《磁共振成像》课件.ppt

The Paper 1、 Introduction Molecular imaging It seems to take photos of molecular , display the morphological structure of our target. In other words, characterization and measurement of the process of living animals, human biology and model system in the cellular and molecular level using the imaging detector in vitro . Features of molecular imaging Non-invasive imaging technique Dynamic acquisition Reflect full-scale Some main imaging techniques Positron emission tomography (PET) Single photon emission computed tomography (SPECT) Magnetic resonance imaging (MRI) Ultrasonic imaging Optical imaging (Bioluminescence ,Fluorescence ) MRI Magnetic resonance imaging (MRI) is one of the most important techniques in medical imaging. It is noninvasive, avoids problems occurring in other imaging techniques such as scattering (optical imaging) or high-energy radiation (computed tomography (CT) or X-ray), and enables the production of 3D images of various tissues. The challenge is to prepare complexes that do not release the toxic metal ion in vivo and yet are efficient contrast agents. 2、Experimental Section The contrast is generated by differences in either the proton density between tissues and/or differences in T1 or T2 relaxation times. A noncovalent approach is to prepare amphiphilic compounds that form aggregates. Targeted contrast agents usually have higher relaxivities when interacting with the target due to the restriction of the rotational motion upon binding. In MRI an ongoing trend is to apply higher magnetic field strengths (1.5 T). This can be achieved by optimizing the average water residence lifetime tM to even shorter values than that predicted of 20–40 ns for high molecular weight agents. One of approaches to find systems with optimal τR is to use the rather rigid calix[4]arene core as a synthetic platform. Calixarenes generally enable the introduction of at least two different functions. ? Aggregation Varia