Jiang Hsieh PhD, Presenter: Nothing to Disclose

John Howard Londt BS, Abstract Co-Author: Nothing to Disclose

Melissa Vass BS, Abstract Co-Author: Nothing to Disclose

Erdogan Cesmeli PhD, Abstract Co-Author: Nothing to Disclose

Xiangyang Tang PhD, Abstract Co-Author: Nothing to Disclose

Darin R. Okerlund MS, Abstract Co-Author: Nothing to Disclose

J.H.,J.H.L.,M.V.,E.C.,X.T.,D.R.O.: Employee of GE Healthcare Technologies

Purpose:  Low-pitch helical is typically used in CT cardiac imaging to ensure complete volume coverage and goo phase registration over multiple cardiac cycles.  Although this approach is effective, it suffers from drawbacks of higher x-ray dose to patients and lack of flexibility in dealing with irregular heart motion.  We present a step-and-shoot acquisition for VCT cardiac imaging. Methods and Materials: A 40mm 64-slice VCT is used in step-and-shoot acquisition mode to perform cardiac scanning.  Because of the large detector coverage, the inter-scan delay is kept to 4.2s.  Since the table remains stationary within each data acquisition, data collection takes place only when normal heart rates are detected to avoid motion artifacts.  In addition, the x-ray is only turned on during the desired phase of the cardiac cycle.  With a 0.35s gantry rotation speed, the entire heart scan can be completed in less then 7s for a wide range of heart rate.  To reduce cone beam artifacts, a multi-scan weighted FDK algorithm is used for image reconstruction. Results:                Phantom, animal, and human studies were performed to demonstrate the efficacy of our approach.  A cardiac phantom was used to test the effectiveness of the proposed reconstruction algorithm on cone beam artifact suppression, and the results show that the reconstructed image is visually free of cone beam artifacts.  Animal studies demonstrated the robustness of the data acquisition in handling irregular heart motion.  Patient studies further confirm the superior image quality obtained with the proposed scheme.  Analysis has shown that the proposed acquisition allows a 67-83% dose reduction as compared to a helical acquisition without current modulation.  The dose reduction enabled by the proposed technique is still well above 35% with current modulation.  Conclusion: Step-and-shoot acquisition combined with the advanced EKG gating and wide detector coverage of VCT enables a significant dose reduction and improved motion artifact suppression in CT cardiac imaging.  The clinical utility of such approach is clearly demonstrated.Financial disclosure:   All authors are employees of GE Healthcare Technologies. 

Hsieh, J, Londt, J, Vass, M, Cesmeli, E, Tang, X, Okerlund, D, Hot Topic: Experimental Results on VCT Step-and-Shoot Cardiac Low-Dose Imaging.  Radiological Society of North America 2005 Scientific Assembly and Annual Meeting, November 27 - December 2, 2005 ,Chicago IL. http://archive.rsna.org/2005/4425807.html