ECG Recording Techniques and Devices

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Questions and Answers

What does the QRS complex in an ECG represent?

Atrial depolarization

Ventricular repolarization

SA node depolarization

Ventricular depolarization (correct)

What is the purpose of the Nyquist theorem in biomedical signal acquisition?

To prevent aliasing in sampled signals (correct)

To convert analog signals to digital signals

To enhance signal strength

To increase the frequency range of signals

Which electrode configuration corresponds to the scalar ECG?

Single electrode + ground

4 electrodes + ground

3 electrodes + ground

2 electrodes + ground (correct)

In an electrical activity chart of the myocardium, what phase follows the T wave?

Atrial repolarization Signup and view all the answers

Which of the following enables the representation of time and frequency domain signals?

Fourier series Signup and view all the answers

What is the primary function of a sensor in biomedical engineering?

To convert a physical parameter to an electrical output Signup and view all the answers

Which statement correctly describes an active sensor?

It generates electrical power directly in response to applied stimulation. Signup and view all the answers

What is the characteristic of passive sensors?

They require an external voltage source to produce an electrical output. Signup and view all the answers

Which of the following is an example of an active sensor?

Solar cell Signup and view all the answers

What distinguishes an active transducer from a passive transducer?

Active transducers do not require an external power source, unlike passive transducers. Signup and view all the answers

Which parameter is essential for classifying a device as a transducer?

It must convert energy from one form to another. Signup and view all the answers

Which of the following is a type of artifact that can affect ECG recordings?

Baseline drift Signup and view all the answers

What does the SNR value represent in the context of ECG recordings?

Signal to Noise Ratio Signup and view all the answers

What is the primary source of gamma rays in nuclear medicine?

Radioactivity inside the patient Signup and view all the answers

What is the primary function of the Gamma Camera?

To capture images of the spatial distribution of radioactivity Signup and view all the answers

How does the Gamma Camera determine the location of gamma ray entry?

By analyzing the fraction of light seen by each photomultiplier Signup and view all the answers

Which of the following best describes the piezoelectric transducer's role in ultrasound scans?

To vibrate and generate sound waves for imaging Signup and view all the answers

What determines the size of the structures that can be examined in ultrasound imaging?

The frequency of the sound wave used Signup and view all the answers

What happens to a sound wave when it crosses the boundary between two regions with different acoustic properties?

It is reflected and/or refracted Signup and view all the answers

Which component of the Gamma Camera captures light generated from gamma rays?

The sodium iodide (NaI) crystal Signup and view all the answers

What is the function of the grid arrangement of photomultipliers in the Gamma Camera?

To uniquely define the gamma ray entry point Signup and view all the answers

Which imaging technique is best suited for visualizing metabolic activity in the body?

Gamma camera imaging Signup and view all the answers

What is a key characteristic of sound waves used in ultrasound imaging?

Their frequency determines the wavelength and imaging capability Signup and view all the answers

What does the amplitude mode (A mode) primarily measure?

Corneal thickness Signup and view all the answers

In a real-time ultrasound scan, what does the horizontal axis represent?

Time evolution Signup and view all the answers

How is a 2-D image generated in B-mode ultrasound scanning?

By combining multiple A-mode signals Signup and view all the answers

What type of ultrasound technique measures blood velocity?

Doppler ultrasound Signup and view all the answers

What is the purpose of tomography in medical imaging?

To map the internal structure without invasive procedures Signup and view all the answers

What primarily determines the brightness of the oscilloscope dot in B-mode ultrasound?

Amplitude of the reflected signal Signup and view all the answers

Which type of ultrasound scan utilizes advanced computer processing for 3D reconstruction?

3D ultrasound scan Signup and view all the answers

What is a characteristic feature of ultrasound tomography?

Combination of various external stimuli to generate internal maps Signup and view all the answers

Which statement about ultrasound is correct?

