Kazuhiko Kojima

New diagnostic approach to brain lesions in nuclear medicine. Differential diagnosis of brain lesions with a computed brain scan diagnosis by the likelihood method.

Using 240 true positive brain scans, a computer system for the differential diagnosis of brain lesions has been evaluated. Eighty-six parameters were extracted from brain scan findings without relationship to neurological signs and symptoms, and the likelihood method was adopted as an example of mathematical logic. The results of our experiment indicated that the overall accuracy was 77 per cent for the maximum likelihood method. The digital computer gave satisfactory results, particularly for diseases such as infarct, meningioma, acoustic neurinoma, and subdural hematoma. In spite of several problems to be solved, this method could provide invaluable help in differential diagnosis of brain lesions.

Whole-body Retention Studies of 167Tm-Citrate-Estimation of Radiation Dose to Human from 167Tm-Citrate-

For the purpose of calculating absorbed dose to humans from 167Tm-citrate, the whole-body retention studies using 5 rats were carried out. Up to 40 days following intravenous injection of 167Tm-citrate, the whole-body counts were monitored with a animal counter. The whole-body retention curve was obtained with three exponentaial components. Namely, the 26% of the injected 167 Tm-citrate had a biological half-time of 3.4 hours, 12.5% had a biological half-time of 99 hours and 61.5% had a biological half-time of 106 days. These results indicate, that three components consist of the rapid clearance from the kidneys, the retention in the liver and other soft tissues with relatively long half-time and the retention in the bones with long half-time. Based on these biological data and the MIRD Committee method, the average dose estimates to the bone and whole-body from intravenous administration of 1 mCi 167Tm-citrate were 7.08 rads and 1.28 rads, respectively.

[Receptor macroautoradiography of 3H-spiroperidol binding in the rat brain].

The kinetic and pharmacological characteristics of 3H-spiroperidol binding sites were studied in slide mounted sections of rat forebrain, and optical binding conditions were defined. Using the receptor macroautoradiographic techniques with tritium-sensitive LKB sheet film, the distribution of dopamine (D2) receptor was determined in slices including striatum of rat brain. The autoradiograms were analyzed using Video Digitizer System combined with video camera and minicomputer, and the subtraction images were obtained. These studies suggest that this quantitative receptor macroautoradiography might be useful in the explanation of etiology in the field of neuro-psychiatric diseases and the fundamental studies of positron emission computed tomography, since this method has several advantages over in vivo autoradiography and in vitro receptor assay.

[Superimpose of images by appending two simple video amplifier circuits to color television (author's transl)].

Images are very useful to obtain diagnostic informations in medical fields. Also by superimposing two or three images obtained from the same patient, various informations, for example a degree of overlapping and anatomical land mark, which can not be found in only one image, can be often found. In this paper characteristics of our trial color television system for the purpose of superimposing X-ray images and/or radionuclide images are described. This color television system, superimposing two images in each different color consists of two monochromatic vidicon cameras and 20 inches conventional color television in which only two simple video amplifier circuits are added. Signals from vidicon cameras are amplified about 40 dB and are directly applied to cathode terminals of color CRT in the television. This system is very simple and economical color displays, and enhance a degree of overlapping and displacement between images. As one of typical clinical applications, pancreas images were superimposed in color by this method. As a result, size and position of pancreas was enhanced. Also X-ray image and radionuclide image were superimposed to find exactly the position of tumors. Furthermore this system was very useful for color display of multinuclides scintigraphy.

Off Line Data Processing for Scintillation Camera Image

シンチカメラによってえられるアイソトープ (RI) イメージは検出器の低い解像力と入射γ線のランダム性などによって, ボケの多いイメージとなる。したがって, RIイメージによる診断能の向上には画像修正が重要と考えられる。われわれは従来のシンチカメラに接続されたデータ処理装置CDS-4096でディジタルに変換されたデータをFACOM-230/35およびNEAC-2230電子計算機を用いてオフライン処理を行ない, 処理結果は印字出力および紙テープ出力でえた。ラインプリンターによる印字出力ではイメージ寸法を実大に変換し, タイプ文字の重ね打ちで濃淡をつけた。また, シンチカメラの検出器感度の不均一からイメージに生じる感度むらを241Am帯状線源のスキャンニング装置を用いて補正した。さらに各種のデータ処理の前段階にはsmoothingを行ない統計的バラツキを軽減したのち, 臓器の輪郭や欠損を強調して表示するためのプログラムを検討したのでその結果をのべる。