ABSTRACT
(18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET) is a useful functional imaging method that complements conventional anatomic imaging modalities for screening patients with colorectal hepatic metastases and hepatocellular cancer to determine their suitability for interventional procedures. FDG PET is more sensitive in detecting colorectal cancer than hepatocellular cancer (~90% versus ~50%). The likelihood of detecting hepatic malignancy with FDG PET rapidly diminishes for lesions smaller than 1 cm. The greatest value of FDG PET in these patients is in excluding extrahepatic disease that might lead to early recurrence after interventional therapy. Promising results have been reported with FDG PET that may show residual (local) or recurrent disease before conventional imaging methods in patients receiving interventional therapy. For patients with colorectal hepatic metastases, many investigators believe that patients with PET evidence of recurrent hepatic disease should receive additional treatment even when there is no confirmatory evidence present on other methodologies. For patients with hepatocellular cancer no conclusions regarding the value of FDG PET for assessment of response to interventional therapy can be reached as there is almost no published data.
ABSTRACT
Substance P (SP) is an ll-amino acid neuropeptide of the tachykinin family. This study investigated the preparation of an SP analog labeled with 99mTc for imaging SP receptor positive tissue (inflammatory diseases and neoplasms with increased expression of SP receptors). High specific activity 99mTc-SP was prepared using the l-imino-4-mercaptobutyl (IMB) group as a bifunctional chelator. Biological distribution in mice showed increased 99mTc-SP uptake in the salivary glands (which have a high concentration of SP receptors), but this activity was displaced in animals pre-treated with excess non-radioactive SP. These data show that the uptake of 99mTc-SP is receptor specific. IMB derivatization at the N-terminal location is suitable for labeling of SP analogues with 99mTc. Synthetic analogues of SP labeled with 99mTc may be an attractive alternative to 111In labeled molecules and merit further investigation.
