Artifacts in Cardiac Imaging

Sources and Presentation

Common Artifact Sources in MPI System

Non-uniformity Bad COR

Patient related Upward creep (heart) Body fat attenuation Diaphragm attenuation Patient motion

System Artifacts Artifacts coming from the camera system are

usually avoidable by performing QC checks on a regular basis Non-uniformity artifacts can show up as “cold” or

“hot” spots on daily floods COR Checks can identify a bad COR

COR artifacts will cause a break in the sinogram of the cine SPECT acquisition and can cause artifacts after reconstruction

Patient Related Upward creep of heart

Sometimes occurs during the post-stress images if the stress test was recently completed (treadmill/exercise)

Change in respiration depth can cause the heart to move upward gradually during acquisition

More common in: Woman COPD

Can result in false-positive results Inferoseptal defect Anteroseptal defect

Patient breathing should be monitored and sufficient time should be waited prior to imaging

Patient Related Soft Tissue

Body weight and habitus Physician must be aware of patient factors that

could contribute to soft tissue attenuation Muscle and fat can both cause attenuation Artifact can be a false-positive Observe wall-motion and thickening; if decreased

then defect is most likely real Breast tissue artifacts

Anterior, anterolateral, and anteroseptal perfusion defects

Defect can appear reversible if the breast tissue is not in the same place in both rest and stress images

Patient Related Soft tissue (cont)

Lateral chest wall fat Fixed lateral wall defect

Diaphragmatic attenuation Can vary in rest and stress images due to different

position of diaphragm Fixed inferior wall defect Common in obese patients Patient can be imaged prone if artifact is suspected, to

move heart away from diaphragm

Patient Related Abdominal Visceral/Bowel Uptake

Artifact causes increased activity in the inferior wall of the heart

Liver, gallbladder, bowel Water and food can displace bowel activity Can image patient prone

Patient Related Patient motion

Location of artifact will depend on when motion occurred during study and in what direction the motion was in

Worse if motion occurs in middle of acquisition Make sure patient is comfortable and understands

that motion can cause a suboptimal study Use patient immobilization straps around

chest/arms to help patient’s chest remain still Keep patient from sleeping Evaluate sinogram for patient motion Motion correction software available from some

vendors