Towards Photoswitchable Contrast Agents for Absolute 3D Temperature MR Imaging. Issue 15 (3rd March 2021)

• Record Type: Journal Article
• Authors: Wellm, Vanessa; Groebner, Jens; Heitmann, Gernot; Sönnichsen, Frank D.; Herges, Rainer
• Is Part Of: Angewandte Chemie international edition. Volume 60:Issue 15(2021)
• Page Start: 8220
• Page End: 8226
• Publication Date: 2021-03-03
• Subjects: azo compounds -- contrast agent -- photoswitches -- porphyrinoids -- temperature MRI; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.202015851
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: Temperature can be used as clinical marker for tissue metabolism and the detection of inflammations or tumors. The use of magnetic resonance imaging (MRI) for monitoring physiological parameters like the temperature noninvasively is steadily increasing. In this study, we present a proof‐of‐principle study of MRI contrast agents (CA) for absolute and concentration independent temperature imaging. These CAs are based on azoimidazole substituted Ni II porphyrins, which can undergo Light‐Driven Coordination‐Induced Spin State Switching (LD‐CISSS) in solution. Monitoring the fast first order kinetic of back isomerisation ( cis to trans ) with standard clinical MR imaging sequences allows the determination of half‐lives, that can be directly translated into absolute temperatures. Different temperature responsive CAs were successfully tested as prototypes in methanol‐based gels and created temperature maps of gradient phantoms with high spatial resolution (0.13×0.13×1.1 mm) and low temperature errors (<0.22 °C). The method is sufficiently fast to record the temperature flow from a heat source as a film. Abstract : Temperature is a clinical marker for tissue metabolism and can be used for the detection of diseases. Besides intrinsic magnetic resonance (MR) methods for relative temperature changes, there are only limited methods for absolute temperature imaging. In this study we present an in vitro method with a photoswitchable contrast agent for absolute and concentration independent 3D temperature imaging.