Digital Signal Processing in Medicine

數位訊號處理之醫學應用 Digital Signal Processing in Medicine 詹曉龍 長庚大學電機系 chanhl@mail.cgu.edu.tw 與電子電機資訊相關之研究 醫學工程 醫療儀器 Monitor and Measure Physiological Event 系統分析與建模 Understand Physiological System 復建工程 Provide Therapeutics and Aids Devices for the Disabled 醫學資訊 Build Medical Information and Decision Support Systems 訊號處理 Detect, Classify and Analyze Biomedical Signals 醫學影像 Display Anatomical Details and Physiological Function 生物資訊 Solve Computational Problems in Molecular Biology HL Chan , EE, CGU Biomagnetic Signals 2 What are Biomedical Signals? EEG ECG Blood Pressure EGG Heart Sound EMG HL Chan , EE, CGU Biomagnetic Signals 3 Research Topics • Brain cell potentials • Epilepsy • Brain states Autonomic function assessment by heart rate variability 數位訊號處理 • • • • Cardiovascular system Anesthesia Physical therapy Sleep Apnea HL Chan , EE, CGU Biomagnetic Signals 4 生物電之起源 (Origin of Biopotentials) Na+ ClExtracellular domain Phospholipid bilayer K+ Intracellular domain 動作電位 (Action Potential) Na+ ++++ ---++ -+ + + Outside cell Plasma membrane --Inside cell K+ 1 Resting phase Na+ ---++++ -++ --+++ K+ 2 Depolarizing phase 4 Undershoot phase 3 Repolarizing phase Na+ ++++ ---++ -+++ --K+ ++++ ---Na+ ++ -+++ --K+ Membrane potential (mV) +50 0 -50 1 2 3 4 -100 t HL Chan , EE, CGU Biomagnetic Signals 6 心電圖：Gensis of Electrocardiogram (ECG) J. Malmivuo, Bioelectromagnetism, Oxfold University Press, 1995. HL Chan , EE, CGU Biomagnetic Signals 7 ECG Features R-R interval R P R T Q S P-R interval S-T interval U Q-T interval QRS interval P wave : Atrial depolarization QRS complex : Ventricular depolarization T wave : Ventricular repolarization U wave : Slow repolarization of ventricular muscle R-R : Heart period P-R : Conduction delay in the AV-node Q-T, S-T : Ventricular repolarization time HL Chan , EE, CGU Biomagnetic Signals 8 Abnormal ECG: Ventricular Premature Contraction (VPC) 心室提早收縮 HL Chan , EE, CGU Biomagnetic Signals 9 心室急速 (Ventricular Tachycardia)及心室纖維顫動 (Ventricular Fibrillation) Ventricular Tachycardia Ventricular fibrillation HL Chan , EE, CGU Biomagnetic Signals 10 Lempel-Ziv Complexity (複雜度) HL Chan , EE, CGU Biomagnetic Signals 11 Detecting Ventricular Tachycardia and Fibrillation by Complexity Measure (Xu-Sheng Zhang, et al, 1999) window length 3s 5s 7s HL Chan , EE, CGU Biomagnetic Signals 12 心電圖量測技術 Patient Monitors First Electrocardiograph (ECG) by William Einthoven in 1903 ECG Holter HL Chan , EE, CGU Biomagnetic Signals 13 Cardiovascular System and Autonomic Nervous System (心臟血管系統與自律神經系統) Rideout, "Mathematical and computer modeling of physiological systems”, Prentice-Hall, Chap 4, p.109, 1991. HL Chan , EE, CGU Biomagnetic Signals 14 Heart Rate Variability (心率變異度) Electrocardiogram ECG ← RR → RR Intervals Equ-sampling RR HL Chan , EE, CGU Biomagnetic Signals 15 Time-Varying HRV in Postural Change Supine Standing Resupine HL Chan , EE, CGU Biomagnetic Signals 16 Time-Varying HRV in General Anesthesia Induction  Conscious  Intubation Stimulation of surgical manipulation Source : 臺大醫院麻醉部 黃慧薰, MD, PhD HL Chan , EE, CGU Biomagnetic Signals 17 HRV in Normal Subject and Congestive Heart Failure (心室衰竭) Complex type of variability More periodic pattern with an apparent loss of complexity HE Stanley, Physica A, 1999 HL Chan , EE, CGU