Abstract
Several physiologic features make interpretation of PET studies of liver physiology an exciting challenge. As with other organs, hepatic tracer kinetics using PET is quantified by dynamic recording of the liver after the administration of a radioactive tracer, with measurements of time–activity curves in the blood supply. However, the liver receives blood from both the portal vein and the hepatic artery, with the peak of the portal vein time–activity curve being delayed and dispersed compared with that of the hepatic artery. The use of a flow-weighted dual-input time–activity curve is of importance for the estimation of hepatic blood perfusion through initial dynamic PET recording. The portal vein is inaccessible in humans, and methods of estimating the dual-input time–activity curve without portal vein measurements are being developed. Such methods are used to estimate regional hepatic blood perfusion, for example, by means of the initial part of a dynamic 18F-FDG PET/CT recording. Later, steady-state hepatic metabolism can be assessed using only the arterial input, provided that neither the tracer nor its metabolites are irreversibly trapped in the prehepatic splanchnic area within the acquisition period. This is used in studies of regulation of hepatic metabolism of, for example, 18F-FDG and 11C-palmitate.
Footnotes
Published online Feb. 9, 2012.
Learning Objectives: On successful completion of this activity, participants should be able to describe (1) the role of the liver's blood supply in the interpretation of dynamic PET measurements for estimating hepatic blood perfusion and metabolism; (2) the limitations of using compartmental analysis of hepatic tracer kinetics in PET studies; and (3) the tracer kinetic advantages of using the metabolic clearance of 18F-FDGal in dynamic PET studies of regional metabolic liver function.
Financial Disclosure: The authors of this article have indicated no relevant relationships that could be perceived as a real or apparent conflict of interest.
CME Credit: SNM is accredited by the Accreditation Council for Continuing Medical Education (ACCME) to sponsor continuing education for physicians. SNM designates each JNM continuing education article for a maximum of 1.0 AMA PRA Category 1 Credit. Physicians should claim only credit commensurate with the extent of their participation in the activity.
For CE credit, participants can access this activity through the SNM Web site (http://www.snm.org/ce_online) through March 2013.
- © 2012 by the Society of Nuclear Medicine, Inc.