n-n-dimethyl-n-(18f)fluoromethyl-2-hydroxyethylammonium and Rhabdomyosarcoma

To compare choline concentration/amount at proton magnetic resonance spectroscopy (H-MRS) and [18F]-fluoromethylcholine (FCH) uptake at positron emission tomography (PET) in a tumour animal model.. Twenty-two rats bearing grafted syngenic rhabdomyosarcoma in both thighs were examined on a 3T MR system and on a small animal PET system. Total choline concentration was measured on proton MR spectra using a so-called 'best internal fitting' volume of interest. Choline uptake was expressed as mean and maximum standardized uptake value (SUV and SUVmax, respectively) and as the percent of injected dose (%ID) after tumour delineation on fused PET-MR images. Data sets were displayed on standard scatter plots.. Thirty-six tumours were available for analysis. The area under the curve of the 3.2 ppm choline peak ranged from 69 to 476 (mean, 192) in arbitrary units. Mean SUV values ranged from 0.05 to 0.49 (mean, 0.19) and the %ID from 0.05 to 2.28 (mean, 0.54). Scatter plots failed to reveal quantitative relationship between choline concentration and uptake. Empirically data-driven cut-off lines applied to choline amount (choline concentration x tumour volume) versus choline uptake suggested a paradoxically negative relationship.. Total choline concentration did not correlate with FCH uptake in a tumour experimental model. A negative feedback of high values of total choline amount on cellular FCH uptake seemed to be present.

Topics: Animals; Choline; Disease Models, Animal; Fluorine Radioisotopes; Magnetic Resonance Spectroscopy; Positron-Emission Tomography; Rats; Rhabdomyosarcoma

To assess early radiation therapy (RT)-induced variations in total choline (tCho) concentration measured by proton magnetic resonance spectroscopy (H-MRS) and in (18)F-labelled fluoromethylcholine (FCH) uptake measured by PET in a rodent tumour model.. Nine rats bearing syngenic rhabdomyosarcoma grafts in both thighs were irradiated (13 Gy, one fraction). H-MRS data and FCH-PET were acquired in the same imaging session prior to and 3, 9 and 16 days after external RT. Total choline concentration was expressed in arbitrary units as the area under the curve of the 3.2-ppm peak on H-MR spectra. FCH uptake was expressed as maximum standardized uptake value (SUV(max)) and as the % of injected dose per gram (%ID/g) after precise tumour delineation on hybrid PET-MR images. Pre- and post-RT data were compared using the Student's paired t test, and results were expressed as mean+/-S.D.. Seventeen tumours were available for analysis. A mean drop in choline concentration of 45% was observed 3 days after irradiation (P<.001), whereas a concomitant mean increase in SUV(max) of 41% was observed (P=.006). Choline concentration reincreased on later time points.. Opposite trend between increased FCH uptake and decreased tCho peak was observed at 3 days. Later (9 and 16 days), uptake remained stable and tCho peak reincreased.

Topics: Alginates; Animals; Biological Transport; Choline; Disease Models, Animal; Glucuronic Acid; Hexuronic Acids; Magnetic Resonance Spectroscopy; Male; Positron-Emission Tomography; Protons; Rats; Rhabdomyosarcoma; Survival Rate; Time Factors; Treatment Outcome