Cardiac Essentials - PMU in MRI | Basics

Continue Button Continue Continue Cardiac Essentials PMU in MRI – Basics Online Training Master Template HOOD05162003052540 | Effective Date: 26-Nov-2019 Physiological Measurement Unit (PMU) for physiological triggering in the Magnetic Resonance Imaging environment ? Cardiac Essentials PMU in MRI – Basics Online Training Identify Physiology of the Heart Recognize ECG User Interface Execute the ECG Learning Phase Describe the Patient Preparation for ECG Triggering 1 4 3 2 Welcome [pmu-in-mri_basics_olt_en_welcome.mp3] Welcome to the Cardiac Essentials PMU in MRI – Basics Online Training, where you will learn about use of the PMU for physiological triggering in the Magnetic Resonance Imaging environment. This course will cover the four learning objectives listed on the right. ? This training is provided to you by our MR Master: Kylie studied radiography in Australia and worked in a large teaching hospital for a number of years where she gained experience in the major imaging modalities, including MRI. Kylie joined Siemens in 2006 as an MR Applications Specialist and moved to Germany in 2013 to spend the next 9 years working as an MR Applications Trainer. Table with 2 columns and 4 rows First Name: Kylie Last Name: Martin Company: Siemens Healthineers Australia Job Title: MR Application Services Team Leader Kylie returned to Australia in 2022 to lead the Australia & New Zealand MR Applications Team. Introduction of our MR Master ? Navigation Hints Before you start, we would like to give you a few tips on how to navigate: Table with 2 columns and 3 rows Not all pages contain audio. Some pages invite you to read for yourself or watch a video. All pages show a ? button in the lower-right corner. Select the ? button to get a quick guide through the navigation elements. Some pages show an X button in the upper right corner. Select the X button to return to the overview page and not miss any information provided. Enjoy the course! ? Navigation Hints Chapter 1: Introduction to ECG Triggering ? Cardiac motion Electrical system of the heart ECG triggering Characteristics of a good ECG waveform Effects of impaired ECG signal Let´s begin! Identify physiology of the heart Introduction to ECG Triggering Cardiac Motion ? MR Cardiac Imaging is different to imaging other organs due to the large amount of motion in the heart region. Breathing Continuous contraction and dilatation Therefore, MR cardiac imaging (CMR) typically uses fast ECG gated breath-hold techniques. ECG triggering may be used for imaging other body regions e.g. non-contrast peripheral angiography. Cardiac Motion [pmu-in-mri_basics_olt_en_cardiac-motion.mp3] MR cardiac imaging is different to imaging other organs due to the large amount of motion in the heart region. The heart changes position as the patient breathes in and out, and is continually contracting and dilating throughout the cardiac cycle. Therefore MR cardiac imaging, or CMR, typically uses fast ECG gated breath-hold techniques. Note that physiological triggering may also be used for imaging other body regions, for example non-contrast peripheral angiography. ? Electrical System of the Heart Electrical System of the Heart [pmu-in-mri_basics_olt_en_electrical-system.mp3] The ECG records electrical activity of the heart using electrodes placed on the skin. (00:09) Specialized heart muscle cells generate electrical impulses. (00:14) The sinoatrial node, or SA node, is the pacemaker where the electrical impulse is generated. The impulse travels from the SA node through the internodal pathways to the atrioventricular node, or AV (00:29) node. This electrical impulse results in the P-wave (00:33) on the ECG signal. (00:37) The AV node is responsible for conduction of the impulse from the atria to the ventricles. (00:43) The impulse is delayed slightly at this point to allow complete emptying of the atria before the ventricles contract. The impulse continues to the AV bundle (00:54) or bundle of His, and down the left and right bundle branches of the Purkinje fibers. (01:01) The Purkinje fibers conduct the impulse to all parts of the ventricles causing contraction, and is visualized by the QRS complex of the ECG. (01:13) As the signal passes out of the ventricles they start to relax and recover. The half circular shaped T wave on the ECG marks this relaxation. (01:23) This cycle repeats with every heartbeat. (01:26) For the ECG signal, the R waves are important, as they are typically used to synchronize MRI data acquisition. (01:35) In summary, each wave or segment of the ECG signal corresponds to a certain event of the cardiac electrical cycle. ? CMR data acquisition is usually spread over several heartbeats making it necessary to synchronize with cardiac motion ECG synchronization is the most common method and requires the detection of an event that occurs once per heartbeat Generally we use the R wave which has the highest amplitude and steepest upslope Enables data acquisition during time period with least motion, or distinct cardiac phases ECG Triggering R wave detection One RR interval ECG Trigger delay (TD) k space ECG Triggering [pmu-in-mri_basics_olt_en_ecg-triggering.mp3] In most cases cardiac MR data acquisition is spread over many heart beats, making it necessary to synchronize