TY - JOUR T1 - Improved Detection of Regional Melanoma Metastasis Using <sup>18</sup>F-6-Fluoro-<em>N</em>-[2-(Diethylamino)Ethyl] Pyridine-3-Carboxamide, a Melanin-Specific PET Probe, by Perilesional Administration JF - Journal of Nuclear Medicine JO - J Nucl Med SP - 115 LP - 122 DO - 10.2967/jnumed.110.078154 VL - 52 IS - 1 AU - Delphine Denoyer AU - Titaina Potdevin AU - Peter Roselt AU - Oliver C. Neels AU - Laura Kirby AU - Ivan Greguric AU - Andrew Katsifis AU - Donna S. Dorow AU - Rodney J. Hicks Y1 - 2011/01/01 UR - http://jnm.snmjournals.org/content/52/1/115.abstract N2 - The efficacy of differing routes of administration of 18F-6-fluoro-N-[2-(diethylamino)ethyl] pyridine-3-carboxamide (18F-MEL050), a new benzamide-based PET radiotracer for imaging regional lymph node metastasis in melanoma, was assessed. Methods: B16-Black/6 metastatic melanoma cells harboring an mCherry transgene were implanted into the left-upper-foot surface of 49 C57 Black/6 mice as a model of popliteal lymph node (PLN) metastasis. Ultrasound scanning of the left PLN was performed at baseline and in combination with 18F-MEL050 PET on days 5, 9, and 14. Mice were divided into 2 groups to compare the results of tracer administration either subcutaneously at the tumor site (local) or in the lateral tail vein (systemic). After PET on each imaging day, 5 mice per group—including any with evidence of metastasis—were sacrificed for ex vivo validation studies including assessment of retained radioactivity and presence of the mCherry transgene as a surrogate of nodal tumor burden. Results: Nine mice were judged as positive for PLN metastasis by ultrasound at day 5, and 8 PLNs were positive on 18F-MEL050 PET, 3 after systemic and 5 after local administration. Ex vivo analysis showed that ultrasound correctly identified 90% of positive PLNs, with 1 false-positive. 18F-MEL050 PET correctly identified 60% of positive PLNs after systemic administration and 100% after local administration with no false-positive results by either route. The average node-to-background ratio for positive PLNs was 6.8 in the systemic-administration group and correlated with disease burden. In the local-administration group, the mean uptake ratio was 48, without clear relation to metastatic burden. Additional sites of metastatic disease were also correctly identified by 18F-MEL050 PET. Conclusion: In addition to its potential for systemic staging, perilesional administration of 18F-MEL050 may allow sensitive and specific, noninvasive identification of regional lymph node metastasis in pigmented malignant melanomas. ER -