A kinetic modeling approach for the quantification of in vivo tracer studies with dynamic positron emission tomography (PET) is presented. The approach is based on a general compartmental description of the tracer's fate in vivo and determines a parsimonious model consistent with the measured data. The technique involves the determination of a sparse selection of kinetic basis functions from an...

Transcranial magnetic stimulation (TMS) is a stimulation method in which a magnetic coil generates a magnetic field in an area of interest in the brain. This magnetic field induces an electric field that modulates neuronal activity. The spatial distribution of the induced electric field is determined by the geometry and location of the coil relative to the brain. Although TMS has been used for ...

Despite being developed in the late 1920s, compartmental epidemic modeling is still a rich and fruitful area of research. The original compartmental epidemic models were SIR (Susceptible, Infectious, Removed) models, which assume permanent immunity after recovery. SIR models, along with the more recent SEIR (Susceptible, Exposed, Infectious, Removed) models are still the gold standard in modeli...

BACKGROUND Retinol isotope dilution (RID) methodology provides a quantitative estimate of total body vitamin A (VA) stores and is the best method currently available for assessing VA status in adults and children. The methodology has also been used to test the efficacy of VA interventions in a number of low-income countries. Infections, micronutrient deficiencies (eg, iron and zinc), liver dise...

Many questions remain regarding vitamin A (VA) supplementation of infants. Herein we compared direct oral VA supplementation of the neonate and indirect treatment through maternal dietary VA (M-VA) treatment on VA status and kinetics in neonatal rats. Treatments included direct VA combined with retinoic acid (RA) [D-VARA; VA (6 mg/kg) + 10% RA, given orally to neonates on postnatal day (P)2 and...

A number of studies indicate that compartmental modeling of indocyanine green (ICG) pharmacokinetics, as measured by near infrared (NIR) techniques, may provide diagnostic information for tumor differentiation. However, compartmental parameter estimation is a highly non-linear problem with limited data available in a clinical setting. Furthermore, pharmacokinetic parameter estimates show statis...

UNLABELLED Assessing cellular proliferation provides a direct method to measure the in vivo growth of cancer. We evaluated the application of a model of 3'-deoxy-3'-(18)F-fluorothymidine ((18)F-FLT) kinetics described in a companion report to the analysis of FLT PET image data in lung cancer patients. Compartmental model analysis was performed to estimate the overall flux constants (K(FLT)) for...

Many infectious diseases spread through populations via the networks formed by physical contacts among individuals. The patterns of these contacts tend to be highly heterogeneous. Traditional "compartmental" modeling in epidemiology, however, assumes that population groups are fully mixed, that is, every individual has an equal chance of spreading the disease to every other. Applications of com...

In the existing compartmental models of human vitamin A metabolism, parameters related to the absorption of the isotopic oral dose have not been well identified. We hypothesised that fixing some poorly identified parameters related to vitamin A absorption would improve parameter identifiability and add statistical certainty to such models. In the present study, data for serum vitamin A kinetics...