data acquisition with cardiac motion. ECG synchronization is the most common method used to achieve this, and requires the detection of an event that occurs once per heartbeat. Generally we use the R wave, which has the highest amplitude and steepest upslope, corresponding to the end diastole. This enables data acquisition during a time period with the least amount of motion, or during distinct phases of the cardiac cycle. ? Characteristics of a Good ECG Waveform Sharp R wave R wave higher in amplitude than T wave while outside the bore (0T) R wave higher than distortion induced by magnetic environment while inside the bore (1.5T, 3T) Small baseline distortion (respiration, electrode contact) P wave: atria contract QRS complex: atria relax & ventricles contract T wave: ventricles relax One cardiac cycle Characteristics of a Good ECG Waveform [pmu-in-mri_basics_olt_en_characteristics.mp3] Characteristics of a good ECG waveform include a sharp R wave. The R wave should be higher in amplitude than the T wave while the patient is outside the magnet bore. The R wave should also be higher than distortion induced by the magnetic environment while the patient is inside the bore. A small baseline distortion is also desirable, and this can be influenced by patient respiration and poor electrode contact. ? #1 Tip Do not start scanning if the ECG is not good!! #1 Tip [pmu-in-mri_basics_olt_en_tip.mp3] The number one tip when performing cardiac MR studies is do not start scanning if the ECG is not good. It is worth taking the time to obtain a good quality ECG prior to starting the examination. ? Effects of Impaired ECG Signal Missed R waves leading to longer breath-holds and therefore breathing motion artefacts Intermittent triggering due to haemodynamic effect caused by flowing blood or RF pulses Miscalculation of heart rate due to incorrect triggers or missed R waves Poor image quality due to acquisition of data during different phases of the cardiac cycle Image blurring may be due to poor ECG, or to arrhythmia Always display and observe the ECG signal during the examination Poor image quality & inaccurate heart rate due to impaired ECG signal Effects of Impaired ECG Signal [pmu-in-mri_basics_olt_en_impaired-ecg-signal.mp3] An impaired ECG signal may result in missed R wave triggers, leading to longer breath-holds and therefore breathing motion artefacts. Intermittent triggering due to the haemodynamic effect caused by flowing blood or RF pulses may also occur if the ECG is impaired. Both may result in miscalculation of the patients heart rate. Poor image quality may result due to the acquisition of data during different phases of the cardiac cycle. Image blurring may be due to a poor quality ECG, or to patient arrhythmia. Therefore, always display and observe the ECG signal during the examination. ? Chapter 2: PMU Hardware, Patient Preparation & Applying Electrodes Hardware LED indicators Battery status Skin preparation Applying and positioning electrodes ECG leads Primary causes of poor ECG signal Attaching the PPU PMU & patient monitoring Describe the patient preparation for ECG triggering PMU Hardware, Patient Preparation & Applying Electrodes ? Hardware PERU (Physiologic ECG and Respiratory Unit) & PPU (Peripheral Pulse Unit) Units are always on and should be placed in charging station when not in use (avoid fully discharging) Maximum charging time: ~3 hours Operating time: 12 – 24 hours Charging stations are linked to the power supply of the system; if MR system is OFF, units are no longer charging! Radio data transmission is enabled only if unit is positioned in static magnetic field (RoHS conforming) Only one PERU and PPU should be located in exam room to avoid signal interference ECG leads with clips Wireless PERU Wireless PPU Control LEDs Transmitter unit Plug for respiration cushion ECG leads with clips Control LEDs Transmitter unit Plug for respiration cushion 3 channel 2 channel Finger adapter Fiber optic cable Transmitter unit Control LEDs Application cushion Hardware [pmu-in-mri_basics_olt_en_hardware.mp3] PERU and PPU wireless technology reduce patient motion artifacts by completely eliminating the transmission cable from the patient to the equipment. The net result is a much cleaner signal. Two channel or three channel wireless PERU units are available, depending on the MR system type. The units are always on and should be placed in the charging station when not in use. The maximum charging time for newer units is approximately three hours. The operating time when fully charged is between 12 to 24 hours. Charging stations are linked to the power supply of the system. Therefore if the MR system is off, the units are no longer charging. To ensure the units are RoHS conforming, radio data transmission is enabled only when the unit is positioned in the static magnetic field, which is approximately at the foot end of the patient table. Importantly, only one PERU and PPU should be located in the exam room at the same time, in order to avoid signal interference. For example, two PERU units in the examination room at the same time will interfere with one another in signal transmission, making it impossible to determine the results. ? LED Indicators The transmitter unit includes three green LEDs for indicating the battery charge