Impact of MR-Based Attenuation Correction on Neurologic PET Studies.

Academic Article


  • UNLABELLED: Hybrid PET and MR scanners have become a reality in recent years, with the benefits of reduced radiation exposure, reduction of imaging time, and potential advantages in quantification. Appropriate attenuation correction remains a challenge. Biases in PET activity measurements were demonstrated using the current MR-based attenuation-correction technique. We aimed to investigate the impact of using a standard MR-based attenuation correction technique on the clinical and research utility of a PET/MR hybrid scanner for amyloid imaging. METHODS: Florbetapir scans were obtained for 40 participants on a hybrid scanner with simultaneous MR acquisition. PET images were reconstructed using both MR- and CT-derived attenuation maps. Quantitative analysis was performed for both datasets to assess the impact of MR-based attenuation correction to absolute PET activity measurements as well as target-to-reference ratio (SUVR). Clinical assessment was also performed by a nuclear medicine physician to determine amyloid status based on the criteria in the Food and Drug Administration prescribing information for florbetapir. RESULTS: MR-based attenuation correction led to underestimation of PET activity for most parts of the brain, with a small overestimation for deep brain regions. There was also an overestimation of SUVRs with cerebellar reference. SUVR measurements obtained from the 2 attenuation-correction methods were strongly correlated. Clinical assessment of amyloid status resulted in identical classification as positive or negative regardless of the attenuation-correction methods. CONCLUSION: MR-based attenuation correction causes biases in quantitative measurements. The biases may be accounted for by a linear model, although the spatial variation cannot be easily modeled. The quantitative differences, however, did not affect clinical assessment as positive or negative.
  • Published In


  • PET/MR, amyloid imaging, attenuation correction, Amyloid, Brain, Humans, Image Processing, Computer-Assisted, Magnetic Resonance Imaging, Multimodal Imaging, Positron-Emission Tomography
  • Digital Object Identifier (doi)

    Author List

  • Su Y; Rubin BB; McConathy J; Laforest R; Qi J; Sharma A; Priatna A; Benzinger TLS
  • Start Page

  • 913
  • End Page

  • 917
  • Volume

  • 57
  • Issue

  • 6