Molecular imaging is a new discipline that combines medical imaging technology with molecular biology, chemistry, physics, radiology, nuclear medicine and computer science. The concept of molecular imaging (MI) was first introduced, i.e., the application of imaging methods to the qualitative and quantitative study of biological processes at the cellular and molecular levels in living organisms. It mainly uses specific molecules in vivo as the source of imaging contrast, and uses some existing medical imaging techniques to image the internal physiological or pathological processes of the human body at the molecular level in a non-invasive, real-time manner. It integrates genetic genetic information, biochemistry and new imaging probes, which are detected by sophisticated imaging techniques, and then through a series of image post-processing techniques, it achieves the purpose of displaying biological processes at the molecular and cellular levels in living tissues. Significance In diagnosis, by imaging key marker molecules in the process of tumorigenesis, a series of pathophysiological changes and characteristics of the disease can be directly observed in vivo, such as the cause, occurrence and development of the disease, rather than just showing the anatomical changes at the end of the disease. In terms of drug development, by designing specific probes, we can directly display the molecular changes of drug therapeutic targets in vivo, and by establishing a high-energy imaging analysis system, we can greatly accelerate the screening and development of drugs. In addition, we can also observe the efficiency of the target gene expression in vivo and directly evaluate the efficacy. The main applications are in oncology, cardiovascular disease, and neurology. Imaging principle Molecular imaging integrates molecular biochemistry, data processing, nanotechnology, image processing and other technologies, and can truly provide qualitative, localized and quantitative information for clinical diagnosis in the future because of its high specificity, high sensitivity and high resolution of images. It is thus clear that molecular imaging is no longer a single technological change, but an integration of various technologies. There are three key elements of molecular imaging technology, the first is a highly specific molecular probe, the second is a suitable signal amplification technology, and the third is a detection system that can sensitively obtain high-resolution images. It integrates genetic information, biochemistry and new imaging probes into the human body, which is used to label the “target” (another molecule) under study, and through molecular imaging technology, the “target” is amplified and detected by sophisticated imaging technology, and then through a series of image post-processing techniques, the “target” is amplified and detected. A series of image post-processing techniques are used to show the biological processes at the molecular and cellular levels in living tissues for subclinical diagnosis and treatment of diseases. Technical Difficulties The most commonly used molecular imaging techniques are nuclear medicine imaging techniques, especially PET molecular imaging research is the most dynamic. In addition, MR imaging and MR spectroscopy (MRS), optical imaging, and infrared optical tomography are also widely used, and each of these imaging techniques has its own advantages and disadvantages. In terms of gene therapy alone, there are many unanswered questions: Is gene transfer or transfection successful? Is the transduced or transfected gene distributed to the target organ or tissue, and is its distribution optimal? Is transgene expression within the target organ or target tissue sufficient to produce a therapeutic effect? Are the transduced or transfected genes localized to other organs or tissues at sufficiently high levels to induce unanticipated toxic responses? What is the optimal timing of transgene expression when acting in combination with a precursor drug and the optimal timing for initiating treatment with the precursor drug? How long can transgene expression persist in the target tissue or organ? Interdisciplinary collaboration It is also because various imaging techniques have their own advantages and disadvantages and various difficulties, therefore, interdisciplinary and multi-faceted intersection and collaboration are often required, which requires both the life sciences to raise urgent problems from the molecular level and the development of theories and technologies adapted to molecular imaging research in physics, chemistry, biomaterials, informatics and other disciplines and applied to the field. At the same time, it needs to be combined with contemporary cutting-edge nanoscience technologies. However, the lack of multidisciplinary cooperation has become a bottleneck that hinders the development of molecular imaging, especially the lack of communication and cooperation with related disciplines such as biology, chemistry, physics, engineering, and computing. For example, the design and preparation of molecular probes as well as the characterization and analysis require close cooperation with relevant experts in bioengineering and biochemistry. Therefore, the interdisciplinary experts should first sit together and look for targets of common interest, which have clinical significance as well as a preexisting basis; common interests, e.g., MRI, CT, PET, ultrasound; and should focus on certain