SPECT Imaging of Treatment-Related Tumor Necrosis Using Technetium-99m-Labeled Rhein

Purpose Noninvasive imaging of treatment-induced necrosis is important to distinguish early responders from patients resistant to the treatment plan, enabling the tailored-made therapeutic intervention. The purpose of this study was to explore the feasibility of [ 99m Tc]EDDA-HYNIC-2C-rhein for early assessment of tumor response to treatment. Procedures In vitro necrosis avidity of [ 99m Tc]EDDA-HYNIC-2C-rhein was evaluated in human lung cancer A549 cells treated with hyperthermia. Single photon emission–computed tomography/X-ray-computed tomography (SPECT/CT) imaging was performed in rats bearing subcutaneous W256 tumor treated with combretastatin A-4 disodium phosphate (CA4P) and rats bearing orthotopic liver W256 tumor treated with a single microwave ablation. All rats were euthanized immediately after the imaging session for biodistribution and histology studies. The mechanism of necrosis avidity for the tracer was further explored by in vivo blocking experiment and in vitro histochemistry and fluorescence staining. Results The uptake of [ 99m Tc]EDDA-HYNIC-2C-rhein in necrotic cells was significantly higher than that in viable cells ( p