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Measurement of the internal diameter of plastic tubes from projection MR images using a model-based least-squares fit approach
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10.1118/1.2194427
/content/aapm/journal/medphys/33/6/10.1118/1.2194427
http://aip.metastore.ingenta.com/content/aapm/journal/medphys/33/6/10.1118/1.2194427

Figures

Image of FIG. 1.
FIG. 1.

Representative hyperpolarized MR image of the human airway tree.

Image of FIG. 2.
FIG. 2.

Schematic of model-based algorithm for measuring tube diameters; (A) the selected tube section has a pixel intensity profile; (B) circles with diameters ranging from 70% to 130% of initial diameter guess are considered; (C) simulated pixel intensity profiles are calculated for each circle size; (D) a least-squares fit is performed between actual pixel intensity profiles and simulated pixel intensity profiles of different diameters; the diameter of the simulated pixel intensity profile with the minimum least-squares error when fit to the actual pixel intensity profile is the measured diameter of the selected tube section.

Image of FIG. 3.
FIG. 3.

The tubes phantom. (a) Digital photograph, (b) HP MR projection negative.

Image of FIG. 4.
FIG. 4.

Comparison of algorithm- and manually measured image tube diameters from Magnevist-filled tubes phantom against physical values in various orientations. (a) Nominal orientation, (b) rotated orientation, (c) inclined orientation, (d) rotated/inclined orientation.

Image of FIG. 5.
FIG. 5.

Comparison of algorithm- and manually measured image tube diameters from -filled tubes phantom against physical values in various orientations. (a) Nominal orientation, (b) rotated orientation, (c) inclined orientation, (d) rotated/inclined orientation.

Image of FIG. 6.
FIG. 6.

Imaged pixel intensity profiles and their corresponding model-based fits. (a) Tube 3, Magnevist-filled, (b) tube 4, Magnevist-filled, (c) tube 3, HP -filled, (d) tube 4, HP -filled.

Image of FIG. 7.
FIG. 7.

Maximum errors of the diameters measured from the images using various approaches; errors are expressed as multiples of the pixel dimension. (a) Magnevist-filled phantom, (b) HP -filled phantom.

Image of FIG. 8.
FIG. 8.

Mean errors of the diameters measured from the images using various approaches; errors are expressed as a percentage of caliper-measured diameters.

Image of FIG. 9.
FIG. 9.

Projected tube sections with and without inclination; a projection through the tube that is perpendicular to the projection direction (dotted line) intersects a circular section (dotted circle); a projection through the tube tilted with respect to the projection direction (dashed line) intersects an elliptical section (dashed circle).

Image of FIG. 10.
FIG. 10.

Expected signal profiles from various configurations of airway projection overlap. (a) Magnevist-filled phantom, (b) HP -filled phantom.(a) No overlap, (b) full overlap, (c) partial overlap.

Tables

Generic image for table
TABLE I.

Number of measurements carried out on MR images of Magnevist-filled tubes phantom to produce the plotted diameters (numbers quoted are model-based/manual).

Generic image for table
TABLE II.

Number of measurements carried out on HP MR images to produce the plotted diameters (numbers quoted are model-based/manual).

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/content/aapm/journal/medphys/33/6/10.1118/1.2194427
2006-05-11
2014-04-25
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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Measurement of the internal diameter of plastic tubes from projection MR images using a model-based least-squares fit approach
http://aip.metastore.ingenta.com/content/aapm/journal/medphys/33/6/10.1118/1.2194427
10.1118/1.2194427
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