level and one red LED as a fault indicator 3 Green LEDs flash: fully or nearly fully (2/3) charged battery 2 Green LEDs flash: 1/3 to 2/3 fully charged battery 1 Green LED flashes: Nearly discharged battery (one hour operating duration remaining) If the battery is fully charged, the 3 green LEDs are on and stop flashing Red LED flashes (as regularly as green LEDs): transmit function deactivated, unit is positioned outside static magnetic field Red LED flashes rapidly: electrode fault, one or more ECG electrodes are not attached correctly (PERU), or pulse sensor not applied correctly to finger (PPU) Charging Station 3 Green LEDs (battery charge level) 1 Red LED (fault) Transmitter unit LED Indicators [pmu-in-mri_basics_olt_en_led-indicators.mp3] There are three LED indicators on the transmitter units for indicating the battery charge level, and one red LED to indicate faults. The flashing pattern indicates the current status, some of which can be seen on this page. More information is available in the MR Operator Manual. The transmitters sit in a wall mounted charger. Always hang them on the charger when not in use, and in between patients, in order to ensure a full charge. ? Battery Status Battery status and electrode faults are indicated on system displays at magnet bore Physio Display Battery level ≤ 25%: a yellow battery icon is shown Battery level ≤ 5%: a red battery empty icon is shown No icon displayed if battery is full Battery Status [pmu-in-mri_basics_olt_en_battery-status.mp3] Battery status and electrode faults are also indicated on the Select&GO or Dot displays at the scanner, as well as on the Physio Display window. If the battery level is below 25%, a yellow battery icon is shown on the Physio Display, and a red battery icon when the level is below 5%. No icon is displayed if the battery is full. ? Skin Preparation Remove chest hair (if necessary) in areas where you intend to place electrodes Remove oil and perspiration to allow better electrode contact Clean skin using Nuprep ECG & EEG Abrasive Skin Prepping Gel (mildly abrasive, highly conductive) Dry the skin completely to remove excess gel Avoid using alcohol based solutions which remove electrolytes from the skin, reducing conductivity Please note: The Nuprep ECG & EEG Abrasive Skin Prepping Gel is not a dedicated gel for applying the electrodes on the skin. Skin Preparation [pmu-in-mri_basics_olt_en_skin-preparation.mp3] As ECG triggering is such a critical part of the cardiac imaging process, certain steps of patient preparation must always be followed to ensure an optimal ECG signal. To ensure the best skin contact, always remove chest hair in areas where you intend to attach the electrodes. Shave the patient outside the exam room to prevent accidents. Remove oil and perspiration to allow for better electrode contact. Clean and roughen the skin using Nuprep abrasive gel and thoroughly dry the skin with a soft clean cloth, ensuring you remove excess gel. Avoid using alcohol based solutions which remove the natural electrolytes from the skin, thereby reducing its conductivity. Please note: The Nuprep ECG & EEG Abrasive Skin Prepping Gel is not a dedicated gel for applying the electrodes on the skin. ? Applying Electrodes Always use MR Safe electrodes Siemens recommends Conmed Cleartrace 2700 electrodes Check electrode expiry date Do not expose to air during storage Do not reuse or reposition electrodes Use of non-MR Safe electrodes typically results in poor ECG quality, and in the worst case may lead to patient burns Applying Electrodes [pmu-in-mri_basics_olt_en_applying-electrodes.mp3] Always use MR safe pre-gelled electrodes with adhesive pads. Siemens recommends Conmed Cleartrace 2700 electrodes. Ensure the electrodes are not expired or exposed to air during storage, as the adhesive can dry up, thereby reducing conductivity. Do not reuse electrodes, and always use a fresh electrode when repositioning. This helps to ensure optimal contact. Use of non MR-safe electrodes typically results in poor ECG quality, and in the worst case may lead to patient burns. ? Electrode Positioning Use guidance images on system displays at magnet bore to position electrodes Position PERU in application cushion (distance between PERU and patient should be at least 2 cm) Typically the PERU is aligned toward the foot end of the patient table, even though the patient may be positioned feet first Caution: Hot ECG cables! Risk of burns to the patient. Place absorbent material between the ECG cables/leads of the PERU and the patient’s skin. Electrode & PERU positioning for three lead ECG systems Electrode & PERU positioning for two lead ECG systems Electrode Positioning [pmu-in-mri_basics_olt_en_electrode-positioning.mp3] Generally the electrodes are aligned obliquely with the electrical axis of the heart. You will need to attach the electrode pads onto the patients chest in the optimal locations in order to detect the voltage. Position the electrodes following the guidance images on the system displays at the magnet bore. Place the unit in the application cushion to ensure a minimum distance of two centimeters between the unit and patient. Typically the PERU is aligned toward the foot end of the patient table, even though the patient may be positioned feet first. It is recommended to