Abstract:
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Purpose: Positive oral contrast agents may induce artifacts into the PET emission data if PET attenuation correction is performed CT-based. The purpose of this study was to determine the value of a negative oral contrast agent for dual-modality PET/CT imaging.
Methods and Materials: 60 patients with different oncological diseases underwent dual-modality PET/CT imaging (biographTM, Siemens Medical Solutions). Barium (20 patients), water (20 patients), and a solution containing 2.5% mannitol and 0.2% locust bean gum (LBG/mannitol — 20 patients) were used for oral contrast. To assess intestinal distension 5 diameters each of the stomach, the jejunum and the ileum were determined by two radiologists. PET images were evaluated qualitatively for areas of increased bowel FDG uptake based on a four-point scale as well as quantitatively by determination of standard uptake values (SUV) of 5 typical small bowel loops. In addition, phantom measurements were performed to quantitatively assess the effect of the different contrast agents onto the CT-based PET attenuation correction.
Results: Intestinal distension with LBG/mannitol proved superior over water and barium. Mean diameters for the stomach were 6.4 +/-1.8 cm (water: 6.1 +/-1.5, p=0.0401; barium 5.0 +/-1.1, p<0.001), the jejunum was distended to 2.1 +/-0.3 cm (water: 1.6 +/-0.3, p<0.001; barium 1.9 +/-0.3, p<0.001), and diameters of the ileum averaged 2.0 +/-0.3 cm (water: 1.4 +/-0.3, p<0.001; barium: 1.9 +/0.20, p<0.001). Quantitative analysis of the bowel¢s glucose uptake revealed SUVs of 1.8 (+/-0.5) for LBG/mannitol, 1.7 (+/-0.5) for water, and 2.5 (+/-0.6) for barium. Increased glucose uptake was demonstrated more often in the presence of barium than with water or LBG/mannitol when evaluated qualitatively. The assessment of the phantom studies revealed an overestimation of the tracer activity concentration within the phantom by 33% in the presence of barium, while the activity concentration was not found to be overestimated in the presence of water and LBG/mannitol.
Conclusion: LBG/mannitol may be used as a negative oral contrast agent in PET/CT imaging as it provides good bowel distension while avoiding potential contrast-induced PET artefacts.
Questions about this event email: gerald.antoch@uni-essen.de
Antoch MD, G,
Can Contrast-induced Artefacts be Avoided in Dual-modality PET/CT Imaging? Assessment of a Negative Oral Contrast Agent. Radiological Society of North America 2003 Scientific Assembly and Annual Meeting, November 30 - December 5, 2003 ,Chicago IL.
http://archive.rsna.org/2003/3100664.html
