Metal artifacts with dental implants: Evaluation using a dedicated CT/MR oral phantom with registration of the CT and MR images

Lee, Min Young; Song, Kwang Hyun; Lee, Jeongwoo; Choe, Bo-Young; Suh, Tae Suk

doi:10.1038/s41598-018-36227-0

Cited by 8 publications

(9 citation statements)

References 34 publications

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“…While the GRE sequence is more sensitive to field heterogeneity or metal-induced susceptibility artifacts than SE ( 15 ), there were no significant differences between the two sequences in the present study. This could have occurred because the aforementioned improved B0 correction compensated the field heterogeneity and the use of a higher bandwidth in CS-3D-T1TFE reduced the distortion by the artifact ( 16 , 17 ). The increased bandwidth might cause decreased SNR, but the SNR of CS-3D-T1TFE was kept equal or higher than MS-SE in our settings.…”

Section: Discussionmentioning

confidence: 99%

Comparison of image quality of head and neck lesions between 3D gradient echo sequences with compressed sensing and the multi-slice spin echo sequence

Kami

Chikui

Togao

et al. 2020

Acta Radiologica Open

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Background Although magnetic resonance imaging (MRI) provides excellent soft-tissue contrast, long acquisition times are major disadvantages. Purpose To evaluate the usefulness of compressed sensing (CS) for contrast-enhanced oral and maxillofacial MRI by comparing the 3D T1 turbo field echo with compressed SENSE (CS-3D-T1TFE) sequence with the multi-slice spin echo (MS-SE) sequence as the reference standard. Material and Methods Thirty patients with orofacial lesions participated in this study. The scan times for MS-SE and CS-3D-T1TFE were 5 min 56 s and 1 min 43 s, respectively. The signal-to-noise ratio (SNR) was calculated for quantitative analysis and seven parameters (degree of lesion conspicuity, motion artifacts, metal artifacts, pulsation artifacts, quality of fat suppression, homogeneity of blood vessel signal intensity, and overall image quality) were evaluated using a 5-point scale (5 = excellent, 1 = unacceptable) by two observers for qualitative analysis. For comparisons between MS-SE and CS-3D-T1TFE, the paired t-test was used. Results The SNR of CS-3D-T1TFE was higher than or equal to that of MS-SE. The CS-3D-T1TFE scores for motion artifacts, pulsation artifacts, and homogeneity of blood vessel signal intensity were higher than the corresponding MS-SE scores in assessments by both observers. The MS-SE scores for fat suppression were higher than or equal to the CS-3D-T1TFE scores. There were no significant differences in lesion conspicuity, metal artifacts, and overall image quality between the two sequences. Conclusion CS-3D-T1TFE imaging, less than 30% of the scan time for MS-SE, showed no image degradation while retaining equal or higher SNR and image quality.

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Section: Discussionmentioning

confidence: 99%

Comparison of image quality of head and neck lesions between 3D gradient echo sequences with compressed sensing and the multi-slice spin echo sequence

Kami

Chikui

Togao

et al. 2020

Acta Radiologica Open

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“…• Spin-echo sequences with modified parameters (i.e., echo time, matrix, bandwidth, slice thickness, and echo train); high bandwidth per voxel, 3D spatial encoding, highresolution matrix, and multi-echo spin-echo sequences or turbo/fast spin-echo sequences. Spin-echo sequences are less sensitive to susceptibility effects thanks to a 180° radiofrequency pulse that refocuses the spins diminishing the phase shifts in the voxel and therefore the field inhomogeneity [58]; • Gradient echo sequence with a very short echo time. These sequences are metal-sensitive and the signal loss is due to the intravoxel dephasing.…”

Section: Mrimentioning

confidence: 99%

“…These sequences are metal-sensitive and the signal loss is due to the intravoxel dephasing. Shortening the echo time and decreasing the voxel size can diminish the intravoxel dephasing and therefore the artifacts [58];…”

Section: Mrimentioning

confidence: 99%

Techniques, Tricks, and Stratagems of Oral Cavity Computed Tomography and Magnetic Resonance Imaging

et al. 2022

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The oral cavity constitutes a complex anatomical area that can be affected by many developmental, inflammatory, and tumoural diseases. MultiSlice Computed Tomography (MSCT) and Magnetic Resonance Imaging (MRI) currently represent the essential and complementary imaging techniques for detecting oral cavity abnormalities. Advanced MRI with diffusion-weighted imaging (DWI) and dynamic contrast-enhanced perfusion-weighted imaging (DCE-PWI) has recently increased the ability to characterise oral lesions and distinguish disease recurrences from post therapy changes. The analysis of the oral cavity area via imaging techniques is also complicated both by mutual close appositions of different mucosal surfaces and metal artifacts from dental materials. Nevertheless, an exact identification of oral lesions is made possible thanks to dynamic manoeuvres and specific stratagems applicable on MSCT and MRI acquisitions. This study summarises the currently available imaging techniques for oral diseases, with particular attention to the role of DWI, DCE-PWI, and dynamic manoeuvres. We also propose MSCT and MRI acquisition protocols for an accurate study of the oral cavity area.

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“…The registration can however be altered by the presence of artifacts, notably dental artifacts for CT ( 31 , 32 ). Concerning MRI, the presence of geometric distortions, related to the system or the patient ( 33 ), can alter the registration.…”

Section: Technical Partsmentioning

confidence: 99%

Trimodality PET/CT/MRI and Radiotherapy: A Mini-Review

Decazes

Hinault

Veresezan³

et al. 2021

Front. Oncol.

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Computed tomography (CT) has revolutionized external radiotherapy by making it possible to visualize and segment the tumors and the organs at risk in a three-dimensional way. However, if CT is a now a standard, it presents some limitations, notably concerning tumor characterization and delineation. Its association with functional and anatomical images, that are positron emission tomography (PET) and magnetic resonance imaging (MRI), surpasses its limits. This association can be in the form of a trimodality PET/CT/MRI. The objective of this mini-review is to describe the process of performing this PET/CT/MRI trimodality for radiotherapy and its potential clinical applications. Trimodality can be performed in two ways, either a PET/MRI fused to a planning CT (possibly with a pseudo-CT generated from the MRI for the planning), or a PET/CT fused to an MRI and then registered to a planning CT (possibly the CT of PET/CT if calibrated for radiotherapy). These examinations should be performed in the treatment position, and in the second case, a patient transfer system can be used between the PET/CT and MRI to limit movement. If trimodality requires adapted equipment, notably compatible MRI equipment with high-performance dedicated coils, it allows the advantages of the three techniques to be combined with a synergistic effect while limiting their disadvantages when carried out separately. Trimodality is already possible in clinical routine and can have a high clinical impact and good inter-observer agreement, notably for head and neck cancers, brain tumor, prostate cancer, cervical cancer.

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Metal artifacts with dental implants: Evaluation using a dedicated CT/MR oral phantom with registration of the CT and MR images

Cited by 8 publications

References 34 publications

Comparison of image quality of head and neck lesions between 3D gradient echo sequences with compressed sensing and the multi-slice spin echo sequence

Comparison of image quality of head and neck lesions between 3D gradient echo sequences with compressed sensing and the multi-slice spin echo sequence

Techniques, Tricks, and Stratagems of Oral Cavity Computed Tomography and Magnetic Resonance Imaging

Trimodality PET/CT/MRI and Radiotherapy: A Mini-Review

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