Metallic artefact reduction with monoenergetic dual-energy CT: systematic ex vivo evaluation of posterior spinal fusion implants from various vendors and different spine levels

Abstract

Objectives To evaluate optimal monoenergetic dual-energy computed tomography (DECT) settings for artefact reduction of posterior spinal fusion implants of various vendors and spine levels. Methods Posterior spinal fusion implants of five vendors for cervical, thoracic and lumbar spine were examined ex vivo with single-energy (SE) CT (120 kVp) and DECT (140/100 kVp). Extrapolated monoenergetic DECT images at 64, 69, 88, 105 keV and individually adjusted monoenergy for optimised image quality (OPTkeV) were generated. Two independent radiologists assessed quantitative and qualitative image parameters for each device and spine level. Results Inter-reader agreements of quantitative and qualitative parameters were high (ICC00.81-1.00, κ00.54-0.77). HU values of spinal fusion implants were significantly different among vendors (P<0.001), spine levels (P<0.01) and among SECT, monoenergetic DECT of 64, 69, 88, 105 keV and OPTkeV (P<0.01). Image quality was significantly (P<0.001) different between datasets and improved with higher monoenergies of DECT compared with SECT (V 00.58, P < 0.001). Artefacts decreased significantly (V00.51, P<0.001) at higher monoenergies. OPTkeV values ranged from 123-141 keV. OPTkeV according to vendor and spine level are presented herein. Conclusions Monoenergetic DECT provides significantly better image quality and less metallic artefacts from implants than SECT. Use of individual keV values for vendor and spine level is recommended. Key Points• Artefacts pose problems for CT following posterior spinal fusion implants.• CT images are interpreted better with monoenergetic extrapolation using dual-energy (DE) CT.• DECT extrapolation improves image quality and reduces metallic artefacts over SECT.• There were considerable differences in monoenergy values among vendors and spine levels.• Use of individualised monoenergy values is indicated for different metallic hardware devices.

CT Metal Artifact Reduction in the Spine: Can an Iterative Reconstruction Technique Improve Visualization?

“…7,14 However, the effectiveness of artifact reduction by using monoenergetic imaging appears to be dependent on implant material and size. 7,9,12,13 Our work used a method for metal artifact reduction that can be employed using conventional single-energy CT acquisition with thresholds and other settings potentially altered to adjust for different types and location of metal implants. Others have previously described a 1D linear interpolation to improve CT sinogram data, 15,16 but such approaches have not been put into clinical practice until recently, primarily due to the high computational time requirements.…”

“…Recent publications have presented several postprocessing methods for decreasing the severity of metal implant artifacts in CT. [7][8][9][10][11] These works describe unique challenges to minimizing metal-related artifacts in different body regions due to differences in local anatomy and in implant composition. 12 However, only a few of these works focused on the unique challenges of the postoperative spine, 12,13 and none assessed visualization of the critical anatomic structures that the neuroradiologist must evaluate in the postoperative setting. Additionally, prior studies have not systematically assessed how metal artifact reduction images should be incorporated into clinical practice (eg, instead of or in addition to routine images).…”

Material differentiation in forensic radiology with single-source dual-energy computed tomography

“…There are a growing number of publications on application of DECT in clinical imaging [11][12][13][14][15][16]. So far, the potential of DECT has not yet been fully appreciated in forensic and post-mortem imaging.…”

“…It can be used to generate virtual non-contrast images, characterize atherosclerotic plaques, measure vascular perfusion of the brain, the heart, or the lungs, assess steatosis or iron overload in the liver, determine renal stone composition, detect bone bruise lesions, or reduce metal artifacts through monoenergetic image reconstruction [11][12][13][14][15][16]. Several of these clinical applications may also be implemented in forensic radiology.…”

Evaluation of monoenergetic imaging to reduce metallic instrumentation artifacts in computed tomography of the cervical spine

“…4,15 Although dual-energy CT scanners are being increasingly used for imaging of patients with metallic spinal instrumentation, there is little information available regarding the effect of acquisition parameters and hardware material on the severity of artifacts. 5,6,13,16 The purpose of the present study was to systematically evaluate and define the optimal dual-energy CT imaging parameters for specific cervical spinal implant alloy compositions.…”