TY - JOUR
T1 - Evaluation of sinus/edge-corrected zero-echo-time–Based attenuation correction in brain PET/MRI
AU - Yang, Jaewon
AU - Wiesinger, Florian
AU - Kaushik, Sandeep
AU - Shanbhag, Dattesh
AU - Hope, Thomas A.
AU - Larson, Peder E.Z.
AU - Seo, Youngho
N1 - Funding Information:
This project was supported in part by grant from GE Healthcare. No other potential conflict of interest relevant to this article was reported.
Publisher Copyright:
COPYRIGHT © 2017 by the Society of Nuclear Medicine and Molecular Imaging.
PY - 2017/11/1
Y1 - 2017/11/1
N2 - In brain PET/MRI, the major challenge of zero-echo-time (ZTE)–based attenuation correction (ZTAC) is the misclassification of air/tissue/ bone mixtures or their boundaries. Our study aimed to evaluate a sinus/edge-corrected (SEC) ZTAC (ZTACSEC), relative to an uncorrected (UC) ZTAC (ZTACUC) and a CT atlas-based attenuation correction (ATAC). Methods: Whole-body 18F-FDG PET/MRI scans were obtained for 12 patients after PET/CT scans. Only data acquired at a bed station that included the head were used for this study. Using PET data from PET/MRI, we applied ZTACUC, ZTACSEC, ATAC, and reference CT-based attenuation correction (CTAC) to PET attenuation correction. For ZTACUC, the bias-corrected and normalized ZTE was converted to pseudo-CT with air (21,000 HU for ZTE, 0.2), soft-tissue (42 HU for ZTE . 0.75), and bone (22,000 · [ZTE 2 1] 1 42 HU for 0.2 # ZTE # 0.75). Afterward, in the pseudo-CT, sinus/edges were automatically estimated as a binary mask through morphologic processing and edge detection. In the binary mask, the overestimated values were rescaled below 42 HU for ZTACSEC. For ATAC, the atlas deformed to MR in-phase was segmented to air, inner air, soft tissue, and continuous bone. For the quantitative evaluation, PET mean uptake values were measured in twenty 1-mL volumes of interest distributed throughout brain tissues. The PET uptake was compared using a paired t test. An error histogram was used to show the distribution of voxel-based PET uptake differences. Results: Compared with CTAC, ZTACSEC achieved the overall PET quantification accuracy (0.2% 6 2.4%, P 5 0.23) similar to CTAC, in comparison with ZTACUC (5.6% 6 3.5%, P, 0.01) and ATAC (20.9% 6 5.0%, P 5 0.03). Specifically, a substantial improvement with ZTACSEC (0.6% 6 2.7%, P, 0.01) was found in the cerebellum, in comparison with ZTACUC (8.1% 6 3.5%, P, 0.01) and ATAC (24.1% 6 4.3%, P, 0.01). The histogram of voxel-based uptake differences demonstrated that ZTACSEC reduced the magnitude and variation of errors substantially, compared with ZTACUC and ATAC. Conclusion: ZTACSEC can provide an accurate PET quantification in brain PET/MRI, comparable to the accuracy achieved by CTAC, particularly in the cerebellum.
AB - In brain PET/MRI, the major challenge of zero-echo-time (ZTE)–based attenuation correction (ZTAC) is the misclassification of air/tissue/ bone mixtures or their boundaries. Our study aimed to evaluate a sinus/edge-corrected (SEC) ZTAC (ZTACSEC), relative to an uncorrected (UC) ZTAC (ZTACUC) and a CT atlas-based attenuation correction (ATAC). Methods: Whole-body 18F-FDG PET/MRI scans were obtained for 12 patients after PET/CT scans. Only data acquired at a bed station that included the head were used for this study. Using PET data from PET/MRI, we applied ZTACUC, ZTACSEC, ATAC, and reference CT-based attenuation correction (CTAC) to PET attenuation correction. For ZTACUC, the bias-corrected and normalized ZTE was converted to pseudo-CT with air (21,000 HU for ZTE, 0.2), soft-tissue (42 HU for ZTE . 0.75), and bone (22,000 · [ZTE 2 1] 1 42 HU for 0.2 # ZTE # 0.75). Afterward, in the pseudo-CT, sinus/edges were automatically estimated as a binary mask through morphologic processing and edge detection. In the binary mask, the overestimated values were rescaled below 42 HU for ZTACSEC. For ATAC, the atlas deformed to MR in-phase was segmented to air, inner air, soft tissue, and continuous bone. For the quantitative evaluation, PET mean uptake values were measured in twenty 1-mL volumes of interest distributed throughout brain tissues. The PET uptake was compared using a paired t test. An error histogram was used to show the distribution of voxel-based PET uptake differences. Results: Compared with CTAC, ZTACSEC achieved the overall PET quantification accuracy (0.2% 6 2.4%, P 5 0.23) similar to CTAC, in comparison with ZTACUC (5.6% 6 3.5%, P, 0.01) and ATAC (20.9% 6 5.0%, P 5 0.03). Specifically, a substantial improvement with ZTACSEC (0.6% 6 2.7%, P, 0.01) was found in the cerebellum, in comparison with ZTACUC (8.1% 6 3.5%, P, 0.01) and ATAC (24.1% 6 4.3%, P, 0.01). The histogram of voxel-based uptake differences demonstrated that ZTACSEC reduced the magnitude and variation of errors substantially, compared with ZTACUC and ATAC. Conclusion: ZTACSEC can provide an accurate PET quantification in brain PET/MRI, comparable to the accuracy achieved by CTAC, particularly in the cerebellum.
KW - Attenuation correction
KW - Brain
KW - Neurology
KW - PET
KW - PET/MRI
KW - ZTE
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U2 - 10.2967/jnumed.116.188268
DO - 10.2967/jnumed.116.188268
M3 - Article
C2 - 28473594
AN - SCOPUS:85032785318
SN - 0161-5505
VL - 58
SP - 1873
EP - 1879
JO - Journal of Nuclear Medicine
JF - Journal of Nuclear Medicine
IS - 11
ER -