Metal artifact reduction in computed tomography: Is it of benefit in evaluating sacroiliac joint fusion?

Selles, Mark; Korte, Jan H.; Boelhouwers, Henk J.; Nijholt, Ingrid M.; Osch, Jochen A.C. van; Nijveldt, Robert J.; Maas, Mario; Boomsma, Martijn F.

doi:10.1016/j.ejrad.2022.110159

Cited by 7 publications

(4 citation statements)

References 25 publications

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“…7 b, Siemens protocol 3* and protocol 6 images of sacroiliac joints were rated significantly higher in patients who had Rialto screws, compared to iFuse in the same patient group (Tables 2 and 3 ), due to artifacts induced by the algorithms. Selles et al [ 24 ] reported similar artifacts with the Philips O-MAR algorithm in a clinical study with the same iFuse screws.…”

Section: Discussionmentioning

confidence: 81%

Metal artifact reduction on musculoskeletal CT: a phantom and clinical study

Midthun,

Kirkhus,

Østerås

et al. 2023

Eur Radiol Exp

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Background Artifacts caused by metal implants are challenging when undertaking computed tomography (CT). Dedicated algorithms have shown promising results although with limitations. Tin filtration (Sn) in combination with high tube voltage also shows promise but with limitations. There is a need to examine these limitations in more detail. The purpose of this study was to investigate the impact of different metal artefact reduction (MAR) algorithms, tin filtration, and ultra-high-resolution (UHR) scanning, alone or in different combinations in both phantom and clinical settings. Methods An ethically approved clinical and phantom study was conducted. A modified Catphan® phantom with titanium and stainless-steel inserts was scanned with six different MAR protocols with tube voltage ranging from 80 to 150 kVp. Other scan parameters were kept identical. The differences (∆) in mean HU and standard deviation (SD) in images, with and without metal, were measured and compared. In the clinical study, three independent readers performed visual image quality assessments on eight different protocols using retrospectively acquired images. Results Iterative MAR had the lowest ∆HU and ∆SD in the phantom study. For images of the forearm, the soft tissue noise for Sn-based 150-kVp UHR protocol with was significantly higher (p = 0.037) than for single-energy MAR protocols. All Sn-based 150-kVp protocols were rated significantly higher (p < 0.046 than the single-energy MAR protocols in the visual assessment. Conclusions All Sn-based 150-kVp UHR protocols showed similar objective MAR in the phantom study, and higher objective MAR and significantly improved visual image quality than single-energy MAR. Relevance statement Images with less metal artifacts and higher visual image quality may be more clinically optimal in CT examination of musculoskeletal patients with metal implants. Key points • Metal artifact reduction algorithms and Sn filter combined with high kVp reduce artifacts. • Metal artifact reduction algorithms introduce new artifacts in certain metals. • Sn-based protocols alone may be considered as low metal artifact protocols. Graphical Abstract

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Section: Discussionmentioning

confidence: 81%

Metal artifact reduction on musculoskeletal CT: a phantom and clinical study

Midthun,

Kirkhus,

Østerås

et al. 2023

Eur Radiol Exp

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“…Fortunately, owing to advances in metal artifact reduction in CT images, several techniques have been proposed, such as projection-based metal artifact reduction algorithms, virtual monoenergetic imaging using dual-energy CT, photon counting CT, and deep learning-based algorithms. These could be implemented in further research to address this limitation [24]. Another limitation is that when the chest image is sliced at the level of the intervertebral disk in patients with severe scoliosis, the sternum and vertebrae in the chest CT image may not simultaneously appear within the middle 10% (our default value) of the screen.…”

Section: Limitationsmentioning

confidence: 99%

Pectus excavatum diagnosis redefined: A fully automatic tool for batch evaluation of chest computed tomography images

Fan,

Ng,

Tzeng

et al. 2024

Preprint

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We aimed to implement a fully automatic computed tomography (CT) image-detection programming algorithm as a pectus excavatum (PE) diagnostic tool, facilitating comprehensive chest wall deformity evaluation. We developed our algorithm using MATLAB®, leveraging the Hounsfield unit threshold and region growing methods. The MATLAB graphical user interface enables the direct use of our program. We validated the model using CT images of anthropomorphic phantoms. The measurement values obtained by our algorithm demonstrated very small difference compared to known anthropomorphic phantom model data. For algorithm testing, 17,214 chest CT images of 57 patients were processed by algorithm and reviewed independently by a radiologist and a thoracic surgeon. The measurements of transverse, anteroposterior, and sternum-to-vertebral distance of the thoracic cavity, and the calculation data of four indices exhibited high positive correlation (0.94 ~ 0.99); asymmetry index and maximum anteroposterior hemithorax distance exhibited moderate correlation (0.40 ~ 0.83). Our automatic PE diagnostic tool demonstrated high accuracy; four chest wall deformity indices were obtained simultaneously without any initial manual marking, which correlated with manual measurements.

