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COPD is a progressive disease characterized by airflow obstruction or limitation. Emphysema is characterized by loss of elasticity of the lung tissue, destruction of structures supporting the alveoli and of capillaries feeding the alveoli. Both have symptoms that include shortness of breath, among other respiratory troubles. If you are a COPD or Emphysema sufferer, join...
Advanced Image Analysis Maps COPD Severity
A CT image processing technique quantifies the mix of small airway disease and emphysema, thus mapping the severity of chronic obstructive pulmonary disease (COPD), researchers found.
The technique, which relies on post-processing software to separate normal from diseased tissue, was able to quantify the extent of functional small airway disease (fSAD) separate from COPD, a distinction that cannot be made from conventional analysis of scans, wrote Brian D. Ross, PhD, of the University of Michigan in Ann Arbor, and colleagues.
The voxel-wise image analysis technique, called parametric response mapping (PRM), involves the use of inspiratory and expiratory CT scans, researchers reported online in Nature Medicine.
Pulmonary specialists have recognized fSAD and emphysema as principal components of COPD. Moreover, a spectrum of COPD phenotypes exists, reflecting varying contributions of SAD and emphysema. The ability to identify and diagnose individual COPD phenotypes might improvement management of patients affected by COPD, the authors noted in their introduction.
But researchers went a step further than merely identifying COPD phenotypes. This mapping technique provided objective, image-based evidence to support a long-held, but unproven, belief about COPD.
"We observed a pattern suggestive of COPD progression that, to our knowledge, has never been demonstrated by CT-based measures," namely that "SAD precedes emphysema in the progression of COPD," the authors wrote.
The technique relies on differences in voxel-distribution patterns, or PRM signatures, that change with progression of SAD and correlate with attenuation patterns on CT images.
CT has proven useful for evaluation of COPD, primarily from qualitative visual analysis. However, applications of quantitative techniques to CT data sets have been studied extensively in an effort to translate images into clinically useful representations of COPD structural abnormalities and disease severity.
An accepted method for determining the emphysema component of COPD is emphysema percentage, derived from an attenuation-based method that normalizes the sum of all image pixels less than -950 Hounsfield units (HUsby total lung volume on the CT inspiratory scan, the authors continued.
But emphysema percentage provides no information about SAD, a limitation of CT owing to the complex histopathology of COPD-affected lung tissue.
PRM is a voxel-based method initially developed by the authors to improve the sensitivity of diffusion MRI data for therapeutic response in glioma. The technique also has been validated as an early marker for survival in several types of cancer. Moreover, the authors have shown that PRM is a generalized method, not restricted to one type of image analysis.
For evaluation of CT scans in patients with COPD, Ross and colleagues modified PRM methods to take advantage of the approach strengths in pairwise analysis of inspiratory and expiratory CT scans.
As described in the article, the application of PRM to quantification of SAD separately from emphysema involves three steps: image acquisition, image processing (including segmentation and co-registration), and classification of voxels with HU values characteristic of normal and diseased lung parenchyma.
The resulting maps represent COPD phenotypes. In the image provided by the authors, for example, emphysema (red 16%) has progressed throughout the upper right lung, SAD (yellow 22%) is seen primarily in the upper left lung, with both lower lungs primarily healthy (green 54%) based on PRM.
The images used to develop maps were of a subset of 10,000 participants in a study of COPD genetics that required paired CT scans. The 194 patients included in the study by Ross and colleagues represented a wide spectrum of GOLD (Global Initiative for Chronic Obstructive Lung Disease) status.
"The ability of PRM to identify and track individual pixels from inspiratory and expiratory scans allows for the individual components of COPD to be quantified and monitored," the authors wrote of their findings.
"In addition, PRM provided unique information on the contribution of SAD and emphysema in a variety of clinical tests that have been identified as being prognostic of COPD."
The technique also has potential to be used in drug trials as a secondary biomarker of therapeutic effect, according to the investigators.
The study was supported by the National Institutes of Health.
By Charles Bankhead, Staff Writer, MedPage Today
Published: October 09, 2012
Reviewed by Robert Jasmer, MD; Associate Clinical Professor of Medicine, University of California, San Francisco
http://www.medpagetoday.com/Pulmonology/SmokingCOPD/35219
I think this is a very good thing and will be helpful for our treatment, and I thought some of you would be interested in reading about it.
