Nuclear medicine diagnostic techniques in the era of pathophysiology-based CSF biomarkers for Alzheimer's disease.

Nuclear medicine techniques were the first functional imaging techniques used to support the clinical diagnosis of Alzheimer's Disease (AD). Perfusion-SPECT allows registration of regional cerebral blood flow (rCBF) which is altered in a characteristic temporal-parietal pattern in AD. Numerous studies have shown the diagnostic value of reduced CBF and metabolic changes using perfusion-SPECT and FDG-PET in AD diagnosis as well as in differential diagnosis against frontotemporal dementia (FTD), dementia with Lewy-Bodies (DLB), and vascular cognitive disorders. This renders perfusion-SPECT an important piece of the puzzle (together with other diagnostic tests) by the clinician is often faced when making a final etiologic dementia diagnosis especially between AD and FTD. A similar diagnostic value can be expected when arterial spin labeling (ASL) MRI sequence is used, but the diagnostic value has yet to be confirmed in lager studies. Recently, more pathophysiology-based biomarkers in CSF and Amyloid-PET tracers have been developed that probably have a higher diagnostic accuracy than the more indirect rCBF changes seen in perfusion-SPECT. In the current review, we describe recent advances in AD biomarkers as well as improvements in the SPECT technique.