A Universal Protocol for Abdominal CT Examinations Performed on a Photon-Counting Detector CT System

Abstract

Objective: The aims of this study were to investigate the feasibility of using a universal abdominal acquisition protocol on a photon-counting detector computed tomography (PCD-CT) system and to compare its performance to that of single-energy (SE) and dual-energy (DE) CT using energy-integrating detectors (EIDs). Methods: Iodine inserts of various concentrations and sizes were embedded into different sizes of adult abdominal phantoms. Phantoms were scanned on a research PCD-CT and a clinical EID-CT with SE and DE modes. Virtual monoenergetic images (VMIs) were generated from PCD-CTand DE mode of EID-CT. For each image type and phantom size, contrast-to-noise ratio (CNR) was measured for each iodine insert and the area under the receiver operating characteristic curve (AUC) for iodine detectability was calculated using a channelized Hotelling observer. The optimal energy (in kiloelectrovolt) of VMIs was determined separately as the one with highest CNR and the one with the highest AUC. The PCD-CT VMIs at the optimal energy were then compared with DE VMIs and SE images in terms of CNR and AUC. Results: Virtual monoenergetic image at 50 keV had both the highest CNR and highest AUC for PCD-CT and DECT. For 1.0 mg I/mL iodine and 35 cm phantom, the CNRs of 50 keV VMIs from PCD-CT (2.01 ± 0.67) and DE (1.96 ± 0.52) were significantly higher (P < 0.001, Wilcoxon signed-rank test) than SE images (1.11 ± 0.35). The AUC of PCD-CT (0.98 ± 0.01) was comparable to SE (0.98 ± 0.01), and both were slightly lower than DE (0.99 ± 0.01, P < 0.01, Wilcoxon signed-rank test). A similar trend was observed for other phantom sizes and iodine concentrations. Conclusions: Virtual monoenergetic images at a fixed energy from a universal acquisition protocol on PCD-CT demonstrated higher iodine CNR and comparable iodine detectability than SECT images, and similar performance compared with DE VMIs.

Quantum Iterative Reconstruction for Low-Dose Ultra-High-Resolution Photon-Counting Detector CT of the Lung

“…Photon-counting detector computed tomography (PCD-CT) is an emerging technology that enables the direct conversion of incident x-ray photons into an electrical signal. As compared to conventional energy-integrating detector (EID)-CT systems, PCD-CT has shown improved spatial resolution, lower image noise, and higher contrast-to-noise ratio (CNR) [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 ]. Previous studies on preclinical prototype PCD-CT suggest that these benefits can be translated to an improved diagnosis of pulmonary nodules [ 10 ] and to improvements in shape and texture image information due to the higher spatial resolution of PCD-CT as compared to EID-CT [ 11 , 12 ].…”

Quantum Iterative Reconstruction for Abdominal Photon-counting Detector CT Improves Image Quality

“…Compared with previous energy-integrating detector CT systems, this first-generation dual-source full fieldof-view PCD CT can detect and weigh single photons on the basis of their energies, enabling spectral separation and multi-material decomposition (1)(2)(3). Prototype PCD CT systems have been shown to provide improved spatial resolution, dose efficiency, contrast-to-noise ratio (CNR), and lower image noise (4)(5)(6)(7)(8)(9)(10)(11)(12).…”

Quantum Iterative Reconstruction for Abdominal Photoncounting Detector CT Improves Image Quality

“…Compared with previous energy-integrating detector CT systems, this first-generation dual-source full fieldof-view PCD CT can detect and weigh single photons on the basis of their energies, enabling spectral separation and multi-material decomposition (1)(2)(3). Prototype PCD CT systems have been shown to provide improved spatial resolution, dose efficiency, contrast-to-noise ratio (CNR), and lower image noise (4)(5)(6)(7)(8)(9)(10)(11)(12).…”