SPECT Imaging of Melanoma Using a ^99mTc-Labeled Melanin-Targeted Probe

Melanoma is a highly aggressive cutaneous malignancy characterized by a poor clinical prognosis, making early and accurate detection paramount for patient survival. Melanin, abundantly expressed in most melanoma lesions, serves as an ideal and highly specific biomarker for targeted molecular imaging. While various imaging modalities exist, single-photon emission computed tomography (SPECT) provides a highly accessible and cost-effective strategy for widespread clinical translation. From our recent studies, ^99mTc-SMIC-4006 emerged as the optimal ^99mTc-labeled radiotracer, demonstrating exceptional radiochemical purity, highly specific melanin binding, and superior tumor-to-blood contrast in B16F10 melanoma xenografts. Herein, we describe the detailed radiosynthesis protocol for ^99mTc-SMIC-4006, alongside comprehensive procedures for its in vitro property evaluation and in vivo SPECT/CT imaging in preclinical melanoma models.