Unidirectional Influx and Net Accumulation of PIB

Abstract

Abstract:The compound {N-methyl-[11 C]}2-(4'-methylaminophenyl)-6-hydroxybenzothiazole, "PIB", measured by positron emission tomography, has been demonstrated to image brain -amyloid deposition in Alzheimer's disease (AD). In the present study the benefit of measuring the PIB accumulation rate together with the unidirectional influx of PIB into the brain was investigated in healthy control subjects and patients with AD. In a monkey changes in the influx rate constant K 1 of PIB closely followed changes in CBF, caused by alteration of Pa CO2 . In addition, K 1 was high both in the monkey and in humans, suggesting that this parameter reflects CBF. Most AD patients studied showed clearly higher accumulation rate for PIB than the controls in cortical brain areas, while a few patients showed as low accumulation as the controls. K 1 did not correlate with the accumulation rate, indicating that K 1 for PIB provides extra information besides the accumulation rate.

In vivo imaging of astrocytosis in Alzheimer’s disease: an 11C-L-deuteriodeprenyl and PIB PET study

“…Similarly, the PIB late frames summation divided by the cerebellum has been used as a measure of PIB retention. A 6 minutes summation of early frames divided by the retention in cerebellum was used as a measure of blood flow as proposed by Blomquist [31] and more recently by Rostomian [32]. Because regional blood flow can be decreased in patients with Alzheimer's disease tracer binding was corrected for regional blood flow using the slope/intercept ratio for DED, and the late (40-60 min)/early (6 min) frame ratio for PIB retention.…”

Dual-Biomarker Imaging of Regional Cerebral Amyloid Load and Neuronal Activity in Dementia with PET and 11C-Labeled Pittsburgh Compound B

“…However, as demonstrated for other ligands (19,20), pharmacokinetic analyses of 11 C-PIB studies may yield diagnostically valuable estimates of relative regional CBF: Invasive compartment models used for 11 C-PIB quantification (21,22) provided estimates of K 1 (i.e., the rate constant for ligand transfer from arterial plasma to tissue). In radiotracers with a high permeability-surface product and, consequently, a high level of first-pass extraction, K 1 is closely related to CBF.…”

Dual-phase amyloid PET: hitting two birds with one stone

“…The concept of dual-phase scanning is not new; it has been tested both with 11C-PIB and with 18F-Florbetapir and is mainly linked to the fact that amyloid tracers have high lipophilicity, which makes them good perfusion surrogates [10,11].…”