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Open Access Highly Accessed Original research

Contrast-enhanced small-animal PET/CT in cancer research: strong improvement of diagnostic accuracy without significant alteration of quantitative accuracy and NEMA NU 4–2008 image quality parameters

Charline Lasnon12, Elske Quak3, Mélanie Briand12, Zheng Gu4, Marie-Hélène Louis12 and Nicolas Aide123*

Author Affiliations

1 Normandie Université, Caen, 14000, France

2 BioTICLA Team, EA 4656, IFR 146, François Baclesse Cancer Centre, 3 Avenue Général Harris, Caen Cedex 5, 14076, France

3 Nuclear Medicine Department, François Baclesse Cancer Centre, 3 Avenue Général Harris, Caen Cedex 5, 14076, France

4 Biomedical Physics Program, UCLA, Los Angeles, CA, 90024, USA

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EJNMMI Research 2013, 3:5  doi:10.1186/2191-219X-3-5

Published: 17 January 2013

Abstract

Background

The use of iodinated contrast media in small-animal positron emission tomography (PET)/computed tomography (CT) could improve anatomic referencing and tumor delineation but may introduce inaccuracies in the attenuation correction of the PET images. This study evaluated the diagnostic performance and accuracy of quantitative values in contrast-enhanced small-animal PET/CT (CEPET/CT) as compared to unenhanced small animal PET/CT (UEPET/CT).

Methods

Firstly, a NEMA NU 4–2008 phantom (filled with 18F-FDG or 18F-FDG plus contrast media) and a homemade phantom, mimicking an abdominal tumor surrounded by water or contrast media, were used to evaluate the impact of iodinated contrast media on the image quality parameters and accuracy of quantitative values for a pertinent-sized target. Secondly, two studies in 22 abdominal tumor-bearing mice and rats were performed. The first animal experiment studied the impact of a dual-contrast media protocol, comprising the intravenous injection of a long-lasting contrast agent mixed with 18F-FDG and the intraperitoneal injection of contrast media, on tumor delineation and the accuracy of quantitative values. The second animal experiment compared the diagnostic performance and quantitative values of CEPET/CT versus UEPET/CT by sacrificing the animals after the tracer uptake period and imaging them before and after intraperitoneal injection of contrast media.

Results

There was minimal impact on IQ parameters (%SDunif and spillover ratios in air and water) when the NEMA NU 4–2008 phantom was filled with 18F-FDG plus contrast media. In the homemade phantom, measured activity was similar to true activity (−0.02%) and overestimated by 10.30% when vials were surrounded by water or by an iodine solution, respectively. The first animal experiment showed excellent tumor delineation and a good correlation between small-animal (SA)-PET and ex vivo quantification (r2 = 0.87, P < 0.0001). The second animal experiment showed a good correlation between CEPET/CT and UEPET/CT quantitative values (r2 = 0.99, P < 0.0001). Receiver operating characteristic analysis demonstrated better diagnostic accuracy of CEPET/CT versus UEPET/CT (senior researcher, area under the curve (AUC) 0.96 versus 0.77, P = 0.004; junior researcher, AUC 0.78 versus 0.58, P = 0.004).

Conclusions

The use of iodinated contrast media for small-animal PET imaging significantly improves tumor delineation and diagnostic performance, without significant alteration of SA-PET quantitative accuracy and NEMA NU 4–2008 IQ parameters.

Keywords:
Small-animal PET/CT; Contrast media; NEMA NU 4–2008; Tumor-bearing rodents; Quantification