aspects, e.g., antibodies. Secondly, in order to improve the efficiency of collaborative research a fixed research group should be formed, with a clear division of responsibilities and a clear time frame. Then the second is the financial guarantee. And the respective focus of the co-published articles, etc. Do all of the above require a written agreement? It is possible to move forward better after sorting this out, otherwise it is not efficient. A key issue in molecular imaging is how to objectively evaluate the effects of delivery and expression, especially in vivo (animal or human) for evaluation. Current methods for showing gene expression are divided into two main categories: invasive as well as non- or less invasive. If specific molecules or (and) genes are to be imaged in vivo, four necessary prerequisites must be met: a high-affinity probe that has a reasonable pharmacokinetic behavior in vivo; these probes can penetrate biological metabolic barriers, such as blood vessels, mesenchymal tissue, cell membranes, etc.; chemical or biological methods of signal amplification; and sensitive, rapid, high-resolution imaging techniques. Prospect So far, the development of imaging medicine has gradually formed 3 main camps: classical medical imaging: mainly X-ray, CT, MR, ultrasound imaging, etc., showing human anatomical structures and physiological functions; interventional radiology as the main therapeutic camp; molecular imaging: mainly MR, PET, optical imaging and small animal imaging equipment, etc., which can be used for imaging at the molecular level. The three are closely linked as a whole, corroborating and collaborating with each other, relying on interventional radiology to enable the target gene to reach the target site more accurately, and through molecular imaging equipment to directly display the therapeutic effect and gene expression. Molecular imaging has contributed to the development of imaging medicine and is closely linked to traditional medical imaging. Several medical device manufacturers have thus developed products, such as Siemens’ Biograph 16 TruePoint (positron emission and computed tomography system), fusion imaging systems, and cutting-edge application software that enable researchers to identify specific biological processes, monitor the potency of compounds, and measure disease progression in real time, facilitating basic research and drug development efforts that Enabling imaging medicine to move from the study of traditional anatomy and physiological function to imaging at the molecular level to explore changes in disease at the molecular level will have a profound impact on the formation of new medical models and human health. Molecular imaging concepts Molecular imaging versus traditional imaging Since the invention of X-ray, the development of medical imaging technology has gone through roughly three stages: structural imaging, functional imaging, and molecular imaging. The advent of medical imaging technologies (including structural imaging and functional imaging) and modern medical imaging devices (e.g., computed tomography CT, magnetic resonance imaging MRI, computerized X-ray imaging PET, ultrasound) has revolutionized traditional medical diagnosis. However, with the completion of human genome sequencing and the advent of the post-genomic era, there is an urgent need to explore the mechanism of disease (especially malignant diseases) development at the cellular, molecular, and genetic levels, and to monitor the production of lesions before the appearance of clinical symptoms, so as to achieve early warning and treatment of diseases and improve the effectiveness of disease treatment. Therefore, in 1999, Weissleder et al. of Harvard University introduced the concept of Molecular Imaging: the application of imaging methods for the qualitative and quantitative study of biological processes at the cellular and molecular levels in the living state. It is a medical imaging technique that uses specific molecules in vivo as imaging contrast, and can directly display physiological and pathological processes at the cellular or molecular level through images in real, intact human or animal bodies. It bridges the interconnection between molecular biology and clinical medicine, and has been named by the American Medical Association as one of the ten most promising frontiers of medical science for the future, the medical imaging of the 21st century. The advantages of molecular imaging can be summarized as three points: first, molecular imaging technology can turn complex processes such as gene expression and biological signaling into visual images, enabling a better understanding of disease mechanisms and characteristics at the molecular cellular level; second, it can detect molecular cellular variation and pathological change processes in the early stages of disease; third, it can continuously observe the mechanism and Third, the mechanism and effect of drug or gene therapy can be continuously observed in vivo. Usually, there are two methods for detecting human molecular cells: ex vivo and in vivo, and the advantage of molecular imaging technology as an in vivo detection method is that it can obtain three-dimensional images of human molecular cells continuously, rapidly, at a long distance and without damage. It can reveal the early molecular biological characteristics of lesions, promote the early diagnosis and treatment of diseases, and also introduce new concepts for clinical diagnosis.