Technetium-99m pertechnetate（99mTcO4）〔テクネシウム（99mTc）〕による慢性穿孔性中耳炎症例の耳管機能検査法—基礎的検討と臨床応用の価値について

AN EUSTACHIAN TUBE FUNCTION TEST IN PATIENTS OF CHRONIC OTITIS MEDIA WITH PERFORATED EARDRUM BY USE OF TECHNETIUM-99M, PERTECHNETATE (99mTcO4)

　I．はじめに

　中耳鼓室の生理機構に，耳管機能が重要な役割をはたすことは，諸家の研究によって明白である。特に慢性中耳炎の鼓室形成術などで耳管機能が術後の成績を左右することは諸家の意見をまつまでもない。このため，耳管機能の検査法にも工夫がなされ，空気圧法，音響法，造影法，味覚法，内視鏡法などが行われている。

　これらの検査法は，それぞれ特徴をもち，検査法の結果に異なった守備範囲がある。そこでこれらの機能表現の特徴を組み合わせることで，耳管のventilationを，生理的に表現することができる。

　Eustachian tube function test in patients having chronic otitis media with perforated eardrum, using ^99mpertechnetate (^99mTc) was developed.

　A dosage of ^99mTc in 0.6 μCi, which in X-ray conversion was 0.4mR/hr/cm, and was a very minute quantity for irradiation was used. Fifteen cases were tested by this method while the controls were tested by the conventional air-pressure method.

　By the test with ^99mTc, it was observed that a hotspot which appeared in the orifice of Eustachian tube in the middle ear cavity, moved to the pharyngeal side by swallowing. The type of the hotspot movement was classified into three types. A type in which a high density hotspot was found on the pharyngeal side immediately after swallowing, another type in which formation of a hotspot density on the pharyngeal side was delayed after swallowing and the last type in which an extremely weak hotspot density was observed after swallowing even though those had shown good air passage by the conventional air-pressure method.

^99mTc used for this experiment was readily available to us, but in the future, we are planning to study on selection of the radioactive agents and on preparation of a dynamism calculation table for the objective observation.

　we conclude that in this method the patients were exposed to the minimum irradiation quantity, and it makes us possible to observe Eustachian tube morphologically as well as functionally.