Computed Tomography Severity Grading of Chronic Obstructive Pulmonary Disease based on Volumetric Assessment of Inspiratory and Expiratory Scans

Shah, Omair; Choh, Naseer; Shera, Faiz; Gojwari, Tariq; Suhail, Jan; Shafi, Fahad; Jan, Rafi

Volume 6, Issue 4 (12-2020) Journal of Research in Applied and Basic Medical Sciences 2020, 6(4): 241-251 | Back to browse issues page

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Shah O, Choh N, Shera F, Gojwari T, Suhail J, Shafi F et al . Computed Tomography Severity Grading of Chronic Obstructive Pulmonary Disease based on Volumetric Assessment of Inspiratory and Expiratory Scans. Journal of Research in Applied and Basic Medical Sciences 2020; 6 (4) :241-251
URL: http://ijrabms.umsu.ac.ir/article-1-137-en.html

Computed Tomography Severity Grading of Chronic Obstructive Pulmonary Disease based on Volumetric Assessment of Inspiratory and Expiratory Scans

Omair Shah ^*

, Naseer Choh

, Faiz Shera

, Tariq Gojwari

, Jan Suhail

, Fahad Shafi

, Rafi Jan

sheri kashmir institute of medical sciences , shahomair133@gmail.com

Abstract: (1957 Views)

Background & Aims: To determine attenuation threshold for detection and quantification of air trapping in obstructive airway disease. Quantify airway dysfunction in patients of obstructive airway disease & its correlation with pulmonary function tests.
Materials & Methods: Paired HRCT scans of 48 patients were done and correlated with Pulmonary Function Tests taken within 2 weeks of the study. Threshold attenuation value on expiratory scan that signifies air trapping was obtained by correlating relative volumes with PFT parameters (PEF 25-75% & RV/TLC). The lung volumes at this threshold were then correlated with PFT values signifying airway dysfunction (FEV1, FEV1/FVC and PEF 25-75%) and airway dysfunction was then quantified based on these volumes.
Results: Maximum correlation of PFT parameters signifying air trapping is with relative volume of limited lung at -850HU (l850) (p<0.005) which was taken as the threshold for air trapping. Using this threshold (-850HU), we calculated the relative volume change of limited and whole lung (l850 & t850) and expiratory relative volume of limited and whole lung (ERV l850 & ERV t850). Significant correlation was seen between l850 and PFT parameters signifying airway dysfunction (p<0.005). A severity classification of obstructive airway disease was formulated based on l850 and classified patients into mild (l850<-30%), moderate (l850= -20 - -30%), severe (l850 =-10 - -20%), and very severe (l850 > -10%).
Conclusion: l850 can be used as a CT parameter to quantify airway dysfunction irrespective of presence or absence of emphysema. Severity classification of obstructive airway disease was formulated based on l850.

Keywords: FEV1 Forced Expiratory Volume in 1 sec, FVC Forced Vital Capacity, HRCT High-Resolution Computed Tomography, PEF25-75% Peak Expiratory Flow (25 – 75 %), PFT Pulmonary Function Test, RV Residual Volume

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