Variation of densitometry on computed tomography in COPD--influence of different software tools.
OBJECTIVE
Quantitative multidetector computed tomography (MDCT) as a potential biomarker is increasingly used for severity assessment of emphysema in chronic obstructive pulmonary disease (COPD). Aim of this study was to evaluate the user-independent measurement variability between five different fully-automatic densitometry software tools.


METHODS
MDCT and full-body plethysmography incl. forced expiratory volume in 1s and total lung capacity were available for 49 patients with advanced COPD (age = 64±9 years, forced expiratory volume in 1 s = 31±6% predicted). Measurement variation regarding lung volume, emphysema volume, emphysema index, and mean lung density was evaluated for two scientific and three commercially available lung densitometry software tools designed to analyze MDCT from different scanner types.


RESULTS
One scientific tool and one commercial tool failed to process most or all datasets, respectively, and were excluded. One scientific and another commercial tool analyzed 49, the remaining commercial tool 30 datasets. Lung volume, emphysema volume, emphysema index and mean lung density were significantly different amongst these three tools (p<0.001). Limits of agreement for lung volume were [-0.195, -0.052 l], [-0.305, -0.131 l], and [-0.123, -0.052 l] with correlation coefficients of r = 1.00 each. Limits of agreement for emphysema index were [-6.2, 2.9%], [-27.0, 16.9%], and [-25.5, 18.8%], with r = 0.79 to 0.98. Correlation of lung volume with total lung capacity was good to excellent (r = 0.77 to 0.91, p<0.001), but segmented lung volume (6.7±1.3-6.8±1.3 l) were significantly lower than total lung capacity (7.7±1.7 l, p<0.001).


CONCLUSIONS
Technical incompatibilities hindered evaluation of two of five tools. The remaining three showed significant measurement variation for emphysema, hampering quantitative MDCT as a biomarker in COPD. Follow-up studies should currently use identical software, and standardization efforts should encompass software as well.
Department of Diagnostic and Interventional Radiology, University Hospital of Heidelberg, Heidelberg, Germany; Translational Lung Research Center Heidelberg (TLRC), Member of the German Center for Lung Research (DZL), Heidelberg, Germany; Department of Diagnostic and Interventional Radiology with Nuclear Medicine, Thoraxklinik at University of Heidelberg, Heidelberg, Germany; Department of Radiology, German Cancer Research Center (dkfz), Heidelberg, Germany.
Mark O
MO
Wielpütz
Department of Diagnostic and Interventional Radiology, University Hospital of Heidelberg, Heidelberg, Germany; Translational Lung Research Center Heidelberg (TLRC), Member of the German Center for Lung Research (DZL), Heidelberg, Germany; Department of Diagnostic and Interventional Radiology with Nuclear Medicine, Thoraxklinik at University of Heidelberg, Heidelberg, Germany.
Diana
D
Bardarova
Department of Diagnostic and Interventional Radiology, University Hospital of Heidelberg, Heidelberg, Germany; Translational Lung Research Center Heidelberg (TLRC), Member of the German Center for Lung Research (DZL), Heidelberg, Germany.
Oliver
O
Weinheimer
Department of Diagnostic and Interventional Radiology, University Hospital of Heidelberg, Heidelberg, Germany; Translational Lung Research Center Heidelberg (TLRC), Member of the German Center for Lung Research (DZL), Heidelberg, Germany; Department of Diagnostic and Interventional Radiology with Nuclear Medicine, Thoraxklinik at University of Heidelberg, Heidelberg, Germany.
Hans-Ulrich
HU
Kauczor
Department of Diagnostic and Interventional Radiology, University Hospital of Heidelberg, Heidelberg, Germany; Translational Lung Research Center Heidelberg (TLRC), Member of the German Center for Lung Research (DZL), Heidelberg, Germany; Department of Diagnostic and Interventional Radiology with Nuclear Medicine, Thoraxklinik at University of Heidelberg, Heidelberg, Germany.
Monika
M
Eichinger
Department of Diagnostic and Interventional Radiology, University Hospital of Heidelberg, Heidelberg, Germany; Translational Lung Research Center Heidelberg (TLRC), Member of the German Center for Lung Research (DZL), Heidelberg, Germany; Department of Diagnostic and Interventional Radiology with Nuclear Medicine, Thoraxklinik at University of Heidelberg, Heidelberg, Germany.
Bertram J
BJ
Jobst
Department of Pneumology and Respiratory Critical Care Medicine, Thoraxklinik at University of Heidelberg, Heidelberg, Germany.
Ralf
R
Eberhardt
Department of Diagnostic and Interventional Radiology, University Hospital of Heidelberg, Heidelberg, Germany; Translational Lung Research Center Heidelberg (TLRC), Member of the German Center for Lung Research (DZL), Heidelberg, Germany; Department of Diagnostic and Interventional Radiology with Nuclear Medicine, Thoraxklinik at University of Heidelberg, Heidelberg, Germany; Department of Radiology, German Cancer Research Center (dkfz), Heidelberg, Germany.
Marcel
M
Koenigkam-Santos
Department of Diagnostic and Interventional Radiology, University Hospital of Heidelberg, Heidelberg, Germany; Translational Lung Research Center Heidelberg (TLRC), Member of the German Center for Lung Research (DZL), Heidelberg, Germany; Department of Diagnostic and Interventional Radiology with Nuclear Medicine, Thoraxklinik at University of Heidelberg, Heidelberg, Germany; Department of Radiology, German Cancer Research Center (dkfz), Heidelberg, Germany.
Michael
M
Puderbach
Department of Diagnostic and Interventional Radiology, University Hospital of Heidelberg, Heidelberg, Germany; Translational Lung Research Center Heidelberg (TLRC), Member of the German Center for Lung Research (DZL), Heidelberg, Germany; Department of Diagnostic and Interventional Radiology with Nuclear Medicine, Thoraxklinik at University of Heidelberg, Heidelberg, Germany.
Claus P
CP
Heussel
D000368:Aged; D003720:Densitometry / Q000379:methods; D004646:Emphysema / Q000503:physiopathology; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008176:Lung Volume Measurements; D008297:Male; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000503:physiopathology*; D012129:Respiratory Function Tests; D012189:Retrospective Studies; D012984:Software; D014057:Tomography, X-Ray Computed / Q000379:methods*