iRadiology最新文献

Emerging stimuli-responsive composite probes active in the second near-infrared window (NIR-II, 1000–1700 nm) hold vast potential for improving in vivo imaging performance with minimized noise interference. The interactions among external irradiation, shell species, and the emissive core are key factors in the design of smart structures. The external irradiation provides energy for shell species and the emissive core to generate intense NIR-II fluorescence signals, while the energy transfer process hinders NIR-II emission in the inner structure of smart composite probes. However, if pathophysiological stimuli interrupt the above processes, then NIR-II fluorescence signals are recovered. This review covers NIR-II imaging based on diverse smart composite NIR-II fluorescent probes responding to various biological stimuli, including ONOO⁻, overexpressed reactive sulfur species, abnormally expressed enzymes, and abnormal levels of physiological metabolites. Finally, to appreciate these advances, the challenges and perspectives of stimuli-responsive composite NIR-II probes are highlighted.

Stabilized microbubbles were commercialized over 30 years ago for use as contrast agents in ultrasound imaging. In recent years, interest in microbubble–acoustic interactions has expanded to applications not only in ultrasound imaging but also in drug and gene delivery. To understand the interaction of a microbubble and ultrasonic field, scientists optically observe the behavior of microbubbles during acoustic excitation. Because of the fast oscillations of microbubbles in ultrasound fields, the application of ultra-high-speed photography is required to capture bubble behavior. This manuscript reviews the approaches, challenges, and progress in high-speed imaging systems utilized for microbubble analysis, focusing on innovations in camera technology.

The use of optical microscopy and labeling methods in intravital imaging allows for direct tracking of cell behavior and dynamic changes at the molecular level in the physiological or pathological microenvironment of living animals, revealing the spatiotemporal information of individual cells in the immune response. The liver is an immunological organ that contains unique innate and adaptive immune cells, including Kupffer cells (KCs) and different types of T cells, and is involved in coordinating multiple immune responses in the body. Using intravital imaging to visualize the movement behaviors and functions of immune cells during the reaction processes of the liver under physiological and pathological conditions has shed new light on the understanding of liver immunity, which is of great significance for the diagnosis and treatment of liver diseases. This review introduces various window models and labeling methods for the liver in intravital optical imaging and describes how it provides movement behavior and functional information about different types of immune cells, such as KCs and T cells, in the liver. Additionally, we highlight recent advances in intravital optical imaging of liver diseases, such as nonalcoholic fatty liver disease, infections, and tumors. This review aims to be a useful resource for comprehending the developments and achievements in intravital imaging of the liver and uncovering spatiotemporal information of immune response in a living microenvironment.

A 17-year-old female patient presented to the neurology department with a 3-month history of left limb numbness and spasm with transient loss of consciousness 3 weeks earlier. A brain MRI revealed a right temporal lobe mass (Figure 1a, arrow) with hypointensity on T1WI, hyperintensity on T2WI, and no diffusion restriction on DWI and ADC mapping. The lesion showed minimal tracer uptake on ¹⁸F-FDG PET (Figure 1b, solid arrowhead) but avid uptake on ¹¹C-MET PET with an SUVmax of 5.7 (Figure 1c, hollow arrowhead) with the contralateral normal tissue as a reference, suggesting a benign tumor other than inflammatory granuloma or malignant tumor. After conservative treatment with hormone and antiepileptic drugs, the patient's symptoms significantly improved. At the 3-month follow-up, the patient presented again with seizures of the left upper limb and transient loss of consciousness. She underwent mass excision in the neurosurgery department. Histopathology (Figure 1d) revealed a neoplasm with cords or trabeculae of small epithelioid to vacuolated cells embedded in a mucin-rich matrix, characteristic of chordoid meningioma (WHO grade 2), a rare type of meningioma [1-3. Immunostaining for SSTR-2 (Figure 1e), EMA, and PR showed strong reactivity in the tumor cells, and the MIB-1 labeling index was about 1%. Postoperative recovery was good, and no positive symptoms were found during a 5-year follow-up period [4]. This case report highlights the need to consider intracranial chordoid meningioma as a differential diagnosis when there is a discrepancy in the extent of tracer uptake on ¹¹C-MET and ¹⁸F-FDG PET [5, 6].

Leilei Yuan: Writing – original draft (Lead). Mengyan Zhang: Writing – original draft (Equal). Li Xu: Resources (Supporting). Xin Wang: Writing – original draft (Supporting). Qian Chen: Writing – review & editing (Supporting). Lin Ai: Writing – review & editing (Lead).

The authors declare no conflicts of interest.

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The first X-ray image of a human hand was taken by Wilhelm C. Röntgen. This achievement marked the beginning of modern medical imaging: Information within living bodies could be noninvasively visualized for the first time, bringing together radiology and medical imaging. Since then, new knowledge and advancements in this field have been rapidly emerging, with no sign of ever reaching a stopping point.

Supported by increasingly powerful computers, X-ray technologies such as computed tomography (CT) provide three-dimensional anatomical images with high resolution and great accuracy, making them the most important tools and gold standards in clinical diagnosis. Gamma rays and positron emissions generated by radionuclides represent other forms of radiation harnessed by clinical imaging, which have led to the development of Single Photon Emission Computed Tomography (SPECT) and Positron Emission Tomography (PET). These imaging modalities realize three-dimension functional and metabolic imaging noninvasively and are widely used in oncology as powerful diagnostic and research tools.

Optical imaging (OI) involves photons within the visible spectrum and surrounding regions (ultraviolet and near infrared). These radiations carry much lower energy, offering several advantages such as their nonionizing character, ease of use, and high spatial and temporal resolutions. OI operating within the second near infrared region represents another attractive research hotspot in the field of medical imaging. Its ability to achieve deep tissue penetration, combined with low biological background signal, supports broad clinical application. Imaging modalities such as Magnetic Resonance Imaging (MRI) and Ultrasound (US) have undergone important developments in recent years and have been widely used in soft tissue imaging. They have contributed irreplaceable and valuable information for condition assessment and medical decision-making.

Equipped with radioactive molecular probes, PET and SPECT are now progressing into a new era of medical imaging: molecular imaging. Unlike CT and related technologies that specialize in the presentation of anatomical information, molecular imaging can visualize biophysical activity in 3D at the molecular level with high resolution, greatly complementing traditional medical imaging. This methodology has played a significant role in many areas, such as clinical diagnosis, therapy monitoring, preclinical disease research, drug discovery, and drug development. Current research efforts are also being directed toward designing imaging probes for other medical imaging modalities, including CT, OI, MRI, and US. These technologies are being intensively investigated with the goal of broadening their use in molecular imaging, offering more imaging perspectives and dimensions. Molecular imaging is now one of the primary driving forces of current medical imaging research and is expected to advance the field in several key directions.