High spatiotemporal resolution measurement of regional lung air volumes from 2D phase contrast x‐ray images. Issue 4 (19th March 2013)

• Record Type: Journal Article
• Authors: Leong, Andrew F. T.; Fouras, Andreas; Islam, M. Sirajul; Wallace, Megan J.; Hooper, Stuart B.; Kitchen, Marcus J.
• Is Part Of: Medical physics. Volume 40:Issue 4(2013)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2013-03-19
• Subjects: X‐ray imaging -- Pneumodyamics, respiration -- Dosimetry/exposure assessment -- Numerical approximation and analysis -- Reconstruction -- Segmentation; diagnostic radiography -- diseases -- dosimetry -- image reconstruction -- image resolution -- image retrieval -- image segmentation -- image sequences -- injuries -- lung -- medical image processing -- numerical analysis -- paediatrics -- pneumodynamics -- ventilation; phase contrast x‐ray imaging -- regional lung volume -- image registration -- thoracic cage segmentation -- temporal subtraction; Heating; Ranges; Ventilating -- Ventilation -- Digital computing or data processing equipment or methods, specially adapted for specific applications -- Image data processing or generation, in general; Lungs -- Medical imaging -- X‐ray imaging -- Medical X‐ray imaging -- Image sensors -- Image registration -- Image analysis -- Time measurement -- Medical image contrast -- Phase retrieval; Medical physics -- Periodicals; Medical physics; Geneeskunde; Natuurkunde; Toepassingen; Biophysics; Periodicals; Periodicals; Electronic journals; 610.153
• DOI: 10.1118/1.4794926
• Languages: English
• ISSNs: 0094-2405

Abstract

Abstract : Purpose: : Described herein is a new technique for measuring regional lung air volumes from two‐dimensional propagation‐based phase contrast x‐ray (PBI) images at very high spatial and temporal resolution. Phase contrast dramatically increases lung visibility and the outlined volumetric reconstruction technique quantifies dynamic changes in respiratory function. These methods can be used for assessing pulmonary disease and injury and for optimizing mechanical ventilation techniques for preterm infants using animal models. Methods: : The volumetric reconstruction combines the algorithms of temporal subtraction and single image phase retrieval (SIPR) to isolate the image of the lungs from the thoracic cage in order to measure regional lung air volumes. The SIPR algorithm was used to recover the change in projected thickness of the lungs on a pixel‐by‐pixel basis (pixel dimensions ∼16.2 μm). The technique has been validated using numerical simulation and compared results of measuring regional lung air volumes with and without the use of temporal subtraction for removing the thoracic cage. To test this approach, a series of PBI images of newborn rabbit pups mechanically ventilated at different frequencies was employed. Results: : Regional lung air volumes measured from PBI images of newborn rabbit pups showed on average an improvement of at least 20% in 16% of pixels within the lungs in comparison to that measured without the use of temporal subtraction. The majority of pixels that showed an improvement was found to be in regions occupied by bone. Applying the volumetric technique to sequences of PBI images of newborn rabbit pups, it is shown that lung aeration at birth can be highly heterogeneous. Conclusions: : This paper presents an image segmentation technique based on temporal subtraction that has successfully been used to isolate the lungs from PBI chest images, allowing the change in lung air volume to be measured over regions as small as the pixel size. Using this technique, it is possible to measure changes in regional lung volume at high spatial and temporal resolution during breathing at much lower x‐ray dose than would be required using computed tomography.