Author: Meghan Lubner, Krista McClure, Aria M. Salyapongse, Timothy P. Szczykutowicz, Giuseppe Toia, Ming Yan, Zhye Yin, Meghan Yue 👨🔬
Affiliation: GE HealthCare, Departments of Radiology and Medical Physics, University Wisconsin-Madison, GE Healthcare, University of Wisconsin-Madison, UW-Madison, University of Wisconsin Madison, Department of Radiology 🌍
Purpose: To evaluate virtual unenhanced (VUE) and true unenhanced (TUE) human subject images on a prototype deep silicon photon-counting detector (PCD) CT with prototype algorithms.
Methods: 5 subjects, including various anatomies (1 chest, 1 head, 1 wrist/hand, 3 abdomens) and phases were scanned on a prototype deep silicon PCD CT acquired at 120 kV and mA adjusted for anatomy and subject size. 5 slices were selected from each image set at two locations to provide a variety of anatomy, including vessels (e.g., aorta, portal bifurcation, inferior vena cava), soft tissue (e.g., liver, spleen, muscle), and adipose. ROIs were drawn over the anatomy on both TUE and VUE images. VUE error was defined as VUE CT number in Hounsfield units (HU) minus the VUE CT number.
Results: For all tested structures, 82% had a VUE error less than 10 HU, and 62% had a VUE error less than 5 HU. Small vessels and adipose were the most likely to have a VUE error greater than 5 or 10 HU. Vessels demonstrated VUE errors less than 10 HU and less than 5 HU for 70.4% and 40.7% of tested anatomies, respectively. Soft tissue had VUE errors less than 10 HU and 5 HU in 96.9% and 84.4%, and adipose had VUE errors less than 10 HU and 5 HU in 75% and 58.4% of tested anatomies.
Conclusion: With the prototype scanner and VUE algorithm, the majority of anatomies tested demonstrated VUE error less than 10 HU, and for all but the vessels, the majority of anatomies demonstrated VUE error less than 5 HU. With such small differences in HU between VUE and TUE images, it could be possible to remove non-contrast phases from scanning protocols.