The sensitivity of various imaging techniques can be compared by considering the cross section required to observe light scattering. In Raman spectroscopy, the intensity, /, (in photons/s/cm2) of scattered light for a molecule is proportional to the scattering cross section per molecule and the intensity of the incident light l0, according to the relation / = OR l0. For Raman spectroscopy, OR is between 10-29 and 10-32 cm2, while the equivalent fluorescence and optical absorption cross sections are on the order of 10-19 to 10-18 and 10-29 to 10-32 cm2, respectively. There are therefore approximately more than twelve orders of magnitude difference between the relative efficiencies of the Raman process and those of optical absorption or fluorescence. Raman spectroscopy benefits, however, from higher laser intensities than optical absorption and fluorescence, which compensate for the low efficiency of the scattering process to make this analytical technique more accessible. Nevertheless, the low sensitivity remains a problem for Raman imaging. In addition, the use of high intensity excitation lasers can alter the samples being examined due to localized heating. In such cases, the acquisition of a Raman image is done by sweeping the light-emitting probe point by point with a reduced intensity to avoid the heating, which makes the acquisition time-consuming and inefficient. Being much more sensitive, fluorescence and absorption/reflection have been heretofore the techniques of choice for optical imaging. Under specific conditions, certain molecules exhibit an increased Raman sensitivity. Nowadays, with the recent advances in lasers, detectors and Raman instrumentation, a cross section of about 10-21 is required to detect single objects. The graph below lists different phenomena and their corresponding Raman sensitivity. A π-conjugated molecule such as rodhamine 6G has a cross section of 10-24 cm2, which is still too low for single object detection. Carbon nanotubes and SERS nanoparticles are known for their efficient Raman scattering properties and are often used in Raman imaging. The dyes@SWNT Raman labels are novel hybrid nanomaterials that also exhibit amplified Raman scattering with sensitivities that make single object detection possible.