1 / 36

QuantitaTive assesment by ct

QuantitaTive assesment by ct. PROF. DR. PINAR BALCI Dokuz Eylül University School of Medicine Department of Radiology. ASSESMENT IN COPD. COPD is currently the 12th leading cause of disability in the world and is predicted to be 5th by the year 2020

tariq
Download Presentation

QuantitaTive assesment by ct

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. QuantitaTive assesment by ct PROF. DR. PINAR BALCI Dokuz Eylül University School of Medicine Department of Radiology

  2. ASSESMENT IN COPD • COPD is currently the 12th leading cause of disability in the world and is predicted tobe 5th by the year 2020 • The annual cost of morbidity and earlymortality due to COPD is high • Smoking is the most important environmental risk factor • Prognosis varies individually • Emphysema + small airway disease

  3. COPD ASSESMENT by ct CT Why ? • Worldwide accessibility of CT scanning is available • Acquisition of lung images equivalent to anatomic evaluation non invasively • CT images themselves are densitometry maps of the lung *Any change in lung leads to image changes via dansitometry

  4. COPD ASSESMENT by cT Limitations • Disagreements on the best method to analyze the lung parenchyma • No definitive study using airway wall algorithms • Exposure of subjects to ionizing radiation • Use of improperly calibrated CT scanners

  5. COPD ASSESMENT by cT Target of assesment • Emphysema • Small airway disease • Rate andconribution of eachpathologystillunknown

  6. QCT Target of assesment • Emphysema • Regional distribution • Measurement of air-trapping in Small airway disease • Directly measuring the airway wall

  7. COPD ASSESMENT by cT • VOLUME • X-RAY ATTENUATION (EVALUATİON OF DENSITOMETRY)

  8. QCT HISTORY OF QCT • Gould first used QCT in lung *Modal CT attenuation value and the value of the fifthpercentile of the lung * This QCT indices correlated well with amorphometric index derived from pathologic sections of the lung • Subsequently,Müllerused the "density mask" program availableon GE CT scanners in the late 1980s to quantify the amount oflung tissue that measured less than –910 HU There is good correlation with both anatomic measures in QCT and pulmonary functionmeasures of emphysema

  9. QCT • Able to measure low density regions by means of histogram analyzis in evaluation of total capacity of lung • In evaluation of residual volume or functional residual capacity identifies regions corresponding airentrapment. • Detection of emphyzema is direct measurement of lungremodelling in COPD • Detection of airentrapment is equivalent of indirect measurement of small air ways. OVERLAPPİNG...?

  10. qct • No universally acceptable QCT method in COPD • 2001 and 2008 workshops : Recomendations for COPD researchers Newell JD Jr, Hogg JC, Snider GL. Report of a workshop: quantitative computed tomography scanning in longitudinal studies of emphysema. EurRespir J. 2004 May;23(5):769-75. Coxson HO. Proc Am Thorac Soc 2008 (5);874–877

  11. qct TECHNICAL CONSIDERATIONS .1 CT : MDCT CT phantoms: Lung, water, soft tissue and bone simulations made of inorganic materials Image acquisition parameters: For optimisation of image quality with minimal radiation exposure CT scanner make and model, CT scanner calibrationusing CT phantoms, image acquisition parameters, image reconstructionparameters, lung volume at acquisition, intravenous contrastmedia, quantitative image analysis method(s), CT radiation dose,CT data handling, and CT image processing

  12. qct TECHNICAL CONSIDERATIONS .2 • Lung volume in acquisition of images maximum inspiratory effort Optional: Respiratory gating; expiratory or paired inspiratory/ expiratory images • IV contrast media should not be administered • Optimal HU thresholds -950 HU 1-mm sections -910 HU 5-7 mm sections • Window settings (WW 1000 HU, WL -700 HU) • Radiation dose low dose technics • CT data management • CT data post-processing

  13. qct TECHNICAL CONSIDERATIONS .3 Standard Quantitative Methodology Density mask Histogram analysis (lowest 15th percentile)Mean lung density (volumetric evaluation) Miscellaneous Techniques Minimum-intensity and maximum-intensity projection images (MinIP and MIP)

  14. qct In assesment of frequency distribution or histogram of lung densities, although the lowest 5th percentile reflects parenchimal density better and well-correlated with respiratory function tests Hayhurst MD. Lancet 1984;2:320–322. Gould GA. Am Rev Respir Dis 1988; 137:380. Heremans A. Chest 1992; 102:805. 2008 the Alpha-1 Foundation sponsored a workshop resulted in recommendations in using lowest 15th percentile point of lung density

  15. COPD ASSESMENT by cT Visual assesment • CT images: The simpliest assesment *Normal, 25% lung involvement by emphysema, between 25% and 50% , between 50% and 75%, or greater than 75% involvement, with the total score expressed as percentage of total lung at that level • In general, visual inspection has yielded good correlations between CT and pathological measures of the extent and severity in all but the mildest cases • Visual assessment may lead to an overestimation of the extent of disease.Accuracy of CT densitometry is higher • As an alternate to routine visual inspection: Minimum-intensity projection (MinIP) is more sensitive (%62- %81) Spouge D, Mayo JR, Cardoso W, et al.J Comput Assist Tomogr 1993;17:710–713 Gevenois PA, Yernault JC. Eur Respir J 1995;8:843–848 Remy-Jardin M, Remy J, Gosselin B, et al. Radiology 1996;200:665–671

