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PXMOD Implementation

Acquisition and Data Requirements

Image Data

A static PET data set representing the measurement of the average brain activity between 40 to 55 min after injection of a FDG bolus. Note: if a dynamic study is loaded, the activity of all loaded frames is averaged at the time of pixel-wise model calculation.

Blood Data

Plasma activity of blood sampled at a peripheral artery from the time of injection until the end of the acquisition.

Blood Preprocessing

Decay correction is the only blood correction option. Note that an uncorrected relative time shift of blood data by 30 sec does not markedly change the calculated glucose consumption.

PXMOD MRGlu (Patlak) Blood Pre-Processing

Model Preprocessing

The rate constants applied in the autoradiographic calculation of MRGlu must be entered in the Model Preprocessing dialog.

PXMOD MRGlu (Autorad) Model Pre-processing

Plasma glucose

Plasma glucose in [mmol/l] measured with a blood sample of the patient.

Lumped constant

The Lumped constant is used to compensate for the difference in uptake between normal glucose and Fluoro-Deoxyglucose (FDG). Proposed as the default is the value determined by Graham et al (J Nucl Med 2002; 43:1157–1166) using 11C Glucose and FDG in 2002. Their results: Normal brain: 0.89+/-0.08; cerebellum: 0.78+/-0.11.

K1

Unidirectional transfer of FDG into tissue. Grey matter: 0.102. White Matter: 0.054.

k2

Clearance of FDG from the tissue. Grey matter: 0.130. White Matter: 0.109.

k3

Phosphorylation rate in tissue. Grey matter: 0.062. White Matter: 0.045.

k4

Dephosphorylation of glucose-phosphate in tissue. Grey matter: 0.0068. White Matter: 0.0058.

Map Parameters

PXMOD MRGlu (Autorad) Model Parameters

MRGlu

Metabolic Rate of Glucose in [mmol/min/100ml] calculated according to eq. (8) in [13].