Dataset Information

Magnetic resonance imaging of intraoral hard and soft tissues using an intraoral coil and FLASH sequences.

ABSTRACT:

Objectives

To ascertain the feasibility of MRI as a non-ionizing protocol for routine dentomaxillofacial diagnostic imaging. Wireless coils were used for MRI of intraoral hard and soft tissues.

Methods

FLASH MRI was applied in vivo with a mandible voxel size of 250?×?250?×?500 ?m³, FOV of 64?×?64?×?28 mm³ and acquisition time of 3:57 min and with a maxilla voxel size of 350 ?m³ and FOV of 34 cm³ in 6:40 min. Ex vivo imaging was performed in 4:38 min, with a resolution of 200 ?m³ and FOV of 36.5 cm³. Cone beam (CB) CT of the mandible and subjects were acquired. MRI was compared to CBCT and histological sections. Deviations were calculated with intraclass correlation coefficient (ICC) and coefficient of variation (c_v).

Results

A high congruence between CBCT, MRI and specimens was demonstrated. Hard and soft tissues including dental pulp, periodontium, gingiva, cancellous bone and mandibular canal contents were adequately displayed with MRI.

Conclusions

Imaging of select intraoral tissues was achieved using custom MRI protocols with an easily applicable intraoral coil in a clinically acceptable acquisition time. Comparison with CBCT and histological sections helped demonstrate dimensional accuracy of the MR images. The course of the mandibular canal was accurately displayed with CBCT and MRI.

Key points

• MRI is a clinically available diagnostic tool in dentistry • Intraoral hard and soft tissues can be imaged with a high resolution with MRI • The dimensional accuracy of MRI is comparable to cone beam CT.

SUBMITTER: Flugge T

PROVIDER: S-EPMC5101280 | biostudies-literature | 2016 Dec

REPOSITORIES: biostudies-literature

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Publications

Magnetic resonance imaging of intraoral hard and soft tissues using an intraoral coil and FLASH sequences.

Flügge Tabea T Hövener Jan-Bernd JB Ludwig Ute U Eisenbeiss Anne-Kathrin AK Spittau Björn B Hennig Jürgen J Schmelzeisen Rainer R Nelson Katja K

European radiology 20160224 12

<h4>Objectives</h4>To ascertain the feasibility of MRI as a non-ionizing protocol for routine dentomaxillofacial diagnostic imaging. Wireless coils were used for MRI of intraoral hard and soft tissues.<h4>Methods</h4>FLASH MRI was applied in vivo with a mandible voxel size of 250 × 250 × 500 μm<sup>3</sup>, FOV of 64 × 64 × 28 mm<sup>3</sup> and acquisition time of 3:57 min and with a maxilla voxel size of 350 μm<sup>3</sup> and FOV of 34 cm<sup>3</sup> in 6:40 min. Ex vivo imaging was performed ...[more]

PMID: 26910905

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Project description:BackgroundA low excitation flip angle (α < 10°) steady-state free precession (SSFP) proton-density (PD) reference scan is often used to estimate the B1-field inhomogeneity for surface coil intensity correction (SCIC) of the saturation-recovery (SR) prepared high flip angle (α = 40-50°) SSFP myocardial perfusion images. The different SSFP off-resonance response for these two flip angles might lead to suboptimal SCIC when there is a spatial variation in the background B0-field. The low flip angle SSFP-PD frames are more prone to parallel imaging banding artifacts in the presence of off-resonance. The use of FLASH-PD frames would eliminate both the banding artifacts and the uneven frequency response in the presence of off-resonance in the surface coil inhomogeneity estimate and improve homogeneity of semi-quantitative and quantitative perfusion measurements.MethodsB0-field maps, SSFP and FLASH-PD frames were acquired in 10 healthy volunteers to analyze the SSFP off-resonance response. Furthermore, perfusion scans preceded by both FLASH and SSFP-PD frames from 10 patients with no myocardial infarction were analyzed semi-quantitatively and quantitatively (rest n = 10 and stress n = 1). Intra-subject myocardial blood flow (MBF) coefficient of variation (CoV) over the whole left ventricle (LV), as well as intra-subject peak contrast (CE) and upslope (SLP) standard deviation (SD) over 6 LV sectors were investigated.ResultsIn the 6 out of 10 cases where artifacts were apparent in the LV ROI of the SSFP-PD images, all three variability metrics were statistically significantly lower when using the FLASH-PD frames as input for the SCIC (CoVMBF-FLASH = 0.3 ± 0.1, CoVMBF-SSFP = 0.4 ± 0.1, p = 0.03; SDCE-FLASH = 10 ± 2, SDCE-SSFP = 32 ± 7, p = 0.01; SDSLP-FLASH = 0.02 ± 0.01, SDSLP-SSFP = 0.06 ± 0.02, p = 0.03). Example rest and stress data sets from the patient pool demonstrate that the low flip angle SSFP protocol can exhibit severe ghosting artifacts originating from off-resonance banding artifacts at the edges of the field of view that parallel imaging is not able to unfold. These artifacts lead to errors in the quantitative perfusion maps and the semi-quantitative perfusion indexes, such as false positives. It is shown that this can be avoided by using FLASH-PD frames as input for the SCIC.ConclusionsFLASH-PD images are recommended as input for SCIC of SSFP perfusion images instead of low flip angle SSFP-PD images.

Dataset Information

Magnetic resonance imaging of intraoral hard and soft tissues using an intraoral coil and FLASH sequences.

Objectives

Methods

Results

Conclusions

Key points

Publications

Magnetic resonance imaging of intraoral hard and soft tissues using an intraoral coil and FLASH sequences.

Similar Datasets

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