...from gene chip technology
...to nuclear medicine and PET
We are both working with PET for more than 20 years at one of the leading centers in the world (our former head of the center got the Nobel prize 2008) and
like to provide some general and specific information
about
this method.
The diagnosis of a malignant lesion is generally based on
morphologic methods like ultrasound, computed tomography
(CT), magnetic resonance imaging (MRI) or conventional
radiology. All these methods provide morphologic
information,
which can be used to describe a lesion according to size,
location, infiltration etc. Besides morphological
procedures,
functional methods are finding increasing attention to
obtain information about biochemical (some name it "
molecular")
aspects of a tumor. These methods are primarily based on
nuclear medicine procedures. In contrast to the conventional nuclear methods, PET is
based on the annihilation of positrons, emitted by beta + Isotopes.
The PET method provides a superior resolution and
enables the use of ´physiologic´ tracers. PET can be used in oncology to obtain information about specific biological properties of a lesion. Perfusion tracers like O-15-water provide information about tumor blood flow, radiolabelled amino acids gave quantitative information about the amino acid transport, tracers involved in cell proliferation can be used to assess tumor growth. Generally nuclear medicine is not confined to just a few tracers. Even cytostatic drugs like fluorouracil (FU), widely used for metastatic colorectal cancer, can be labelled with F-18 and the quantitative assessment of the pharmacokinetics of F-18-FU can help to predict the individual therapeutic result in patients receiving chemotherapy based on FU.
Recently results obtained with gene chip technology are used to search for new possible targets for radiopharmaceuticals. We noted in patients with colorectal cancer and some other tumors a higher expression of the gastrin-releasing peptide receptor (GRPR, see arrow at the gene chip displayed upper left). Bombesin, a small peptide, is known to bind to GRPR, neuromedin and the bombesin receptor. Therefore, based on the gene chip data, Ga-68-bombesin was used to enhance the specificity of PET in oncological patients (image upper right). The example shows, how different technologies can be combined to design new radiopharmaceuticals to enhance tumor diagnostics as well as therapy management.
ATT: We are sorry but we had to remove the links to the individual papers due to copyright aspects. We will try to provide information about the topics without using the published papers. Please contact us for any questions.