  16. COPD ASSESMENT by cT Density mask It would be possible to disthinguish lung regions (voxel) lower than certain threshold by means of this method

  17. qct Inspiratory and Expiratory Scanning Several controversies Inspiratory /paired inspiratory-expiratory imaging • Measurements of lung attenuation obtained at inspiration and visual score better reflect abnormal results of pulmonary function tests in patients with less severe chronic obstructive pulmonary disease than do measurements obtained at expiration • Measurements of lung attenuation obtained at expiration better reflect pulmonary function abnormalities in patients with severe chronic obstructive pulmonary disease. Akira M. AJR 2009;192:262-277

  18. COPD ASSESMENT by cT Assessment of Airway Wall • Not standardized • CT scanner with a minimum of 64 detectors • The first and • Obvious limitation is the resolution of the CT scanner *Pixel size 0.5 mm *The airways that are responsible for airflow limitation are below the resolution of the CT scanner • Three-dimensional algorithms are still insufficient • There are now many airways to asses • Parameters affecting assesment ?

  19. qct There are three basic steps in the image processing • The first step is to load a large three-dimensionalCT image dataset of the lungs on a specific patient • Thenext step is to use the image processing software to extractthe lungs from the rest of the cervical, thoracic, and upperabdominal anatomy, a process referred to as image segmentation. This image segmentation process is best accomplished with semiautomaticor fully automatic methods • The third step is to analyzethe lung image data using histogram-type statistical methods.More advanced texture processing can be done as a fourth stepif required • The next step in the image processing of emphysema is to lookat the distribution and types of emphysema present. There arereports of successfully quantitating the cranio-caudal distributionof emphysema in the lungs

  20. COPD ASSESMENT by cTCLINICAL APPLICATIONS • HRCT is of particular value in the diagnosis of emphysema when other diseases are suspected clinically • Preoperative and postoperative evaluation of emphysema *Bullectomy * Lung Transplantation * Lung Volume Reduction Surgery • Phenotyping of Chronic Obstructive Pulmonary Disease in diagnosis and follow up • The association between emphysema and lung cancer has been recently re-examined in the context of low-dose lung cancer screening with conflicting results

  21. COPD ASSESMENT by cTCLINICAL APPLICATIONS Bullectomy • It’s correlated CT quantification of bullae volume with improvement in respiratory function and showed good correlation between the size of bullae and the probability of improved postoperative lung function Mineo TC. J Thorac Cardiovasc Surg. 2007 Dec;134(6):1491-7

  22. COPD ASSESMENT by cTCLINICAL APPLICATIONS Lung Volume Reduction Surgery • QCT is the most successful method of reflecting morphologic alterations, severity and extention of emphysema Bae KT. Radiology 1997;1997:705–714 Becker. Am J Respir Crit Care Med 1998;157:1593–1599. Gierada DS.Radiology 1997;205:235–242. Gierada DS Chest 2000;117:991–998

  23. COPD ASSESMENT by cTCLINICAL APPLICATIONS Lung Volume Reduction Surgery • QCT is the most successful method in identification of lung volume to be removed, preoperatively Gilbert S. . Acad Radiol 2006;13:1379–1386

  24. COPD ASSESMENT by cTCLINICAL APPLICATIONS Lung Volume Reduction Surgery • Patient with large upper lobe lesions respond better to LVRS than patients with small uniformly distributed disease • LVRS is more successful in cases dominant findings peripherally with respect to cases showing remarkable findings centrally Coxson HO. Thorax 2003;58:510–514. Nakano Y. Am J Respir Crit Care Med 2001;164:2195–2199

  25. COPD ASSESMENT by cT Recommendations from workshop 2008. 1 • Quantitative CT scanning will provide useful data concerninglung structure that is responsible for changes in lung function that define COPD • These structural data are extremely important in understanding both pathogenesisand the effect of therapeutic interventions • Either the threshold cutoffanalyzis or the percentile point analyzisprovides useful information about the extent of emphysema • the volume measurements are strongly recommended notonly for correction of the density data but for studiesthatrequireinformationabout lung orlober volume changes Alpha-1 Foundation workshop

  26. COPD ASSESMENT by cTCLINICAL APPLICATIONS Recommendations from workshop 2008. 2 • There is no strict recommendation for airway analysis • The X-ray doseshould be kept as low as possible in all studies • The CT scanner must be treated just like all measuringdevices, and be properly calibrated and used withoutchanging the features of the measuring device . A simple change in the X-ray dose or the reconstruction algorithm for the images have a greatpotentialproducinghuge changes in theextent of emphysema being measured Alpha-1 Foundation workshop

  27. THANK YOU

More Related