Image Processing Reference
In-Depth Information
CHAPTER 6
Rebuilding IVUS images from
raw data of the RF signal
exported by IVUS equipment
1
Department of Biomedical Engineering, DEB/
FEEC/UNICAMP, Campinas, Brazil
2
Federal Institute of Education, Science and Technology São Paulo—IFSP, Sao Paulo, Brazil
3
Division of Informatics/Heart Institute, HCFMUSP, Sao Paulo, Brazil
Abstract
The study of composition and classification of atherosclerotic plaque has been a very active research
ield, both in cardiology and image processing. Intravascular ultrasound (IVUS) is an effective tool,
which can insight on the cross-section of blood vessels, with sufficient accuracy to allow an accurate as-
sessment of computed tomography slices. This enables information about blood vessel structures to be
determined. During an IVUS medical examination, physicians subjectively adjust a set of parameters to
improve the visualization of a region of interest and produce corresponding images in Digital Imaging
and Communications format (DICOM Images), for later analysis and study. DICOM is appropriate for
storage, transportation, and access, but limits subsequent changes to image parameters, such as contrast
for brightness. This makes comparison across patient populations difficult and restricts image-process-
ing operations. This article details an alternative to using DICOM, which is to rebuild IVUS images from
raw radiofrequency (RF) signal data. The main advantage of this process is the independence of the ac-
quisition parameters adjusted during the exam. This advantage makes possible the comparison between
exams and can be used to monitor the evolution of cardiovascular disease. Beyond this, once the recon-
structed images and the RF signal are stored, operations relating to texture and spectral analysis can be
carried out and automatic classifiers employed. From a clinical point of view these reconstructed images
share the same characteristics as DICOM images with an advantage that the former have a higher con-
trast than the later, allowing deeper regions to be seen.
Keywords
RF signal
IVUS image
Rebuilding process
Ultrasound image
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