Using a high-speed drill, a 1 mm burr opening of the skull was made in the right hemisphere, anterior to the coronal fissure. labeled 2-DG, IRDye800CW 2-DG. Real-time whole body images acquired immediately after i.v. infusion clearly visualized the near-infrared dye circulating into numerous internal organs sequentially. Dynamic fluorescence imaging exposed significantly higher signal intensity in the tumor part of the brain than the contralateral normal mind 24 h after injection (tumor/normal percentage, TNR = 2.80.7). Actually stronger contrast was achieved by eliminating the scalp (TNR = 3.71.1) and skull (TNR = 4.21.1) of the mice. In contrast, a control dye, IRDye800CW carboxylate, showed little difference (1.10.2).Ex lover vivofluorescence imaging performed about ultrathin cryosections (20 m) of tumor bearing whole mind revealed distinct tumor margins. Microscopic imaging recognized cytoplasmic locations of the 2-DG dye in tumor cells. == Summary and Significance == Our results suggest that the near-infrared dye labeled 2-DG may serve as a useful fluorescence imaging probe to noninvasively assess intracranial tumor burden in preclinical animal models. == Intro == Glioblastoma multiform (GBM) is definitely a lethal intracranial malignancy, which exhibits a relentless malignant progression and is highly resistant to standard multimodal therapies. GBM is characterized by the nature of considerable infiltration into surrounding normal brain cells, which results in incomplete tumor resection and consequent recurrence[1],[2]. It is imperative to improve diagnostic imaging to evaluate intracranial tumor growth and therapeutic reactions. Optical imaging has been rapidly adapted to malignancy study. Recently, optical imaging using fluorescent dye labeled tumor-specific molecules has been successfully applied to imaging glioma in preclinical animal models based on overexpression of such markers in glioma[3][5]. In the medical center, several recent studies have demonstrated the ability of fluorescence imaging to facilitate radical Timegadine resection of GBM during surgery[6][8]. Promising results reported by Stummer,et al.have shown that gross total resection of glioma guided by intraoperative fluorescence imaging is definitely associated with improved prognosis of the patients having a median survival of 1518 weeks, compared to 1012 weeks after a subtotal resection Timegadine or about 6 months after biopsy alone[8]. It is well recognized that malignancy cells exhibit highly elevated glucose rate of metabolism and up-regulated glucose transporters (GLUTs) compared to non-tumor cells. On this basis,18FDG, the THSD1 glucose analogue, has been used as the most common PET radiotracer to visualize medical tumors and their metastases. However, a drawback of18FDG PET for mind tumors is strong background signals of normal brain tissues, which often compromise the ability to diagnose the brain tumors. Moreover, PET Timegadine has a low spatial resolution in spite of high level of sensitivity. Optical imaging by visualizing fluorescently labeled tumor cells has recently emerged as a good approach to facilitate recognition of infiltrative tumors and sentinel lymph node metastases[9][14]. Alternative to radioactive deoxyglucose, fluorescent derivatives of 2-DG,e.g., 2-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino]-2-deoxy-D-glucose (2-NBDG) have shown a greater inclination to be delivered and caught in tumor cells[15],[16]. However, the short wavelength of 2-NBDG (excitation, 475 nm; emission, 550 nm) limits its applications forin vivoimaging. Near infrared fluorescence offers several advantages over the use of visible fluorophores including deeper penetration due to less cells absorption and scattering of light, and minimal autofluorescence. IRDye800CW 2-DG (Li-Cor Bioscience), a NIR dye conjugated with 2-deoxyglucose (maximum excitation 785 nm, emission 810 nm), has recently been developed and shown like a tumor-targeting optical contrast agent in various tumors implanted subcutaneously in mice, which can be visualizedin vivoby fluorescence imaging[17],[18]. Moreover, a recent study of pharmacokinetics has shown that there is essentially no retention of the dye in normal mouse mind 24 h after injection[19]. Timegadine Thus, the 2-DG NIR dye may serve as an ideal contrast agent for optically imaging mind tumors. In this study, we 1st applied bioluminescence imaging (BLI) and MRI to assess non-invasively intracranial tumor growth in an orthotopic glioma model in nude mice. We then exploited IRDye800CW 2-DG for dynamicin vivoimaging of these mind tumors.In vivoobservations were validated by bothex vivofluorescence imaging of cryosections of tumor bearing brain cells and histological staining. Finally, fluorescence microscopic studies were performed to identify locations of the 2-DG dye in tumors and normal brain. == Results == Immunohistochemical study showed extensive manifestation of luciferase in the U87-luc cells of intracranial tumor cells (Fig. 1A). Longitudinal BLI studies exposed a fragile transmission in the beginning 11 days after tumor implantation, which became stronger on follow-up to day time 24 (Fig. 1B). The mean light intensity detected on day time 24 for the group of tumor bearing mice was significantly greater than on day time 11 (16107versus 11106photons/s; p<0.05). MRI studies based on T2-weighted and T1-weighted contrast enhanced images confirmed an intracranial tumor located in the right part of the brain of each animal (Fig. 1C). A significant correlation was found between BLI transmission and actual tumor volume measured by MRI (r.