TY - JOUR T1 - Multi-Atlas–Based Attenuation Correction for Brain <sup>18</sup>F-FDG PET Imaging Using a Time-of-Flight PET/MR Scanner: Comparison with Clinical Single-Atlas– and CT-Based Attenuation Correction JF - Journal of Nuclear Medicine JO - J Nucl Med SP - 1258 LP - 1264 DO - 10.2967/jnumed.115.169045 VL - 57 IS - 8 AU - Tetsuro Sekine AU - Ninon Burgos AU - Geoffrey Warnock AU - Martin Huellner AU - Alfred Buck AU - Edwin E.G.W. ter Voert AU - M. Jorge Cardoso AU - Brian F. Hutton AU - Sebastien Ourselin AU - Patrick Veit-Haibach AU - Gaspar Delso Y1 - 2016/08/01 UR - http://jnm.snmjournals.org/content/57/8/1258.abstract N2 - In this work, we assessed the feasibility of attenuation correction (AC) based on a multi-atlas–based method (m-Atlas) by comparing it with a clinical AC method (single-atlas–based method [s-Atlas]), on a time-of-flight (TOF) PET/MRI scanner. Methods: We enrolled 15 patients. The median patient age was 59 y (age range, 31–80). All patients underwent clinically indicated whole-body 18F-FDG PET/CT for staging, restaging, or follow-up of malignant disease. All patients volunteered for an additional PET/MRI scan of the head (no additional tracer being injected). For each patient, 3 AC maps were generated. Both s-Atlas and m-Atlas AC maps were generated from the same patient-specific LAVA-Flex T1-weighted images being acquired by default on the PET/MRI scanner during the first 18 s of the PET scan. An s-Atlas AC map was extracted by the PET/MRI scanner, and an m-Atlas AC map was created using a Web service tool that automatically generates m-Atlas pseudo-CT images. For comparison, the AC map generated by PET/CT was registered and used as a gold standard. PET images were reconstructed from raw data on the TOF PET/MRI scanner using each AC map. All PET images were normalized to the SPM5 PET template, and 18F-FDG accumulation was quantified in 67 volumes of interest (VOIs; automated anatomic labeling atlas). Relative (%diff) and absolute differences (|%diff|) between images based on each atlas AC and CT-AC were calculated. 18F-FDG uptake in all VOIs and generalized merged VOIs were compared using the paired t test and Bland–Altman test. Results: The range of error on m-Atlas in all 1,005 VOIs was −4.99% to 4.09%. The |%diff| on the m-Atlas was improved by about 20% compared with s-Atlas (s-Atlas vs. m-Atlas: 1.49% ± 1.06% vs. 1.21% ± 0.89%, P &lt; 0.01). In generalized VOIs, %diff on m-Atlas in the temporal lobe and cerebellum was significantly smaller (s-Atlas vs. m-Atlas: temporal lobe, 1.49% ± 1.37% vs. −0.37% ± 1.41%, P &lt; 0.01; cerebellum, 1.55% ± 1.97% vs. −1.15% ± 1.72%, P &lt; 0.01). Conclusion: The errors introduced using either s-Atlas or m-Atlas did not exceed 5% in any brain region investigated. When compared with the clinical s-Atlas, m-Atlas is more accurate, especially in regions close to the skull base. ER -