TY - JOUR
T1 - Effect of lung orientation on measurement and resolvability of airways using computed tomography
AU - Wood, Susan A.
AU - Meiyappan, S.
AU - Zerhouni, Elias A.
AU - Mitzner, Wayne
N1 - Funding Information:
The authors would like to thank Dr. Eric Hoffman for his continual support of this project and the use of the VIDA Image Analysis Software Package. Bea Mudge for her technical help with data acquisition and Dr. Thomas Beck for his advice regarding to the study and his review of the manuscript. This work was supported by grants from the National Institute of Environmental Health Sciences (ES 038 19) and the National Institutes of Health (HL 10342).
Publisher Copyright:
© 1995 SPIE. All rights reserved.
PY - 1995/5/24
Y1 - 1995/5/24
N2 - Volumetric data sets in the lung are formed by stacking sequential computed tomography (CT) slices. The resulting volumetric image file, however, is nonuniformly resolved; the in plane resolution is greater than that in the z-axis (slice thickness) dimension. The purpose of this study was to determine the effect of branch orientation within the image volume on the measurement and resolvability of airway branches. An isolated canine lobe was sequentially scanned at three orientations with a Siemens Somotom Plus S CT Scanner using a 124.4 mm field of view, 137 kVp, 220 mAs, a 2 mm slice thickness, and a 1 mm table feed. A grid size of 2562, resulted in an in plane pixel dimension of 0.49 mm. The lobe was inflated to an airway pressure of 20 cm H2O with the main bronchus of the lobe aligned approximately perpendicular to the scan plane. The entirety of the lobe was scanned at this orientation. The inflated lobe was then reoriented 90° clockwise (as if the lobe was sitting on a clock face) and again the entirety of the lobe was scanned. The lobe was rotated a third time 90° in plane from the first lobe alignment and again rescanned. Airway trees were segmented for each orientation and there were significant differences in the number of resolved branches among the three segmented trees. Measurement of airways over four millimeters in diameter was not affected by orientation. Airways smaller than two millimeters in diameter showed surprising similarity in measured diameter, but all airways were not resolved at all orientations. The angle of orientation of the individual airways with respect to the scan axis was therefore calculated to determine the angle at which a branch of given diameter was no longer resolved. There was surprising similarity of measured diameter in these smaller airways with orientation, if the branch was resolved. The orientation at which branches were resolved was quite variable, suggesting a high degree of randomness in the segmented branches at this level of branch resolution.
AB - Volumetric data sets in the lung are formed by stacking sequential computed tomography (CT) slices. The resulting volumetric image file, however, is nonuniformly resolved; the in plane resolution is greater than that in the z-axis (slice thickness) dimension. The purpose of this study was to determine the effect of branch orientation within the image volume on the measurement and resolvability of airway branches. An isolated canine lobe was sequentially scanned at three orientations with a Siemens Somotom Plus S CT Scanner using a 124.4 mm field of view, 137 kVp, 220 mAs, a 2 mm slice thickness, and a 1 mm table feed. A grid size of 2562, resulted in an in plane pixel dimension of 0.49 mm. The lobe was inflated to an airway pressure of 20 cm H2O with the main bronchus of the lobe aligned approximately perpendicular to the scan plane. The entirety of the lobe was scanned at this orientation. The inflated lobe was then reoriented 90° clockwise (as if the lobe was sitting on a clock face) and again the entirety of the lobe was scanned. The lobe was rotated a third time 90° in plane from the first lobe alignment and again rescanned. Airway trees were segmented for each orientation and there were significant differences in the number of resolved branches among the three segmented trees. Measurement of airways over four millimeters in diameter was not affected by orientation. Airways smaller than two millimeters in diameter showed surprising similarity in measured diameter, but all airways were not resolved at all orientations. The angle of orientation of the individual airways with respect to the scan axis was therefore calculated to determine the angle at which a branch of given diameter was no longer resolved. There was surprising similarity of measured diameter in these smaller airways with orientation, if the branch was resolved. The orientation at which branches were resolved was quite variable, suggesting a high degree of randomness in the segmented branches at this level of branch resolution.
KW - Airway reactivity
KW - Lung mechanics
KW - Lung morphology
KW - Lung morphometry
KW - Medical imaging
KW - Nonuniform scanner resolution
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U2 - 10.1117/12.209687
DO - 10.1117/12.209687
M3 - Conference article
AN - SCOPUS:85076758541
SN - 0277-786X
VL - 2433
SP - 149
EP - 157
JO - Proceedings of SPIE - The International Society for Optical Engineering
JF - Proceedings of SPIE - The International Society for Optical Engineering
T2 - Medical Imaging 1995: Physiology and Function from Multidimensional Images
Y2 - 26 February 1995 through 2 March 1995
ER -