Molecular imaging of mesothelioma with (99m)Tc-ECG and (68)Ga-ECG

Our plain-English summary of Molecular imaging of mesothelioma with (99m)Tc-ECG and (68)Ga-ECG, by Y.H. Zhang, J. Bryant, F.L. Kong, et al (Journal of Biomedicine & Biotechnology, 2012).

The study

• Authors: Y.H. Zhang, J. Bryant, F.L. Kong, D.F. Yu, R. Mendez, E. Edmund Kim, D.J. Yang
• Journal: Journal of Biomedicine & Biotechnology
• Published: 2012;2012:232863
• Cited by: 11 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

We have developed ethylenedicysteine-glucosamine (ECG) as an alternative to (18)F-fluoro-2-deoxy-D-glucose ((18)F-FDG) for cancer imaging. ECG localizes in the nuclear components of cells via the hexosamine biosynthetic pathway. This study was to evaluate the feasibility of imaging mesothelioma with (99m)Tc-ECG and (68)Ga-ECG. ECG was synthesized from thiazolidine-4-carboxylic acid and 1,3,4,6-tetra-O-acetyl-2-amino-D-glucopyranose, followed by reduction in sodium and liquid ammonia to yield ECG (52%). ECG was chelated with (99m)Tc/tin (II) and (68)Ga/(69)Ga chloride for in vitro and in vivo studies in mesothelioma. The highest tumor uptake of (99m)Tc-ECG is 0.47 at 30 min post injection, and declined to 0.08 at 240 min post injection. Tumor uptake (%ID/g), tumor/lung, tumor/blood, and tumor/muscle count density ratios for (99m)Tc-ECG (30-240 min) were 0.47 ± 0.06 to 0.08 ± 0.01; 0.71 ± 0.07 to 0.85 ± 0.04; 0.47 ± 0.03 to 0.51 ± 0.01, and 3.49 ± 0.24 to 5.06 ± 0.25; for (68)Ga-ECG (15-60 min) were 0.70 ± 0.06 to 0.92 ± 0.08; 0.64 ± 0.05 to 1.15 ± 0.08; 0.42 ± 0.03 to 0.67 ± 0.07, and 3.84 ± 0.52 to 7.00 ± 1.42; for (18)F-FDG (30-180 min) were 1.86 ± 0.22 to 1.38 ± 0.35; 3.18 ± 0.44 to 2.92 ± 0.34, 4.19 ± 0.44 to 19.41 ± 2.05 and 5.75 ± 2.55 to 3.33 ± 0.65, respectively. Tumor could be clearly visualized with (99m)Tc-ECG and (68)Ga-ECG in mesothelioma-bearing rats. (99m)Tc-ECG and (68)Ga-ECG showed increased uptake in mesothelioma, suggesting they may be useful in diagnosing mesothelioma and also monitoring therapeutic response.

In plain English

This animal study tested whether ECG, a glucosamine-based compound made by the authors, could show mesothelioma on scans when tagged with radioactive technetium-99m or gallium-68. No asbestos exposure was studied. Female Fischer 344 rats had malignant pleural mesothelioma cells from the IL-45 cell line injected into their hind leg muscles. Three rats were used per time point. Average tumor uptake of 99mTc-ECG fell from 0.47 to 0.08 percent of the injected dose per gram between 30 minutes and 4 hours. Tumor uptake of 68Ga-ECG rose from 0.70 to 0.92 percent of the injected dose per gram between 15 and 60 minutes. For the standard scanning tracer 18F-FDG, average tumor uptake was 1.86 percent of the injected dose per gram at 30 minutes. Tumors could be clearly seen on scans with all three tracers. Tumor-to-blood ratios for both ECG tracers were lower than for FDG. In three paclitaxel-treated rats, the authors reported that 68Ga-ECG scans could monitor treatment response; they showed before-and-after images but no numerical measurements. The authors concluded that the tracers are feasible for assessing tumor volume and called for further experiments.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Laboratory chemistry and animal imaging experiment (rats with implanted mesothelioma tumors)
• Who was studied: Female Fischer 344 rats, 3 per time point, with malignant pleural mesothelioma cells from the IL-45 cell line injected into the hind legs. They were studied 14 to 17 days later, when tumors were about 1 cm across. The study was done at the University of Texas MD Anderson Cancer Center.
• Exposure: No asbestos exposure was studied. Rats were given intravenous injections of the radiotracers 99mTc-ECG, 68Ga-ECG or 18F-FDG (10 μCi per rat for tissue studies). Three rats were also treated with a single dose of paclitaxel (20 mg/kg).
• Main results:
  • Tumor uptake was measured as percentage of the injected dose per gram of tissue wet weight (%ID/g).
  • In rats given 99mTc-ECG, tumor uptake (percent of injected dose per gram) was 0.47 ± 0.06 at 30 min, 0.12 ± 0.01 at 2 h and 0.08 at 4 h.
  • In rats given 68Ga-ECG, tumor uptake (percent of injected dose per gram) was 0.70 ± 0.06 at 15 min, 0.72 ± 0.06 at 30 min and 0.92 ± 0.08 at 60 min.
  • In rats given 18F-FDG, tumor uptake (percent of injected dose per gram) was 1.86 ± 0.22 at 30 min, 1.63 ± 0.19 at 90 min and 1.38 ± 0.35 at 180 min.
  • Tumor-to-muscle ratios rose from 3.49 ± 0.24 to 5.06 ± 0.25 for 99mTc-ECG (30 min to 4 h). They rose from 3.84 ± 0.52 to 7.00 ± 1.42 for 68Ga-ECG (15 to 60 min). For 18F-FDG they went from 5.75 ± 2.55 to 3.33 ± 0.65 (30 to 180 min).
  • Tumors could be clearly visualized on scans with 68Ga-ECG, 99mTc-ECG and 18F-FDG at 0.5 to 4 hours.
  • Two rats given 99mTc-ECG were compared with one rat given 99mTc-EC as a control. Tumors in the 99mTc-ECG rats showed much higher uptake at 1 and 2 hours.
  • In 3 rats imaged before and 7 days after paclitaxel treatment, the authors reported that 68Ga-ECG could monitor treatment response. Before-and-after images were shown (Figure 6), but no numerical measurements of response were reported.
  • Tumor-to-brain ratios of both ECG tracers were better than those of FDG.
  • Higher kidney uptake was seen with both ECG tracers.
• The authors' conclusion: The authors concluded that 68Ga-ECG and 99mTc-ECG showed increased uptake in mesothelioma in the model tested, indicating they are feasible for assessing tumor volume. They suggested the tracers may be useful for screening, diagnosis, staging and treatment assessment.
• Limitations the authors state:
  • Tumor-to-blood ratios of 99mTc-ECG and 68Ga-ECG were lower than those of FDG.
  • Further experiments, such as mechanistic and differential-diagnosis studies, are needed.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Mesothelioma.

Medical terms in this study, explained in our Lexicon: Mesothelioma, F-fluoro-2-deoxy-D-glucose (FDG).

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