Rie Tanaka PhD, Presenter: Nothing to Disclose

Shigeru Sanada PhD, Abstract Co-Author: Stockholder, Hologic, Inc (R2 Technology, Inc), Sunnyvale, CA Research grant, Canon Inc, Tokyo, Japan

Katsumi Tsujioka PhD, Abstract Co-Author: Nothing to Disclose

Takeshi Matsui, Abstract Co-Author: Nothing to Disclose

Tadanori Takata, Abstract Co-Author: Nothing to Disclose

Osamu Matsui MD, Abstract Co-Author: Nothing to Disclose

To investigate the feasibility of cardiac evaluation with a dynamic flat-panel detector (FPD), based on changes in pixel values during cardiac pumping.

Sequential radiographs of a novel cardiac motion phantom we designed were obtained at 6 frames per second (fps) using a FPD system. Various combinations of cardiac output and cardiac rate were evaluated with and without contrast media. Ventricular area and summation of pixel values in the ventricles were measured and the rate of changes were then calculated (EFarea and EFpv ). The findings with and without contrast media were compared using EF obtained from CT images. An index of changes in pixel values was developed using water equivalent material step. In addition, slight changes in pixel values were visualized using inter-frame subtraction and Color mapping. The usefulness of this method was evaluated in clinical cases.

There were strong correlations between EF and EFpv (r=0.96), and between EF and EFarea (r=0.97). There was no significant difference between the findings with and without contrast media, indicating that contrast media was not necessary in the present method. When the cardiac rate was greater than 60 beats per minute (bpm), EFarea and EFpv were underestimated. It is necessary for a patient with cardiac rate from 60 bpm to 84 bpm to be examined at an imaging rate between 7.5 and 10 fps at least. In addition, ±1.0% change in pixel value was equivalent to ±10 mm change in thickness of water. In clinical cases, color-mapping images were very useful for interpreting slight changes in pixel values. The results provide diagnostic information on cardiac blood flow.

Evaluating changes in pixel values on dynamic chest radiography with FPD has the potential to demonstrate cardiac function without contrast media. Inter-frame subtraction and color mapping are very useful for interpreting changes in pixel value as blood flow velocities.

The present method is expected to be a rapid and simple procedure for evaluating cardiac function, as an additional examination in conventional chest radiography.

Tanaka, R, Sanada, S, Tsujioka, K, Matsui, T, Takata, T, Matsui, O, Development of a Cardiac Evaluation Method Using a Dynamic Flat-panel Detector (FPD) System: A Feasibility Study in a Cardiac Motion Phantom and Clinical Cases.  Radiological Society of North America 2007 Scientific Assembly and Annual Meeting, November 25 - November 30, 2007 ,Chicago IL. http://archive.rsna.org/2007/5007321.html