小橋 昌司

Investigating the shape and time to peak (HR delay) of hemodynamic response (HR) introduces a new facet of researches on human brain function. We have proposed an analysis method for detecting activated areas and measuring HR delay simultaneously using event related function magnetic resonance images (ER-fMRI). The method has been based on wavelet transform. In this paper, we investigate the performance of the method by modifying a mother wavelet. The modified mother wavelet is based on mathematically defined HR function by SPM (statistic parametric mapping) software by Friston et al. To evaluate the proposed method, we applied the proposed method and conventional methods to the phantom data. The results showed that the method could detect the activated area equivalent to and more than conventional methods. We also estimated the accuracy of measuring HR delay. The results showed that the proposed method could measure HR delay more accurate than the conventional method.

The human lung is composed of five compartments called "Lung lobes." Segmenting lung lobes from chest Multidetector-row Computed Tomography (MDCT) images can provide effective information for analyzing pulmonary conformation and detecting pulmonary diseases such as the emphysema. Our method finds the boundary surface between lung lobes by the fuzzy control that fits a curved surface into the space with lower density of tubular tissues, which are defined as peripheral blood vessels and bronchus. This paper describes the performance evaluation of the proposed method and the application method for estimating the forced vital capacity of individual lung lobes.

This paper describes a computer sided support system for localizing the distal transverse screw hole in interlocking intramedullary nailing. It is required to localize the distal transverse screw hole under surgeries for femur fracture. Conventional X-ray CT method can find the hole in the CT table. In it, when we move patients from the CT table to the surgery table, the exact potion is missed. Therefore, a real time determination of the hole position is required to enhance the quality. This paper solves the problem by using an ultrasonic system aided by fuzzy logic. First, we show the details of the equipments. Second fuzzy inferences effectively determine the fuzzy degree being the screw hole inserting to cattle femur. Finally, the experimental result shows that our system can determine the screw hole with 1.0mm of error.

Functional assessments of the meniscus assists to diagnose diseases of the knee joint. To estimate the degree of the degeneration of the injured meniscus, this paper proposes an automated method for segmenting the region of the meniscus from multidetector computed tomography (MDCT) images. The novel feature of the proposed method is that we segment the meniscus based on a fuzzy rule-based representative line finding algorithm. The representative line, which is a new concept, is a line that abstracts the position and shape of the meniscus. Experimental results on the extended and flexed knee joints for three healthy subjects show that our method found a proper representative line, and segmented the meniscus successfully.

言語優位半球の判定は, これまで後遺症の危険を伴ったWadaテストが用いられてきた.近年, 近赤外分光法(NIRS)の原理を応用した光トボグラフィ装置が, 言語野の解析に適用できる無侵襲な方法として用いられるようになってきた.本文ではファジィモデルを用いた言語優位半球判定法を提案する.本方法は, まず言語野の所属度をファジィモデルを用いて表現し, 言語野の同定作業を行う.次に言語野の所属度に基づいた左右性指標の計算を行う.本文では3例に適用し, 本方法は言語野の同定に有効であることを示した.

functional MRI (fMRI)とは頭部MR画像の連続撮像を行い, MR信号の時間変化から脳機能を解析する技術である.刺激に伴い賦活の生じた領域ではMR信号が上昇し, やがて信号はベースラインに戻る.これをヘモダイナミクスレスポンス(以下HR)という.本文ではウエーブレット変換を用いた賦活領域の同定, HR反応遅延を計測するfMRI解析法を提案する.実験では20例のfMRIデータに本方法を適用した.本方法の賦活領域の同定精度はSPMと同等であり, さらにHRの遅延の計測が可能である.また, 本方法を用いることで補足運動野と運野においてHRの遅延に有意差があることが初めて確認された.

脊椎疾患の手術療法において, 術者が脊椎神経を損傷する危険性があるため, 現在はMRやCTによる脊髄造影画像で術前に脊椎内の神経の状態を観察する.しかしこれらの画像は2次元画像で, 医師が関心領域である硬膜嚢の正確な3次元形状を認識するのは困難である.組織間の形状を術前に把握できる支援システムの開発が望まれている.そこで本研究では, 支援システムの基礎となる腰部MR画像からの硬膜嚢の自動抽出法を提案する.本抽出法は硬膜嚢の形状に関する知識からファジィ論理により硬膜嚢らしさを求める.実験では, 被験者5人(健常者4人, 疾患者1人)から得られたMR画像に対して本方法を適用し, 抽出領域の3次元表示と医師による手抽出の結果との一致度から提案法の有効性を確認した.

Assessment of language dominance is one of important pre-treatments of brain surgery. The objective of this paper is to propose an estimation method of 'Laterality Index (LI)', which is a measure of language dominance, using near-infrared spectroscopy and imaging (NIRS/I) modality. The proposed method called fuzzy LI is a fuzzy-extension of the conventional estimation method (Watanabe et. al., Neuroscience Letters, 1998) called crisp LI. The benefit of our method is that the fuzzy degree belonging to language area for each measurement point is given, and that the language area is dynamically determined study by study using only NIRS/I. Experimental results on seven normal healthy right-handed volunteers showed that the fuzzy LI was correlated with one's handedness investigated by Edinburgh score at 77%.