Artifact Examples

Question 1

Artifact

Answer 1

Arise from various sources and interfere with interpretation of signals causing distortion

Question 2

Artifacts in cardiac devices

Answer 2

Motion (irregular baseline)
Electrical interference (50Hz noise)
Pacemaker spikes (sharp spikes)
Muscle tremors (high frequency noise)
Respiratory/breathing (baseline wander)

Question 3

Artifacts in respiratory devices

Answer 3

Motion (irregular waveforms)
Cough/swallowing (spikes/interruptions)
Electrical interference (50Hz noise)
Obstructive noise (background noise)
Improper sensor placement (distortion/diminished signals)

Question 4

Artifacts in neurological devices

Answer 4

Eye movement/blinking (large slow waves)
Muscle activity (high frequency noise)
Electrical noise (50Hz)
Sweat (drifting baselines)
Movement (abrupt spikes/signal disruption)

Question 5

Artifacts in gastro devices

Answer 5

Motion (irregular signals)
Respiratory/cardiac interferences (periodic, overlapping signals)
Signal loss in capsule endoscopy (gaps in data, weak transmission, obstructions)
External interference (50Hz)
Food/fluid interference (mimics abnormalities)

Question 6

Artifacts in vascular devices

Answer 6

Motion (poor accuracy)
Low perfusion (weak signals)
Venous pulsation (overlapping signals on Doppler)
Electrical noise (50Hz)
Improper cuff position (incorrect BP reading)

Question 7

Artifacts specific to ultrasound

Answer 7

Acoustic shadowing (dark shadow distal to the dense object - soundwaves absorbed/reflected by dense structure)
Reverberation (repeated, evenly spaced linear echoes - multiple reflections between two highly reflective surfaces)
Aliasing (wrap around of flow signals on opposite side of baseline - frequency too low)
Refraction (duplicated/misplaced structure - soundwaves bending)
Mirror Image (duplicated structure on opposite side)

Question 8

Mitigating artifacts

Answer 8

Secure sensor/electrode placement
Minimise patient movement/tension
Filters to remove noise/interference
Calibration to improve quality
Controlled environments
Adjust Nyquist limit/frequency
Optimise gain
US - adjust probe, apply more gel