Cerenkov radiation, visible as emitted optical photons, is produced when a charged particle moves faster than the speed of light in the medium within which it travels. This phenomenon is what produces the ‘blue glow’ seen emanating from a nuclear reactor shielded by water. Cherry and colleagues published work in 2009 demonstrating the ability to detect measureable light emitted from animals administered B-emitting radionuclides, such as those routinely used for positron emission tomography, using a sensitive CCD camera. Interestingly, the dose of injected activity required to produce a detectable signal is consistent with that required for small animal molecular imaging applications. Cerenkov radiation is produced continuously from the near ultraviolet range through the visible, but occurs mainly in the blue wavelengths of light. Thus in the case of in vivo imaging applications, the emitted photons are subject to significant attenuation by tissue. This type of imaging has been coined Cerenkov luminescence imaging (CLI) and applications for its use are the subject of ongoing investigation.

In the current study by Kothapalli et al, the feasibility of using Cerenkov luminescence imaging for endoscopic imaging applications is investigated. Due to the strong tissue attenuation of Cerenkov light, noninvasive imaging applications are limited to superficial sites. The ability to detect Cerenkov luminescence through an endoscope or laparoscope would greatly extend tissue accessibility. The work published here is focused on development of a preliminary system consisting of fiber optics coupled with a sensitive CCD camera for detection of low light levels. Tissue phantom experiments were completed using different types of fiber optics to determine the most optical Cerenkov detection instrumentation, where the fiber optic with the largest diameter (6 mm) gave the best signal detection. Fiber optics of this size are consistent with the design of current clinical endoscopes and detection could be further improved by use of specialized fiber optics of similar diameter with high light transmission efficiency in the visible wavelengths. Using the preliminary setup, the authors also demonstrate the ability to detect Cerenkov luminescence emanating from mouse organs such as liver, kidney, heart, brain, muscle, and subcutaneously implanted tumors one hour after intravenous administration of fluorodeoxyglucose. From these preliminary studies, endoscopic imaging of Cerenkov luminescence appears to be a promising tool warranting further investigation.

---

---

 Add Comment

You must log in to add comments.