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“…15,[19][20][21][22] Three strategies to mitigate metal artifacts are: (1) simulation of mono-energetic energies at high energy, (2) use of raw data with modified iterative reconstruction, (3) application of dedicated Metal Artefact Reduction (MAR) algorithms on projection data. [23][24][25][26] PCCT holds great promise for cardiac imaging in patients during LVAD therapy, and there is a consensus on the utilization of CT for postoperative imaging of LVAD patients. 11,27 However, a CT protocol delineating the optimal combination of metal artifact mitigating strategies for EID 11 and PCCT for LVAD imaging is currently lacking.…”

Section: Introductionmentioning

confidence: 99%

“…Three strategies to mitigate metal artifacts are: (1) simulation of mono‐energetic energies at high energy, (2) use of raw data with modified iterative reconstruction, (3) application of dedicated Metal Artefact Reduction (MAR) algorithms on projection data 23–26 …”

Section: Introductionmentioning

confidence: 99%

Optimization of photon counting CT for cardiac imaging in patients with left ventricular assist devices: An in‐depth assessment of metal artifacts

Konst,

Ohlsson,

Henriksson

et al. 2024

J Applied Clin Med Phys

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PurposePhoton counting CT (PCCT) holds promise for mitigating metal artifacts and can produce virtual mono‐energetic images (VMI), while maintaining temporal resolution, making it a valuable tool for characterizing the heart. This study aimed to evaluate and optimize PCCT for cardiac imaging in patients during left ventricular assistance device (LVAD) therapy by conducting an in‐depth objective assessment of metal artifacts and visual grading.MethodsVarious scan and reconstruction settings were tested on a phantom and further evaluated on a patient acquisition to identify the optimal protocol settings. The phantom comprised an empty thoracic cavity, supplemented with heart and lungs from a cadaveric lamb. The heart was implanted with an LVAD (HeartMate 3) and iodine contrast. Scans were performed on a PCCT (NAEOTOM Alpha, Siemens Healthcare). Metal artifacts were assessed by three objective methods: Hounsfield units (HU)/SD measurements (DiffHU and SDARTIFACT), Fourier analysis (AmplitudeLowFreq), and depicted LVAD volume in the images (BloomVol). Radiologists graded metal artifacts and the diagnostic interpretability in the LVAD lumen, cardiac tissue, lung tissue, and spinal cord using a 5‐point rating scale. Regression and correlation analysis were conducted to determine the assessment method most closely associated with acquisition and reconstruction parameters, as well as the objective method demonstrating the highest correlation with visual grading.ResultsDue to blooming artifacts, the LVAD volume fluctuated between 27.0 and 92.7 cm3. This variance was primarily influenced by kVp, kernel, keV, and iMAR (R2 = 0.989). Radiologists favored pacemaker iMAR, 3 mm slice thickness, and T3D keV and kernel Bv56f for minimal metal artifacts in cardiac tissue assessment, and 110 keV and Qr40f for lung tissue interpretation. The model adequacy for DiffHU SDARTIFACT, AmplitueLowFreq, and BloomVol was 0.28, 0.76, 0.29, and 0.99 respectively for phantom data, and 0.95, 0.98, 1.00, and 0.99 for in‐vivo data. For in‐vivo data, the correlation between visual grading (VGSUM) and DiffHU SDARTIFACT, AmplitueLowFreq, and BloomVol was −0.16, −0.01, −0.48, and −0.40 respectively.ConclusionWe found that optimal scan settings for LVAD imaging involved using 120 kVp and IQ level 80. Employing T3D with pacemaker iMAR, the sharpest allowed vascular kernel (Bv56f), and VMI at 110 keV with kernel Qr40 yields images suitable for cardiac imaging during LVAD‐therapy. Volumetric measurements of the LVAD for determination of the extent of blooming artifacts was shown to be the best objective method to assess metal artifacts.

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Metal artifact reduction in computed tomography: Is it of benefit in evaluating sacroiliac joint fusion?

Cited by 7 publications

References 25 publications

Metal artifact reduction on musculoskeletal CT: a phantom and clinical study

Metal artifact reduction on musculoskeletal CT: a phantom and clinical study

Pectus excavatum diagnosis redefined: A fully automatic tool for batch evaluation of chest computed tomography images

Optimization of photon counting CT for cardiac imaging in patients with left ventricular assist devices: An in‐depth assessment of metal artifacts

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