Basic And Applied Research On Photoacoustic Imaging Technique In The Diagnosis Of Steosarcoma

Background : Osteosarcoma is one of the most common primary malignant tumors of the bone in the pediatric age group. More than 80% of these tumors tend to occur in the long bones of the appendicular skeleton, which undergo rapid growth and have poor prognosis. The two-year survival rate for patients has increased to 50 percent with the help of improvement of neoadjuvant chemotherapy and postoperative chemotherapy, the prerequisite of which is early diagnosis and proper treatment. However, the early diagnosis and proper treatment is very difficult because osteosarcoma has a wide variety of clinical and imaging manifestations. Photoacoustic imaging (PAI) is a new imaging technology and a potential ideal candidate for clinical biomedical imaging, which is a hybrid technique that combines the high intrinsic contrast of pure optical imaging with the high spatial resolution of pure ultrasound imaging. It has many advantages such as noninvasive, no radiation damage, easy to find small lesions in early stage and so on, which make PAI become one of the hottest research point in the field of biomedical imaging. It's significant for diagnosis and treatment of osteosarcoma that use PAI to detect osteosarcoma.Objective:To establish SD rat models of osteosarcoma, collect photoacoustic signal and reconstruct images of different stages of SD rat model of osteosarcoma using PAI technique. Photoacoustic signal of SD rat model of osteosarcoma was enhanced using gold nanorods and images were reconstructed. The feasibility of detecting osteosarcoma using PAI technique was explored by comparing photoacoustic images with pathological sections of SD rat model of osteosarcoma. Photoacoustic images with high intrinsic contrast and high spatial resolution were reconstructed which could detect osteosarcoma, and we want to create a new method to detect osteosarcoma in clinical medicine.Methods:The UMR-106 osteosarcoma cell line syngeneic to SD rats was cultured by conventional methods. Osteosarcoma model of SD rat was established by injecting osteosarcoma cell into rat leg directly. Photoacoustic imaging system was established and images of tumor of osteosarcoma model in different stages were reconstructed by photoacoustic imaging system. Then, gold nanorods were used to enhance photoacoustic sigal and the images of tumor of osteosarcoma model before and after the enhancement were reconstructed. At last, comparison was made between photoacoustic images with pathological sections of SD rat model of osteosarcoma.Results: The UMR-106 osteosarcoma cell line syngeneic to SD rats was cultured and SD rat model of osteosarcoma was established successfully. Photoacoustic images of tumor of osteosarcoma model in different stages were reconstructed successfully, too. And the reconstructed images are in keeping with pathological sections. Intrinsic contrast of photoacoustic signal of tumor area was enhanced obviously with the help of gold nanorods, so the abnormal photoacoustic signal could be found much earlier.Conclusion:In this study, we verified the feasibility of detecting osteosarcoma using PAI in vivo. The PAI technique has the advantages such as noninvasive, no radiation damage, high intrinsic contrast, high spatial resolution and so on. Photoacoustic signal of tumor area was higher obviously with the help of gold nanorods and a tinier tumor will be found earlier. The results suggest that PAI has the potential clinical application for detecting osteosarcoma in the early stage.