place absorbent material between the ECG leads and the patient’s skin, as the ECG cables may become warm. ? Electrode Positioning - Hint For some examinations the placement of electrodes may differ As an example: for head measurements with ECG-triggering such as cerebrospinal fluid head examinations Electrode Positioning - Hint [pmu-in-mri_basics_olt_en_electrode-positioning02.mp3] For some examinations the placement of electrodes may differ. As an example: for head measurements with ECG-triggering such as cerebrospinal fluid head examinations. ? ECG Leads ECG Lead is the potential difference between a pair of electrodes The leads are acquired and used in parallel via the ECG channels Simultaneous acquisition and overlaying of the orthogonal leads (vector cardiography) is used to minimize trigger errors due to gradient switching and the magneto-hydrodynamic effect 3 channels 2 channels Table with 2 columns and 4 rows ECG lead Potential difference I LA - RA II RL – RA III RL - LA RA RL LL LA Table with 2 columns and 3 rows ECG lead Potential difference I RL - LL aVF RL – RA RA RL LL ECG Leads [pmu-in-mri_basics_olt_en_ecg-leads.mp3] An ECG lead is the potential difference between a pair of electrodes. Leads are acquired and used in parallel via the ECG channels. Siemens wireless PERU units may be three channel or two channel, depending on the type of MR scanner. The three channel system consists of one vertical signal which is lead one, and two horizontal signals, leads two and three. The two channel system consists of one vertical signal, lead AVF, and one horizontal signal, lead one. Vector cardiography is the simultaneous acquisition and overlaying of two orthogonal leads, and is used to minimize trigger errors due to gradient switching and the magneto-hydrodynamic effect. ? Hint: Attach the electrodes so that interferences from electrical potentials caused by muscle movement and baseline drifts are minimized. Suitable contact points are therefore areas that show very little muscle or fatty tissue. Electrode Positioning Tips Electrode positioning varies according to the position and electrical axis of the heart. Electrical axis is the direction of the net sum of all voltages Points caudal and to the left Direction based on patient body habitus Tall patients – more vertical Short patients – more horizontal May change during a deep breath-hold or due to pathology (e.g. dilatative cardiomyopathy) May need to adapt electrode positions Electrode Positioning Tips [pmu-in-mri_basics_olt_en_elec-pos-tips.mp3] Generally the electrodes are aligned obliquely with the electrical axis of the heart. The electrical axis is the direction of the net sum of all voltages, and generally points caudal and to the left. The direction varies depending on body habitus, being more vertical for tall patients and more horizontal for shorter patients. The direction also varies cyclically during the cardiac cycle. The cardiac axis may also change during a deep breath-hold, or in certain pathological conditions such as dilatative cardiomyopathy. Optimal electrode positioning may vary according to the position and electrical axis of the heart, and the position may need to be adapted in order to achieve an optimal ECG signal. It may also help to position electrodes on areas that have very little muscle or fatty tissue. This helps to avoid interference from electrical potentials caused by muscle movement, and minimize baseline drift. ? Primary Causes of Poor ECG Signal Poor patient preparation Shave chest hair if required Prepare skin using Nuprep gel Avoid alcohol based products to clean skin Incorrect electrode usage Use Siemens recommended electrodes (Conmed Cleartrace 2700) Do not use dry electrodes (check expiry date) Do not reuse electrodes Primary Causes of Poor ECG Signal [pmu-in-mri_basics_olt_en_poor-ecg-signal.mp3] The most typical cause of poor ECG signal is due to poor electrode contact resulting from poor patient preparation. Always shave chest hair if required, and apply Nuprep gel correctly. Do not use alcohol based products to clean the patient skin. Another typical cause of poor ECG signal is incorrect electrode usage. Always use Siemens recommended electrodes, and ensure they have not expired. Do not reuse electrodes. If repositioning, use a new electrode each time. ? Attaching the PPU Ensure suitable finger adapter is attached (available in different sizes) Ensure cable is not bent Attach the pulse sensor to a finger or toe Ensure the pulse sensor is attached properly Red LED (fault) flashing rapidly indicates no signal available; check attachment Attaching the PPU [pmu-in-mri_basics_olt_en_attaching-ppu.mp3] When attaching the PPU ensure a suitable finger adapter is attached, as they are available in different sizes. Ensuring the cable is not bent, attach the pulse sensor to the patients finger or toe. Make sure it is attached properly. A rapidly flashing LED indicates there is no analyzable signal available. Check the attachment and secure with tape if necessary. ? PMU & Patient Monitoring PMU components must only be used to control MR measurement sequences and are not approved to monitor patient vital parameters MR Safe or MR Conditional patient monitoring systems must be used for monitoring patient vital parameters if required If misuse