Funktionelle Magnetresonanzbildgebung des Verdauungstrakts: Klinische Anwendungsmöglichkeiten?

Zusammenfassung: Die Magnetresonanztomographie (MRT) stellt eine vielseitige bildgebende Methode in der Medizin dar, für welche ein Spektrum neuer diagnostischer Optionen entwickelt wurde. Neben der in der klinischen Praxis etablierten Darstellung von Organstrukturen, wird die MRT zunehmend zur Bildgebung humaner Organfunktionen wie zum Beispiel des Herzen und des zentralen Nervensystems herangezogen. Der Einsatz zur funktionellen Bildgebung des Verdauungstrakts ist neuartig und erfolgt an wenigen Zentren im Bereich der Grundlagen- und klinischen Forschung. Die hochauflösende kontrastreiche schnelle Bildgebung, die fehlende Belastung durch ionisierende Strahlung und die Untersucherunabhängigkeit in der Bildakquisition und Analyse machen die MRT zu einer idealen Methode der Funktionsdiagnostik des Verdauungstrakts. In dieser Übersicht werden gegenwärtige Anwendungen der MRT in der gastroenterolgischen Funktionsdiagnostik vorgestellt und mit herkömmlichen diagnostischen Methoden vergliche

Funktionelle Magnetresonanzbildgebung des Verdauungstrakts

Magnetic resonance imaging (MRI) is a versatile medical imaging tool for which several new applications have been developed. Beside its broad clinical use for the detection of anatomical structures and pathologies MRI has been successfully applied for the non-invasive imaging of human organ functions, including the brain and the cardiovascular system. The use of MRI for the assessment and analysis of gastrointestinal (GI) function is a new approach that is currently performed in only a few research sites. Several characteristics make MRI an ideal technique for the direct assessment of GI physiology: MRI acquires high resolution images with excellent soft tissue contrast, it does not expose subjects to ionizing radiation, is non-invasive, and the acquisition and analysis of the images can be independently verified. In this article we summarize recent developments of MRI techniques in GI research. We will also discuss the advantages and limitations of MRI for this purpose in relation to established medical imaging tools and investigations

Non-invasive investigation of gastrointestinal functions with magnetic resonance imaging: towards an "ideal" investigation of gastrointestinal function

Gastrointestinal (GI) function is complex and physiological measurements are subject to a variety of technical difficulties and practical limitations. The ideal technique would be non-invasive, widely available, convenient, and reliable and would not expose the subject to ionising radiation. It would permit direct assessment of GI function in the postprandial as well as the resting state, and be able to differentiate between food, secretion, and air in the lumen. GI structure and function are interdependent and the ideal technique would permit simultaneous assessment of these factors. Finally, the bowel operates as a functional whole and assessment of the GI tract proximal and distal to the area of interest is desirable. In this article the authors summarise the development and validation of magnetic resonance imaging techniques that overcome many of the deficiencies of existing methods, and have many characteristics of the "ideal" investigation of GI function

Non-invasive measurement of gastric accommodation in humans

Gastric accommodation describes the reduction in gastric tone and increase in compliance that follows ingestion of a meal and involves at least two responses: "receptive relaxation" which allows the stomach to accept a volume load without a significant rise in gastric pressure and "adaptive relaxation" which modulates gastric tone in response to the specific properties of the meal ingested. However, there are considerable technical difficulties in measuring the accommodation process. The current standard barostat studies, and other methods such as conventional and three dimensional ultrasound, or single photon emission computed tomography have significant disadvantages. Preliminary findings from the development and validation of a new magnetic resonance imaging technique that addresses many of the deficiencies of previous methods are presented

Model matters: Differences in orthotopic rat hepatocellular carcinoma physiology determine therapy response to sorafenib.

PURPOSE: Preclinical model systems should faithfully reflect the complexity of the human pathology. In hepatocellular carcinoma (HCC), the tumor vasculature is of particular interest in diagnosis and therapy. By comparing two commonly applied preclinical model systems, diethylnitrosamine induced (DEN) and orthotopically implanted (McA) rat HCC, we aimed to measure tumor biology non-invasively and identify differences between the models. EXPERIMENTAL DESIGN: DEN and McA tumor development was monitored by magnetic resonance imaging (MRI) and positron emission tomography (PET). A slice-based correlation of imaging and histopathology was performed. Array CGH analyses were applied to determine genetic heterogeneity. Therapy response to sorafenib was tested in DEN and McA tumors. RESULTS: Histologically and biochemically confirmed liver damage resulted in increased 18F-fluordeoxyglucose (FDG) PET uptake and perfusion in DEN animals only. DEN tumors exhibited G1-3 grading compared to uniform G3 grading of McA tumors. Array comparative genomic hybridization revealed a highly variable chromosomal aberration pattern in DEN tumors. Heterogeneity of DEN tumors was reflected in more variable imaging parameter values. DEN tumors exhibited lower mean growth rates and FDG uptake and higher diffusion and perfusion values compared to McA tumors. To test the significance of these differences, the multikinase inhibitor sorafenib was administered, resulting in reduced volume growth kinetics and perfusion in the DEN group only. CONCLUSION: This work depicts the feasibility and importance of in depth preclinical tumor model characterization and suggests the DEN model as a promising model system of multifocal nodular HCC in future therapy studies