Octreotide imaging plus bone scintigrams to optimally localize gastroenteropancreatic neuroendocrine tumors

In-111 pentetreotide (Octreotide) is highly sensitive for detecting gastroenteropancreatic neuroendocrine tumors and their metastases. However, a lack of landmarks makes it difficult to localize them anatomically. To overcome this difficulty, the authors simultaneously obtained Octreotide and bone tomoscintigrams, in addition to standard planar images. They used a bicolor scale to display pairs of scintigrams to easily identify the distribution of both tracers.

Twenty-one hours after Octreotide injection, Tc-99m MDP was also administered to the patients. Three hours later, dual-energy planar and tomographic data were acquired simultaneously. The latter were reconstructed using a filtered back-projection algorithm using a Metz filter. Both sets of data were displayed simultaneously using a bicolor scale, such that Octreotide data appear in green and bone data in red.

Planar, tomographic, and three-dimensional data were obtained. With this approach, foci of abnormal uptake are localized more precisely. Hard data can be transmitted easily to referring physicians, who appreciate this compact and efficient means to locate foci of abnormal uptake, especially during surgery planning. However, this method is not well suited to the visualization of small lesions with low Octreotide uptake because the intensity range is drastically reduced. Such lesions are better seen on Octreotide planar images and standard tomoscintigrams.

This approach, which involves only standard image processing, provides landmarks to easily localize significant Octreotide uptake. It can be implemented readily in most nuclear medicine workstations. It complements but does not replace the usual method to display Octreotide data.