Objective: Our objective was to show that oral and IV contrast materials improve CT image quality in dual-modality positron emission tomography (PET) and CT, resulting in an increase in diagnostic capacity. We also present a standardized scanning protocol for whole-body PET-CT with oral and IV contrast materials.
Subjects and methods: To evaluate the use of whole-body PET-CT in clinical practice, we examined 30 patients according to the protocol. The CT images were evaluated quantitatively by signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) analyses and qualitatively by two radiologists in consensus. PET quality was assessed quantitatively by measurements of standard uptake values that were compared with standard uptake values in 10 PET-CT examinations without contrast agents.
Results: . The application of oral and IV contrast materials led to a highly sufficient delineation of vascular and intestinal structures in 26 of 30 patients. Quantitative analysis revealed a mean vascular SNR of 15.8 +/- 7.71 for the 30 patients who received contrast materials compared with 4.79 +/- 1.45 for the 10 control group patients (p < 0.001). Similarly, the mean intestinal SNR of 17.06 +/- 7.96 far exceeded that seen in the control group of 3.83 +/- 1.16 (p < 0.001). Analyses led to a vessel-to-muscle CNR of 10.78 +/- 5.89 (control group, -1.21 +/- 0.89; p < 0.001) and an intestine-to-muscle CNR of 12.04 +/- 6.07 (control group, -2.17 +/- 1.22; p = 0.001) in the 30 patients. An evaluation of PET quality in patients who received contrast materials showed a mean standard uptake value of 2.09 +/- 1.16 compared with 2.04 +/- 0.83 in the control group (p = 0.702).
Conclusion: Our whole-body PET-CT protocol provided good vascular and intestinal enhancement without compromising PET quality, leading to a potential improvement in the diagnostic capacity of the combined PET-CT examination.