Evaluation of three rhenium-188 candidates for intravascular radiation therapy with liquid-filled balloons to prevent restenosis.

Abstract

BACKGROUND:

Intravascular brachytherapy is an effective method for inhibiting coronary restenosis after percutaneous transluminal coronary angioplasty. A new concept for preventing restenosis is the use of a liquid-filled balloon containing a beta-ray-emitting radioisotope. Generator-produced rhenium-188 (Re-188) is a good candidate for intravascular brachytherapy. However, in the unlikely event of balloon rupture, release of Re-188 perrhenate may cause a high radiation dose to the thyroid and stomach. In this study, we compared the biodistributions of three Re-188 preparations (Re-188 perrhenate, Re-188 pentetic acid [DTPA], and Re-188 MAG3) to assess the radiation dose to organs in a rat model that mimicked balloon rupture.

METHODS AND RESULTS:

After injection of Re-188 preparations intravenously, rats were killed at 10 minutes, 30 minutes, 60 minutes, 2 hours, and 6 hours (n = 5/group). Tissue concentrations were calculated and expressed as percent injected dose per gram or per milliliter. In addition, urine excretion and thyroid gland uptake were evaluated in rats (n = 5/group) with a gamma camera after administration of 37 MBq (1 mCi) of each agent. Our data showed all 3 agents were excreted primarily via urine. In the Re-188 MAG3 group, 82% was excreted within 1 hour, but in the Re-188 perrhenate group, only 28% was excreted. The biodistribution data for these agents revealed that radioactivity levels in the stomach and the thyroid gland were high in the perrhenate group but low in the Re-188 DTPA and Re-188 MAG3 groups. The concentration levels in other tissues including lung, liver, testis, muscle, and blood were low throughout this study for all 3 agents. The thyroid radiation values were 0.163, 0.0167, and 0.00728 mGy/MBq for Re-188 perrhenate, Re-188 DTPA, and Re-188 MAG3, respectively. The stomach radiation values were 0.127 mGy/MBq for Re-188 perrhenate, 0.013 mGy/MBq for Re-188 DTPA, and 0.0104 mGy/MBq for Re-188 MAG3.

CONCLUSIONS:

In the event of balloon rupture, the release of Re-188 MAG3 or Re-188 DTPA results in lower radiation doses than release of Re-188 perrhenate, especially to the thyroid gland and the stomach.

• Authors: W Y Lin, S C Tsai, B T Hsieh, T W Lee, G Ting, S J Wang
• Journal: Journal of nuclear cardiology : official publication of the American Society of Nuclear Cardiology (J Nucl Cardiol) 2000 Jan-Feb Vol. 7 Issue 1 Pg. 37-42 ISSN: 1071-3581 [Print] United States
• PMID: 10698233 (Publication Type: Journal Article)

Chemical References

• Radioisotopes
• Radiopharmaceuticals
• perrhenate
• N-(mercaptoacetyl)glycine
• Rhenium
• Pentetic Acid
• Glycine

Topics

• Angioplasty, Balloon, Coronary
• Animals
• Brachytherapy
• Coronary Disease (radiotherapy)
• Evaluation Studies as Topic
• Glycine (analogs & derivatives)
• Male
• Pentetic Acid
• Radiation Dosage
• Radioisotopes (pharmacokinetics, therapeutic use)
• Radiopharmaceuticals (pharmacokinetics, therapeutic use)
• Rats
• Rats, Sprague-Dawley
• Recurrence
• Rhenium (pharmacokinetics, therapeutic use)
• Tissue Distribution