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. 2021 Dec;16(12):2494-2498.
doi: 10.4103/1673-5374.313062.

11C-PK11195 plasma metabolization has the same rate in multiple sclerosis patients and healthy controls: a cross-sectional study

Aline Morais de Souza  1 , Milena Sales Pitombeira  2 , Larissa Estessi de Souza  1 , Fabio Luiz Navarro Marques  1 , Carlos Alberto Buchpiguel  1 , Caroline Cristiano Real  1 , Daniele de Paula Faria  3
Affiliations

11C-PK11195 plasma metabolization has the same rate in multiple sclerosis patients and healthy controls: a cross-sectional study

Aline Morais de Souza et al. Neural Regen Res. 2021 Dec.

Abstract

11C-PK11195 is a positron emitter tracer used for Positron Emission Tomography (PET) imaging of innate immune cell activation in studies of neuroinflammatory diseases. For the image quantitative analysis, it is necessary to quantify the intact fraction of this tracer in the arterial plasma during imaging acquisition (plasma intact fraction). Due to the complexity and costs involved in this analysis it is important to evaluate the real necessity of individual analysis in each 11C-PK11195 PET imaging acquisition. The purpose of this study is to compare 11C-PK11195 plasma metabolization rate between healthy controls and multiple sclerosis (MS) patients and evaluate the interference of sex, age, treatment, and disease phenotype in the tracer intact fraction measured in arterial plasma samples. 11C-PK11195 metabolization rate in arterial plasma was quantified by high performance liquid chromatography in samples from MS patients (n = 50) and healthy controls (n = 23) at 20, 45, and 60 minutes after 11C-PK11195 injection. Analyses were also stratified by sex, age, treatment type, and MS phenotype. The results showed no significant differences in the metabolization rate of healthy controls and MS patients, or in the stratified samples. In conclusion, 11C-PK11195 metabolization has the same rate in patients with MS and healthy controls, which is not affected by sex, age, treatment, and disease phenotype. Thus, these findings could contribute to exempting the necessity for tracer metabolization determination in all 11C-PK11195 PET imaging acquisition, by using a population metabolization rate average. The study procedures were approved by the Ethics Committee for Research Projects Analysis of the Hospital das Clinicas of the University of Sao Paulo Medical School (approval No. 624.065) on April 23, 2014.

Keywords: 11C-PK11195; HPLC; PET imaging; PET tracer; kinetic modeling; metabolization; multiple sclerosis; neuroinflammation; radiometabolites.

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Conflict of interest statement

None

Figures

Figure 1
Figure 1
HPLC chromatogram profile of 11C-PK11195 intact fraction and its radiometabolites (M1 and M2) at 20, 45, and 60 minutes post tracer injection. Note that 11C-PK11195 intact fraction decreases with time (20 minutes in light grey, 45 minutes in dark grey, and 60 minutes in black) while the radiometabolites fractions increase with time.
Figure 2
Figure 2
11C-PK11195 metabolization rate over time in the different groups analyzed. (A) Tracer metabolization by sex. (B) Tracer metabolization by age. (C) Tracer metabolization comparing healthy controls and multiple sclerosis (MS) patients. (D) Tracer metabolization in the different MS phenotypes and healthy controls. (E) Tracer metabolization by treatment categories. PPMS: Primary-progressive MS; RRMS: relapsing-remitting MS; SPMS: secondary-progressive MS.
See this image and copyright information in PMC

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