This was the first-in-humans clinical study of 18F-fludarabine, which is a radiopharmaceutical for PET imaging in lymphoma, for which many issues remain controversial with the standard radiotracer 18F-FDG. Methods:18F-fludarabine PET or PET/CT was performed on 10 patients: 5 with diffuse large B-cell lymphoma (DLBCL) and 5 with chronic lymphocytic leukemia. The tumor uptake, biodistribution, and radiation dosimetry of 18F-fludarabine were evaluated. Six successive partial-body PET scans were acquired for 250 min after an intravenous 4 MBq/kg bolus of 18F-fludarabine. SUVs were recorded for each involved lymph node territory and for several extranodal sites, with particular reference to the liver. To assess the time-related uptake profile of 18F-fludarabine, PET images were analyzed by delineating volumes of interest over the uptake sites on the optimal scan for visual observation and were projected onto all coregistered scans of the same subject. Physical examination, laboratory studies, and contrast-enhanced CT were performed on all patients. For the DLBCL group, 18F-FDG PET was also considered. Results: In DLBCL patients, increased 18F-fludarabine uptake was observed in sites considered abnormal by CT or 18F-FDG, with SUVs significantly higher in involved lesions than in physiologic nontarget sites. Nonetheless, the comparison of 18F-fludarabine and 18F-FDG PET showed discrepancies in 2 patients. In chronic lymphocytic leukemia patients, the uptake of 18F-fludarabine coincided with sites expected to be involved (including splenic invasion) according to conventional clinical and CT staging and was significant in hematopoietic bone marrow. No uptake was observed, whatever the disease group, in cardiac muscle or brain. The mean effective dose from a mean injected 18F-fludarabine activity of 305 ± 76 MBq was 3.07 ± 0.81 mSv. Conclusion:18F-fludarabine PET might well be a promising tool for lymphoproliferative diseases. The radiation dose of this radiopharmaceutical is below that of 18F-FDG. The specificity of this PET probe for lymphoid cells, its absence of accumulation in reactive tissues, and its feasibility for detection of bone marrow infiltration might play an innovative role in lymphoma imaging.
Lithiation of (S)-N-(1-phenylpropyl)-2-phenylquinoline-4-carboxamide with the complex n-BuLi/TMEDA (1/1 molar ratio) in THF at −60 °C for 5 h occurred selectively at the position 3 of the quinoline ring. This selectivity was shown by the absence of racemization of the stereogenic center and the formation of the corresponding functionalized quinolines in 59−74% yield by subsequent reaction with an electrophile at −60 °C for 1 h. The 3-trimethylstannyl derivative was subjected to a Stille reaction using methyl, phenyl, or thienyliodide to afford the alkyl or aryl quinolines in moderate to good yields. This methodology was successfully applied to the radiosynthesis of [11C]SB 222200 using methyl iodide labeled with carbon-11 (β+ emitter, t1/2 = 20.4 min) for the in vivo study of NK-3 receptor by positron emission tomography (48−58% radiochemical yields from [11C]CH3I, decay corrected, 45 min total synthesis time).
Quantitative imaging modalities for the analysis of hypoxia in brain tumors are lacking. The objective of this study was to generate absolute maps of tissue ptO2 from [18F]-FMISO images in glioblastoma and less aggressive glioma patients in order to quantitatively assess tumor hypoxia. An ancillary objective was to compare estimated ptO2 values to other biomarkers: perfusion weighted imaging (PWI) and tumor metabolism obtained from 1H-MR mono-voxel spectroscopy (MRS). Ten patients with glioblastoma (GBM) and three patients with less aggressive glioma (nGBM) were enrolled. All patients had [18F]-FMISO and multiparametric MRI (anatomic, PWI, MRS) scans. A non-linear regression was performed to generate ptO2 maps based on normal appearing gray (NAGM) and white matter (NAWM) for each patient. As expected, a marked [18F]-FMISO uptake was observed in GBM patients. The ptO2 based on patient specific calculations was notably low in this group (4.8 ± 1.9 mmHg, p < 0.001) compared to all other groups (nGBM, NAGM and NAWM). The rCBV was increased in GBM (1.4 ± 0.2 when compared to nGBM tumors 0.8 ± 0.4). Lactate (and lipid) concentration increased in GBM (27.8 ± 13.8%) relative to nGBM (p < 0.01). Linear, nonlinear and ROC curve analyses between ptO2 maps, PWI-derived rCBV maps and MRS-derived lipid and lactate concentration strengthens the robustness of our approaches.
