Christopher C. Riedl MD, Presenter: Nothing to Disclose

Peter Brader MD, Abstract Co-Author: Nothing to Disclose

Pat Zanzonico PhD, Abstract Co-Author: Nothing to Disclose

C. Clifton Ling PhD, Abstract Co-Author: Nothing to Disclose

Hedvig Hricak MD, PhD, Abstract Co-Author: Nothing to Disclose

Fong Yuman MD, Abstract Co-Author: Nothing to Disclose

Humm L. John PhD, Abstract Co-Author: Nothing to Disclose

et al, Abstract Co-Author: Nothing to Disclose

et al, Abstract Co-Author: Nothing to Disclose

To compare the uptake of two clinically promising PET hypoxia targeting agents 124I-iodoazomycin galactopyranoside and 18F-fluoromisonidazole by dynamic microPET imaging, in the same rats bearing liver tumors and peritoneal metastases.

Morris hepatoma (RH7777) fragments were surgically implanted into the liver of nude rats. Tumors formed in the liver. The study was performed on 4 rats, each with a total of 2 to 3 liver tumors and peritoneal metastasis of 10-15 mm in size. Animals were injected with 18F-FMISO, followed on the next day (upon complete 18F decay) by 124I-IAZG. Animals were imaged in list mode on the microPET systems from the time of injection of each tracer for 3 hours and then again at 6 and 24 h for the long-lived 124I-IAZG tracer (4.2 day half-life). MicroCT scans of each rat were performed for co-registration with microPET scan 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 and time-activity curves (TACs) were drawn for each tissue ROI.

The 18F-FMISO signal was observed to increase in the tumor over the 3-hour time course of observation. In contrast, the 124I-IAZG, after the initial blood bolus, slowly and continuously declined in the tumor. Nevertheless, tumor-to-normal tissue ratios improved, but more slowly than for 18F-FMISO, and as a result of the differentially faster clearance from the surrounding normal tissues. These described pharmacokinetic patterns were seen in all 11 tumors of the four animals.

The present study shows that 18F-FMISO localizes in the same intra-tumor regions as 124I-IAZG. The contrast ratios (tumor/background) reach similar values for the two hypoxia tracers, but at later times for 124I-IAZG than for 18F-FMISO; therefore with poorer count statistics. As a consequence, the 18F-FMISO images are of superior diagnostic image quality to 124I-IAZG in the Morris hepatoma McA-R-7777 tumor model.

To our knowledge the present report offers the first data on tumor hypoxia imaging in a liver tumor model comparing two diferent hypoxia tracers in the same animals.

Riedl, C, Brader, P, Zanzonico, P, Ling, C, Hricak, H, Yuman, F, John, H, et al, , et al, , Tumor Hypoxia Imaging in Orthotopic Liver Tumors Comparative Study Featuring Dynamic 18F-MISO and 124I-IAZG PET in the Same Study Cohort.  Radiological Society of North America 2007 Scientific Assembly and Annual Meeting, November 25 - November 30, 2007 ,Chicago IL. http://archive.rsna.org/2007/5004668.html