Frontotemporal Dementia Can Be Distinguished from Alzheimer’s Disease and Subcortical White Matter Dementia by an Anterior-to-Posterior rCBF-SPET Ratio

Abstract

Sixteen patients with frontotemporal dementia (FTD), 27 with early-onset Alzheimer’s disease, 25 with late-onset Alzheimer’s disease, 19 with subcortical white matter dementia (SWD) and 28 normal controls underwent semiquantitative regional cerebral blood flow measurement (rCBF) using single-photon emission tomography (SPET; ^99mTc-HMPAO) and either computerized tomography (CT) or magnetic resonance imaging (MRI) of the brain. An anterior-to-posterior rCBF-SPET ratio (mesial superior frontal gyrus/medial temporal lobes) was calculated, which significantly separated the FTD group from the other dementia groups and controls with a sensitivity of 87.5% and a specificity of at least 78.6%. CT/MRI was found to be helpful in the differential diagnosis between FTD and SWD. In FTD patients, the mesial superior frontal gyrus, near the polus frontalis, was found to be the region with the most reduced rCBF values.

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“…All patients diagnosed with FTD had a predominating frontal lobe syndrome and hypofrontal cerebral blood flow. None of them had signs of infarcts, and only mild white matter changes were found in some of them [21].…”

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“…The quantification of the relative rCBF was conducted according to the min-max method [19,34] where minimum and maximum counts per pixel (c/p) were registered in white and grey matter regions. In grey matter, rCBF was calculated as the ratio between max c/p in grey matter regions of interest (ROIs) to max c/p in the cerebellar ROI.…”

“…This pattern of rCBF changes has been suggested to be a marker of AD [15]. However, it seems to be an unreliable marker, since the same pattern may be found in vascular dementia and Parkinson's disease [18,19]. Although differences in the pattern of rCBF changes have been suggested between early and late onset AD [20], few studies have taken age into account when investigating differences in this pattern between clinical subtypes of AD.…”

“…Although differences in the pattern of rCBF changes have been suggested between early and late onset AD [20], few studies have taken age into account when investigating differences in this pattern between clinical subtypes of AD. In FTD, reductions in the rCBF in frontal regions often prevail [16,19,21]. A frontal to posterior rCBF index may be useful in the differentiation of FTD from AD [19].…”

“…In FTD, reductions in the rCBF in frontal regions often prevail [16,19,21]. A frontal to posterior rCBF index may be useful in the differentiation of FTD from AD [19].…”