is suspected, immediately advise customer Excerpt from Operator Manual – MR System and Coils syngo MR XA31 Chapter 4 Physiological Imaging Excerpt from Operator Manual Hint: All components of the MR system mentioned here must only be used to control MR measurement sequences. They are not approved as a patient monitoring system! Warning: Physiological displays are not approved to monitor vital parameters! Anomalies of the vital parameters may not be recognized or recognized too late Never use the physiological displays (either at the system or at the computer) to monitor the vital parameters of a patient. Only use suitable patient monitoring systems for monitoring vital parameters (MR Safe or MR Conditional). PMU & Patient Monitoring [pmu-in-mri_basics_olt_en_patient-monitoring.mp3] It is important to realize that PMU components must only be used to control MR measurement sequences, and are not approved to monitor patient vital parameters. MR safe or MR conditional patient monitoring systems must be used for monitoring the patients vital parameters if required. This is clearly stated in our operator manuals. If misuse is suspected, immediately advise the customer. Chapter 3: ECG Learning Phase ? Learning phase of the VCG Learning status indication Signal strength indicator Execute the ECG learning phase ECG Learning Phase ? Learning Phase of the VCG VCG triggering requires a learning phase which obtains a clean ECG signal while the patient is outside the magnet bore. Used as a reference pattern to look for R waves when patient is inside bore Select the numbered steps below to learn more about the learning phase of the VCG. 1 1 1 2 2 2 3 3 3 4 4 4 Learning Phase of the VCG [pmu-in-mri_basics_olt_en_learning-phase01.mp3] VCG triggering requires a learning phase which obtains a clean ECG signal while the patient is outside the magnet bore. R waves should be clearly visible during the learning phase, and this signal is used as a reference pattern to look for R waves when the patient is inside the bore. Select the numbered steps below to learn more about the learning phase of the VCG. [pmu-in-mri_basics_olt_en_learning-phase02.mp3] The learning phase is active while the patient table is within 300 mm of the home position, known as the learning range. The home position works best due to the lowest B zero stray field, ensuring minimal T wave elevation due to the magnetohydrodynamic effect. [pmu-in-mri_basics_olt_learning-phase03.mp3] At least 10 regular heartbeats are needed for a successful learning phase, during which there is no patient or table motion. [pmu-in-mri_basics_olt_learning-phase04.mp3] The learning phase is interrupted as soon as the table is moved. If the table is stopped within the learning range, the learning phase is continued. The learning phase is terminated if the table is moved more than 300 mm from the Home position. [pmu-in-mri_basics_olt_learning-phase05.mp3] Note that if the patient is moved out during the examination, repeat the Learning Phase within the 300 mm zone. Also note that if the scanner is rebooted while the patient is inside the bore, the learning phase is lost and must be repeated. Checklist Item Title 2 Please note: If patient is moved out during exam, repeat Learning Phase within 300 mm zone If scanner is rebooted while patient inside bore, learning phase is lost and must be repeated 4 Checklist Item Title 2 Learning phase is interrupted as soon as table is moved; if table is stopped within learning range, the learning phase is continued Learning phase is terminated if table is moved more than 300 mm from Home position 3 Checklist Item Title 2 At least 10 regular heartbeats are recommended for a successful learning phase, during which there is no patient or table motion 2 Checklist Item Title 1 Learning phase is active while patient table is within 300 mm of Home position (learning range) Home position works best due to lowest B0 stray field, ensuring minimal T wave elevation due to magnetohydrodynamic effect 1 ? Learning Status Indication The learning phase status is indicated at the magnet to avoid premature termination. As long as one complete learning cycle is observed, it is successful Select the numbered steps below to learn more about the learning phase status. 1 1 1 2 2 2 3 3 3 Learning Status Indication [pmu-in-mri_basics_olt_en_learning-status01.mp3] The learning phase status is indicated at the magnet to avoid premature termination. As long as one complete learning cycle is observed, it is successful. Select the numbered steps below to learn more about the learning phase status. [pmu-in-mri_basics_olt_en_learning-status02.mp3] After completion, a new learning cycle begins. The loop continues until the cycle is interrupted by moving the patient table, and the last complete cycle is used. [pmu-in-mri_basics_olt_en_learning-status03.mp3] The advanced or auto algorithm requires 3 heartbeats for the learning phase, whereas the standard algorithm requires 10 heartbeats. [pmu-in-mri_basics_olt_en_learning-status04.mp3] Note that the learning phase starts immediately after the electrodes are connected, and does not consider the patient preparation status. It is recommended that once the patient and coils are completely prepared, to allow another 10 regular heartbeats with no patient motion, immediately