scholarly journals Synchrotron-based dynamic computed tomography of tissue motion for regional lung function measurement

2012 ◽  
Vol 9 (74) ◽  
pp. 2213-2224 ◽  
Author(s):  
Stephen Dubsky ◽  
Stuart B. Hooper ◽  
Karen K. W. Siu ◽  
Andreas Fouras
Keyword(s):  
Computed Tomography ◽  
Lung Function ◽  
Ct Scanning ◽  
Bronchial Tree ◽  
Dynamic Computed Tomography ◽  
Lung Inflation ◽  
Regional Dynamics ◽  
Lung Expansion ◽  
Regional Lung

During breathing, lung inflation is a dynamic process involving a balance of mechanical factors, including trans-pulmonary pressure gradients, tissue compliance and airway resistance. Current techniques lack the capacity for dynamic measurement of ventilation in vivo at sufficient spatial and temporal resolution to allow the spatio-temporal patterns of ventilation to be precisely defined. As a result, little is known of the regional dynamics of lung inflation, in either health or disease. Using fast synchrotron-based imaging (up to 60 frames s −1 ), we have combined dynamic computed tomography (CT) with cross-correlation velocimetry to measure regional time constants and expansion within the mammalian lung in vivo . Additionally, our new technique provides estimation of the airflow distribution throughout the bronchial tree during the ventilation cycle. Measurements of lung expansion and airflow in mice and rabbit pups are shown to agree with independent measures. The ability to measure lung function at a regional level will provide invaluable information for studies into normal and pathological lung dynamics, and may provide new pathways for diagnosis of regional lung diseases. Although proof-of-concept data were acquired on a synchrotron, the methodology developed potentially lends itself to clinical CT scanning and therefore offers translational research opportunities.

Effect of body orientation on regional lung expansion: a computed tomographic approach

1985 ◽  
Vol 59 (2) ◽  
pp. 468-480 ◽  
Author(s):  
E. A. Hoffman
Keyword(s):  
Gravitational Effect ◽  
Body Posture ◽  
Lung Inflation ◽  
Computed Tomographic ◽  
Air Content ◽  
Lung Expansion ◽  
Regional Lung ◽  
Residual Capacity ◽  
Potato Flakes

The Dynamic Spatial Reconstructor (DSR) was used to study in vivo lung geometry and function. By replacing the lungs of three dogs with potato flakes and ping-pong balls of known air content and scanning these realistic phantoms in the DSR we have estimated accuracy of lung density to be within 7% and have demonstrated a high (+/- 3%) internal consistency (relative density within dogs). Change in total lung air content (y) as calculated from DSR volume imaging of anesthetized dogs matched the known inflation steps (x) to within 7% [range was 1–7% with a mean of 3 +/- 0.5% (SE)]. A gradient of decreasing percent lung air content was measured in the ventral-dorsal direction at functional residual capacity (FRC) in the supine body posture (y = 3.29% air content/cm lung height + 46.48% air content; r = 0.90). Regional lung air content change with lung inflation was greatest in the dependent lung regions. In contrast, regional lung air content at FRC was approximately uniform along the ventral-dorsal direction with the dog in the prone posture and was 66 +/- 0.6% (SE). Ventral-dorsal gradients in lung air content measured within an isogravimetric plane of the dogs in the left or right lateral body posture suggest that regional differences in lung air content cannot be explained solely on the basis of a direct gravitational effect on the lung. Evidence is presented to suggest a possible major role of the intrathoracic position of the mediastinal contents in determining these lung air content distributions.

scholarly journals Real-time in vivo imaging of regional lung function in a mouse model of cystic fibrosis on a laboratory X-ray source

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Rhiannon P. Murrie ◽  
Freda Werdiger ◽  
Martin Donnelley ◽  
Yu-wei Lin ◽  
Richard P. Carnibella ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Lung Function ◽  
Mouse Model ◽  
Real Time ◽  
In Vivo Imaging ◽  
X Ray ◽  
Regional Lung Function ◽  
Regional Lung

scholarly journals In Vivo Computed Tomography as a Research Tool to Investigate Asthma and COPD: Where Do We Stand?

