[68Ga]Ga-Α-Msh As a Pet Radiotracer for Detection of Metastatic Melanomas: A Preliminary Study Publisher



Y Salehi YALDA ; M Bakhshikashi MOHSEN ; M Abbasi MEHRSHAD ; S Farzanehfar SAEED ; N Safarian NADER ; H Yousefnia HASSAN ; E Eppard ELISABETH ; N Vahidfar NASIM
Source: Journal of Radioanalytical and Nuclear Chemistry Published:2025

Abstract

Melanoma is a form of skin cancer with a poor prognosis, especially when diagnosis and treatment are delayed. Detecting metastasis is a significant challenge, with [18F]FDG PET/CT scans offering both advantages and limitations. Given the high affinity of α-MSH analogs for melanoma tumors, we aimed to clinically assess the [68Ga]Ga-α-MSH PET/CT scan for the first time in Iran. This preliminary descriptive-analytical study was conducted from 2023 to 2024 on 10 patients with biopsy-confirmed melanoma. Each patient underwent whole-body scans with both [68Ga]Ga-α-MSH PET/CT and [18F]FDG PET/CT. Lesions detected in each scan were described and compared, with standardized uptake ratios calculated as lesion SUVmax normalized to liver SUVmean. A total of 10 melanoma patients were evaluated (mean age 55 ± 12 years, 60% female). A mean dose of 163 ± 30 MBq (4.4 ± 0.8 mCi) of [68Ga]Ga-α-MSH was administered. The SUVmax of the blood pool, liver, spleen, brain, kidney, soft tissue, and lung in [68Ga]Ga-α-MSH scans were 2.02 ± 0.17, 1.57 ± 0.29, 1.62 ± 0.17, 0.05 ± 0.02, 5.19 ± 0.85, 0.64 ± 0.16, and 0.88 ± 0.15, respectively. Primary lesions were detected in three patients, and recurrent lesions were seen in four patients (SUVmax of 4.11 ± 1.61). The mean SUVmax in primary/recurrent lesions was significantly higher than in the brain, lung, liver, spleen, and soft tissue (p = 0.000, p = 0.001, p = 0.044, p = 0.044, p = 0.000, respectively), while no significant difference was found between the primary/recurrent lesions and the blood pool or kidney. The kidney was revealed to be the target organ in [68Ga]Ga-α-MSH PET/CT scans. No significant difference was found in the mean standardized uptake values for the cervical, axillary, mediastinal, retroperitoneal, pelvic, lung, liver, and bone metastatic lesions between [18F]-FDG and [68Ga]Ga-α-MSH scans (p = 0.133, p = 0.510, p = 0.243, p = 0.506, p = 0.780, p = 0.846, p = 0.511, and p = 0.222, respectively). Due to the few intraperitoneal and soft tissue lesions, statistical comparison was not possible. Our findings indicate that [68Ga]Ga-α-MSH PET/CT can detect malignant melanoma lesions with a comparable tumor-to-background ratio to [18F]FDG PET/CT. Despite the promising performance of [68Ga]Ga-α-MSH in imaging melanoma lesions, its utility for theranostic purposes needs further evaluations in the future studies mainly due to its relatively elevated uptake in non-target organs such as blood pool and kidneys. © 2025 Elsevier B.V., All rights reserved.