prior to moving the table into bore. Allowing a learning phase of 10 heartbeats enables use of both the Advanced and Standard trigger algorithms during the examination. Checklist Item Title 2 Please note: The learning phase starts immediately after the electrodes are connected, and does not consider patient preparation status Recommendation: once patient and coil are completely prepared, allow another 10 regular heartbeats with no patient motion, immediately prior to moving table into bore Learning phase of 10 heartbeats enables use of both Advanced and Standard trigger algorithms during exam 3 Checklist Item Title 2 Advanced (Auto) algorithm requires 3 heartbeats for learning phase, whereas Standard algorithm requires 10 heartbeats 2 Checklist Item Title 2 After completion, a new learning cycle begins; the loop continues until the cycle is interrupted by moving patient table, and the last complete cycle is used 1 ? Signal Strength Indicator Quality of signal can be deceptive due to auto-gain feature Even a low amplitude R wave will look good outside bore, but may be wiped out by noise and flow artifact inside bore (especially at 3T) Strength indicator represents amplitude strength of R wave; range is from 1 to 5 bars To ensure reliable triggering, a minimum of 2 bars should be visible on at least 2 ECG channels Optimize signal strength if needed (remove hair, Nuprep, Conmed 2700, electrode position) Signal Strength Indicator [pmu-in-mri_basics_olt_en_signal-strength.mp3] The quality of the signal displayed can be deceptive due to an auto-gain feature. Even a low amplitude R wave will look good outside the bore, but may be wiped out by noise and flow artifact once the patient is inside the bore, particularly at 3 Tesla. The signal strength indicator represents the amplitude strength of the R wave, and ranges from one to five bars, or stars. To ensure reliable triggering, a minimum of two bars should be visible on at least 2 ECG channels prior to starting the examination. Optimize the signal strength if needed, for example by removing chest hair, preparing the skin with Nuprep gel, using the Siemens recommended electrodes and trying different electrode positions. Chapter 4: User Interface ? Triggering methods Trigger statistics Recognize ECG user interface User Interface ? Triggering Methods Physio display options Table with 2 columns and 5 rows Auto Default setting Advanced learning algorithm Automatic selection of 2 best leads for VCG Large triangle indicates which leads are used for VCG Relearn with patient inside bore VCG Standard VCG derived from Lead I & II Standard learning algorithm ECG I Lead I only; VCG inactive ECG II Lead II only; VCG inactive ECG III Lead III only; VCG inactive ECG trigger options Triggering Methods [pmu-in-mri_basics_olt_en_user-interface.mp3] A number of different triggering methods are available. Open the Settings context menu on the Physio Display to select the desired trigger method from the ECG Trigger list. Note that it is not possible to change the trigger method during a measurement. Auto is the default setting, and uses the advanced learning algorithm. Here the system automatically selects the two best leads for the VCG. A larger sized triangle above the signal curve indicates which leads are being used for the VCG. If Auto is used, the signal characteristics can be relearned by selecting Relearn in the context menu of the Physio Display. In this instance the learning phase lasts for three heartbeats. VCG standard uses the standard learning algorithm, and the signal is derived from leads one and two. ECG one, ECG two and ECG three use a single lead only which means that the VCG is inactive. It is recommended to always begin an examination using the default Auto mode. In cases where the Auto mode is not working, try changing to VCG standard. Single lead modes should only be used if both VCG algorithms are not working well. However single lead ECG is not recommended particularly at 3 Tesla, due to the strong magnetohydrodynamic effect. ? Trigger Statistics PMU periodically transmits a set of current statistical data (heart rate, average cardiac interval, etc.) to the scanner software Open Settings in the Physio Display context menu and select Statistics from menu Standard deviation of trigger interval reflects variations in RR intervals (e.g. can be high, e.g. up to 100ms in arrhythmic patients) Reset Statistics possible if desired Hint: When the patient table has been moved out of the bore, the trigger is getting lost and has to be set up again via Relearn. Trigger Statistics [pmu-in-mri_basics_olt_en_trigger-statistics.mp3] The PMU periodically transmits a set of current statistical data, such as heart rate and cardiac interval to the scanner software. To display the statistics, open Settings in the physio display context menu and select Statistics. The standard deviation of the trigger interval reflects variations in the RR intervals. You can also select Reset Statistics from the context menu if desired. Please note: When the patient table has been moved out of the bore, the trigger is getting lost and has to be set up again via Relearn. ? Course Review Congratulations. You have completed the Cardiac Essentials PMU in MRI – Basics Online Training. Select the numbered buttons below