Degradation of acetonitrile in eluent solutions for [¹⁸F]fluoride PET chemistry: impact on radiosynthesis of [¹⁸F]FACBC and [¹⁸F]FDG

Abstract

In [18F]fluoride chemistry, an eluent solution containing a weak aqueous base is used to release [18F]fluoride after adsorption on an anion exchange resin. Traditionally, the eluent solution is freshly prepared, but modern PET tracer manufacturers may utilize the benefits of preparing bulk solutions or prefilled vials for storage. We discovered that typical eluent solutions containing kryptofix and K2CO3 in aqueous acetonitrile degraded upon storage. Acetonitrile will at alkaline pH hydrolyse to acetamide and ammonium acetate. Acetate may serve as a competing nucleophile to [18F]fluoride. Eluent solutions used in the synthesis of [18F]FACBC and [18F]FDG generated mg/ml levels of acetamide and ammonium acetate during storage at room temperature or above. The synthesis of [18F]FACBC was prone to eluent degradation, with gradual reduction of radiochemical yield (RCY) from 62.5% to 44.7% during 12 months of storage at 30 °C. The synthesis of [18F]FDG was only affected when the eluent was stored at 50 °C, reducing the RCY from 86.8% to 66.7% after 3 months of storage. For degradation effects to be avoided, an alternative eluent solution with no acetonitrile was investigated in the synthesis of [18F]FACBC. A methanol‐based eluent was successfully made, showing no degradation and unchanged RCY after 6 months of storage at 50 °C. Copyright © 2012 John Wiley & Sons, Ltd.

Localized Prostate Cancer Detection with18F FACBC PET/CT: Comparison with MR Imaging and Histopathologic Analysis

“…Mean prostate tumor SUV max (15-20min) was significantly higher than that of the normal prostate (4.5 6 0.5 vs 2.7 6 0.5) (P , .001); however, it was not significantly different from that of BPH (4.3 6 0.6) (P = .27). Sector-based comparison with histopathologic analysis, including all tumors, revealed sensitivity and specificity of 67% and 66%, respectively, for 18 F FACBC PET/CT and 73% and 79%, respectively, for T2-weighted MR imaging. 18 F FACBC PET/CT and MP MR imaging were used to localize dominant tumors (sensitivity of 90% for both).…”

“…Sector-based comparison with histopathologic analysis, including all tumors, revealed sensitivity and specificity of 67% and 66%, respectively, for 18 F FACBC PET/CT and 73% and 79%, respectively, for T2-weighted MR imaging. 18 F FACBC PET/CT and MP MR imaging were used to localize dominant tumors (sensitivity of 90% for both). Combined 18 F FACBC and MR imaging yielded positive predictive value of 82% for tumor localization, which was higher than that with either modality alone (P , .001).…”

“…18 F FACBC PET/CT and MP MR imaging were used to localize dominant tumors (sensitivity of 90% for both). Combined 18 F FACBC and MR imaging yielded positive predictive value of 82% for tumor localization, which was higher than that with either modality alone (P , .001).…”

“…Twenty-one men underwent dynamic and static abdominopelvic 18 F FACBC combined positron emission tomography (PET) and computed tomography (CT) and multiparametric (MP) 3-T endorectal MR imaging before robotic-assisted prostatectomy. PET/CT and MR images were coregistered by using pelvic bones as fiducial markers; this was followed by manual adjustments.…”

“…Whole-mount histopathologic specimens were sliced with an MR-based patientspecific mold. 18 F FACBC PET standardized uptake values (SUVs) were compared with those at MR imaging and histopathologic analysis for lesion-and sector-based (20 sectors per patient) analysis. Positive and negative predictive values for each modality were estimated by using generalized estimating equations with logit link function and working independence correlation structure.…”