Biomagnetic Signals 18 Portable ECG and Physical Activity Holter ECG Amp Tri-axial accelerometer Uni-axial accelerometer HL Chan , EE, CGU Biomagnetic Signals 19 Classified activities Sleeping Time, hour Time-frequency distribution of HRV using short-time Fourier transform Frequency, Hz Time, hour HL Chan , EE, CGU Biomagnetic Signals 20 Brain (大腦) From JJ Carr, Introduction to Biomedical Equipment Technology, Prentice-Hall, 1998. HL Chan , EE, CGU Biomagnetic Signals 21 Electroencephalogram (EEG) J. Malmivuo, Bioelectromagnetism, Oxfold University Press, 1995. HL Chan , EE, CGU Biomagnetic Signals 22 EEG Changes in Sleep J. Malmivuo, Bioelectromagnetism, Oxfold University Press, 1995. HL Chan , EE, CGU Biomagnetic Signals 23 EEG waveform recorded from one patient under sevoflurane in different states LZ complexity awake state intermediate state asleep state HL Chan , EE, CGU Biomagnetic Signals 24 正常(左)與昏迷(右)之非線性腦波圖譜 HL Chan , EE, CGU Biomagnetic Signals 25 麻醉深度監測 by EEG/AEP EEG Monitoring Audio Evoked Potential Monitoring http://www.danmeter.dk/ HL Chan , EE, CGU Biomagnetic Signals 26 Source Imaging of Brain Forward Propagation High-Resolution Surface EEG or MEG Electromagnetic Model with Real Head MR Images HL Chan , EE, CGU Biomagnetic Signals 27 Inverse Problem Brain Computer Interface (BCI) Gerwin Schalk, BCI2000: A General-Purpose Brain-Computer Interface (BCI) System, IEEE Trans. BME, 2004 HL Chan , EE, CGU Biomagnetic Signals 28 Brain Machine Interface (BMI) 圖文摘自 隨心而動︰以意念操控機器, 科學人,12月號, 2002 HL Chan , EE, CGU Biomagnetic Signals 29 Brain Machine Interface (BMI) 有朝一日，腦機界面將可幫助因脊髓受傷導致 上下肢癱瘓的病人。將微金屬絲組成的微小陣 列植入腦中好幾個運動皮質區域，並與頭骨上 的神經晶片連結。病人以想像的方式，使其癱 瘓的手臂以某種方式移動，好比說伸手去拿桌 上的食物，該晶片能把這種意念轉換成一連串 無線電頻率的訊號，以無線傳輸方式送給掛在 輪椅後頭以電池操作的背包式小型電腦。該電 腦會將訊號轉換成動作的指令，並以無線方式 傳送到植在病人手臂上的另一個晶片。這第二 個晶片會刺激控制手臂肌肉的神經，讓手臂產 生適宜的動作。除此之外，背包裡的電腦也能 隨病人的意願，直接控制輪椅的馬達及方向控 制器，讓輪椅朝她想要去的地方而行。電腦也 可以傳送訊號給機械手臂（如果病人失去她原 來的手臂），或是接在輪椅上的機械手臂。杜 克大學的沃爾夫製造了一個如下圖所示的神經 晶片及背包的原型。 圖文摘自 隨心而動︰以意念操控機器, 科學人,12月號, 2002 HL Chan , EE, CGU Biomagnetic Signals 30 長庚大學電機系之整合型醫工研究  生理檢測系統晶片(SoC)   數位訊號處理、類比IC、微處理器核心及無線傳輸設計 長庚大學電子系及電機系 腦神經訊號、三維影像融合及顯示系統開發 長庚醫院神經外科及神經內科 長庚大學電機系及機械系 工研院、資策會及國網中心  腦部擴增實境系統     HL Chan , EE, CGU Biomagnetic Signals 31 生理檢測系統晶片 (System-on-Chip, SoC) 子計劃四 Flash memory External Memory Interface ARM 922T Internal Memory Reset Controller 子計劃二 DSP core QRS Detection Compression Arrhythmia AHB 子計劃一 子計劃二 生理訊號即時 檢測演算法之 開發 Real Time Clock Interrupt Controller AHB to APB Bridge APB LCD Display 其他I/O 訊號 子計劃三 Arbiter/ Decoder Test Interface Controller TICBox Amp ECG 子計劃五 系統單晶片之 時序 功率與訊 、 號完整性實體 設計驗證 Lowpass Filter GPIO UART LCD Interface Sample-and -hold circuit Analog-todigital converter Baseband RF ECG Compression coding coding 16 clk reset 3 16 [D1 D2 D3] Thresholds 16 clk reset Memory (800 bytes) 3 16 3 ECG 16 DWT Counter (3 bits) Threshold Processing clk reset Coding Significant Coefficient Significant Map coding coding reset reset clk clk HL Chan , EE, CGU Biomagnetic Signals 33 Real-Time Algorithm Pan-Tompkins QRS Detection ECG Band-Pass Filter 2~10Hz d  dt  2 1 32  32 n1 QRS Classification Template Match Template update Heart Period Calculation Partial Median Filter Heart Period Resampling Spectral Analysis HRV Index HL Chan , EE, CGU Biomagnetic Signals 34 HL Chan , EE, CGU Biomagnetic Signals 35