Global Inhomogeneity Index Evaluation of a DCT-based EIT Lung Imaging

Rongqing Chen,Knut Möller

doi:10.1515/cdbme-2020-3010

Abstract

Abstract Purpose: To evaluate a novel structural-functional DCT-based EIT lung imaging method against the classical EIT reconstruction. Method: Taken retrospectively from a former study, EIT data was evaluated using both reconstruction methods. For different phases of ventilation, EIT images are analyzed with respect to the global inhomogeneity (GI) index for comparison. Results: A significant less variant GI index was observed in the DCTbased method, compared to the index from classical method. Conclusion: The DCT-based method generates more accurate lung contour yet decreasing the essential information in the image which affects the GI index. These preliminary results must be consolidated with more patient data in different breathing states.

Highlights

IntroductionElectrical Impedance Tomography (EIT) is a feasible noninvasive imaging method with great capability to visualise the regional ventilation distribution of lungs to assist clinician in adjusting proper PEEP levels for patients under mechanical ventilation [1], and further to avoid ventilator induced lung injury [2,3]
Electrical Impedance Tomography (EIT) is a feasible noninvasive imaging method with great capability to visualise the regional ventilation distribution of lungs to assist clinician in adjusting proper PEEP levels for patients under mechanical ventilation [1], and further to avoid ventilator induced lung injury [2,3].the spatial resolution of EIT is low, yet temporal resolution higher than traditional morphological imaging methods, such as computed tomography (CT)
Our team have previous combined imaging modalities of CT and EIT to roughly restrict EIT image to CT generated anatomy [4]. This DCT-based EIT approach includes detailed prior information about both the thorax contour and lung shape obtained from the discrete cosine transformation (DCT) of the CT image, which as a side effect is resulting in improved interpretability for clinicians

Summary

Introduction

Electrical Impedance Tomography (EIT) is a feasible noninvasive imaging method with great capability to visualise the regional ventilation distribution of lungs to assist clinician in adjusting proper PEEP levels for patients under mechanical ventilation [1], and further to avoid ventilator induced lung injury [2,3]. Our team have previous combined imaging modalities of CT and EIT to roughly restrict EIT image to CT generated anatomy [4]. This DCT-based EIT approach includes detailed prior information about both the thorax contour and lung shape obtained from the discrete cosine transformation (DCT) of the CT image, which as a side effect is resulting in improved interpretability for clinicians. In a first step Global Inhomogeneity (GI) index is used for comparison, which indicates the difference of the volume distribution within a ventilation period [5]

Classical EIT Reconstruction

DCT-based EIT Reconstruction

Global Inhomogeneity Index

Discussion

Findings

Conclusion