Publisher：Journal of Oral and Maxillofacial Surgery Medicine and Pathology  

Objective: To evaluate useful parameters for differentiating metastatic lymph nodes in oral squamous cell carcinoma using dual-energy computed tomography (DECT) in the venous phase. Methods: A total of 117 lymph nodes without visually obvious necrosis (83 non-metastatic and 34 metastatic) from 40 patients were retrospectively analyzed. The region of interest was defined at the area with the maximum short diameter. Nine parameters were calculated and correlated with the pathology images: CT values of virtual monochromatic X-ray images at 40, 70, and 100 keV (HU<inf>40 keV</inf>, HU<inf>70 keV</inf>, HU<inf>100 keV</inf>), iodine concentration (IC), CT value variation at 40–70 keV (λ<inf>40–70</inf> <inf>HU</inf>), 40–100 keV (λ<inf>40–100</inf> <inf>HU</inf>), lymph node long diameter, short diameter, and long-short diameter ratio. Results: Metastatic lymph nodes had lower CT and IC values than non-metastatic nodes. However, the short diameter had the highest the area under the receiver operating characteristic curve (AUC) with 0.846 (95 % confidence interval: 0.741–0.914), and the respective sensitivity and specificity were 82.4 % and 84.3 % at a cutoff of 7.54 mm. For parameters using CT values and IC, HU<inf>100 keV</inf> had the highest AUC (0.737), followed by HU<inf>70 keV</inf> (0.717), HU<inf>40 keV</inf> (0.686), IC (0.660), λ<inf>40–100</inf> <inf>HU</inf> (0.659), and λ<inf>40–70</inf> <inf>HU</inf> (0.659). Six DECT-derived parameters showed the significant negative correlation to the short axis length. Conclusion: In the venous phase, although the significant differences were found in the DECT-derived parameters, the maximal short diameter was found to be the most useful parameter for the differentiation of metastatic lymph nodes.

DOI： 10.1016/j.ajoms.2025.01.012

Scopus

Language：English   Publisher：Dentomaxillofacial Radiology  

Objectives: The purpose of this study was to compare the image quality of ultra-high-resolution CT (U-HRCT) with that of conventional multidetector row CT (convCT) and demonstrate its usefulness in the dentomaxillofacial region. Methods: Phantoms were helically scanned with U-HRCT and convCT scanners using clinical protocols. In U-HRCT, phantoms were scanned in super-high-resolution (SHR) mode, and hybrid iterative reconstruction (HIR) and filtered-back projection (FBP) techniques were performed using a bone kernel (FC81). The FBP technique was performed using the same kernel as in convCT (reference). Two observers independently evaluated the 54 resulting images using a 5-point scale (5 = excellent diagnostic image quality; 4 = above average; 3 = average; 2 = subdiagnostic; and 1 = unacceptable). The system performance function (SPF) was calculated for a comprehensive evaluation of the image quality using the task transfer function and noise power spectrum. Statistical analysis using the Kruskal-Wallis test was performed to compare the image quality among the 3 protocols. Results: The observers assigned higher scores to images acquired with the SHRHIR and SHRFBP protocols than to those acquired with the reference (P < 0.0001 and P < 0.0001, respectively). The relative SPF value at 1.0 cycles/mm in SHRHIR and SHRFBP compared to the reference protocol were 151.5% and 45.6%, respectively. Conclusions: Through phantom experiments, this study demonstrated that U-HRCT can provide superior-quality images compared to conventional CT in the dentomaxillofacial region. The development of a better image reconstruction method is required to improve image quality and optimize the radiation dose.

DOI： 10.1093/dmfr/twae068

Web of Science

Scopus

PubMed

Language：Japanese   Publisher：(NPO)日本歯科放射線学会  

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Language：English   Publisher：(NPO)日本歯科放射線学会  

CT画質や照射線量低減に対し、深層学習をベースとした画像再構成(DLR)がもたらす効果について検討し、歯科インプラント手術における術前画像診断として、低照射線量マルチスライスCT(MDCT)スキャンによるプロトコルを提案した。ヒト頭部モデル下顎ファントムを用いて、読影者評価には、Catphan phantom600とTOSファントムを物理特性分析に用いた。管電圧120kV、管電流120-60mA～40-30mAの条件下で、320列MDCT装置でスキャンし、DLR画像を再構成した。また、120mAで取得し、フィルタ補正逆投影(FBP)法で再構成した画像を参照画像として比較した。なお、再構成処理した画像は、読影者2名により、それぞれ盲検下で4点スケール法で画質を評価した。その結果、管電流40mAで取得しDLRで再構成した画像(40DLR)と、参照プロトコルによる取得画像の画質に有意差はみられなかったが、40DLRで取得した1.0cycles/minでのシステム性能関数(SPF)では、参照プロトコルで取得した画像に比べ、156.7%も改善が得られた。以上の実験結果から、今回提案したDLRプロトコルにより、照射線量が2/3低減することに成功し、歯科インプラント手術に際し、高速スキャンで最小侵襲の術前画像診断として、有用なMDCT画質が得られることが確認された。

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Oral Radiology  

Objectives: This study aimed to investigate the impact of a deep learning-based reconstruction (DLR) technique on image quality and reduction of radiation exposure, and to propose a low-dose multidetector-row computed tomography (MDCT) scan protocol for preoperative imaging for dental implant surgery. Methods: The PB-1 phantom and a Catphan phantom 600 were scanned using volumetric scanning with a 320-row MDCT scanner. All scans were performed with a tube voltage of 120 kV, and the tube current varied from 120 to 60 to 40 to 30 mA. Images of the mandible were reconstructed using DLR. Additionally, images acquired with the 120-mA protocol were reconstructed using filtered back projection as a reference. Two observers independently graded the image quality of the mandible images using a 4-point scale (4, superior to reference; 1, unacceptable). The system performance function (SPF) was calculated to comprehensively evaluate image quality. The Wilcoxon signed-rank test was employed for statistical analysis, with statistical significance set at p value < 0.05. Results: There was no significant difference between the image quality acquired with the 40-mA tube current and reconstructed with the DLR technique (40DLR), and that acquired with the reference protocol (3.00, 3.00, p = 1.00). The SPF at 1.0 cycles/mm acquired with 40DLR was improved by 156.7% compared to that acquired with the reference protocol. Conclusions: Our proposed protocol, which achieves a two-thirds reduction in radiation dose, can provide a minimally invasive MDCT scan of acceptable image quality for dental implant surgery.

DOI： 10.1007/s11282-021-00584-w

Web of Science

Scopus

PubMed

Event date： 2023.5

Language：Japanese  

Venue：九州大学医学部百年講堂   Country：Japan  

Event date： 2022.6

Language：English  

Venue：じゅうろくプラザ（岐阜市文化産業交流センター）＋オンライン配信   Country：Japan  

Event date： 2021.4 - 2021.6

Language：Japanese  

Venue：パシフィコ横浜   Country：Japan  

Event date： 2019.11

Language：Japanese  

Venue：九州歯科大学   Country：Japan  

Event date： 2019.1

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：鹿児島県鹿児島市　鹿児島大学   Country：Japan  

Language：English   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

Language：English   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

Repository Public URL： https://hdl.handle.net/2324/7173603

Type：Competition, symposium, etc. 

Number of participants：80

Audience：General,　Scientific,　Company,　Civic organization,　Governmental agency

Type：Lecture

Type：Lecture

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