Albert Hsiao MD, PhD, Presenter: Nothing to Disclose

Michael Lustig, Abstract Co-Author: Nothing to Disclose

Marcus T. Alley PhD, Abstract Co-Author: Nothing to Disclose

Mark Murphy, Abstract Co-Author: Nothing to Disclose

Robert J. Herfkens MD, Abstract Co-Author: Nothing to Disclose

Shreyas Shreenivas Vasanawala MD, PhD, Abstract Co-Author: Research support, General Electric Company Consultant, Zimmer Holdings, Inc Consultant, ArthroCare Corporation

Valvular regurgitation and intracardiac shunts in congenital heart disease (CHD) are time-consuming to identify with conventional MRI techniques (2D cine phase contrast and 2D cine balanced steady state imaging), often requiring a skilled targeted search at the time of scanning. 4D phase-contrast MRI (4DPC) provides a time-varying vector field of cardiovascular flow over the whole chest, which holds the necessary information, but is challenging to interpret. We therefore developed and implemented 4DPC visualization methods, and assessed the feasibility of using 4DPC to detect CHD cardiac shunts and valvular regurgitation.

Multiplanar, volume-rendered, and stereoscopic 3D velocity-fusion visualization algorithms were developed in Java and OpenGL. To enable real-time interactive navigation, implementation of these techniques was optimized on dedicated graphics hardware and a 3D monitor. With IRB approval, two radiologists independently reviewed 20 consecutive parallel-imaging compressed-sensing 4DPC studies performed as part of CHD MRI exams and tabulated visible shunts and valvular regurgitation. These results were subsequently compared against color Doppler echocardiography and the official cardiac MRI reports, which were generated without the benefit of the 4DPC visualization tools.

Of 70 valves on 20 4DPC exams, 16 valves had regurgitation by 4DPC with good agreement between observers (κ=0.87) and the presence of at least mild regurgitation on echo (κ=0.79, 0.85). Further, one VSD patch leak, one muscular VSD and two ASD were identified by 4DPC and echo, but not 2D MRI. Also, an aortic baffle leak was identified by 4DPC, undetected by echo and 2D MRI, which altered the patient's care and led to surgery. No regurgitant valves or intracardiac shunts were found on echo alone.

Real-time interactive, stereoscopic 3D velocity-fusion volume-rendering is a feasible method for evaluating high-dimensional 4DPC MRI data, enabling detection of intracardiac shunts and regurgitation. Performance of 4DPC in this CHD population was better than 2D MRI and similar to echocardiography.

With advanced visualization software and stereoscopic 3D hardware, 4DPC MRI can complement existing CHD imaging techniques and enable prospective identification of shunts and valvular regurgitation.

Hsiao, A, Lustig, M, Alley, M, Murphy, M, Herfkens, R, Vasanawala, S, Stereoscopic 3D Volume-rendering of Shunts and Valvular Regurgitation with Parallel-imaging Compressed-sensing 4D Phase-contrast MRI.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11003004.html