[Hyperpolarized 13C magnetic resonance imaging-a window into metabolism : High-resolution images of human metabolism]. / Hyperpolarisierte 13C­Magnetresonanztomographie ­ ein Fenster in den Stoffwechsel : Hochauflösende Darstellung des humanen Metabolismus.

CLINICAL ISSUE: Despite being one of the main pillars of modern diagnostics, magnetic resonance imaging (MRI) uses only a tiny fraction of its potential: no more than a millionth of all nuclear spins contribute to the MRI signal. In order to increase this fraction, called polarization, MRI scanners with stronger magnetic fields are being developed. However, even the most modern scanners do not exploit the potential of MRI. METHODOLOGICAL INNOVATIONS: To make full use of this potential, hyperpolarized MRI (HP-MRI) is an excellent tool: quantum mechanical tricks can be used to generate contrast agents whose nuclear spins can deliver a MRI signal that is up to a 100,000 times stronger. This signal enhancement allows imaging of in vivo processes that would be otherwise impossible to measure. It is particularly interesting to introduce these magnetically labeled nuclei into metabolic processes so that the metabolism can be investigated non-invasively and in vivo. PERFORMANCE: Small but diagnostically important changes in metabolism could be found before macroscopic tissue changes were otherwise visible. High-resolution images can be acquired within a few 100 ms, enabling metabolic monitoring in real-time. Heart, brain, and prostate are among the organs that have already been investigated in over 90 clinical trials using this emerging technology. ACHIEVEMENTS: So far, displaying tissue in a similar manner was only possible using nuclear medicine, e.g., positron emission tomography (PET) utilizing radionuclides and without resolution of various metabolic steps. A change in tumor metabolism following treatment was shown within hours in HP-MRI. These applications coupled with background information about the technology are the subject of this review.

Performance and reproducibility of 13C and 15N hyperpolarization using a cryogen-free DNP polarizer.

The setup, operational procedures and performance of a cryogen-free device for producing hyperpolarized contrast agents using dissolution dynamic nuclear polarization (dDNP) in a preclinical imaging center is described. The polarization was optimized using the solid-state, DNP-enhanced NMR signal to calibrate the sample position, microwave and NMR frequency and power and flip angle. The polarization of a standard formulation to yield ~ 4 mL, 60 mM 1-13C-pyruvic acid in an aqueous solution was quantified in five experiments to P(13C) = (38 ± 6) % (19 ± 1) s after dissolution. The mono-exponential time constant of the build-up of the solid-state polarization was quantified to (1032 ± 22) s. We achieved a duty cycle of 1.5 h that includes sample loading, monitoring the polarization build-up, dissolution and preparation for the next run. After injection of the contrast agent in vivo, pyruvate, pyruvate hydrate, lactate, and alanine were observed, by measuring metabolite maps. Based on this work sequence, hyperpolarized 15N urea was obtained (P(15N) = (5.6 ± 0.8) % (30 ± 3) s after dissolution).

[Noninvasive functional lung imaging with hyperpolarized xenon : Breakthrough for diagnostics?] / 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, X­ray-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.

Imaging Inflammation - From Whole Body Imaging to Cellular Resolution.

Imaging techniques have evolved impressively lately, allowing whole new concepts like multimodal imaging, personal medicine, theranostic therapies, and molecular imaging to increase general awareness of possiblities of imaging to medicine field. Here, we have collected the selected (3D) imaging modalities and evaluated the recent findings on preclinical and clinical inflammation imaging. The focus has been on the feasibility of imaging to aid in inflammation precision medicine, and the key challenges and opportunities of the imaging modalities are presented. Some examples of the current usage in clinics/close to clinics have been brought out as an example. This review evaluates the future prospects of the imaging technologies for clinical applications in precision medicine from the pre-clinical development point of view.