ECG edition in dual source CT
The following question has been sent by Sofiane Hadjadj, MD, clinical research, Canada:
hi, we have just aquired the dual source ct, and I am very impressed by the quality of images for coro ct even with high calccium scoring, my question is regarding the EKG editing, are their any rules regarding this process for arythmias, which complex has to be deleted, which phase is the best for short rr, etc….
thank in advance for your help.
Kai U. Juergens, MD, Associate Professor, University Hospital Muenster, Germany:
The following hints might help you in your practical work with the Dual Source CT:
• In a patient presenting with high heart rate (i.e. short RR-interval)
an additional systolic reconstruction, e.g. 330 to 350 ms after the R-wave or applying the “Best systolic phase”-reconstruction option, might facilitate your image analysis.
• According to our experience, in a patient with arrhythmia the
exclusion of the ectopic beat and the switch to “ms-triggering” instead of “percentage triggering” is necessary in patients with arrhythmia: if the RR-interval then is too long, a manual insertion of (an) additional synchronization signal(s) evenly distributing the reconstruction bars might become necessary. Alternatively, you might apply the pulsing algorithm adjusting the range of heart rate.
See another answer to this question by Dr. Heuschmid
See another answer to this question by Dr. Achenbach
The ECG edit has been the saving grace for a few of our challenging patients. The aberrant beat is easy, but the pesky pacemaker is not. I have found in attempting to clear the aberrant beat, the area of interest is easier to address than the entire dataset. Pick your battle. Delete a sync prior and reconstruct the segmeted area, post and try to change the temporal resolution to 145 ms or 165 ms over that area of fault. The pacemaker steps have kicked into play if the patient happens to drop below the dial down during the scan. Reviewing the ecg tracing, delete the sync on each of the pacer spikes, set a median TR, you might also try using the Best systolic phase if the heartrate still remains high after the count is adjusted. I have had what began as a horrible scan, become a motion free dataset with this technique.