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Near-Infrared Imaging with Fluorescent Contrast Agents
Published in Mary-Ann Mycek, Brian W. Pogue, Handbook of Biomedical Fluorescence, 2003
Eva M. Sevick-Muraca, Anuradha Godavarty, Jessica P. Houston, Alan B. Thompson, Ranadhir Roy
A significant advancement in the design of optical contrast agents mimicked those used in other medical imaging modalities. Achilefu et al. [40–42] and Bugaj et al. [39], used area illumination and area CCD detection in tumor-bearing rats in order to detect about 6–7 μmol/kg bw of cyanine dye conjugated to small peptides for targeting somatostatin and bombesin receptors. One commercial nuclear diagnostic agent, Octreoscan, is based on targeting of the somatostatin receptor, which is overexpressed in neuroendocrine tumors. Bugaj and coworkers showed that optical imaging using the derivatized and peptide conjugated ICG, cytate (see Fig. 19 for their structure) is similar to that using the radiolabeled peptide analogue for somatostatin. Similar results were reported for the peptide-conjugated derivative of ICG, cybesin (see Fig. 19 for their structure), which is similar to the radiolabeled peptide analogue for bombesin. Becker et al. [43] reported similar work in tumor-bearing mice with detection limits reduced to 0.02 μmol/kg bw using a similar targeting construct. In their work, they conjugated the indodicarbocyanine (IDCC) and the indotricarbocyanine (ITCC) dyes with analogues of somatostatin, somatostatin-14, and octreotate (see Fig. 20 for their structure). In another approach, Becker and coworkers [31,34] followed the targeting approach previously employed for methotrexate and photodynamic therapies, MRI gadolinium and magnetic particle contrast by using human serum albumin (HSA) and transferrin (Tf) coupled to indotricarbocyanine dyes. While Tf binds to specific cell-surface receptors, HSA binds nonspecifically. Their studies show the contrast enhancement of targeting specificity using Tf-ITCC (Fig. 21).
Nuclear Medicine in Oncology
Published in Computer Methods in Biomechanics and Biomedical Engineering: Imaging & Visualization, 2018
Carla Oliveira, Rui Parafita, Ana Canudo, Joana Correia Castanheira, Durval C. Costa
Even though other radiopharmaceuticals analogous to somatostatin – non-positron emitters such as 111In-octreotide (Octreoscan) and 99mTc-octreotide – may be used in scintigraphic studies (gamma camera), the PET/CT with 68Ga-conjugated peptides offers the advantages of a better spatial resolution, greater sensitivity and better and faster pharmacokinetics (Virgolini et al. 2010).