Effects of time delays in echoes indicate structural positions. Signup and view all the answers

What is the main difference between pulsating and continuous sound wave techniques in ultrasound?

Continuous sound waves offer frequency change measurements while pulsating do not. Signup and view all the answers

What is the main component of myofilaments in skeletal muscles?

Actin and myosin Signup and view all the answers

Which feature is NOT associated with surface EMG electrodes?

Extremely sensitive Signup and view all the answers

What is the primary advantage of using needle electrodes for EMG recording?

Recorded signals are less affected by cross-talk Signup and view all the answers

Which frequency range is typically associated with surface EMG?

10-1000 Hz Signup and view all the answers

In EEG recording, which electrode placement system is commonly used?

10/20 system Signup and view all the answers

What is a characteristic of the EEG signal produced by pyramoid neural cells?

Sum of field potentials Signup and view all the answers

Which of the following is a disadvantage of needle electrodes?

Pain and discomfort Signup and view all the answers

What factors can contribute to noise in EMG signals?

Electrode movement Signup and view all the answers

Which type of amplifier is used with bipolar electrodes?

Differential amplifier Signup and view all the answers

What is an application of EMG recording?

Neurological disorder assessment Signup and view all the answers

Which of the following best describes an axial section of the brain?

Displays both gyri and sulci Signup and view all the answers

Which factor is NOT relevant to the dynamic range of medical imaging?

Physical size of the equipment Signup and view all the answers

What does QEEG help to evaluate?

Memory and cognitive functions Signup and view all the answers

Study Notes

ECG Recording

ECG is recorded using bipolar leads
3 electrodes are used with a ground at the right leg: right arm, left arm, and left leg
Precordial leads (+ esophageal) are used to provide a horizontal planar projection
The recording technique can be monopolar or bipolar
Baseline wander is an artifact introduced by electrode placement
Muscle artifact can occur due to muscle movement

ECG Noise

Noise can originate from electrode displacement
SNR (Signal-to-Noise Ratio) is used to quantify the level of noise
-6dB SNR indicates the signal is weak and masked by noise
18dB SNR indicates a strong signal and minimal noise

Electrodes

ECG electrodes are available in various configurations
Electrodes can be attached using adhesives or clips

ECG Recording Devices

ECG recorders are available in home and clinic settings
The recorders range from multi-channel advanced devices to simpler, portable devices.

Transducers vs Sensors vs Actuators

Transducer: converts energy from one form to another.
Sensor: converts a physical parameter into an electrical output signal.
Actuator: converts electrical energy into a mechanical or physical output.

Sensor Types

Active sensors: generate electrical power directly in response to a stimulus.
Passive sensors: require an external voltage source to produce an electrical output signal.

Fiberoptic biosensor

A sensor that uses fiber optic technology for detecting various biological parameters.

EMG Recording

Electrodes are used to measure the electrical activity produced by skeletal muscles
EMG can be recorded using surface or needle electrodes
Mono- and bipolar electrodes can be used
The electrical impulses generated by the muscle fibers are detected by the electrodes
Two main types of electrodes used are surface and needle electrodes
EMG is used to examine muscle physiology and detect neuromuscular diseases

EMG Recording Electrodes

Surface electrodes are applied easily, but are more susceptible to noise and interference.
Needle electrodes are more sensitive, but need trained personnel application and can be uncomfortable.
Both types of electrodes are essential for understanding muscle activity.

EMG Recording Equipment

A recording device, typically equipped with an amplifier, is necessary to record EMG signals.
Signals can be analyzed using a computer and software specifically for EMG analysis.

EMG Signal Processing

EMG signals can be analyzed to evaluate muscle state, muscle fatigue, and movement patterns.
Denoising techniques can be used to analyze EMG signal due to movement artifact.

EEG Recording

EEG is the electrical activity of the brain recorded from the scalp.
It is used for monitoring brain function, diagnosis of brain disorders, and research purposes.
EEG signals are measured by placing electrodes on the scalp to detect electrical activity.

