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150-μm Spatial Resolution Using Photon-Counting Detector Computed Tomography Technology

Technical Performance and First Patient Images

Leng, Shuai, PhD*; Rajendran, Kishore, PhD*; Gong, Hao, PhD*; Zhou, Wei, PhD*; Halaweish, Ahmed F., PhD; Henning, Andre, PhD; Kappler, Steffen, PhD; Baer, Matthias, PhD; Fletcher, Joel G., MD*; McCollough, Cynthia H., PhD*

doi: 10.1097/RLI.0000000000000488
Original Articles

Objective The aims of this study were to quantitatively assess two new scan modes on a photon-counting detector computed tomography system, each designed to maximize spatial resolution, and to qualitatively demonstrate potential clinical impact using patient data.

Materials and Methods This Health Insurance Portability Act–compliant study was approved by our institutional review board. Two high–spatial-resolution scan modes (Sharp and UHR) were evaluated using phantoms to quantify spatial resolution and image noise, and results were compared with the standard mode (Macro). Patients were scanned using a conventional energy-integrating detector scanner and the photon-counting detector scanner using the same radiation dose. In first patient images, anatomic details were qualitatively evaluated to demonstrate potential clinical impact.

Results Sharp and UHR modes had a 69% and 87% improvement in in-plane spatial resolution, respectively, compared with Macro mode (10% modulation-translation-function values of 16.05, 17.69, and 9.48 lp/cm, respectively). The cutoff spatial frequency of the UHR mode (32.4 lp/cm) corresponded to a limiting spatial resolution of 150 μm. The full-width-at-half-maximum values of the section sensitivity profiles were 0.41, 0.44, and 0.67 mm for the thinnest image thickness for each mode (0.25, 0.25, and 0.5 mm, respectively). At the same in-plane spatial resolution, Sharp and UHR images had up to 15% lower noise than Macro images. Patient images acquired in Sharp mode demonstrated better delineation of fine anatomic structures compared with Macro mode images.

Conclusions Phantom studies demonstrated superior resolution and noise properties for the Sharp and UHR modes relative to the standard Macro mode and patient images demonstrated the potential benefit of these scan modes for clinical practice.

From the *Department of Radiology, Mayo Clinic, Rochester, MN;

Siemens Healthcare, Malvern, PA; and

Siemens Healthcare, Forchheim, Germany.

Received for publication February 1, 2018; and accepted for publication, after revision, April 16, 2018.

The project described was supported by the National Institutes of Health under award numbers R01 EB016966 and C06 RR018898 and in collaboration with Siemens Healthcare. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institute of Health. The device described is a research scanner and not commercially available.

The authors report no conflicts of interest.

Correspondence to: Cynthia H. McCollough, PhD, Department of Radiology, Mayo Clinic, 200 First St SW, Rochester, MN 55905. E-mail:

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