Hussein Rabie Farghaly MD, Abstract Co-Author: Nothing to Disclose

Medhat M. Osman MD, Abstract Co-Author: Speakers Bureau, Koninklijke Philips Electronics NV

Jon W Piper BEng, Abstract Co-Author: Employee, MIMvista Corp Stockholder, MIMvista Corp

Aaron S. Nelson MD, Abstract Co-Author: Owner, MIMvista Corp, Cleveland, OH Employee, MIMvista Corp, Cleveland, OH

Nghi Co Nguyen MD, PhD, Presenter: Nothing to Disclose

Automated asymmetry indices (L/R%) of the same subject and differential Z-scores (∆ Z-score) as compared to a normal data base are helpful tools to evaluate for asymmetric brain FDG uptake. We retrospectively compared L/R% and ∆ Z-score distributions in healthy controls (NC).

Brain FDG PET images of 10 NC were extracted from their whole-body FDG PET/CT scan and analyzed using a commercial software (MIMneuro, MIMvista Corp.). L/R% calculation was based on total volume counts with L/R% = (L-R)/L expressed in % and ∆ Z-score = L Z-score - R Z-score. Results of single brain and probalistic atlas were evaluated together. Normal distribution tests, paired t-tests and linear regression were used.

L/R% was normal distributed in 97% regions and was more often less on the left (-3.5 ± 2.5%) than on the right (2.2 ± 2.7%). Regions with greater L/R% (> 10%) were primarily in the anterior frontal, occipital, middle temporal and medial temporal lobes. In contrast, the primary motor-sensory cortex, cerebellum and limbic system showed less asymmetry (<10%). ∆ Z-scores of 99% of regions were normal distributed and were more often less on the left (-0.5 ± 1.1) than on the right (0.3 ± 1.0). There was a good correlation (r = 0.76) between ∆ Z-score and L/R%.

No homogeneous L/R% or ∆ Z-score distributions exist in cerebral FDG PET of NC. Different brain regions appear to have their individual L/R% or ∆ Z-score normal distributions. Given their good correlation, combined use of L/R% and ∆ Z-score may increase diagnostic accuracy.

No homogeneous Left-Right-%Difference or ∆ Z-score distributions exist in cerebral FDG PET even in normal subjects. However, their combined use may be complementary in disease diagnosis.

Farghaly, H, Osman, M, Piper, J, Nelson, A, Nguyen, N, Cerebral FDG PET: Correlation of Asymmetry Indices and Differential Z-scores in Healthy Volunteers.  Radiological Society of North America 2009 Scientific Assembly and Annual Meeting, November 29 - December 4, 2009 ,Chicago IL. http://archive.rsna.org/2009/8016808.html