On the accuracy and reproducibility of a novel probabilistic atlas-based generation for calculation of head attenuation maps on integrated PET/MR scanners Articles uri icon

publication date

  • March 2017

start page

  • 398

end page

  • 407

issue

  • 3

volume

  • 44

International Standard Serial Number (ISSN)

  • 1619-7070

Electronic International Standard Serial Number (EISSN)

  • 1619-7089

abstract

  • Purpose: To propose an MR-based method for generating continuous-valued head attenuation maps and to assess its accuracy and reproducibility. Demonstrating that novel MR-based photon attenuation correction methods are both accurate and reproducible is essential prior to using them routinely in research and clinical studies on integrated PET/MR scanners.

    Methods: Continuous-valued linear attenuation coefficient maps ("mu-maps") were generated by combining atlases that provided the prior probability of voxel positions belonging to a certain tissue class (air, soft tissue, or bone) and an MR intensity-based likelihood classifier to produce posterior probability maps of tissue classes. These probabilities were used as weights to generate the mu-maps. The accuracy of this probabilistic atlas-based continuous-valued mu-map ("PAC-map") generation method was assessed by calculating the voxel-wise absolute relative change (RC) between the MR-based and scaled CT-based attenuation-corrected PET images. To assess reproducibility, we performed pair-wise comparisons of the RC values obtained from the PET images reconstructed using the mu-maps generated from the data acquired at three time points.

    Results: The proposed method produced continuous-valued mu-maps that qualitatively reflected the variable anatomy in patients with brain tumor and agreed well with the scaled CT-based mu-maps. The absolute RC comparing the resulting PET volumes was 1.76±2.33 %, quantitatively demonstrating that the method is accurate. Additionally, we also showed that the method is highly reproducible, the mean RC value for the PET images reconstructed using the mu-maps obtained at the three visits being 0.65±0.95 %.

    Conclusion: Accurate and highly reproducible continuous-valued head mu-maps can be generated from MR data using a probabilistic atlas-based approach.

subjects

  • Biology and Biomedicine

keywords

  • attenuation correction; reproducibility; pet/mr; probabilistic atlas