Feasibility of PET-enabled dual-energy CT imaging: First physical phantom and initial patient study results

• Published in: European journal of nuclear medicine and molecular imaging Vol. 52; no. 5; pp. 1912 - 1923
• Main Authors: Zhu, Yansong, Li, Siqi, Xie, Zhaoheng, Leung, Edwin K., Bayerlein, Reimund, Omidvari, Negar, Abdelhafez, Yasser G., Cherry, Simon R., Qi, Jinyi, Badawi, Ramsey D., Spencer, Benjamin A., Wang, Guobao
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.04.2025; Springer Nature B.V
• Subjects: Bone lesions; Cardiology; Computed tomography; Correlation coefficients; Decomposition; Feasibility Studies; Gamma rays; Hardware; Humans; Image Processing, Computer-Assisted; Image quality; Image reconstruction; Imaging; Lesions; Male; Medicine; Medicine & Public Health; Nuclear Medicine; Oncology; Original Article; Orthopedics; Phantoms, Imaging; Positron emission; Positron emission tomography; Positron Emission Tomography Computed Tomography - instrumentation; Positron Emission Tomography Computed Tomography - methods; Radiation; Radiation dosage; Radiation effects; Radiology; Scanners; Tomography, X-Ray Computed; Upgrading; X-rays; Dual-energy CT; Real data validation; PET-enabled dual-energy CT; Kernel method
• ISSN: 1619-7070; 1619-7089; 1619-7089
• DOI: 10.1007/s00259-024-06975-5

Purpose Dual-energy (DE) CT enables material decomposition by using two different x-ray energies and may be combined with PET for improved multimodality imaging. However, this increases radiation dose and may require a hardware upgrade due to the added second x-ray CT scan. The recently proposed PET-enabled DECT method allows dual-energy imaging using a conventional PET/CT scanner without the need to change scanner hardware or increase radiation exposure. Here we demonstrate the first-time physical phantom and patient data evaluation of this method. Methods The PET-enabled DECT method reconstructs a gamma-ray CT (gCT) image at 511 keV from the time-of-flight PET data with the maximum-likelihood attenuation and activity (MLAA) approach and then combines this image with the low-energy x-ray CT images to form a dual-energy image pair for material decomposition. To improve the image quality of gCT, a kernel MLAA method was developed using the x-ray CT as a priori information. Here we developed a general open-source implementation for gCT reconstruction and used this implementation for the first real data validation using both physical phantom study and human-subject study. Results from PET-enabled DECT were compared using x-ray DECT as the reference. Further, we applied the PET-enabled DECT method in another patient study to evaluate bone lesions. Results Compared to the standard MLAA, results from the kernel MLAA showed significantly improved image quality. PET-enabled DECT with the kernel MLAA was able to generate fractional images that were comparable to the x-ray DECT, with high correlation coefficients for both the phantom study and human subject study ( R  > 0.99). The application study also indicates that PET-enabled DECT has potential to characterize bone lesions. Conclusion Results from this study have demonstrated the feasibility of this PET-enabled method for CT imaging and material decomposition. PET-enabled DECT shows promise to provide comparable results to x-ray DECT.