Hepatobiliary imaging agents

Technetium-99m teboroxime is a myocardial imaging agent and is excreted primarily by the hepatobiliary system. It is rapidly taken up by the myocardium and mosdy washes out within 30 minutes. Imaging protocols are performed immediately after injection. The product is a lyopbili ed mixture of boronic acid, dioxine, and other excipients, and the agent is formed with a beating step. 

Fig. 5. Chelating agents used to formulate "mTc-hepatobiliary imaging agents A) Mebrofenin R2.4.6 =CH3, R3 = Br, R5=H and Disofenin R2 6 = CH(CH3)2 R3 5 = H B) N-pyridoxyl-5-methyltryptophan (PMT)...

The development of the instant radiopharmaceutical kit in the 1970s was followed by the development of technetium imaging agents for renal, skeletal, and hepatobiliary imaging. At that time, the coordination chemistry of technetium was not well understood and as a result, the early radiopharmaceuticals are not fully characterized. Studies of the coordination chemistry of technetium intensified in the late 1970s leading to the discovery of Tc brain, heart, and renal agents. These... 

Moonen, R Gorree, G. C. M. Hoekstra, A. Radioiodinated rhodamine-123 a potential cationic hepatobiliary imaging agent. Nucl. Med. Commun. 1987, 8, 99-104. 

Intestinal absorption studies of Mn-MP were undertaken in an effort to assess the viability of the metalloporphyrin as an oral hepatobiliary agent [101, 102]. Mixed micelles of Mn-MP complexed with monoolein and taurocholate were administered to rats, resulting in liver image enhancement 68% above baseline levels six hours after administration [101]. In pigs, the mixed micelle preparation showed variable enhancement over 24 hours. Observation that Mn-MP interacts with oleic acid vesicles [103] led to investigations of the effect of oleic acid on the absorption rate of Mn-MP from the small bowel into the circulatory system [102,104]. The increase in absorption of the complex was mediated by a decrease in the relaxivity of the metalloporphyrin resulting from the interaction with the lipid vesicles. 

CT is a technique that uses ionising radiation and computer processing to generate cross-sectional three-dimensional images of the internal organs. In assessment of the hepatobiliary tract both an oral contrast agent and an intravenous contrast medium are required to visualise the bowel and blood vessels, respectively. In the context of hepatobiliary disease, CT is particularly useful in assessing the extent of mass lesions. 

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