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A model for quantitative correction of coronary calcium scores on multidetector, dual source, and electron beam computed tomography for influences of linear motion, calcification density, and temporal resolution: A cardiac phantom study
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10.1118/1.3213536
/content/aapm/journal/medphys/36/11/10.1118/1.3213536
http://aip.metastore.ingenta.com/content/aapm/journal/medphys/36/11/10.1118/1.3213536

Figures

Image of FIG. 1.
FIG. 1.

Programmable moving cardiac phantom (QRM. Möhrendorf, Germany). To the robot arm artificial calcified coronary arteries were attached (Fig. 2) which moved in a water container inside a thorax phantom (QRM, Möhrendorf, Germany). A linear movement of the robot arm was programmed (Fig. 3) at an angle of approximately 90° to the center axis of the scanner in the horizontal plane.

Image of FIG. 2.
FIG. 2.

Two artificial calcified coronary arteries of water equivalent material with a length of 70 mm and a diameter of 5 mm. Each coronary artery contains two artificial coronary plaques with a length of 10 mm and a diameter of 5 mm and with densities of 196 and 380 mg HA per and 408 and 800 mg HA per , respectively (Table I). The artificial arteries have been produced by QRM, Möhrendorf, Germany.

Image of FIG. 3.
FIG. 3.

Displacement of the moving cardiac phantom as a function of time. The linear velocity of the artificial coronary arteries was changed between 0 and 120 mm/s with steps of 10 mm/s and a periodic cycle of 1 s as indicated. The acquisition windows of EBT, DSCT, and 64-slice MDCT (64CT) are shown.

Image of FIG. 4.
FIG. 4.

Reconstructed axial images of the 800 mg HA per artificial coronary calcification on EBT, 64-slice MDCT, and DSCT from top to bottom and for 0, 30, 60, 90, and 120 mm/s from left to right.

Image of FIG. 5.
FIG. 5.

Volume score on 64-slice MDCT for calcifications of 196, 380, 408, and 800 mg HA per as a function of velocity. The PV is indicated. Every calcium score has been measured five times. The error bars represent the standard deviation in this measurement.

Image of FIG. 6.
FIG. 6.

Correction factor for the volume score as defined in Eqs. (3) and (4) on EBT, DSCT, and 64-slice MDCT (64CT) as a function of mean calcification density for the velocity range of 10–50 mm/s.

Image of FIG. 7.
FIG. 7.

Slope (top) and offset (bottom) as defined in Eqs. (4) and (5) as a function of temporal resolution for AS, VS, and MS. Temporal resolutions were 50, 83, and 165 ms for EBT, DSCT, and 64-slice MDCT, respectively.

Image of FIG. 8.
FIG. 8.

CMS index (top) and average CMS index over all artificial calcifications times 100 (bottom) for AS, VS, and MS for the 196, 380, 408, and 800 mg HA per artificial coronary calcification as measured on EBT, DSCT, and 64-slice MDCT. The average CMS index is shown for the uncorrected (uncorr) and the corrected (corr) calcium scores (bottom). Significant differences between two modalities are indicated by the symbol .

Image of FIG. 9.
FIG. 9.

Delta index for AS, VS, and MS (top) and average delta index over all artificial calcifications (bottom) for the 196, 380, 408, and 800 mg HA per artificial coronary calcification as measured on EBT, DSCT, and 64-slice MDCT. Delta index for AS is indicated versus EBT score; delta indices for VS and MS are indicated versus physical volume and physical mass, respectively. The average delta index is shown for the uncorrected (uncorr) and the corrected (corr) calcium scores (bottom). Significant differences between two modalities are indicated by the symbol .

Tables

Generic image for table
TABLE I.

Artificial coronary arteries 1 and 2 used in the motion experiment. Each artificial coronary artery consists out of two cylindrical homogeneous calcium inserts with the densities given in mg HA per , the volume in , and the corresponding masses in mg.

Generic image for table
TABLE II.

Linear fit parameters , , , and as given in Eq. (5) and corresponding and values for Agatston (AS), volume (VS), and mass (MS). The units of and are given in , , and for Agatston, volume, and mass scores, respectively. The units of and are given in , , and for Agatston, volume and mass scores, respectively.

Generic image for table
TABLE III.

Slope and offset as defined in Eqs. (4) and (5) for EBT, DSCT, and 64-slice CT (64CT) for temporal resolutions of 50, 83, and 165 ms, respectively, for Agatston (AS), volume (VS) and mass (MS).

Generic image for table
TABLE IV.

Estimated minimal velocity in mm/s of the RCA, LCX, and LAD artery for temporal resolutions of 50, 83, and 165 ms (Ref. 31). The velocities at 83 and 165 ms were interpolated.

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/content/aapm/journal/medphys/36/11/10.1118/1.3213536
2009-10-08
2014-04-23
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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: A model for quantitative correction of coronary calcium scores on multidetector, dual source, and electron beam computed tomography for influences of linear motion, calcification density, and temporal resolution: A cardiac phantom study
http://aip.metastore.ingenta.com/content/aapm/journal/medphys/36/11/10.1118/1.3213536
10.1118/1.3213536
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