Human Biodistribution and Radiation Dosimetry of S-11C-Methyl-L-Cysteine Using Whole-Body PET

Abstract

The potential radiation risks associated with C-MCYS PET imaging are within accepted limits. C-MCYS is a safe amino acid PET tracer for tumor imaging and can be used in further clinical studies.

First-in-Human PET Imaging and Estimated Radiation Dosimetry of l-[5-11C]-Glutamine in Patients with Metastatic Colorectal Cancer

“…While a full range of timepoints across the whole body were not collected in this study, our calculated value is comparable to other reported effective doses for 11 C-labeled PET tracers (52,(54)(55)(56)(57). This effective dose is similar to those reported for other 11 C-labeled amino acid radiopharmaceuticals (52,54,55) and a magnitude lower than dose estimates for 18 F-labeled radiopharmaceuticals found in the literature (50,(58)(59)(60)(61)(62) due mainly to the short half-life of carbon-11.…”

“…While a full range of timepoints across the whole body were not collected in this study, our calculated value is comparable to other reported effective doses for 11 C-labeled PET tracers (52,(54)(55)(56)(57). This effective dose is similar to those reported for other 11 C-labeled amino acid radiopharmaceuticals (52,54,55) and a magnitude lower than dose estimates for 18 F-labeled radiopharmaceuticals found in the literature (50,(58)(59)(60)(61)(62) due mainly to the short half-life of carbon-11. This value compares well with the mean effective dose (5.9E-03 ± 2.0E-03 mSv/MBq) reported in a review of 37 dose estimates for 11 C-labeled PET tracers (56) and with the average effective dose (5.2E-03 ± 1.7E-03 mSv/MBq) from a recent review of 77 literature publications for a wide range of 11 C-labeled tracers (57).…”

PET Imaging with S-[11C]Methyl-L-Cysteine and L-[Methyl-11C]Methionine in Rat Models of Glioma, Glioma Radiotherapy, and Neuroinflammation

“…A successful alternative is the amino acid analog O -2-[ 18 F]fluoroethyl-L-tyrosine ([ 18 F]FET) [ 4 ]. Another amino acid analog which has been proposed for the same purpose is S -[ 11 C]methyl-L-cysteine ([ 11 C]MCYS) [ 5 , 6 ]. MCYS is a naturally occurring derivative of the amino acid L-cysteine.…”

Synthesis of enantiopure 18F-trifluoromethyl cysteine as a structure-mimetic amino acid tracer for glioma imaging

“…However, [ 11 C]MET is taken up not only by tumors but also by other inflammatory lesions, leading to low tumor specificity 30-33; additionally, it is susceptible to in vivo metabolism 34, complicating kinetic analysis. To address these deficiencies, S- [ 11 C]-methyl-L-cysteine 1L ( S -[ 11 C]CH 3 -L-CYS) and S- [ 11 C]-methyl-D-cysteine 1D ( S -[ 11 C]CH 3 -D-CYS), a pair of 11 C-labelled S -methylcysteine enantiomers ( Figure 1A and Figure S1B ), were successively developed via 11 C-isotopic substitution in our previous studies 35-38. Preliminary studies indicated that the tracers were superior to [ 18 F]FDG and [ 11 C]MET in the differentiation of tumor from inflammation 35, 36, 38-40.…”

“…To address these deficiencies, S- [ 11 C]-methyl-L-cysteine 1L ( S -[ 11 C]CH 3 -L-CYS) and S- [ 11 C]-methyl-D-cysteine 1D ( S -[ 11 C]CH 3 -D-CYS), a pair of 11 C-labelled S -methylcysteine enantiomers ( Figure 1A and Figure S1B ), were successively developed via 11 C-isotopic substitution in our previous studies 35-38. Preliminary studies indicated that the tracers were superior to [ 18 F]FDG and [ 11 C]MET in the differentiation of tumor from inflammation 35, 36, 38-40. Nevertheless, the short half-life of 11 C ( t 1/2 = 20.4 min) restricts the widespread application of these tracers, resulting in an urgent demand for 18 F-labelled SAA tracers ( 18 F, t 1/2 = 109.8 min).…”