by ecancer reporter Janet Fricker

A new non invasive method for imaging glucose proved to be as effective as the current gold standard techniques ¹⁸FDG autoradiography in detecting tumours in mouse models, finds a study published in Nature Medicine.

The ability to probe glucose uptake by MRI without using radioactive tracers, the UK investigators believe, could offer substantial cost-savings and clinical benefits through reductions in radiation exposure. Raised glucose uptake is a hallmark of solid tumours.

GlucoCEST is a new technique that allows uptake of unlabeled glucose to be measured through the chemical exchange of protons between hydroxyl groups and water.

The technique utilizes two properties of hydroxyl protons: first, when exposed to magnetic fields, the magnetic moments of hydroxyl protons ‘precess’ at a different frequency as those of bulk tissue water and can therefore be selectively labelled using radiofrequency pulses.

Second, hydroxyl and water protons undergo exchange, thereby allowing magnetic labelling to be transferred from glucose to water and for glucose to be detected from the change in water signal in the MRI images.

“The CEST technique thus provides an amplification of detection by using the very large water signal rather than relying on the much smaller signal from glucose,” write the authors.

In the current study Simon Walker-Samuel and colleagues, from University College London Centre for Advanced Biomedical Imaging, compared glucoseCEST imaging to ¹⁸ FDG autoradiography in two subcutaneous human colorectal tumours xenografted on to mouse models.
The tumours LS174T and SW1222had markedly different phenotypes.

Results revealed that glucoCEST was sufficiently sensitive to allow the detection of millimolar changes in tumour hydroxyl group concentrations after injection.

“GlucoCEST could thus offer a viable alternative to FDG-PET, particularly as ¹⁸FDG is expensive to manufacture and necessarily has an associated radiation dose, which limits the ability to perform repeated, longitudinal measurements and can prohibit examination of certain patient populations (such as young children or pregnant women),” write the authors.

The investigators believe that the technique could be used for tumour detection, monitoring tumour progression and evaluating tumour responses to therapy.

Although the current study focused on tumours, the investigators anticipate that the technology could eventually be used to also detect Alzheimer’s disease or strokes.


Reference:

S Walker-Samuel, R Ramasawmyl, F Torrealdeal, et al. In vivo imaging of glucose uptake and metabolism in tumors. Nature Medicine. doi:10.1038/nm.3252