Easy breathing to each of you,
Love Holly
A CT image processing technique quantifies the mix of small airway disease and emphysema, thus mapping the severity of chronic obstructive pulmonary disease (COPD), researchers found.
The technique, which relies on post-processing software to separate normal from diseased tissue, was able to quantify the extent of functional small airway disease (fSAD) separate from COPD, a distinction that cannot be made from conventional analysis of scans, wrote Brian D. Ross, PhD, of the University of Michigan in Ann Arbor, and colleagues.
The voxel-wise image analysis technique, called parametric response mapping (PRM), involves the use of inspiratory and expiratory CT scans, researchers reported online in Nature Medicine.
Pulmonary specialists have recognized fSAD and emphysema as principal components of COPD. Moreover, a spectrum of COPD phenotypes exists, reflecting varying contributions of SAD and emphysema. The ability to identify and diagnose individual COPD phenotypes might improvement management of patients affected by COPD, the authors noted in their introduction.
But researchers went a step further than merely identifying COPD phenotypes. This mapping technique provided objective, image-based evidence to support a long-held, but unproven, belief about COPD.
"We observed a pattern suggestive of COPD progression that, to our knowledge, has never been demonstrated by CT-based measures," namely that "SAD precedes emphysema in the progression of COPD," the authors wrote.
The technique relies on differences in voxel-distribution patterns, or PRM signatures, that change with progression of SAD and correlate with attenuation patterns on CT images.
CT has proven useful for evaluation of COPD, primarily from qualitative visual analysis. However, applications of quantitative techniques to CT data sets have been studied extensively in an effort to translate images into clinically useful representations of COPD structural abnormalities and disease severity.
An accepted method for determining the emphysema component of COPD is emphysema percentage, derived from an attenuation-based method that normalizes the sum of all image pixels less than -950 Hounsfield units (HUsby total lung volume on the CT inspiratory scan, the authors continued.
But emphysema percentage provides no information about SAD, a limitation of CT owing to the complex histopathology of COPD-affected lung tissue.
PRM is a voxel-based method initially developed by the authors to improve the sensitivity of diffusion MRI data for therapeutic response in glioma. The technique also has been validated as an early marker for survival in several types of cancer. Moreover, the authors have shown that PRM is a generalized method, not restricted to one type of image analysis.
For evaluation of CT scans in patients with COPD, Ross and colleagues modified PRM methods to take advantage of the approach strengths in pairwise analysis of inspiratory and expiratory CT scans.
As described in the article, the application of PRM to quantification of SAD separately from emphysema involves three steps: image acquisition, image processing (including segmentation and co-registration), and classification of voxels with HU values characteristic of normal and diseased lung parenchyma.
The resulting maps represent COPD phenotypes. In the image provided by the authors, for example, emphysema (red 16%) has progressed throughout the upper right lung, SAD (yellow 22%) is seen primarily in the upper left lung, with both lower lungs primarily healthy (green 54%) based on PRM.
The images used to develop maps were of a subset of 10,000 participants in a study of COPD genetics that required paired CT scans. The 194 patients included in the study by Ross and colleagues represented a wide spectrum of GOLD (Global Initiative for Chronic Obstructive Lung Disease) status.
"The ability of PRM to identify and track individual pixels from inspiratory and expiratory scans allows for the individual components of COPD to be quantified and monitored," the authors wrote of their findings.
"In addition, PRM provided unique information on the contribution of SAD and emphysema in a variety of clinical tests that have been identified as being prognostic of COPD."
The technique also has potential to be used in drug trials as a secondary biomarker of therapeutic effect, according to the investigators.
The study was supported by the National Institutes of Health.
By Charles Bankhead, Staff Writer, MedPage Today
Published: October 09, 2012
Reviewed by Robert Jasmer, MD; Associate Clinical Professor of Medicine, University of California, San Francisco
http://www.medpagetoday.com/Pulmonology/SmokingCOPD/35219
I think this is a very good thing and will be helpful for our treatment, and I thought some of you would be interested in reading about it.
Easy breathing to each of you,
Love Holly
kaput
The small airway disease is interesting. Maybe it's why I've been stable for so many years. Now if they can figure out why some people are more affected by this than others that would be very helpful. I guess they are saying genetics. Still waiting for that cure though:>) Debbie
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