| Fully Automatic and Validated Alzheimer's Discrimination (PALZ) |
- Based on the FDG scans acquired in a large multi-center trial a group of dementia experts lead by Prof. K. Herholz has developed a fully automated method for the discrimination between Alzheimer's Dementia (AD) and normal controls [1].
- The PMOD Alzheimer's discrimination analysis tool (PALZ) is an exact and authorized implementation of this methodology. It is a standalone and automatic processing tool, and the analysis has been carefully validated with the study data.
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Procedure Outline
The PALZ discrimination analysis performs an age correction of the measured FDG uptake, and then compares the corrected uptake in each image pixel with the predicted uptake. The resulting deviations are expressed as t-values and presented as a t-map which can be fused with the patient images.
All abnormal t-values within an AD specific mask are summed, resulting in a score which provides the basis for a statistical test. Based on the data of the control group, a 95% prediction limit and error probabilities can be calculated. The score has been shown to be a highly sensitive indicator of scan abnormality with a 93% sensitivity. If the score is outside the 95% prediction limit of the statistical test states "Score within AD regions is abnormal", and the calculated error probability is stated (eg. "Error probability < 0.0001"). In conjunction with clinical symptoms, this finding supports a diagnosis of AD. |
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Applicability
The PALZ tool may only be used to analyze FDG scans of patients older than 48 years with clinical symptoms of AD. The patients should keep the eyes closed during the uptake phase and during scanning, and the data must be reconstructed with attenuation and scatter corrections. The PALZ tool is not a general brain FDG analysis tool and thus not suited to search for non AD-related defects in FDG brain scans. Any other disease that also affects the association brain areas, which are abnormal in AD, may also lead to a significantly abnormal result. |
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[1] K. Herholz, E. Salmon, D. Perani, et al., Discrimination between Alzheimer Dementia and Controls by Automated Analysis of Multicenter FDG PET. NeuroImage 17, 302-316 (2002).
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Alzheimer's Discrimination]
