### Abstract

A computer algorithm for the three-dimensional (3D) alignment of PET images is described. To align two images, the algorithm calculates the ratio of one image to the other on a voxel-by-voxel basis and then iteratively moves the images relative to one another to minimize the variance of this ratio across voxels. Since the method relies on anatomic information in the images rather than on external fiducial markers, it can be applied retrospectively. Validation studies using a 3D brain phantom show that the algorithm aligns images acquired at a wide variety of positions with maximum positional errors that are usually less than the width of a voxel (1.745 mm). Simulated cortical activation sites do not interfere with alignment. Global errors in quantitation from realignment are <2%. Regional errors due to partial volume effects are largest when the gantry is rotated by large angles or when the bed is translated axially by one-half the interplane distance. To minimize such partial volume effects, the algorithm can be used prospectively, during acquisition, to reposition the scanner gantry and bed to match an earlier study. Computation requires 3-6 min on a Sun SPARC station 2.

Original language | English (US) |
---|---|

Pages (from-to) | 620-633 |

Number of pages | 14 |

Journal | Journal of Computer Assisted Tomography |

Volume | 16 |

Issue number | 4 |

State | Published - 1992 |

### Fingerprint

### Keywords

- Emission computed tomography
- Image acquisition
- Image registration
- Quantitative analysis

### ASJC Scopus subject areas

- Radiology Nuclear Medicine and imaging
- Radiological and Ultrasound Technology

### Cite this

*Journal of Computer Assisted Tomography*,

*16*(4), 620-633.

**Rapid automated algorithm for aligning and reslicing PET images.** / Woods, R. P.; Cherry, Simon R; Mazziotta, J. C.

Research output: Contribution to journal › Article

*Journal of Computer Assisted Tomography*, vol. 16, no. 4, pp. 620-633.

}

TY - JOUR

T1 - Rapid automated algorithm for aligning and reslicing PET images

AU - Woods, R. P.

AU - Cherry, Simon R

AU - Mazziotta, J. C.

PY - 1992

Y1 - 1992

N2 - A computer algorithm for the three-dimensional (3D) alignment of PET images is described. To align two images, the algorithm calculates the ratio of one image to the other on a voxel-by-voxel basis and then iteratively moves the images relative to one another to minimize the variance of this ratio across voxels. Since the method relies on anatomic information in the images rather than on external fiducial markers, it can be applied retrospectively. Validation studies using a 3D brain phantom show that the algorithm aligns images acquired at a wide variety of positions with maximum positional errors that are usually less than the width of a voxel (1.745 mm). Simulated cortical activation sites do not interfere with alignment. Global errors in quantitation from realignment are <2%. Regional errors due to partial volume effects are largest when the gantry is rotated by large angles or when the bed is translated axially by one-half the interplane distance. To minimize such partial volume effects, the algorithm can be used prospectively, during acquisition, to reposition the scanner gantry and bed to match an earlier study. Computation requires 3-6 min on a Sun SPARC station 2.

AB - A computer algorithm for the three-dimensional (3D) alignment of PET images is described. To align two images, the algorithm calculates the ratio of one image to the other on a voxel-by-voxel basis and then iteratively moves the images relative to one another to minimize the variance of this ratio across voxels. Since the method relies on anatomic information in the images rather than on external fiducial markers, it can be applied retrospectively. Validation studies using a 3D brain phantom show that the algorithm aligns images acquired at a wide variety of positions with maximum positional errors that are usually less than the width of a voxel (1.745 mm). Simulated cortical activation sites do not interfere with alignment. Global errors in quantitation from realignment are <2%. Regional errors due to partial volume effects are largest when the gantry is rotated by large angles or when the bed is translated axially by one-half the interplane distance. To minimize such partial volume effects, the algorithm can be used prospectively, during acquisition, to reposition the scanner gantry and bed to match an earlier study. Computation requires 3-6 min on a Sun SPARC station 2.

KW - Emission computed tomography

KW - Image acquisition

KW - Image registration

KW - Quantitative analysis

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UR - http://www.scopus.com/inward/citedby.url?scp=0026776405&partnerID=8YFLogxK

M3 - Article

C2 - 1629424

AN - SCOPUS:0026776405

VL - 16

SP - 620

EP - 633

JO - Journal of Computer Assisted Tomography

JF - Journal of Computer Assisted Tomography

SN - 0363-8715

IS - 4

ER -