2012 ◽  
Vol 2012 ◽  
pp. 1-11 ◽  
Author(s):  
Gaël Dournes ◽  
Michel Montaudon ◽  
Patrick Berger ◽  
François Laurent
Keyword(s):  
Computed Tomography ◽  
Quantitative Research ◽  
Three Dimensional ◽  
Lung Parenchyma ◽  
Airway Disease ◽  
Bronchial Tree ◽  
Research Tool ◽  
Airway Wall ◽  
Clinical Tool

Computed tomography (CT) is a clinical tool widely used to assess and followup asthma and chonic obstructive pulmonary disease (COPD) in humans. Strong efforts have been made the last decade to improve this technique as a quantitative research tool. Using semiautomatic softwares, quantification of airway wall thickness, lumen area, and bronchial wall density are available from large to intermediate conductive airways. Skeletonization of the bronchial tree can be built to assess its three-dimensional geometry. Lung parenchyma density can be analysed as a surrogate of small airway disease and emphysema. Since resident cells involve airway wall and lung parenchyma abnormalities, CT provides an accurate and reliable research tool to assess their role in vivo. This litterature review highlights the most recent advances made to assess asthma and COPD with CT, and also their drawbacks and the place of CT in clarifying the complex physiopathology of both diseases.

Measurement of lung expansion with computed tomography and comparison with quantitative histology

1995 ◽  
Vol 79 (5) ◽  
pp. 1525-1530 ◽  
Author(s):  
H. O. Coxson ◽  
J. R. Mayo ◽  
H. Behzad ◽  
B. J. Moore ◽  
L. M. Verburgt ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Pressure Gradient ◽  
Pleural Pressure ◽  
Lung Volumes ◽  
Quantitative Histology ◽  
Volume Curve ◽  
Pressure Volume Curve ◽  
Lung Structure ◽  
Lung Expansion ◽  
Regional Lung

The total and regional lung volumes were estimated from computed tomography (CT), and the pleural pressure gradient was determined by using the milliliters of gas per gram of tissue estimated from the X-ray attenuation values and the pressure-volume curve of the lung. The data show that CT accurately estimated the volume of the resected lobe but overestimated its weight by 24 +/- 19%. The volume of gas per gram of tissue was less in the gravity-dependent regions due to a pleural pressure gradient of 0.24 +/- 0.08 cmH2O/cm of descent in the thorax. The proportion of tissue to air obtained with CT was similar to that obtained by quantitative histology. We conclude that the CT scan can be used to estimate total and regional lung volumes and that measurements of the proportions of tissue and air within the thorax by CT can be used in conjunction with quantitative histology to evaluate lung structure.

Lung weight in vivo measured with computed tomography and rebreathing of soluble gases

1989 ◽  
Vol 67 (1) ◽  
pp. 166-173 ◽  
Author(s):  
R. W. Hyde ◽  
J. C. Wandtke ◽  
P. J. Fahey ◽  
M. J. Utell ◽  
D. B. Plewes ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Mass Density ◽  
Ct Scanning ◽  
Beam Hardening ◽  
Lung Weight ◽  
Total Lung Volume ◽  
Serial Measurement ◽  
Residual Capacity ◽  
Ct Density

In nine anesthetized dogs, accuracy of noninvasive measurements of lung weight (W) and gas volume in vivo was determined from volume and density determined by computed tomography (CT) and by rebreathing helium and the soluble gases dimethyl ether (WDME) and acetylene (WC2H2). Reference standards were obtained from the postmortem scale weight of the frozen lungs (Wscale) and compared with the CT lung weights measured in the living dog (WCT-38) and the frozen carcass (WCT-cold). WCT-cold did not significantly differ from Wscale [-2 +/- 9% (SD), P = 0.7]. WCT-cold was 10% greater than WCT-38 (0.10 greater than P greater than 0.05), suggesting an increase in lung weight despite immediately commencing freezing after death. WDME measured 64 +/- 6% and WC2H2 56 +/- 12% of WCT-38. Serial multiple measurements in three dogs over 14 wk showed a coefficient of variation (CV) of 10 +/- 2% for WDME, 18 +/- 2% for WC2H2, 4.1 +/- 0.9% for WCT, 2.6 +/- 0.8% for CT density, and 3.5 +/- 1.6% for functional residual capacity (FRC) by CT. FRC calculated from CT consistently underestimated FRC measured by rebreathing helium by 18 +/- 8% (P less than 0.005). This error, despite good agreement between WCT and Wscale, was explained by underestimation of CT total lung volume and overestimation of lung density by factors known to affect CT readings, such as partial volume effects, beam hardening, and limited number of input signals. These data show that CT scanning can provide serial measurement of the mass, density, and volume of the lungs with a CV in the order of 5%, but the rebreathing of soluble gases gives more than double this variability. Measurements of WDME performed on the same day had a CV of 3 +/- 1%, so that WDME provides a precise noninvasive means to measure lung weight in acute studies.

