江藤 芳浩

Yoshihiro ETO

医療法人慈恵会西田病院放射線部

Department of Radiology, Nishida Hospital

キーワード : extensor tendon, elevational resolution, fibrillar pattern, narrow aperture method

目的：皮下の極めて浅い領域のスライス方向分解能を改善するため，音響レンズ「狭開口法」を独自に考案し，その有効性を先行研究にて物理的に検証している．本研究では，一般的に普及している単層高周波リニアプローブの狭開口法を利用し，小指伸筋腱の中央索および側索の描出能について検討した．対象と方法：健常者60名の小指伸筋腱を通常走査と狭開口法で走査し，各走査法での描出能を比較した．また，狭開口法による解剖学的構造の描出能と腱描出に対する年齢性別の影響について検討した．結果と考察：狭開口法は通常走査に比べ描出能が高く，臨床的に有用であることがわかった．計測した腱の厚さは中央索が平均0.50 mm，側索が平均0.39 mmであり，MRI画像とほぼ一致したが，個人差が認められた．また，fibrillar pattern一層の厚さは中央索，側索ともに平均0.16 mmであり，プローブ周波数とスライス方向分解能の限界であると考えられた．年齢や性別による腱描出に有意差は認めなかったが，腱の走行や皮下組織構造には個人差が認められた．結論：狭開口法は臨床的に有用な腱描出が可能であることを検証した．

Purpose: The author devised an acoustic lens "narrow aperture method" in order to improve the elevational resolution in the extremely shallow region, and the effectiveness of the acoustic lens was physically verified in a previous study. In this study, visualization of the central slip and the lateral slips of the extensor tendon of the little finger was evaluated using the narrow aperture method of a linear probe with a single layer and high frequency, which is generally prevalent. Subjects and Methods: The extensor tendon of the little finger of 60 healthy volunteers was scanned by normal scanning and the narrow aperture method, and the visualization capabilities of the two scanning methods were compared. In addition, the effect of visualization of anatomical structures and the effect of age and sex on tendon visualization by the narrow aperture method were examined. Results and Discussion: The narrow aperture method was clinically useful because it had higher visual capability than normal scanning. The average thickness of the tendon was 0.50 mm for the median slip and 0.39 mm for the lateral thickness, which corresponded approximately to that of MRI images, although individual differences were observed. Furthermore, the average thickness of one layer in the fibrillar pattern was 0.16 mm for both central and lateral slips, which was considered to be the limit of the probe frequency and elevational resolution. There was no significant difference in tendon visualization by age and sex, but individual differences were observed in terms of the tendon course and subcutaneous tissue structure. Conclusion: The clinical usefulness of the narrow aperture method for visualization of the extensor tendon of the little finger was verified.