Z. Tu, C. Dence, D. Ponde
Jul 1, 2005
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Journal
Nuclear Medicine and Biology
Abstract
Abstract Four conformationally flexible benzamide analogs having a high affinity and outstanding selectivity for σ 2 versus σ 1 receptors were synthesized and radiolabeled with carbon-11 by reaction with [ 11 C]methyl iodide. The four 11 C-labeled radiotracers were evaluated for their potential to image the proliferative status of breast tumors with positron emission tomography (PET). In vivo studies in female BALB/C mice bearing EMT-6 breast tumors showed that one radiotracer, (2-methoxy- 11 C)- N -(4-(3,4-dihydro-6,7-dimethoxy-isoquinolin-2(1 H )-yl)butyl)-5-methylbenzamide ([ 11 C] 2 ), had a high tumor uptake and suitable tumor/background ratio for imaging purposes. Blocking studies were consistent with the labeling of σ 2 receptors in vivo. A study comparing the in vivo properties of [ 11 C] 2 and 18 F-3′-fluoro-3′-deoxy- l -thymidine ([ 18 F]FLT) indicated that [ 11 C] 2 had either similar (lung, fat) or better (blood, muscle) tumor/organ ratios than [ 18 F]FLT in the tissues that are important for breast tumor imaging. Consequently, [ 11 C] 2 is a potential radiotracer for imaging the proliferative status of breast tumors in vivo with PET.