Drug – bio-affecting and body treating compositions – In vivo diagnosis or in vivo testing – Magnetic imaging agent
Patent
1992-11-24
1995-01-10
Hollinden, Gary E.
Drug, bio-affecting and body treating compositions
In vivo diagnosis or in vivo testing
Magnetic imaging agent
436173, 1286534, 528 10, 528 29, A61B 5055, C08G 7700, C08G 7704
Patent
active
053805143
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a method for study of internal body tissues (i.e. the tissues themselves and cavities within them), and more particularly to a method for the non-invasive examination of internal body tissues by nuclear magnetic resonance imaging procedures, and especially for examination of soft body tissues for example the alimentary tract.
Nuclear magnetic resonance is conventionally referred to, for convenience, as "NMR."
It is known to examine internal body tissues and cavities by a variety of techniques, among which the examination by X-ray techniques is most widely used. This depends upon the extent to which the body tissues and cavities can be differentiated from each other, and this can be difficult, especially for soft tissues. Even the use of opacifiers to produce "shadows" or image contrasts in the regions of interest are not sufficiently satisfactory for many clinical purposes. This problem is most marked in dealing with non-invasive examination of the gut (for example the bowel) but is evident for other body tissues too.
More recently, NMR has been proposed as a method for imaging certain parts of the body. It has been proposed to use imaging techniques in which a contrast agent or opacifying agent is used, which is chosen to be a compound which has the property of enhancing the NMR response signal when in the body. Unfortunately, the compounds so far proposed are not entirely satisfactory for the purpose. These are compounds derived from metals (e.g. iron, manganese, gadolinium) and, though they have the desired NMR characteristics, their properties with respect to the body of a patent can be undesirable, so that their use is not attractive. For example, such materials have the disadvantages that the metal-based compounds can produce undesirable side-effects on the patient to whom they are administered, for example diarrhoea and flatulence. Some patients therefore cannot tolerate these imaging media (contrast agents) to an acceptable degree.
We have found that this problem can be overcome by use of selected organo-silicon polymers as contrast agents or media.
Thus according to our invention we provide a method for the study of internal body tissues by nuclear magnetic resonance imaging techniques which comprises the step of administering an inert proton-rich organo-silicon polymer as the contrast medium within the body of the subject to be examined.
In such polymers, the silicon is chemically bound to organic groups, usually hydrocarbon groups. The polymers can be referred to by a variety of names, for example as "organic silicon-containing polymers," "silicon-containing organic polymers" or "silicones," but the term "organo-silicon polymers" is used herein to make it clear that the silicon is chemically bound and is not merely mixed in as a separate component (e.g. in elemental form).
The inert proton-rich organo-silicon polymer used for the purposes of the present invention may be especially one or more of those known as polysiloxanes. These are polymers having a series of units linked by silicon-oxygen bonds and with organic substituents on the silicon atoms. These organic substituents contain the hydrogen atoms which produce the NMR image.
Thus, especially, we provide according to our invention such a method in which the organo-silicon polymer used as the contrast medium is a polysiloxane.
The properties which make organo-silicon polymers, and especially a polysiloxane, useful for this purpose are: shift and relaxation time differences from those of body tissues. Both the chemical shift and relaxation times can be utilised to give selective contrast to the gut contents or other body tissues; and physiologically towards body tissues, and have a low absorbability in the animal body. They also have a long history of previous use for medical proposes without any evidence of adverse properties or effects.
Accordingly, our invention also comprises the use as a contrast medium in the study of internal body tissues by nuclear magnetic resonance imaging, of an inert proton-rich organo-si
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STN File Server, Accession No. 317955, Bioses, vol. 87, M. Friedrich et al: "MR-Tomography of the breast additional information in selected cases", & Radiologe, vol. 27, No. 4, (1987), Coden: RDLGBC ISSN:, pp. 165-177.
Anie Sylvia J.
Fell John T.
Waigh Roger D.
Wood Brian
Hollinden Gary E.
The Victoria University of Manchester
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