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Radiolabeled hypoxic cell sensitizers: tracers for assessment of ischemia
Abstract:
Hypoxic, non-functional, but viable, tissue may exist in heart and brain following an arterial occlusion. Identification of such tissue in vivo is crucial to the development of effective treatment strategies. It has been suggested that certain compounds capable of sensitizing hypoxic tumor cells to killing by x-rays (i.e., misonidazole) might serve as in vivo markers of hypoxic tissue in ischemic myocardium or brain if properly radiolabeled. To this end we have radiolabeled two fluorinated analogs of nitroimidazole based hypoxic cell sensitizers with the 110 minute half-lived positron-emitting fluorine-18. The ability of these tracers to quantitate the presence of hypoxic tissue has been studied in a gerbil stroke model. The in vivo uptake of one of these tracers [F-18]-fluoronormethyoxymisonidazole is dependent on the extent of tissue hypoxia, and thus, appears to have potential as a diagnostic indicator of non-functional but viable tissue when the tracer is used in conjunction with positron emission tomography.
Insights
Researchers developed a new imaging tracer, [F-18]-fluoronormethyoxymisonidazole, to detect non-functional but viable hypoxic tissue in the brain and heart. This tracer shows potential for diagnosing conditions like stroke using positron emission tomography.
Area of Science:
- Biomedical Imaging
- Radiochemistry
- Neurology
Background:
- Hypoxic, non-functional, yet viable tissue can persist in the heart and brain after arterial occlusion.
- Identifying this tissue in vivo is critical for developing effective treatments for ischemic conditions.
- Radiolabeled hypoxic cell sensitizers, like misonidazole, are potential in vivo markers for such tissue.
Purpose of the Study:
- To radiolabel fluorinated analogs of nitroimidazole-based hypoxic cell sensitizers with fluorine-18.
- To evaluate the potential of these tracers for in vivo detection and quantification of hypoxic tissue.
- To assess the diagnostic utility of [F-18]-fluoronormethyoxymisonidazole in a gerbil stroke model.
Main Methods:
- Radiolabeling of two fluorinated nitroimidazole analogs with fluorine-18 (t½ = 110 minutes).
- In vivo study of tracer uptake in a gerbil stroke model to assess tissue hypoxia.
- Utilizing positron emission tomography (PET) for imaging and quantification.
Main Results:
- One tracer, [F-18]-fluoronormethyoxymisonidazole, demonstrated in vivo uptake that correlated with the extent of tissue hypoxia.
- The tracer's uptake was dependent on the degree of hypoxia, indicating its specificity.
- [F-18]-fluoronormethyoxymisonidazole showed potential as a diagnostic indicator for non-functional, viable tissue.
Conclusions:
- [F-18]-fluoronormethyoxymisonidazole is a promising radiotracer for identifying hypoxic tissue.
- This tracer, when used with PET, may aid in the diagnosis of ischemic conditions affecting the brain and heart.
- Further development could lead to improved diagnostic strategies for non-functional but viable tissue detection.