Up to now, the diagnosis of cancers depends mainly on in vitro detection procedures and such imaging techniques as ultrasonic imaging, X-ray photography, X-ray computed tomography, nuclear magnetic resonance imaging and positron emission tomography(PET), etc.. The determination and confirmation of cancers are relying on the morphology and other macroscopic characteristics of tumor tissues or ill cells, and this is usually an invasive and time-consuming process. Such procedure is definitely not suitable for early diagnostics of cancers. Aforementioned imaging techniques are difficult to find the symptom of cancers at molecular lever. Thus, the early-stage diagnosis of cancers remains an unprecedented challenge that doctors are facing. Optical imaging technolgies, especially fluorescence molecular imaging(FMI), possess advantages of harmlessness, nonivasiveness, super sensitivity and possibility for in vivo multi-targeting imaging and are believed to have the possibility to realize the diagnosis of cancers at molecular and cell levels. In this review, several important advances of FMI techniques working in the short-wavelength near infrared region are introduced and critically reviewed.
