A multiscale MDCT image-based breathing lung model with time-varying regional ventilation

Abstract

A novel algorithm is presented that links local structural variables (regional ventilation and deforming central airways) to global function (total lung volume) in the lung over three imaged lung volumes, to derive a breathing lung model for computational fluid dynamics simulation. The algorithm constitutes the core of an integrative, image-based computational framework for subject-specific simulation of the breathing lung. For the first time, the algorithm is applied to three multi-detector row computed tomography (MDCT) volumetric lung images of the same individual. A key technique in linking global and local variables over multiple images is an in-house mass-preserving image registration method. Throughout breathing cycles, cubic interpolation is employed to ensure C1 continuity in constructing time-varying regional ventilation at the whole lung level, flow rate fractions exiting the terminal airways, and airway deformation. The imaged exit airway flow rate fractions are derived from regional ventilation with the aid of a three-dimensional (3D) and one-dimensional (1D) coupled airway tree that connects the airways to the alveolar tissue. An in-house parallel large-eddy simulation (LES) technique is adopted to capture turbulent-transitional-laminar flows in both normal and deep breathing conditions. The results obtained by the proposed algorithm when using three lung volume images are compared with those using only one or two volume images. The three-volume-based lung model produces physiologically-consistent time-varying pressure and ventilation distribution. The one-volume-based lung model under-predicts pressure drop and yields un-physiological lobar ventilation. The two-volume-based model can account for airway deformation and non-uniform regional ventilation to some extent, but does not capture the non-linear features of the lung.

640-slice DVCT multi-dimensionally and dynamically presents changes in bladder volume and urine flow rate

“…For example, when volumetric imaging of the bladder and urethra is conducted, dynamic volume images of the bladder and urethra are continuously captured by 640-slice MDCT during urination, and measurements of the bladder and urethra are made at the early, early to middle, middle, middle to late, and late phases by division of the images according to time point, and collected for statistical analysis. Previous studies have reported the use of DVCT for imaging of the osteo-odonto-keratoprosthesis lamina, acute chest pain or calcified coronary atherosclerotic plaque and airway deformation (17)(18)(19)(20). Therefore, in the present study, DVCT technology was applied to predict the bladder volume and urine flow rate of patients.…”

Tissue-Engineered Tracheal Replacement in a Child: A 4-Year Follow-Up Study

“…Cross‐sectional area of the trachea was calculated following methods previously described 7. Tracheal airflow was calculated using a validated method through computational fluid dynamics 8, 9.…”

Numerical assessment of airflow and inhaled particles attributes in obstructed pulmonary system

“…Furthermore, authors in [17] introduced a technique to build a multiscale breathing lung model from multidetector computer tomography (MDCT) volumetric data sets acquired at different inflation levels. Additional efforts towards modeling of airway structure (conducting airways), lung function (regional ventilation and boundary conditions), and flow characteristics (modeling of turbulent flow and its effect on particle transport) have been presented by [18].…”