Lung function, surfactant apoprotein content, and level of PEEP in prematurely delivered rabbits

1994 ◽  
Vol 77 (4) ◽  
pp. 1840-1849 ◽  
Author(s):  
A. Ogawa ◽  
C. L. Brown ◽  
M. A. Schlueter ◽  
B. J. Benson ◽  
J. A. Clements ◽  
...  
Keyword(s):  
Lung Function ◽  
Protein Interactions ◽  
Static Pressure ◽  
Lung Compliance ◽  
Assisted Ventilation ◽  
Protein Protein Interactions ◽  
Lung Expansion ◽  
Surfactant Composition ◽  
Surfactant Apoprotein

To study the in vivo activity of the surfactant apoproteins (SP-A, SP-B, SP-C), we administered surfactants with defined apoprotein compositions to prematurely delivered rabbit pups. Rabbits given simple phospholipid mixtures containing dipalmitoylphosphatidylcholine and phosphatidylglycerol supplemented with both SP-B and SP-C or either protein alone had significantly greater lung compliance during ventilation and lung expansion during a quasi-static pressure-volume maneuver than did saline-or lipid-treated controls. The response to the surfactants containing SP-B/C was markedly dependent on the level of end-expiratory pressure used during ventilation. When the rabbits were ventilated with a positive end-expiratory pressure (PEEP) of 4 cmH2O, lung function in the pups treated with SP-B/C was not significantly different from rabbit surfactant-treated controls. Addition of SP-A to the surfactants containing SP-B/C did not significantly further improve lung function if the pups were ventilated with a PEEP of 4 cmH2O. With a lower PEEP of 1 cmH2O, lung function in the pups given surfactants containing SP-B/C was no longer equivalent to the lung function of the rabbit surfactant-treated controls. At the lower PEEP, SP-A significantly improved lung function when it was added to surfactants containing SP-B and SP-C. No beneficial effect of SP-A was seen when the surfactant contained either SP-B or SP-C alone. We conclude that with assisted ventilation that includes a moderate level of PEEP, SP-B and SP-C significantly enhance the effect of a simple phospholipid mixture on the lung function of prematurely delivered rabbits. At lower levels of PEEP the effects of SP-B and SP-C on lung function are markedly reduced but can be restored by the addition of SP-A. Our results are consistent with the existence of cooperative protein-protein interactions in surfactant function in vivo and suggest that the response to a surfactant will be determined by both the ventilation strategy and the surfactant composition. composition.

Prototypical metal/polymer hybrid cerebral aneurysm clip: in vitro testing for closing force, slippage, and computed tomography artifact

2007 ◽  
Vol 107 (6) ◽  
pp. 1198-1204 ◽  
Author(s):  
Alexander C. Mamourian ◽  
Namrata Mahadevan ◽  
Nischala Reddy ◽  
Steven P. Marra ◽  
John Weaver
Keyword(s):  
Computed Tomography ◽  
Mechanical Properties ◽  
Cerebral Aneurysm ◽  
Ct Scanning ◽  
Cobalt Chromium ◽  
Aneurysm Clip ◽  
Closing Force ◽  
Set Up

Object The aim of this study was to explore the possibility that a hybrid aneurysm clip with polymeric jaws bonded to a metal spring could provide mechanical properties comparable to those of an all-metal clip as well as diminished artifacts on computed tomography (CT) scanning. Methods Three clips were created, and Clips 1 and 2 were tested for mechanical properties. Clip 1 consisted of an Elgiloy spring (a cobalt-chromium-nickel alloy) bonded to carbon fiber limbs; Clip 2 consisted of an Elgiloy spring with polymethylmethacrylate (PMMA) jaws; and Clip 3 consisted of PMMA limbs identical to those in Clip 2 but bonded to a titanium spring. Custom testing equipment was set up to measure the aneurysm clip clamping forces and slippage. Clips 2 and 3 were visualized in vivo using a 64-slice CT unit, and the slices were reformatted into 3D images. Results According to the testing apparatus, Clip 2 had a similar closing force but less slippage than three similar commercial aneurysm clips. The artifact from the cobalt alloy spring on CT scanning largely offset the advantage of the nonmetal PMMA limbs, which created no artifact. The hybrid titanium/PMMA clip (Clip 3) created very little artifact on CT and allowed visualization of the phantom through the limbs. Conclusions It is feasible to build a potentially biocompatible hybrid cerebral aneurysm clip with mechanical properties that closely resemble those of conventional metallic clips. Further testing should be directed toward establishing the reliability and biocompatibility of such a clip and optimizing the contour and surface treatments of the polymer limbs.

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