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This Article Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Piert, M. Articles by Guo, C. PubMed Articles by Piert, M. Articles by Guo, C.

Performance of a beta- and high-energy gamma probe for the detection of cancer under challenging in-vivo conditions

¹ Radiology, University of Michigan, Ann Arbor, Michigan

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Objectives: High-energy gamma and beta probes have gained considerable attention due to their ability to intraoperatively detect cancerous lesions using 18F-FDG in humans. However, the limitations to detect very small disease under presence of high background radiation are currently not well described. Therefore, the performance of a commercial system (GE/IMI NodeSeeker®) was investigated in a rat tumor model.

Methods: 9L tumors (4 primary, 6 lymph node lesions) were generated in 2 Fisher 344 rats injecting 5 Mill. cells into bilateral lower legs. After 2 weeks, microPET was performed to verify increased 18F-FDG tumor uptake. Tumors were surgically exposed and probe readings of tumor and background tissues were performed in triplicate. To evaluate the ability to detect tiny tumor lesions, 7 tumor fragments (range 1–16mg) were placed in the resection bed and measured. All tumor and muscle tissues were weighted (range 0.001-5.9g) and counted in a scintillation counter for reference. The presence/absence of tumor tissue was verified by histology.

Results: The beta probe detected all but one small (4mg) tumor with a tumor-to-background ratio (TBR) of >= 1.4 (range 1.1-5.9). Detection was influenced by the tumor weight and the "true" TBR as determined by scintillation counting. Despite heavy shielding, gamma probe readings were clearly limited by the presence of access radioactivity in the urinary bladder. As a result, only 3 of 4 primary tumor lesions (weight range 2.8 – 5.6g) were found, while smaller lesions remained undetected.

Conclusions: The beta probe identified minute amounts of vital tumor tissue (exposed on the surface) which remained undetected by the gamma probe. Beta probes are especially useful under challenging detection conditions when intense gamma background radiation is present.

This Article Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Piert, M. Articles by Guo, C. PubMed Articles by Piert, M. Articles by Guo, C.