Rendon C. Nelson MD, Presenter: Consultant, General Electric Company Research support, Bracco Group Research support, Becton, Dickinson and Company Speakers Bureau, Siemens AG Royalties, Lippincott, Williams & Wilkins

Amy Kiyo Hara MD, Abstract Co-Author: License agreement, General Electric Company Researcher, General Electric Company

W. Dennis Foley MD, Abstract Co-Author: Consultant, General Electric Company

Erik K. Paulson MD, Abstract Co-Author: Research Consultant, Siemens AG Stockholder, ZONARE Medical Systems, Inc

Dushyant V. Sahani MD, Abstract Co-Author: Grant, General Electric Company Consultant, Bracco Group

William Phelps Shuman MD, Abstract Co-Author: Research grant, General Electric Company

CT utilization and contribution to the collective radiation dose remains a dominant topic in medical imaging. The purpose of this study is to confirm the effectiveness of a new model-based iterative reconstruction (IR) technique to reduce radiation dose and improve image quality in patients compared to currently available reconstruction algorithms.

A pilot study of 120 patients recruited across four institutions have imaging in one of four anatomic arms: (1) anatomy/pathology in the posterior fossa, (2) lung cancer staging/restaging, (3) detection/characterization of focal liver lesions, or (4) urolithiasis. For each patient, two datasets are acquired: a standard-of-care radiation dose and an ultra-low radiation dose, both utilizing the Discovery CT750 HD (GE Healthcare, trial sponsor). Both datasets are reconstructed with filtered back projection (FBP), adaptive statistical iterative reconstruction (ASiR), and model-based IR (Veo), resulting in six datasets per patient. Two experienced readers independently assess qualitative clinical value, lesion characterization, diagnostic confidence and recommended treatment for each dataset. Additional quantitative results measure image quality (contrast, noise, CNR) vs dose and reconstruction type. Initial pilot study results will be presented and will confirm design for a large 800-patient global Multi-center Trial (12 sites worldwide) to follow.

Results of the quantitative and observer phantom studies presented at RSNA 2010 indicate a 40-80% dose reduction is possible while maintaining diagnostic and quantitative image quality parameters, potentially yielding scanning well under the annual background radiation dose for many protocols. Initial study results will show specific translation into the clinical population for each anatomic arm and reconstruction technique (FBP, ASiR, and Veo) evaluated.

These pilot study results will indicate if a dose reduction of up to 80% can provide diagnostic image quality in patients using an ultra-low dose IR technique. A well-designed and comprehensive multi-center trial is an ideal method to provide objective evidence to encourage appropriate introduction of new methodology into clinical practice.

Diagnostic CT scans may be possible using radiation doses well below background radiation dose when reconstructing with a model-based iterative reconstruction technique.

Nelson, R, Hara, A, Foley, W, Paulson, E, Sahani, D, Shuman, W, Ultra-Low Radiation Dose 64-row MDCT: Multicenter Clinical Trial to Assess the Diagnostic Feasibility of Model-based Iterative Reconstruction (Ultra-Low IR Study).  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11006007.html