MRI-based attenuation correction of PET images in clinical PET/MR
Final Report Abstract
The atlas- and pattern-recognition based approach proposed by Hofmann et al was favorably compared against a purely atlas-based method on a dataset of 11 patients. The quantification accuracy of segmentation-based methods and ATPR was found to be similar on soft tissue lesions, which led to the introduction of the hybrid method SEGwBONE, that only employs ATPR prediction on regions where bone tissue is likely present. The accuracy of the method was similar to ATPR with reduced computational complexity. The prediction of bone tissue, while necessary for brain imaging, had limited impact on quantification of whole body PET images in our studies outside of bone tissue. Bone lesions and lesions adjacent to bone showed a significant underestimation when bone tissue was omitted from MRI-based attenuation maps. Soft tissue lesions further away from bony tissue were not influenced. MR susceptibility artifacts can affect quantification accuracy in regions where the MRI data used for the generation of the attenuation map is deteriorated, as well as in adjacent areas. Therefore, a method for artifact correction using an atlas was proposed and evaluated. Artifacts caused by hip prostheses and by sternal cerclages could be corrected by the method. Larger deteriorations of the body outline would require additional steps, such as using active contour models, which was not pursued during this work. Since pediatric imaging is an important application of PET/MRI systems, we investigated factors that can influence the accuracy of MRAC and evaluated the quantification accuracy using the baseline segmentation method and the hybrid method SEGwBONE. Significant age-related variations in tissue density between adult and pediatric collectives were found in lung and femur tissue. We created an atlas database for pediatric patients, which showed improved accuracy of the attenuation maps in osseous regions. The omission of bone tissue in attenuation maps was found to yield statistically significant deviations in quantification from reference PET with CTAC in bone marrow and femur-adjacent VOIs. The magnitude, while not as high as deviations for bone lesions in adult patients, can nevertheless be relevant for quantitative evaluation of primary bone tumors.
Publications
- MRI-based attenuation correction for whole- body PET/MRI: quantitative evaluation of segmentation- and atlas-based methods., J. Nucl. Med., vol. 52, pp. 1392–9, 2011
M. Hofmann∗, I. Bezrukov∗, F. Mantlik, P. Aschoff, F. Steinke, T. Beyer, B. J. Pichler, and B. Schölkopf
- MR-Based Attenuation Correction Methods for Improved PET Quantification in Lesions Within Bone and Susceptibility Artifact Regions., J. Nucl. Med., vol. 54, pp. 1768– 1774, 2013
I. Bezrukov, H. Schmidt, F. Mantlik, N. Schwenzer, C. Brendle, B. Schölkopf, and B. J. Pichler
(See online at https://doi.org/10.2967/jnumed.112.113209) - MR-Based PET Attenuation Correction for PET/MR, Semin. Nucl. Med., vol. 43, pp. 45–59, 2013
I. Bezrukov∗, F. Mantlik∗, H. Schmidt, B. Schölkopf, and B. J. Pichler
- Principles of PET/MR Imaging. J. Nucl. Med., vol. 55 (Supplement 2), 2S–10S, 2014
J. Disselhorst, I. Bezrukov, A. Kolb, C. Parl, B. J. Pichler
(See online at https://dx.doi.org/10.2967/jnumed.113.129098) - Simultaneous Whole-Body PET/MR Imaging in Comparison to PET/CT in Pediatric Oncology: Initial Results. Radiology, 1317-32, 2014
J. F. Schäfer, S. Gatidis, H. Schmidt, B. Gückel, I. Bezrukov, C. Pfannenberg, M. Reimold, M. Ebinger, J. Fuchs, C. Claussen, and N. Schwenzer
(See online at https://doi.org/10.1148/radiol.14131732) - Assessment of murine brain tissue shrinkage caused by different histological fixatives using magnetic resonance and computer tomography imaging. Histology and Histopathology, 2015 May;30(5):601-13
H. F. Wehrl, I. Bezrukov, S. Wiehr, M. Lehnhoff, K. Fuchs, J. G. Mannheim, L. Quintanilla- Martinez, M. Kneilling B. J. Pichler, A. W. Sauter
(See online at https://doi.org/10.14670/HH-30.601) - Quantitative evaluation of segmentation- and atlas- based attenuation correction for PET/MR on pediatric patients, J. Nucl. Med., vol. 56, pp. 1067-74, 2015
I. Bezrukov, H. Schmidt, S. Gatidis, F. Mantlik, J. F. Schäfer, N. Schwenzer, B. J. Pichler
(See online at https://doi.org/10.2967/jnumed.114.149476) - Segmentation-Based Attenuation Correction in Positron Emission Tomography/Magnetic Resonance: Erroneous Tissue Identification and Its Impact on Positron Emission Tomography Interpretation. Investigative Radiology, 2015 May;50(5):339-46
C. Brendle, H Schmidt, A Oergel, I Bezrukov, M Mueller, C Schraml, C Pfannenberg, C la Fougère, K Nikolaou, N Schwenzer
(See online at https://doi.org/10.1097/RLI.0000000000000131)