EEG Rhythms

Normal waveforms are classified as α, β, θ, and δ rhythms
The superposition of these rhythms is recorded during the EEG measurement.

EEG Recording Devices

EEG devices are used to monitor brain activity and can be used in various research settings and for brain-computer interfaces (BCI).
EEG data can offer insights into cognitive processes and emotions

QEEG

QEEG refers to quantitative EEG, a technique that analyzes EEG signals to extract quantitative information, such as power and frequency characteristics of different brain regions.
QEEG can help with identifying brain abnormalities and changes in brain function.

Brain Imaging

Brain imaging refers to the use of various techniques to visualize and study the structure and function of the brain.
Imaging techniques play a crucial role in understanding brain activity and diagnosing neurological disorders.

Medical Imaging

Medical imaging refers to the use of technologies to create images of the inside of the human body for diagnoses, monitoring, and treatment planning.
Medical imaging techniques play a critical role in modern healthcare.

Spatial Frequency in Medical Imaging

Spatial frequency refers to how often image detail changes across space.
Higher spatial frequency represents finer details.
Spatial frequency determines the image resolution in a medical image and is critical in image reconstruction.

Nuclear Medicine

Nuclear medicine is a medical specialty that utilizes radioactive substances called radiopharmaceuticals.
Nuclear medicine techniques are used to examine various internal body parts, including the brain, heart, bones, and organs.

Gamma Camera

Gamma camera is a device used in nuclear medicine to detect and image radioactive isotopes injected into the body.
It is a powerful tool for imaging and studying the structure and functionality of organs and tissues.

Positron Emission Tomography (PET)

PET is a medical imaging technique that uses a radioactive tracer to image organ and tissue function.
It is mainly used for diagnosing cancers, heart diseases, and brain disorders.

Ultrasound Imaging

Ultrasound imaging is a medical procedure that uses high-frequency sound waves to create images of internal organs and tissues.
It is a versatile imaging method used in various medical specialties.

Ultrasound Transducer

Ultrasound transducer is the key component of an ultrasound device.
It functions as both a sound wave emitter and receiver.
Ultrasound can be used for various medical purposes, including diagnosis, treatment, and monitoring.

Ultrasound A-Mode

A-mode ultrasound is used to map the distribution of reflected intensity as a function of time.
It generates peaks that represent tissue discontinuities along the scan axis.
A-mode is used in ophthalmology to measure corneal thickness.

Real-Time Ultrasound Scan

Real-time ultrasound is an extension of A-mode.
Depth is represented on the vertical axis.
Amplitude of the reflected pulse modulates brightness.
Time is represented on the horizontal axis.

B-Mode Ultrasound Scan

B-mode ultrasound combines A-mode information from multiple directions to form a 2D image.
The amplitude of the reflected signal (echo) modulates the brightness of the image.
The position of the dot is determined by the time delay of the received echo.
B-mode images are created by moving a scan bar.

Ultrasound Triplex

While standard ultrasound is pulsating, triplex ultrasound utilizes a continuous sound wave.
Doppler systems detect blood velocity by measuring the frequency difference between the transmitted and reflected signals.

3D Ultrasound Scan

Sound waves are emitted in many angles, not just vertically.
The return echoes are processed by a computer to reconstruct a 3D volume.
3D ultrasound is used in pregnancy and breast ultrasound scanning.

Tomography

Tomography allows for 3D mapping of internal structures without invasive procedures.
Excitation of the internal system from the outside generates a response that depends on the internal structure.
By combining different responses, a map of the interior can be constructed.
Depending on the excitation method, there are X-ray tomography, magnetic resonance tomography, and ultrasound tomography.
Other imaging techniques provide a cumulative view of the entire body area.

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Description

Explore the fundamentals of ECG recording through this quiz, covering lead configurations, noise management, and electrode types. Understand the various ECG devices and their applications in both home and clinical settings.