Applied Biomechanics

**Chapter 5**

**Abstract**

rial blood samples.

**1. Introduction**

[

**77**

interest, time activity curve

undergoing this diagnostic tool.

Biomechanical Model Improving

The aim this study is to describe the algorithms of kinetic modeling to analyze the pattern of deposition of amyloid plaques and glucose metabolism in Alzheimer's dementia. A two-tissue reversible compartment model for Pittsburgh Compound-B ([11*C*]*PIB*) and a two-tissue irreversible compartment model for [18*F*]2-fluoro-2-deoxy-D-glucose ([18*F*]*FDG*) are solved applying the Laplace transform method in a system of two first-order differential equations. After calculating a convolution integral, the analytical solutions are completely described. In order to determine the parameters of the model, information on the tracer delivery is needed. A noninvasive reverse engineer technique is described to determine the input function from a reference region (carotids and cerebellum) in PET image processing, without arte-

**Keywords:** noninvasive input function, Laplace transform, kinetic modeling, radiotracer, positron emission tomography (PET), reference region, region of

tration of a tracer in the region of interest (ROI) or target tissue.

Positron emission tomography (PET) [1, 2], is a functional imaging technology that visualizes physiological changes through the administration of radiopharmaceutical molecular tracers into living systems. PET with measures the local concen-

PET with [11*C*]*PIB* and [18*F*]*FDG* radiotracers are widely used in the clinical setting for patients with neurodegenerative diseases like Alzheimer's disease. The

<sup>18</sup>*F*]*FDG*-PET indirectly measures neuronal metabolism, subsequently allowing the identification of brain regions with increased or decreased activity. Individuals with progressive amnestic dementia show a specific pattern of FDG uptake that distinguishes their brains from other types of pathologies. Thus, this technique directly impacts the treatment selected for this patient. However, this technique is still under study to improve its accuracy power and to decrease patient discomfort

Cognitive aging is also a subject of interest of PET studies. This technique can be used to investigate abnormal binding occurs in clinically normal individuals, prior to the development of cognitive changes. Higher binding in nondemented subjects suggests that [11*C*]*PIB* amyloid imaging may be sensitive for detection of a preclinical Alzheimer's disease state. Age-related cognitive changes impact the brain functioning

*Eliete Biasotto Hauser, Wyllians Vendramini Borelli*

Alzheimer's Disease

*and Jaderson Costa da Costa*
