Takanori Masuda, Presenter: Nothing to Disclose

Yun Shen PhD, Abstract Co-Author: Employee, General Electric Company

Takayuki Oku, Abstract Co-Author: Nothing to Disclose

Naoyuki Imada, Abstract Co-Author: Nothing to Disclose

Hiroya Asou, Abstract Co-Author: Nothing to Disclose

Satoshi Inada, Abstract Co-Author: Nothing to Disclose

Cheng Zhou MD, Abstract Co-Author: Nothing to Disclose

One method of exposure reduction is the use of High pitch helical scan.　In the 2007 RSNA presentation we confirmed the 0.24 pitch was proven to be ample only for ECG CT scan of children with heartbeats of 100bpm or higher. For slower heart rates (less than 50pm for instance)the 0.24 pitch was initially not effective without raw phase data. However we were determind to find a way in which the 0.24 pitch could be used for ECG gated scan in full heart rate area including slower heart rates. The purpose of this paper is to evaluate the usefulness of low DOSE cardiac scan using a combination of double trigger editor technique and ECG gated high helical pitch cardiac scan over the full heartbeat range.

Helical scan of pulsating cardiac phantom on the 40-80bpm (10bpm step) was performed using ECG gated 64row 40mm volume computed tomography (VCT) (GE LightSpeed VCT 64x0.625mm, 0.35s/r, reconstruction algorithm: half recon (CHR),helical pitch 0.16,0.18,0.2,0.22,0.24). The image quality of VR and MPR from different helical pitch and different heartbeats was analyzed and compared in 5 point scoring (5: Excellent;-1: poor; 3: accepted diagnosis) by 5 MDs/RTs mean scoring values (MSV) and mean banding artifact index values (MBV).After phantom experiment evaluation, the clinical date will be demonstrated using the new technique

Using Pitch0.24 compared to using pitch0.16 results in about 33% reduction in dose. MSV of no Editor and Editor on all heartbeats was 1.33±0.58（Max：2、Min：1）and 3.88±0.23（Max：4、Min：3）,respectively and BAI of no Editor and Editor on all the heartbeat was 52.73±7.5and 24.35±0.38.The MSV and BAI on all the heartbeats were significantly different between that of no Editor and of Editor. Also we confirmed this technique is useful on the clinical patient demonstrated.  

Our experimental and child patients analysis demonstrates that our proposed new technique, using a combination of double trigger editor technique and ECG gated high helical pitch cardiac scan is useful for adopting low DOSE cardiac scanning for the full heartbeat range in child patient cardiac diagnosis.

This study gives a guideline for children with congenital heart disease diagnosis by low DOSE technique in cardiac CT scan.

Masuda, T, Shen, Y, Oku, T, Imada, N, Asou, H, Inada, S, Zhou, C, Double Trigger in the Process of High Pitch Helical Scan.  Radiological Society of North America 2009 Scientific Assembly and Annual Meeting, November 29 - December 4, 2009 ,Chicago IL. http://archive.rsna.org/2009/8014557.html