《磁共振成像》课件

• 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.
• 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.
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 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.
ቤተ መጻሕፍቲ ባይዱ
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
• Aggregation
• Variable-temperature 17O NMR measurements
• Within the experimental error, the hyperfine coupling constant is identical to commonly observed values for oxygen atoms directly coordinated to Gd.
Calix[4]arenes as Molecular Platforms for Magnetic Resonance Imaging (MRI) Contrast Agents
The Paper
Outline
1
Introduction
2
Experimental Section
3
Conclusion
• 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
• Targeted contrast agents usually have higher relaxivities when interacting with the target due to the restriction of the rotational motion upon binding.
• Nuclear magnetic relaxation dispersion
• NMRD is a powerful technique for characterizing MRI contrast agents.
• NMRD profiles show the relaxivity of the monomer to be almost independent of the magnetic field strength up to 60 MHz.
• Some main imaging techniques
Positron emission tomography (PET) Single photon emission computed tomography (SPECT) Magnetic resonance imaging (MRI) Ultrasonic imaging Optical imaging (Bioluminescence ,Fluorescence )