to review the material before proceeding to the final assessment. Recognize ECG User Interface Execute the ECG Learning Phase Describe the Patient Preparation for ECG Triggering Identify Physiology of the Heart 1 1 2 2 2 3 3 3 4 4 4 Course Review Recognize ECG User Interface ECG trigger options Triggering methods Auto: Default setting; advanced learning algorithm; automatic selection of 2 best leads for VCG; Relearn with patient inside bore VCG Standard: Standard learning algorithm; VCG derived from Lead I & II ECG I/II/III: Lead I/II/III only; VCG inactive Physio display options Trigger statistics Display statistics (heart rate, average cardiac interval, etc.) Reset statistics 1 1 2 2 2 Execute the ECG Learning Phase Select the X button to return to the overview page. Signal Strength Indicator Strength indicator represents amplitude strength of R wave; range is from 1 to 5 bars To ensure reliable triggering, a minimum of 2 bars should be visible on at least 2 ECG channels Execute the ECG Learning Phase 1 1 2 2 Select page 2 to continue. 1 Learning Phase of the VCG Requires a ‘clean’ ECG signal obtained while patient is outside magnet bore Used as a reference pattern to look for R waves when patient is inside bore Learning phase is active while patient table is within 300 mm of Home position (learning range) Advanced (Auto) algorithm requires 3 heartbeats for learning phase, Standard algorithm requires 10 heartbeats At least 10 regular heartbeats are recommended for a successful learning phase, during which there is no patient or table motion; this enables use of both trigger algorithms during exam Describe the Patient Preparation for ECG Triggering Attaching the PPU (Peripheral Pulse Unit) Ensure suitable finger adapter is attached (available in different sizes) Ensure cable is not bent Attach the pulse sensor to a finger or toe and ensure it is attached properly Red LED (fault) flashing rapidly indicates no signal available; check attachment 1 1 2 2 3 3 4 4 4 Select the X button to return to the overview page. Describe the Patient Preparation for ECG Triggering Electrode Positioning Position PERU (Physiologic ECG and Respiratory Unit) in application cushion (distance between PERU and patient should be at least 2 cm) Typically the PERU is aligned toward the foot end of the patient table, even though the patient may be positioned feet first 1 1 2 2 3 3 4 4 3 Select page 4 to continue. Three lead ECG systems Two lead ECG systems Describe the Patient Preparation for ECG Triggering Applying Electrodes Always use MR Safe electrodes (Conmed Cleartrace 2700 electrodes) Ensure the electrodes are not expired or exposed to air during storage Do not reuse or reposition electrodes 1 1 2 2 3 3 4 4 2 Select page 3 to continue. Describe the Patient Preparation for ECG Triggering Skin Preparation ​Remove chest hair (if necessary) in areas where you intend to place electrodes Remove oil and perspiration to allow better electrode contact Clean skin using Nuprep ECG & EEG Abrasive Skin Prepping Gel Dry the skin completely to remove excess gel Avoid using alcohol based solutions which remove electrolytes from the skin, reducing conductivity 1 1 2 2 3 3 4 4 Select page 2 to continue. 1 1 1 2 2 3 3 3 Effects of impaired ECG signal Missed R waves, leading to longer breath-hold and motion Intermittent triggering on flow or gradient artifact Miscalculation of heart rate due to incorrect triggers or missed R waves Poor image quality due to acquisition of data during different phases of the cardiac cycle Identify Physiology of the Heart Select the X button to return to the overview page. 1 1 2 2 3 3 2 Select page 3 to continue. Characteristics of a good ECG Waveform Identify Physiology of the Heart Sharp R wave R wave higher in amplitude than T wave while outside the bore (0T) higher than distortion induced by magnetic environment while inside the bore (1.5T, 3T) Baseline distortion Small baseline distortion (respiration, electrode contact) Identify Physiology of the Heart Electrical System of the Heart Select page 2 to continue. SA node AV node Bundle of His Right bundle branch Left bundle branch R wave P T Q S 1 1 2 2 3 3 1 QRS complex atria relax & ventricles contract P-wave atria contract T wave ventricles relax R wave For the ECG signal, the R waves are important, as they are typically used to synchronize MRI data acquisition. ECG The ECG records electrical activity of the heart using electrodes placed on the skin. Each wave or segment of the ECG signal corresponds to a certain event of the cardiac electrical cycle. ECG Triggering Cardiac MR data acquisition is usually spread over several heartbeats making it necessary to synchronize with cardiac motion. Disclaimer Please note that the learning material is for training purposes only. For the proper use of the software or hardware, please always use the Operator Manual or Instructions for Use (hereinafter collectively “Operator Manual”) issued by Siemens Healthineers. This material is to be used as training material only and shall by no means substitute the Operator Manual. Any material used in this training will not be updated on a regular basis and does not necessarily reflect the latest version of the software and hardware available at the time of the training. The Operator Manual shall be used as your main reference, in particular for relevant safety information like warnings and cautions. Please note: Some functions shown in this material are optional and might not be part of your system. 