Imaging of colorectal carcinoma with radiolabeled antibodies

Image Subtraction Analysis with Technetium-99M Labeled Monoclonal Antibody and Colloid for Evaluation of Liver Lesions: Phantom Measurements and Patient Studies

“…The criterion used for proper subtraction was to obtain the best possible cancellation of normal liver activity according to equation [2]. Fig.…”

“…, the originally recorded 99mTc-MoAb-image (A), the originally recorded y9mTc-MoAb + 99"'Tc-colloid-image (B), the corrected "'"Tc-colloid-image (C), the subtracted 9ymTc-MoAb -yymTc-colloid-image (D). The (C) image was obtained by subtracting (A) and (B), using equation [2]. The (D) image finally, was obtained by subtracting (C) and (A) using the best possible cancellation of normal liver activity by iterating with scaling factors.…”

“…Two false positive findings were observed, and (D) image was obtained by subtracting (C) from (A) using iteration for liver background activity (equations [2]). two false negative findings as compared to conventional diagnostic methods (CT, US).…”

“…A double-headed gamma camera was not available for our patient subtraction procedure and therefore subtraction calculations were performed with AP view data only according to equation [2]. The detection limits in phantom measurements were calculated using the conjugate view method which gives better statistical information.…”

Carcinoembryonic Antigen as a Target Cancer Antigen for Radiolabeled Antibodies: Prospects for Cancer Imaging and Therapy

“…However, where RAID requires high tumormontumor ratios of the radioactivity in order to achieve se lective images, RAIT also requires a high radiation dose delivered to the tumor for a critical period. Unfortunately, a major limita tion of current RAIT strategies is the relative ly low accrection of radiolabeled antibody in tumors, and thus the delivery of low radiation doses [55], and this represents a discrepancy between animal models and humans, where antibody uptake can approach 50% of the injected dose per gram of tumor in the former, whereas it is usual for less than 0.05% of the injected dose per gram of tumor to accrete in the latter. Other major differences between human cancer and animal models include cross-reactivity of the MAb with certain nor mal tissues in patients, the extent of tumor burden and the presence of established metastases in humans, profound tumor cell hetero geneity within a tumor and between different tumor sites in humans, frequently high levels of circulating target antigen in patients, and the immunogenicity of rodent (foreign) anti bodies administered to humans.…”