Improving Treatment Design by Image Fusion Techniques

Selective internal radiation therapy (SIRT) is based on the injection of microspheres into the hepatic artery and their microembolization of the tumoral vascular network. It has been well described that not all hepatic tumours present with the same irrigation [1, 2]. Only those with high vessel density will be truly susceptible to this kind of selective treatment. Additionally, these tumours present a typical pattern on conventional diagnostic images (CT or MRI) consisting in a lesion with high contrast uptake [3]. Therefore, it is logical that those tumours presenting with high contrast uptake in conventional imaging techniques should also appear as “hot spots” on scintigraphy with Tc-99m labelled macroaggregated albumin (MAA), since the administration of MAA is performed at the same location as the injection of radiological iodine contrast (Fig. 7.1). But it is not uncommon to find some differences between the radiological vascularization pattern visualized on angiography (using iodinated based contrast) and the distribution of activity of radiolabeled MAA.