PT  - JOURNAL ARTICLE
AU  - Yi Su
AU  - Brian B. Rubin
AU  - Jonathan McConathy
AU  - Richard Laforest
AU  - Jing Qi
AU  - Akash Sharma
AU  - Agus Priatna
AU  - Tammie L.S. Benzinger
TI  - Impact of MR-Based Attenuation Correction on Neurologic PET Studies
AID  - 10.2967/jnumed.115.164822
DP  - 2016 Jun 01
TA  - Journal of Nuclear Medicine
PG  - 913--917
VI  - 57
IP  - 6
4099  - http://jnm.snmjournals.org/content/57/6/913.short
4100  - http://jnm.snmjournals.org/content/57/6/913.full
SO  - J Nucl Med2016 Jun 01; 57
AB  - 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.