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Tumor hypoxia imaging in orthotopic liver tumors and peritoneal metastasis: a comparative study featuring dynamic 18F-MISO and 124I-IAZG PET in the same study cohort
Journal article   Open access   Peer reviewed

Tumor hypoxia imaging in orthotopic liver tumors and peritoneal metastasis: a comparative study featuring dynamic 18F-MISO and 124I-IAZG PET in the same study cohort

Christopher C. Riedl, Peter Brader, Pat Zanzonico, Vincent Reid, Yanghee Woo, Bixiu Wen, C. Clifton Ling, Hedvig Hricak, Yuman Fong and John L. Humm
European journal of nuclear medicine and molecular imaging, Vol.35(1), pp.39-46
2008
DOI: 10.1007/s00259-007-0522-2
PMCID: PMC2723938
PMID: 17786438
url
https://www.ncbi.nlm.nih.gov/pmc/articles/2723938View
Open Access

Abstract

Purpose The purpose of this paper is to compare the uptake of two clinically promising positron emission tomography (PET) hypoxia targeting agents, 124 I-iodoazomycin galactopyranoside ( 124 I-IAZG) and 18 F-fluoromisonidazole ( 18 F-FMISO), by dynamic microPET imaging, in the same rats bearing liver tumors and peritoneal metastasis. Methods Morris hepatoma (RH7777) fragments were surgically implanted into the livers of four nude rats. Tumors formed in the liver and disseminated into the peritoneal cavity. Each rat had a total of two to three liver tumors and peritoneal metastasis measuring 10–15 mm in size. Animals were injected with 18 F-FMISO, followed on the next day (upon complete 18 F decay) by 124 I-IAZG. The animals were imaged in list mode on the microPET system from the time of injection of each tracer for 3 h and then again at 6 h and 24 h for the long-lived 124 I-IAZG tracer (4.2-day half-life). Micro computed tomography (CT) scans of each rat were performed for co-registration with the microPET scans acquired with a liver contrast agent, allowing tumor identification. Regions of interest (ROIs) were drawn over the heart, liver, muscle, and the hottest areas of the tumors. Time–activity curves (TACs) were drawn for each tissue ROI. Results The 18 F-FMISO signal increased in tumors over the 3-h time course of observation. In contrast, after the initial injection, the 124 I-IAZG signal slowly and continuously declined in the tumors. Nevertheless, the tumor-to-normal-tissue ratios of 124 I-IAZG increased, but more slowly than those of 18 F-FMISO and as a result of the differentially faster clearance from the surrounding normal tissues. These pharmacokinetic patterns were seen in all 11 tumors of the four animals. Conclusions 18 F-FMISO localizes in the same intra-tumor regions as 124 I-IAZG. The contrast ratios (tumor/background) reach similar values for the two hypoxia tracers, but at later times for 124 I-IAZG than for 18 F-FMISO and, therefore, with poorer count statistics. As a consequence, the 18 F-FMISO images are of superior diagnostic image quality to the 124 I-IAZG images in the Morris hepatoma McA-R-7777 tumor model.
 Cardiology Imaging Medicine Medicine & Public Health Nuclear Medicine Oncology Original Article Orthopedics Radiology

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