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Disclaimer Assessment This assessment will test your retention of the presented content. A passing score of 80% or higher is required to complete the course and earn your certificate. You may repeat the assessment as many times as needed. Start ? Assessment Select the best answer. ? Question 1 of 5 What are characteristics of a good ECG waveform? Sharp T wave, T wave higher in amplitude than R wave while outside the bore R wave higher than distortion induced by magnetic environment while inside the bore, high baseline distortion Sharp P wave, small baseline distortion Sharp R wave, R wave higher in amplitude than T wave while outside the bore (0T) Multiple Choice Correct Incorrect A sharp P wave is not a characteristic of a good ECG waveform. Incorrect High baseline distortion is not a characteristic of a good ECG waveform. Incorrect This are not characteristics of a good ECG waveform. Select the best answer. ? Question 2 of 5 Which wave or segment of the ECG signal is used to synchronize cardiac MR data acquisition with cardiac motion? P wave R wave QRS complex T wave Multiple Choice Incorrect The T wave is not used to synchronize cardiac MR data acquisition with cardiac motion. Incorrect The QRS complex is not used to synchronize cardiac MR data acquisition with cardiac motion. Correct Incorrect The P wave is not used to synchronize cardiac MR data acquisition with cardiac motion. Select the best answer. ? Question 3 of 5 What is not part of the patient preparation for ECG triggering? Prepare patient skin using Nuprep gel Attach the electrode pads onto the patient chest Position PERU in application cushion (distance between PERU and patient > 2 cm) Reposition electrodes if ECG quality is not good enough Multiple Choice Correct Incorrect Positioning the PERU in the application cushion is part of the patient preparation. Incorrect Attaching the electrode pads onto the patient chest is part of the patient preparation. Incorrect Preparing the patient skin with Nuprep gel is part of the patient preparation. Select the best answer. ? Question 4 of 5 What is the minimum number of heartbeats required for a successful learning phase to enable the use of the Advanced (Auto) algorithm during the examination? 3 5 7 10 Multiple Choice Incorrect The Advanced (Auto) algorithm requires less heartbeats for the learning phase. Incorrect The Advanced (Auto) algorithm requires less heartbeats for the learning phase. Incorrect The Advanced (Auto) algorithm requires less heartbeats for the learning phase. Incorrect Select the best answer. ? Question 5 of 5 What characterizes the Auto trigger method? Standard learning algorithm, VCG derived from Lead I & II Lead I only; VCG inactive Advanced learning algorithm, Automatic selection of 2 best leads for VCG Standard learning algorithm, Automatic selection of 3 best leads for VCG Multiple Choice Incorrect There is no trigger method with these characteristics. Incorrect Incorrect ECG I uses a single lead only which means that the VCG is inactive. Incorrect VCG standard uses the standard learning algorithm, and the signal is derived from leads one and two. Assessment Results YOUR SCORE: PASSING SCORE: Review Retry Retry Continue Continue Continue %Results.ScorePercent%% %Results.PassPercent%% ? Assessment Results You did not pass the course. Take time to review the assessment then select Retry to continue. Congratulations. You passed the course.. Exit To access your Certificate of Completion, select the Launch button drop down on the course overview page. You can also access the certificate from your PEPconnect transcript. ? You have completed the Cardiac Essentials PMU in MRI – Basics Online Training. Completion Navigation Help Select the icon above to open the table of contents. Click Next to continue. Next Welcome Slide The timeline displays the slide progression. Slide the orange bar backwards to rewind the timeline. Click Next to continue. Next Timeline Select the X to close the pop-up. Click Next to continue. Next Layer Slide Select Submit to record your response. Click the X in the upper right corner to exit the navigation help. Assessment Slide Question Bank 1 HOOD05162003246976 | Effective Date: 07 FEB 2022 1.1 Welcome 1.2 Introduction of our MR Master 1.3 Navigation Hints 1.4 Introduction to ECG Triggering 1.5 Cardiac Motion 1.6 Electrical System of the Heart 1.7 ECG Triggering 1.8 Characteristics of a Good ECG Waveform 1.9 #1 Tip 1.10 Effects of Impaired ECG Signal 1.11 PMU Hardware, Patient Preparation & Applying Electrodes 1.12 Hardware 1.13 LED Indicators 1.14 Battery Status 1.15 Skin Preparation 1.16 Applying Electrodes 1.17 Electrode Positioning 1.18 Electrode Positioning - Hint 1.19 ECG Leads 1.20 Electrode Positioning Tips 1.21 Primary Causes of Poor ECG Signal 1.22 Attaching the PPU 1.23 PMU & Patient Monitoring 1.24 ECG Learning Phase 1.25 Learning Phase of the VCG 1.26 Learning Status Indication 1.27 Signal Strength Indicator 1.28 User Interface 1.29 Triggering Methods 1.30 Trigger Statistics 1.31 Course Review 1.32 Disclaimer 1.33 Assessment