“…The gadolinium chelate, gadopentetate dimeglumine (Gd-DTPA; Magnevist, Berlex Inc., Montville, NJ), which primarily shortens T 1 relaxation, has been used for the detection of various types of tumor (Huang et al, 2006;Rosen et al, 2003) as well as brain lesions associated with multiple sclerosis (Martino et al, 2002). On the other hand, the ultrasmall superparamagnetic iron oxide (SPIO) contrast agent, ferumoxides injectable solution (Feridex, Berlex Inc.-hereafter referred to SPIO) is another class of contrast agent that is clinically used to detect alterations in the reticuloendothelial system (RES) associated with hepatic tumors (Kanematsu et al, 2001) or to detect primary site or nodal metastases of various tumors (Mack et al, 2002;Bellin and Roy, 2007).…”