Metal artifact reduction in ultra-high-resolution cone-beam CT imaging with a twin robotic X-ray system

Abstract

Cone-beam computed tomography (CBCT) has been shown to be a powerful tool for 3D imaging of the appendicular skeleton, allowing for detailed visualization of bone microarchitecture. This study was designed to compare artifacts in the presence of osteosynthetic implants between CBCT and multidetector computed tomography (MDCT) in cadaveric wrist scans. A total of 32 scan protocols with varying tube potential and current were employed: both conventional CBCT and MDCT studies were included with tube voltage ranging from 60 to 140 kVp as well as additional MDCT protocols with dedicated spectral shaping via tin prefiltration. Irrespective of scanner type, all examinations were conducted in ultra-high-resolution (UHR) scan mode. For reconstruction of UHR-CBCT scans an additional iterative metal artifact reduction algorithm was employed, an image correction tool which cannot be used in combination with UHR-MDCT. To compare applied radiation doses between both scanners, the volume computed tomography dose index for a 16 cm phantom (CTDIvol) was evaluated. Images were assessed regarding subjective and objective image quality. Without automatic tube current modulation or tube potential control, radiation doses ranged between 1.3 mGy (with 70 kVp and 50.0 effective mAs) and 75.2 mGy (with 140 kVp and 383.0 effective mAs) in UHR-MDCT. Using the pulsed image acquisition method of the CBCT scanner, CTDIvol ranged between 2.3 mGy (with 60 kVp and 0.6 mean mAs per pulse) and 61.0 mGy (with 133 kVp and 2.5 mean mAs per pulse). In essence, all UHR-CBCT protocols employing a tube potential of 80 kVp or more were found to provide superior overall image quality and artifact reduction compared to UHR-MDCT (all p < .050). Interrater reliability of seven radiologists regarding image quality was substantial for tissue assessment and moderate for artifact assessment with Fleiss kappa of 0.652 (95% confidence interval 0.618–0.686; p < 0.001) and 0.570 (95% confidence interval 0.535–0.606; p < 0.001), respectively. Our results demonstrate that the UHR-CBCT scan mode of a twin robotic X-ray system facilitates excellent visualization of the appendicular skeleton in the presence of metal implants. Achievable image quality and artifact reduction are superior to dose-comparable UHR-MDCT and even MDCT protocols employing spectral shaping with tin prefiltration do not achieve the same level of artifact reduction in adjacent soft tissue.

Photon-Counting Detector CT Virtual Monoenergetic Images in Cervical Trauma Imaging—Optimization of Dental Metal Artifacts and Image Quality

“…Tin prefiltration might lead to another benefit regarding metal artifact reduction as previous studies described; further studies will have to evaluate the effects of spectral shaping especially on vascular structures and on PCD-CT, as previous studies have examined only non-contrast-enhanced scans [ 12 ] or datasets from dual-source CT scanners [ 11 ].…”

“…This can lead to increased radiation dose concomitant with greater risks to the patients [ 8 ]. Dual-energy CT technologies have shown effects on metal artifact reduction in past research using VME imaging [ 9 , 10 ]; in addition, tin prefiltration has also been used in previous studies for artifact reduction [ 11 , 12 ]. Along with the acquisition of spectral CT datasets from the latest generations of CT devices, VME images can be reconstructed and used for metal artifact reduction.…”

Osseodensification vs. Conventional Osteotomy: A Case Series with Cone Beam Computed Tomography

“…Additionally, the improvement in reconstruction algorithms and newer metal artifact reduction algorithms is becoming increasingly common [ 23 ].…”