ASNC presentationThe increasing role of quantification in clinical nuclear cardiology: The Emory approach
Section snippets
ECTb philosophy
Our primary goal as a research team is to stay at the leading edge of scientific discovery to diagnose heart disease. We have implemented ECTb as a pipeline to distribute the software tools that we and others have researched, developed, and validated to be clinically useful so that diagnosticians everywhere can benefit from our work. We use a high-level scientific language (IDL) to shorten the time between concept and general distribution, and this frees our scientists to devote most of their
Integration
Our experience has demonstrated that integration of all software tools in a common platform is the optimal approach to promote both accuracy and efficiency. Accuracy is promoted because in the common platform, all functions are synergistic. For example, all automatic processing is performed before displaying the tomographic oblique slices for visual interpretation. Because the algorithm has already detected the apex and the base of the rest and stress MPI studies, the software automatically
Polar Map Representation
For representation of the patient’s LV myocardial perfusion distribution and for identifying hypoperfused segments, we use the polar map approach first reported by Garcia et al.1 In this approach the 3-dimensional (3D) maximal LV count distribution is synthesized onto a single 2-dimensional polar map, where the count distribution at the base of the left ventricle corresponds to the intensity at the periphery of the map and the counts at the apex to the center of the polar map. For detecting
Myocardial Thickening
All measurements of LV function in ECTb are based on our ability to measure myocardial thickening throughout the cardiac cycle. In 1990 Galt et al13 from our group showed that as a result of the limited spatial resolution of our imaging cameras compared with the myocardial thickness, partial-volume effects cause an almost linear change in maximal counts in myocardial segments as a change in thickness. Thus we determined that thickening could be measured for a myocardial segment as a change in
PET tools for quantitative analysis
Quantification of myocardial perfusion of PET tracers uses the same database quantification approach explained earlier except that the normal limits are generated by use of PET radiopharmaceuticals. Normal patterns are shown in Figure 2 for rubidium 82 and nitrogen 13 ammonia, and the PET normal databases are listed in Table 2. These have been validated clinically including the latest Rb-82 PET/computed tomography (CT) protocol.21
To quantify the perfusion/metabolism match/mismatch pattern as a
Three-Dimensional Displays
We use 3D graphics techniques to overlay results of perfusion quantification onto a representation of a specific patient’s left ventricle. This representation is generated by use of endocardial or epicardial surface points extracted from the perfusion data. Our approach for detecting the surface of the myocardium starts with the 3D coordinates of the maximal myocardial count samples created during perfusion quantification.23 The coordinates of each sampled point are filtered to remove noise. By
Summary
The inherently digital nuclear cardiology images coupled with the tremendous advances in computer hardware and software have facilitated our progress in total automatic analysis; multidimensional, multimodality display; quantification of all clinically relevant parameters; and computer-assisted decision support. Our Emory team has created ECTb as a pipeline to take advantage of this modern technology to bring to nuclear cardiology practitioners clinically validated tools to visualize and
Acknowledgment
The research that generated the science implemented in ECTb was funded in part by National Institutes of Health grants HL070422, HL068904, HL42052, and LM06726. Some of the authors receive royalties from the sale of ECTb (E.V.G., T.L.F., C.D.C., and R.D.F.) related to the research described in this article. The terms of this arrangement have been reviewed and approved by Emory University in accordance with its conflict-of-interest practice.
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