RT Journal Article
SR Electronic
T1 Gluc-Lys([<sup>18</sup>F]FP)-TOCA PET in Patients with SSTR-Positive Tumors: Biodistribution and Diagnostic Evaluation Compared with [<sup>111</sup>In]DTPA-Octreotide
JF Journal of Nuclear Medicine
JO J Nucl Med
FD Society of Nuclear Medicine
SP 566
OP 573
VO 47
IS 4
A1 Günther Meisetschläger
A1 Thorsten Poethko
A1 Alexander Stahl
A1 Ingo Wolf
A1 Klemens Scheidhauer
A1 Margret Schottelius
A1 Michael Herz
A1 Hans J. Wester
A1 Markus Schwaiger
YR 2006
UL http://jnm.snmjournals.org/content/47/4/566.abstract
AB A recently developed 18F-labeled PET tracer for somatostatin receptor (sstr) imaging, Nα-(1-deoxy-d-fructosyl)-Nε-(2-[18F]fluoropropionyl)-Lys0-Tyr3-octreotate (Gluc-Lys([18F]FP)-TOCA), was evaluated in patients with sstr-positive tumors by assessing the pharmacokinetics, biodistribution, and diagnostic performance in comparison with [111In]DTPA-octreotide. Methods: Twenty-five patients with different sstr-positive tumors were included in the study and were injected with 105 ± 50 MBq Gluc-Lys([18F]FP)-TOCA. PET was performed up to 120 min with 2 different dynamic imaging protocols. Tracer kinetics in tumors and nontumor tissues and tumor-to-background ratios were described by region-of-interest analysis and standardized uptake values (SUVs). In 16 patients, sstr scintigraphy with [111In]DTPA-octreotide was performed (whole-body scans and SPECT). Two independent experts on PET and γ- camera scans performed lesion counts. Results: Gluc-Lys([18F]FP)-TOCA showed a fast and intense tumor accumulation as well as a rapid clearance from blood serum (biexponential elimination, with the half-lives of the initial and the terminal elimination phase calculated as t1/2(1) = 2.3 ± 1.3 min and t1/2(2) = 26.4 ± 14.6 min, respectively). Tumor-to-background ratios at 16 ± 9 min and 34 ± 12 min were as high as 80% and 90% (% of maximum ratios), respectively. Tumors showed high SUVs ranging from 13.7 ± 2.3 (tumors in lung) up to 26.9 ± 15.4 (abdominal tumors). Tracer distribution within tumor and nontumor tissues was stable up to 120 min (except spleen). No significant bowel activity was observed. Comparison of 29 tumors located in the liver showed a mean tumor-to-background ratio of 5.3 ± 2.6 for Gluc-Lys([18F]FP)-TOCA vs. 4.6 ± 3.3 for [111In]DTPA-octreotide (P = 0.24). Visual image analysis revealed a significantly higher number of lesions (factor of 2.4) and improved interobserver correlation (r = 0.99 vs. 0.86) for PET. Conclusion: Gluc-Lys([18F]FP)-TOCA PET allows a fast, high- contrast imaging of sstr-positive tumors. The biokinetics and diagnostic performance of Gluc-Lys([18F]FP)-TOCA are superior to [111In]DTPA-octreotide and—as far as can be derived from the literature—comparable with [68Ga]-DOTA-d Phe1-Tyr3-octreotide ([68Ga]DOTATOC).