Nanomed. Nanotechnol. Biol. Med. 10.1016/j.nano.2010.06.007 (2010)

Several imaging methods, such as mammography and magnetic resonance imaging, are used to detect cancer at present, but they lack sensitivity and are expensive. Thermography — a method that detects temperature differences on the skin surface when tumours are present — has been proposed for breast cancer, but has low sensitivity for deep and small tumours. Moreover, it is difficult to distinguish tumours from natural 'hot spots' that result from, for example, inflammation. Now Israel Gannot and co-workers at Tel Aviv University show that magnetic nanoparticles can mark tumours for improved detection using thermography.

The idea essentially relies on targeting magnetic nanoparticles to tumours using antibodies, and heating up the tumour using alternating magnetic fields. Changes in the skin temperature above the tumour are measured using an infrared camera and the data are processed using an algorithm to determine the presence of the tumour and estimate its location and depth. Gannot and colleagues tested this by embedding an electrical heat source in an aqueous gel, or by embedding an agar gel containing magnetic nanoparticles inside a piece of pig skin, to simulate a magnetically targeted tumour inside a tissue. The proposed algorithm detected the embedded tumour with high sensitivity but this depended on the tumour depth and the amount of power it emitted. Thermal power of 0.5 W (which is shown to be equivalent to a tumour of 0.5 mm) could be detected as deep as 14 mm below the tissue surface, suggesting potentially huge improvements compared with other methods of cancer detection.