Optimizing airway wall segmentation and quantification by reducing the influence of adjacent vessels and intravascular contrast material with a modified integral-based algorithm in quantitative computed tomography.

Philip Konietzke,Claus P Heussel,Juergen Biederer,Hans-Ulrich Kauczor,Willi L Wagner,Mark O Wielpütz,Christian Hintze,Oliver Weinheimer,Felix Wuennemann,Aleksandra Barac

doi:10.1371/journal.pone.0237939

Abstract

IntroductionQuantitative analysis of multi-detector computed tomography (MDCT) plays an increasingly important role in assessing airway disease. Depending on the algorithms used, airway dimensions may be over- or underestimated, primarily if contrast material was used. Therefore, we tested a modified integral-based method (IBM) to address this problem.MethodsTemporally resolved cine-MDCT was performed in seven ventilated pigs in breath-hold during iodinated contrast material (CM) infusion over 60s. Identical slices in non-enhanced (NE), pulmonary-arterial (PA), systemic-arterial (SA), and venous phase (VE) were subjected to an in-house software using a standard and a modified IBM. Total diameter (TD), lumen area (LA), wall area (WA), and wall thickness (WT) were measured for ten extra- and six intrapulmonary airways.ResultsThe modified IBM significantly reduced TD by 7.6%, LA by 12.7%, WA by 9.7%, and WT by 3.9% compared to standard IBM on non-enhanced CT (p<0.05). Using standard IBM, CM led to a decrease of all airway parameters compared to NE. For example, LA decreased from 80.85±49.26mm2 at NE, to 75.14±47.96mm2 (-7.1%) at PA (p<0.001), 74.96±48.55mm2 (-7.3%) at SA (p<0.001), and to 78.95±48.94mm2 (-2.4%) at VE (p = 0.200). Using modified IBM, the differences were reduced to -3.1% at PA, -2.9% at SA and -0.7% at VE (p<0.001; p<0.001; p = 1.000).ConclusionsThe modified IBM can optimize airway wall segmentation and reduce the influence of CM on quantitative CT. This allows a more precise measurement as well as potentially the comparison of enhanced with non-enhanced scans in inflammatory airway disease.

Highlights

Quantitative analysis of multi-detector computed tomography (MDCT) plays an increasingly important role in assessing airway disease
Quantitative airway analysis has drawn increasing interest as software tools allow the quantification of airway dimensions of the whole tracheobronchial tree based on thin-section MDCT
Bronchial wall remodeling was histopathologically described in lung diseases like asthma and chronic obstructive pulmonary disease (COPD) [8], showing corresponding changes in bronchial dimensions on MDCT such as airway dilatation and wall-thickening [9,10,11,12]

Summary

Methods

Resolved cine-MDCT was performed in seven ventilated pigs in breath-hold during iodinated contrast material (CM) infusion over 60s. All animal studies have been approved by the ethics committee of the Ministry of Agriculture, Environment and, Rural Areas in Kiel, Germany, and were performed in accordance with federal animal protection regulations. Animals were intubated in supine position, and total intravenous anesthesia was maintained throughout the experiment with the respiration being dependent solely on the mechanical ventilator. Central venous catheterization was performed with the catheter being placed in the superior vena cava. Physiologic parameters, such as blood pressure and heart rate, were monitored continuously. Mature, female domestic pigs (Hohenschulen Experimental Farm, Achterwehr, Germany) with a mean weight of 43 kg (range 40–45 kg) were scanned.

Results

Discussion

Conclusion