Multimodal PET/MRI Imaging Results Enable Monitoring the Side Effects of Radiation Therapy

The use of PET/MRI in radiotherapy

Positron emission tomography/magnetic resonance imaging (PET/MRI) is a hybrid imaging technique that quantitatively combines the metabolic and functional data from positron emission tomography (PET) with anatomical and physiological information from MRI. As PET/MRI technology has advanced, its applications in cancer care have expanded. Recent studies have demonstrated that PET/MRI provides unique advantages in the field of radiotherapy and has become invaluable in guiding precision radiotherapy techniques. This review discusses the rationale and clinical evidence supporting the use of PET/MRI for radiation positioning, target delineation, efficacy evaluation, and patient surveillance.Critical relevance statement This article critically assesses the transformative role of PET/MRI in advancing precision radiotherapy, providing essential insights into improved radiation positioning, target delineation, efficacy evaluation, and patient surveillance in clinical radiology practice.Key points• The emergence of PET/MRI will be a key bridge for precise radiotherapy.• PET/MRI has unique advantages in the whole process of radiotherapy.• New tracers and nanoparticle probes will broaden the use of PET/MRI in radiation.• PET/MRI will be utilized more frequently for radiotherapy.

A systematic review of normal tissue neurovascular unit damage following brain irradiation-Factors affecting damage severity and timing of effects

Background

Radiotherapy is key in the treatment of primary and secondary brain tumors. However, normal tissue is inevitably irradiated, causing toxicity and contributing to cognitive dysfunction. The relative importance of vascular damage to cognitive decline is poorly understood. Here, we systematically review the evidence for radiation-induced damage to the entire neurovascular unit (NVU), particularly focusing on establishing the factors that influence damage severity, and timing and duration of vascular effects relative to effects on neural tissue.

Methods

Using PubMed and Web of Science, we searched preclinical and clinical literature published between January 1, 1970 and December 1, 2022 and evaluated factors influencing NVU damage severity and timing of NVU effects resulting from ionizing radiation.

Results

Seventy-two rodents, 4 canines, 1 rabbit, and 5 human studies met inclusion criteria. Radiation increased blood-brain barrier (BBB) permeability, reduced endothelial cell number and extracellular matrix proteoglycans, reduced tight junction proteins, upregulated cellular adhesion molecule expression, reduced activity of glucose and BBB efflux transporters and activated glial cells. In the brain parenchyma, increased metalloproteinases 2 and 9 levels, demyelination, cell death, and inhibited differentiation were observed. Effects on the vasculature and neural compartment were observed across acute, delayed, and late timepoints, and damage extent was higher with low linear energy transfer radiation, higher doses, lower dose rates, broader beams, and in the presence of a tumor.

Conclusions

Irradiation of normal brain tissue leads to widespread and varied impacts on the NVU. Data indicate that vascular damage is in most cases an early effect that does not quickly resolve. More studies are needed to confirm sequence of damages, and mechanisms that lead to cognitive dysfunction.

The Application of Nucleic Acid Probe-Based Fluorescent Sensing and Imaging in Cancer Diagnosis and Therapy

It is well known that cancer incidence and death rates have been growing, but the development of cancer theranostics and therapeutics has been a challenging work. Recently, nucleic acid probe-based fluorescent sensing and imaging have achieved remarkable improvements in a variety of cancer management techniques, credited to their high sensitivity, good tolerance to interference, fast detection, and high versatility. Herein, nucleic acid probe-based fluorescent sensing and imaging are labeled with advanced fluorophores, which are essential for fast and sensitive detection of aberrant nucleic acids and other cancer-relevant molecules, consequently performing cancer early diagnosis and targeted treatment. In this review, we introduce the characteristics of nucleic acid probes, summarize the development of nucleic acid probe-based fluorescent sensing and imaging, and prominently elaborate their applications in cancer diagnosis and treatment. In discussion, some challenges and perspectives are elaborated in the field of nucleic acid probe-based fluorescent sensing and imaging.

A promising cancer diagnosis and treatment strategy: targeted cancer therapy and imaging based on antibody fragment

With the arrival of the precision medicine and personalized treatment era, targeted therapy that improves efficacy and reduces side effects has become the mainstream approach of cancer treatment. Antibody fragments that further enhance penetration and retain the most critical antigen-specific binding functions are considered the focus of research targeting cancer imaging and therapy. Thanks to the superior penetration and rapid blood clearance of antibody fragments, antibody fragment-based imaging agents enable efficient and sensitive imaging of tumour sites. In tumour-targeted therapy, antibody fragments can directly inhibit tumour proliferation and growth, serve as an ideal carrier for delivery of anti-tumour drugs, or manipulate the immune system to eliminate tumour cells. In this review, the excellent physicochemical properties and the basic structure of antibody fragments are expressly depicted depicted, the progress of antibody fragments in cancer therapy and imaging are thoroughly summarized, and the future development of antibody fragments is predicted.

Preclinical models of radiation-induced lung damage: challenges and opportunities for small animal radiotherapy

Despite a major paradigm shift in radiotherapy planning and delivery over the past three decades with continuing refinements, radiation-induced lung damage (RILD) remains a major dose limiting toxicity in patients receiving thoracic irradiations. Our current understanding of the biological processes involved in RILD which includes DNA damage, inflammation, senescence and fibrosis, is based on clinical observations and experimental studies in mouse models using conventional radiation exposures. Whilst these studies have provided vital information on the pulmonary radiation response, the current implementation of small animal irradiators is enabling refinements in the precision and accuracy of dose delivery to mice which can be applied to studies of RILD. This review presents the current landscape of preclinical studies in RILD using small animal irradiators and highlights the challenges and opportunities for the further development of this emerging technology in the study of normal tissue damage in the lung.