Technetium and Gallium Derived Radiopharmaceuticals: Comparing and Contrasting the Chemistry of Two Important Radiometals for the Molecular Imaging Era

Bartholomä, Mark; Louie, Anika S.; Valliant, John F.; Zubieta, Jon

doi:10.1021/cr1000755

Cited by 279 publications

(265 citation statements)

References 249 publications

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“…As newer radiotracers are developed that target specific receptors, chelation of 99m Tc into small molecules or peptides still poses challenges in chelator and pharmacophore size, affecting the overall affinity and clearance. In a review of chelators for technetium and gallium radiotracers [81], recommendation was made for a design strategy that takes into account the fundamental coordination chemistry of technetium and factors such as coordination preferences, robust core structures and ligand selection as these are critical to creating effective radiotracers. For SPECT to continue to be the modality of choice, better radiotracer design has to be combined with improvements in hardware to improve image quality.…”

Section: Discussionmentioning

confidence: 99%

Radiotracers for SPECT imaging: current scenario and future prospects

Adak¹,

Bhalla²,

Raj³

et al. 2011

Radiochimica Acta

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Summary. Single photon emission computed tomography (SPECT) has been the cornerstone of nuclear medicine and today it is widely used to detect molecular changes in cardiovascular, neurological and oncological diseases. While SPECT has been available since the 1980s, advances in instrumentation hardware, software and the availability of new radiotracers that are creating a revival in SPECT imaging are reviewed in this paper.The biggest change in the last decade has been the fusion of CT with SPECT, which has improved attenuation correction and image quality. Advances in collimator design, replacement of sodium iodide crystals in the detectors with cadmium zinc telluride (CZT) detectors as well as advances in software and reconstruction algorithms have all helped to retain SPECT as a much needed and used technology.Today, a wide spectrum of radiotracers is available for use in cardiovascular, neurology and oncology applications. The development of several radiotracers for neurological disorders is briefly described in this review, including [123 I]FP-CIT (DaTSCAN™) available for Parkinson's disease. In cardiology, while technetium-99m labeled tetrofosmin and technetium-99m labeled sestamibi have been well known for myocardial perfusion imaging, we describe a recently completed multicenter clinical study on the use of [ 123 I]mIBG (AdreView™) for imaging in chronic heart failure patients. For oncology, while bone scanning has been prevalent, newer radiotracers that target cancer mechanisms are being developed. Technetium-99m labeled RGD peptides have been reported in the literature that can be used for imaging angiogenesis, while technetium-99m labeled duramycin has been used to image apoptosis.While PET/CT is considered to be the more advanced technology particularly for oncology applications, SPECT continues to be the modality of choice and the workhorse in many hospitals and nuclear medicine centers. The cost of SPECT instruments also makes them more attractive in developing countries where the cost of a scan is still prohibitive for many patients.

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Section: Discussionmentioning

confidence: 99%

Radiotracers for SPECT imaging: current scenario and future prospects

Adak¹,

Bhalla²,

Raj³

et al. 2011

Radiochimica Acta

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“…The reaction kinetics for the incorporation of Ga 3+ is inversely related to pH [65]. The complexation of Ga 3+ by DOTA shows slow kinetics because of its cavity size and eight donor atoms.…”

Section: Ga For Manymentioning

confidence: 99%

Radiolabeled Dendrimers as Potential PET Agents for Molecular Imaging of Tumor Angiogenesis

Ghai¹,

Singh²,

Chopra³

et al. 2018

Dendrimers - Fundamentals and Applications

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Introduction: Angiogenesis is a normal physiological process that plays an imperative role during tumor development. We believe that the development of a non-invasive imaging technique targeting angiogenesis can provide a better understanding of this important process. Positron emission tomography (PET) -a highly sensitive imaging technique can offer accurate degree of disease quantification. The phenomenon of enhanced permeability and retention effect (EPR effect) is now becoming the gold standard in cancer targeting drug designing. Dendrimers have the ability to exhibit EPR effect for targeted therapeutic/drug delivery approach. Therefore, molecular imaging of tumor angiogenesis using radio-labeled dendrimers is expected to broaden the possibilities for drug development. Body:In the present chapter, the significance of performing conjugation chemistry of bifunctional chelators quality control parameters of the radiolabeled dendrimer conjugates in vitro stability, animal biodistribution, radiation dosimetry and molecular imaging of animal tumor model after injecting radiotracer have also been discussed in detail. Conclusion:Conjugation of the radio-metal complexes to larger molecules like dendrimers has created a new domain of research in the field of biomedical applications. Therefore, it has been proposed to develop new effective targeting moieties suitable for radiolabeling with PET tracers so as to perform molecular imaging studies.

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“…In aqueous solution, gallium complexes predominantly exist in the third oxidation state (Ga 3+ ) [91]. Oxidation and reduction of Ga 3+ do not occur under physiological conditions, but in the 3-7 pH range; hydrolysis can lead to precipitation of Ga(OH)3, which dissolves at pH>7 as [Ga (OH)4] -.…”

Section: Gallium Nitroimidazole Complexesmentioning

confidence: 99%

Bifunctional Metal – Nitroimidazole Complexes for Hypoxia Theranosis in Cancer

Ricardo¹,

Kumar²,

Wiebe³

2015

J Diagn Imaging Ther

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Oxygen supply -demand imbalances can render proliferating cells acutely or chronically hypoxic. In cancer cells, hypoxia-induced pathophysiological changes give rise to genetic changes that lead to treatment-resistant, aggressive phenotypes. The reduced curability of hypoxic tumours by radiotherapy is one of consequent challenges, but their hypoxia also offers unique, exploitable properties. Nitroimidazoles, for example, capitalize on oxygen-sensitive reductive activation to achieve hypoxiaselective localization for theranostic consequence. The discovery of 2-nitroimidazole (azomycin) heralded the development of many drugs, including effective radiosensitizers of hypoxic cells. These electron-affinic, reductively bioactivated nitroheterocyclics undergo initial oxygen-reversible, enzymatic one-electron reductions that lead to the formation of molecular adducts that impair vital

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Technetium and Gallium Derived Radiopharmaceuticals: Comparing and Contrasting the Chemistry of Two Important Radiometals for the Molecular Imaging Era

Cited by 279 publications

References 249 publications

Radiotracers for SPECT imaging: current scenario and future prospects

Radiotracers for SPECT imaging: current scenario and future prospects

Radiolabeled Dendrimers as Potential PET Agents for Molecular Imaging of Tumor Angiogenesis

Bifunctional Metal – Nitroimidazole Complexes for Hypoxia Theranosis in Cancer

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