Monday, July 6, 2009

Detecting cancer with MRI based pH imaging

It is known that cancerous tumours tend to exhibit acidic pH levels. In fact the urine of patients with advanced cancer can be extremely acidic. It is plausible that the acidity of cancerous tissues is detectable via MRI when the tumour is still very small.

I have found three studies that have looked at measuring pH levels with MRI with the help of a contrast agent [1,2,3]. However, these studies were not applying the technique to the detection of cancer. Since we know of the potential acidity of malignant lesions, using pH sensitive contrast agents (or similar techniques) seems like a good research avenue for the detection of cancer.

Furthermore, it would be interesting to see how effective targeted delivery of a basic solution (to raise the pH level of the tumour), can assist in cancer treatment. Targeted drug delivery is an interesting area of research that can be guided with a variety of imaging techniques.

[1] S. Evans, L. Hall, “Evaluation of a range of MRI-active pH indicators using a multiple-sample method,” AIChE, vol. 51(5), 2005.
[2] K.-E. Lokling, et al., “pH-sensitive paramagnetic liposomes as MRI contrast agents: in vitro feasibility studies,” Magnetic Resonance Imaging, vol. 19(5), 2001.
[3] N. Raghunand, et al., “Renal and systemic pH imaging by contrast-enhanced MRI,” Magnetic Resonance in Medicine, vol. 49(2), 2003.

I found a study published in Nature in 2008 that looks at this problem by performing pH imaging using a tagged form of baking soda (which can also apparently be used to treat a tumour as my wife has posted in the comments section). I wonder if the aforementioned [1,2,3] contrast agents would be helpful in this problem, or if techniques like the one published in Nature can be used for treatment as well as detection.