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Immunoscintigraphy is a tumour imaging technique that can have specificity, but high background radioactivity makes it difficult to obtain tumour imaging soon after the injection of radioconjugate. The aim of this study is to see whether clear tumour images can be obtained soon after injection of a radiolabelled reagent using a new linker with antibody fragments (Fab), in conditions of induced hypertension in mice. Fab fragments of a murine monoclonal antibody against human osteosarcoma were labelled with radioiodinated 3′-iodohippuryl N-ε-maleoyl-L-lysine (HML) and were injected intravenously to tumour-bearing mice. Angiotensin II was administered for 4 h before and for 1 h after the injection of radiolabelled Fab. Kidney uptake of [SUP125]I-labelled-HML-Fab was much lower than that of [SUP125]I-labelled-Fab radioiodinated by the chloramine-T method, and the radioactivity of tumour was increased approximately two-fold by angiotensin II treatment at 3 h after injection, indicating high tumour-to-normal tissue ratios. A clear tumour image was obtained with [SUP131]I-labelled-HML-Fab at 3 h post-injection. The use of HML as a radiolabelling reagent, combined with angiotensin II treatment, efficiently improved tumour targeting and enabled the imaging of tumours. These results suggest the feasibility of PET scan using antibody fragment labelled with [SUP18]F-fluorine substitute for radioiodine. [ABSTRACT FROM AUTHOR]

99mTc labeled galactosyl serum albumin (GSA) has been used clinically as a receptor-binding agent for the assessment of liver function. The aim of this study was to investigate the usefulness of 99mTc-GSA in intraperitoneal (i.p.) tumor imaging. A tumor model was established by i.p. inoculating nude mice with human ovarian cancer cell SHIN-3, or colon cancer cell LS 180. Radiolabels were i.p. injected into the tumor-bearing mice and the biodistribution of radioactivity was examined. After administration, 99mTc-GSA rapidly accumulated in the tumor. The tumor uptake was 5.82-8.46 %ID/g from 30 min to 6 h after the injection. Radioactivity in the blood was very low, less than 0.3 %ID/g, resulting in high tumor-to-blood ratio. Tumors could be clearly seen by scintigraphic imaging. Accumulation of i.p.-injected 99mTc labeled human serum albumin (HSA) in i.p. tumors was similar to that of 99mTc-GSA, but radioactivity of 99mTc-HSA in the circulation was high, resulting in a significantly lower tumor-to-blood ratio. In conclusion, 99mTc-GSA, when i.p. injected, accumulated in i.p. tumors and cleared from circulation rapidly, which would make it useful for the imaging of i.p. tumors. [ABSTRACT FROM AUTHOR]

A macroporous styrene–divinylbenzene copolymer containing N-methylglucamine groups was selected for a new 68Ge/68Ga generator system. This resin packed into a column effectively adsorbed the parent nuclide 68Ge. The daughter 68Ga was eluted from the resin with a solution of a low-affinity gallium chelating ligand such as citric or phosphoric acid. The 68Ge leakage was less than 0.0004% of the 68Ge adsorbed on the resin. By simple mixing of transferrin and desferoxamine conjugated HSA and IgG with the eluate from the column, 68Ga-labeling was completed in high yield. [Copyright &y& Elsevier]

Gallium-68 (68Ga) is a important positron-emitting radionuclide available for positron emission tomography. Since the 68Ga is prepared by decay of germanium-68 (68Ge) having a long half-life, separation of 68Ga from 68Ge is essential for the utilization of 68Ga. In this study, a macroporous styrene-divinylbenzene copolymer containing N-methylglucamine groups (R-MGlu) was selected as an adsorbent for 68Ge. This resin effectively and rapidly adsorbed 68Ge above pH 5. By a batch method, 0.1 mol l−1 trisodium citrate eluted over 90% of 68Ga built up in the resin by decay of 68Ge on the resin, although distilled water did not elute the 68Ga. A solution of ethylenediaminetetraacetic acid or desferroxamine at a lower concentration also desorbed the 68Ga in higher yield. These results indicated that 68Ga was eluted by the formation of a complex with a suitable ligand. When 0.1 mol l−1 sodium citrate was used as the eluting agent by a column method, most of the 68Ga on the R-MGlu was recovered using 0.1 mol l−1 sodium citrate, while the 68Ge leakage was less than 0.0004% of the 68Ge adsorbed on R-MGlu. [Copyright &y& Elsevier]