Kent P. Friedman MD, Presenter: Nothing to Disclose

Rajan Rakheja, Abstract Co-Author: Nothing to Disclose

Timothy Michael Shepherd MD, PhD, Abstract Co-Author: Nothing to Disclose

Rachel Bartlett PhD, Abstract Co-Author: Nothing to Disclose

Yu-Shin Ding PhD, Abstract Co-Author: Nothing to Disclose

Fernando Boada, Abstract Co-Author: Nothing to Disclose

Simultaneous PET/MR is a new technology that may be used in the evaluation of dementia patients. There are few data in the literature regarding quantitative differences between PET data obtained at PET/CT versus PET/MR and how this may impact image interpretation. This study compared the PET interpretation of PET/CT versus PET/MR by two independent experienced nuclear medicine physicians.

Forty-five minutes following injection of 10 mCi of FDG, 19 patients with clinically-suspected dementia underwent a 15-minute clinical brain PET/CT. Simultaneous PET/MR scanning was subsequently performed (60 minute list-mode) at approximately 90 minutes post-injection. Two experienced nuclear medicine physicians blindly interpreted the PET portion of all PET/CT scans, attributing a specific diagnosis (normal, AD, FTD, LBD, other dementia, mixed phenotype or unspecified disease) and severity scale (mild, moderate or severe abnormality). The readers then blindly interpreted the PET data obtained from PET/MR. Concordance between PET/CT (reference standard) and PET/MR with respect to diagnosis and disease severity was assessed for each reader.

Reader A classified 12 PET/CT scans as AD, 5 as unspecified dementia, 1 as LBD and 1 as normal with a mean severity score of 2.0. Reader B classified 10 PET/CT scans as AD, 3 as unspecified, 1 as LBD and 5 as normal with mean severity score of 2.1. PET/MR interpretations with comparison to PET/CT yielded an 84% (16/19) intra-reader concordance of diagnosis, with 95% (18/19) of severity scores varying by one point or less. Reader B exhibited 84% intra-reader concordance of dementia pattern diagnosis, with 89% (17/19) of all scores varying by one point or less.

Our preliminary analysis in clinically-suspected dementia patients showed a relatively high concordance of intra-reader assignment of diagnosis and severity of findings between PET/CT and PET/MR when evaluated by two blinded experienced nuclear medicine physicians. These results suggest PET/MR brain scans acquired on hybrid PET/MR are of diagnostic quality and interpretation results compare favourably to PET/CT.

Prior to widespread implementation of PET/MR for dementia evaluation; PET results obtained by PET/MR need to be validated and compared to PET/CT.

Friedman, K, Rakheja, R, Shepherd, T, Bartlett, R, Ding, Y, Boada, F, PET/CT versus PET/MR for the Clinical Evaluation of Patients with Dementia: Comparison of Visual Interpretation by Two Experienced Readers.  Radiological Society of North America 2013 Scientific Assembly and Annual Meeting, December 1 - December 6, 2013 ,Chicago IL. http://archive.rsna.org/2013/13028628.html