Contrast agent 97 - detector

Boronated protoporphyrin (2,4-(a,/Tdihydroxyethyl)deuteroporphyrin IX, BOPP, Fig. 8), a neutron capture agent, localizes in cerebral gliomas with a ratio of 400 1 as compared with normal brain tissue [116]. The manganese(III) complex of BOPP was investigated as a MRI contrast agent in the expectation that it would behave similarly to the free base BOPP and would act in the dual role of tumor detector and radiation sensitizer [117]. The 1 value for Mn-BOPP at... 

With the advent of multidetector CT (MDCT) scanners with 16, 32 and 64 rows of detectors there has been renewed interest in assessing the small bowel with CT. These studies, often referred as CT enterography, bring new challenges even to new oral contrast agents administration. 

X-ray Compton back-scattering can 5deld indications of delaminations in PMC without the use of contrast agents, ie, including those that do not extend to the surface. The basis is a special source-detector arrangement (86). 

In this chapter, current multi-detector CT (MDCT) and MR imaging protocols including the use of different liver-specific MR contrast agents will be discussed. The CT and MR imaging features of different hepatic metastases and pitfalls will be presented. The role of MDCT and MR in the assessment of patients with extrahepatic malignancies prone to metastasize into the liver and in the preoperative evaluation of surgical candidates will be highlighted. 

Determination of Nerve Agents In contrast to those rather unusual methods, GC coupled to diverse detection systems, e.g. flame ionization detector (FID), nitrogen-phosphorus detector (NPD), flame photometric detector or mass spectrometer, as well as liquid chromatographic (LC) methods, represent the most common techniques for OP determination especially for biological samples. These methods offer high resolution, sufficient limits of detection, good reproducibility, and robust hardware devices. For more detailed information readers are referred to recent review articles (Hooijschuur et al, 2002 John et al, 2008). 

Unlike the commonly made potentiometric pH measurement, electrochemical detection is an amperometric (current) measurement, at controlled potential. Electrochemical detection involves a chemical redox reaction, in contrast to ultraviolet or fluorescence detection where a passive, physical absorption of radiation occurs. The reaction occurs at an electrode suiface, placed in or alongside the flow of effluent from the column. Either an oxidation or reduction may be forced to occur by judicious selection of a potential applied to the cell by the controlling potentiostat. The potential is a source of electrochemical selectivity, in the same manner as the wavelength selected with a variable wavelength UV detector. In essence the electrode acts as an oxidizing or reducing agent of variable power. 

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