct comparison of structural and functional changes is possible by this methodology, which might improve the early diagnosis of AD.
