Does scatter correction of cardiac SPECT improve image quality in the presence of high extracardiac activity?
BACKGROUND
Extracardiac activity confounds conventional cardiac single photon emission computed tomography (SPECT) image reconstruction. It has been proposed that applying scatter correction (SC) may improve image quality. This study was done to test whether SC improves several quantitative measures of cardiac imaging in the presence of high extracardiac activity.


RESULTS
An anatomic anthropomorphic phantom with a cardiac insert filled with technetium 99m was used. We obtained acquisitions using a dual-headed SPECT camera at 13 different levels of liver-to-heart activity. Each acquisition was reconstructed by use of each of 6 different methods: filtered backprojection with or without SC, maximum likelihood with or without SC, and maximum likelihood with attenuation correction (AC) and with or without SC. Three different parameters were used to assess the effect of the processing methods on image quality: image variability, contrast, and signal-to-noise ratio. Only image contrast improved significantly with SC. By adding SC to filtered backprojection, image contrast improved by 13% (P <.01). Maximum likelihood reconstruction with AC resulted in further improvement in contrast (increase of 17%), variability (decrease of 5%), and signal-to-noise ratio (increase of 6%) over filtered backprojection (all P <.01).


CONCLUSIONS
Image quality improved significantly when SC was applied, especially when combined with maximum likelihood reconstruction with AC. This improvement was present despite increased extracardiac activity in close proximity to the heart.
Khalil
Mohammed E
ME
Department of Medicine, Bronx-Lebanon Hospital Center, NY 10457, USA.
Brown
Edward J
EJ
Heller
Eliot N
EN
D000465:Algorithms; D016477:Artifacts; D006321:Heart / Q000000981:diagnostic imaging*; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008099:Liver / Q000000981:diagnostic imaging*; D019047:Phantoms, Imaging; D011785:Quality Assurance, Health Care / Q000379:methods*; D015203:Reproducibility of Results; D012542:Scattering, Radiation; D012680:Sensitivity and Specificity; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*