Conversion of arterial input functions for dual pharmacokinetic modeling using Gd‐DTPA/MRI and ¹⁸F‐FDG/PET

Abstract

Reaching the full potential of magnetic resonance imaging (MRI)-positron emission tomography (PET) dual modality systems requires new methodologies in quantitative image analyses. In this study, methods are proposed to convert an arterial input function (AIF) derived from gadolinium-diethylenetriaminepentaacetic acid (Gd-DTPA) in MRI, into a (18)F-fluorodeoxyglucose ((18)F-FDG) AIF in PET, and vice versa. The AIFs from both modalities were obtained from manual blood sampling in a F98-Fisher glioblastoma rat model. They were well fitted by a convolution of a rectangular function with a biexponential clearance function. The parameters of the biexponential AIF model were found statistically different between MRI and PET. Pharmacokinetic MRI parameters such as the volume transfer constant (K(trans)), the extravascular-extracellular volume fraction (ν(e)), and the blood volume fraction (ν(p)) calculated with the Gd-DTPA AIF and the Gd-DTPA AIF converted from (18)F-FDG AIF normalized with or without blood sample were not statistically different. Similarly, the tumor metabolic rates of glucose (TMRGlc) calculated with (18) F-FDG AIF and with (18) F-FDG AIF obtained from Gd-DTPA AIF were also found not statistically different. In conclusion, only one accurate AIF would be needed for dual MRI-PET pharmacokinetic modeling in small animal models.

Test–retest repeatability of myocardial blood flow and infarct size using 11C-acetate micro-PET imaging in mice

“…Each symbol represents an individual mouse the surrounding organs and more closely matched the invasive carotid artery blood sampled curve. This is reflected by the similarity in iMBF values between the carotid artery STD sampled blood input function and the IDIF curve of the inferior VC, but at the expense of higher variability [41]. Further studies are needed to Fig.…”

Determination of the Input Function at the Entry of the Tissue of Interest and Its Impact on PET Kinetic Modeling Parameters

“…The fraction υ is usually calculated together with the tissue kinetic parameters (rate constants K 1 -k 4 ) during the modeling, and consequently, TBV is evaluated (see Annex). Reciprocally, if TBV is known by means of image decomposition by image analysis [5,39,40], by contrast enhanced magnetic resonance imaging (MRI) [41], or by other means, then IF can be determined from TBV as IF(t)=μTBV(t) with μ91, and in this case, the iterations during the TAC modeling are made on μ instead of on υ. At the end, μ=1/ υ.…”

Determination of an Optimal Pharmacokinetic Model of 18F-FET for Quantitative Applications in Rat Brain Tumors

“…Blood sampling and tracer dosing were performed according to a published protocol (14). The plasma curve (Fig.…”