Multiatlas Fusion with a Hybrid CT Number Correction Technique for Subject-Specific Pseudo-CT Estimation in the Context of MRI-Only Radiation Therapy

To propose a hybrid multiatlas fusion and correction approach to estimate a pseudo-computed tomography (pCT) image from T2-weighted brain magnetic resonance (MR) images in the context of MRI-only radiotherapy. A set of eleven pairs of T2-weighted MR and CT brain images was included. Using leave-one-...

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Bibliographic Details
Published in:Journal of medical imaging and radiation sciences Vol. 50; no. 3; p. 425
Main Authors: Boukellouz, Wafa, Moussaoui, Abdelouahab, Taleb-Ahmed, Abdelmalik, Boydev, Christine
Format: Journal Article
Language:English
Published: United States 01.09.2019
Subjects:
Pseudo-CT
hybrid CT number correction
multiatlas fusion
brain
MR-only radiotherapy
ISSN:1876-7982, 1876-7982
Online Access:Get more information
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Summary:To propose a hybrid multiatlas fusion and correction approach to estimate a pseudo-computed tomography (pCT) image from T2-weighted brain magnetic resonance (MR) images in the context of MRI-only radiotherapy. A set of eleven pairs of T2-weighted MR and CT brain images was included. Using leave-one-out cross-validation, atlas MR images were registered to the target MRI with multimetric, multiresolution deformable registration. The subsequent deformations were applied to the atlas CT images, producing uncorrected pCT images. Afterward, a three-dimensional hybrid CT number correction technique was used. This technique uses information about MR intensity, spatial location, and tissue label from segmented MR images with the fuzzy c-means algorithm and combines them in a weighted fashion to correct Hounsfield unit values of the uncorrected pCT images. The corrected pCT images were then fused into a final pCT image. The proposed hybrid approach proved to be performant in correcting Hounsfield unit values in terms of qualitative and quantitative measures. Average correlation was 0.92 and 0.91 for the proposed approach by taking the mean and the median, respectively, compared with 0.86 for the uncorrected unfused version. Average values of dice similarity coefficient for bone were 0.68 and 0.72 for the fused corrected pCT images by taking the mean and the median, respectively, compared with 0.65 for the uncorrected unfused version indicating a significant bone estimation improvement. A hybrid fusion and correction method is presented to estimate a pCT image from T2-weighted brain MR images.
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ISSN:1876-7982
1876-7982
DOI:10.1016/j.jmir.2019.03.184