Nichtinvasive funktionelle Lungenbildgebung mit hyperpolarisiertem Xenon: Durchbruch für die Diagnostik?

BACKGROUND: Magnetic resonance imaging (MRI) is a noninvasive technique that provides excellent contrast for soft tissue organs. However, due to the low density of protons and many air–tissue junctions, its application in the lung is limited. Thus, X‑ray-based methods are often used here (with the well-known disadvantages of ionizing radiation). OBJECTIVES: In this review, we discuss pulmonary MRI with hyperpolarized xenon-129 (Xe-MRI). Xe-MRI provides unique valuable insights into lung microstructure and function, including gas exchange with red blood cells—parameters not accessible by any standard clinical methods. METHODS: By magnetic labelling, i.e. hyperpolarization, the signal from xenon-129 is amplified by up to 100,000 times. In this process, electrons from rubidium are first polarized to 100% using laser light and then transferred to xenon by collisions. Then the hyperpolarized gas is brought to the patient in a bag and inhaled shortly before the MRI scan. RESULTS: Using special programming (sequences) of the MRI, the ventilation, microstructure, or gas exchange of the lungs, can be displayed in 3D. This allows, for example, quantitative visualization of ventilation defects, alveolar size, tissue gas uptake and gas transfer to the blood. CONCLUSIONS: Xe-MRI provides unique information about the state of the lung—noninvasively, in vivo and in less than a minute.