子牛の水無脳症および水頭症の超音波診断

1. 子牛の水無脳症40例,水頭症2例および対照正常脳8例に対して,超音波断層法を応用した.一部の例では脳室空気造影法を併用した.
2. 超音波断層法により,診断が可能と判断されたものは, 水無脳症40例中25例(63%),水頭症2例中1例(50%),および正常脳8例中5例(63%)であった.
3. メカニカルセクタ型探触子(3.5MHz) と電子リニア型探触子(3.5MHz) とを比較した結果,前者は操作性,脳エコー像の描出率について後者よりも優れていた反面,多重反射エコーの出現,画像の鮮明さの点で,後者よりも劣っていた.
4. 頭蓋骨の厚さ,とくに緻密質骨の厚さが,画像描出能に最も影響が大であると考えられた.
5. 脳室空気造影法を実施した水無脳症8例では,全例で大脳半球の完全欠損を示唆する水平面像(水平方向撮影)が得られた.

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Abstract

内容記述

Recently, over a period of 4 months, 40 calves with hydranencephaly, 2 calves with hydrocephalus and 8 normal calves as a control were examined by transcranial two-dimensional, real-time ultrasonography, and some also by X-ray pneumoventriculography. The ages of the animals were all under 4 months, and more than two thirds were less than 2 weeks old. A 3.5-MHz mechanical sector scanner and occasionally a 3.5-MHz electronic linear array or 5-MHz convex array scanner were used, with the transducer placed along the surface of the head over the frontal and/or fronto-parietal region indicated in Figure 1.
The results are shown in Table 1. The proportions of cases diagnosed correctly, i. e. , the success rates of adequate visualization of brain structures by ultrasonography were 63% (25/40) for hydranencephaly, 50% (1/2) for hydrocephalus, and 63% (5/8) for normal calves. Measurement studies of cranial thicknesses at necropsy clearly showed that the thickness of the skull, especially compact substance, is the major limiting factor in obtaining adequate ultrasound penetration of the skull.
In accordance with the ultrasound principle that the higher the ultrasound frequency, the higher the absorption rate of the ultrasound in bone tissue, the 3.5-MHz transducer had superior ability to the 5-MHz one for visualizing the brain, at least for ultrasonographic examination via the transcranial approach. The mechanical sector scanner had the major advantage of providing large areas of cerebral visualization from limited acoustic windows on the skull but had the disadvantage of frequently producing an artifact of near-field reverberations, which interfered with the quality of the brain image. By contrast, the advantage of the linear array scanner was that it revealed a comparatively larger area of near-field structures with only slight reverberations. However, only a small part of the scanner could usually make contact with the skull, so that the area of the image obtained with this scanner was much less than that obtained with the sector scanner.
By the use of image-processing techniqes for ultrasonograms, low-level echoes obtained from the cerebrum were delineated more clearly than those of the original image, which assisted in differentiating normal brain echoes from echo-free areas of fluid-filled dilated ventricles in hydranencephaly and hydrocephalus.
As it is non-invasive, safer, and simpler, two-dimensional ultrasonography would seem to be a valuable adjunct to the initial examination of calves with suspected hydranencephaly and hydrocephalus.

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書誌情報

ja : 宮崎大学農学部研究報告
en : Bulletin of the Faculty of Agriculture, Miyazaki University

巻 33, 号 1, p. 73-84, 発行日 1986-10

出版者

宮崎大学農学部

言語

出版者

Miyazaki University

言語

ISSN

収録物識別子タイプ

ISSN

収録物識別子

05446066

書誌レコードID

収録物識別子タイプ

NCID

収録物識別子

AN00236503

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出版タイプ

VoR

出版タイプResource

http://purl.org/coar/version/c_970fb48d4fbd8a85

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