ANALYSIS OF IOFLUPANE-SPECT FINDINGS USING DATQUANT IN PATIENTS WITH IDIOPATHIC REM SLEEP BEHAVIOR DISORDER

Abstract

Reduced striatonigral uptake on ioflupane SPECT reflects dopamine deficiency, and this finding can be seen in patients with Lewy body disease (LBD) pathology. The patients with idiopathic REM sleep behavior disorder (iRBD) tend to have underlying LBD pathology, and a high percentage ultimately develop clinically-diagnosed dementia with Lewy bodies (DLB) or Parkinson's disease. We analyze ioflupane SPECT findings in patients with iRBD compared to Alzheimer's disease dementia (ADem; uptake tends to be normal) and DLB (uptake tends to be abnormal, using z-scores from DaTQUANT software (GE Healthcare). The mean DaTQUANT z-scores of the caudate and putamen for iRBD, ADem and DLB who had undergone ioflupane SPECT at the Mayo Alzheimer's Disease Research Center were analyzed and compared. Data on 22 iRBD patients (mean age 62.8 ± 7.6 years, 14 male) were analyzed and compared to 16 ADem and 40 DLB patients. The mean z-scores for each group of interest was iRBD - putamen: −0.19 ± 1.35 and caudate −0.09 ± 1.39; ADem - putamen: 0.47 ± 1.80 and caudate 0.89 ± 2.02, DLB - putamen: −1.99 ± 1.28 and caudate −2.40 ± 1.41. iRBD had z-scores which did not differ from ADem (putamen P=0.21, caudate p=0.08), but which were higher than DLB scores (putamen P<0.001, caudate P<0.001). Two (9%) iRBD patients had at least one z-score value <−1.5, compared to 1 (6%) for ADem (this patient had mixed LBD and Alzheimer's disease pathology) and 32 (80%) for DLB. The striatonigral uptake using DaTQUANT quantitation is reduced in a minority of iRBD patients. Analyses using longitudinal ioflupane SPECT and associated quantitation may provide insights on those iRBD patients who are evolving to DLB or Parkinson's disease. Supported by NIH grants (P50 AG016574, U01 AG006786, R01 AG015866, U01 NS100620), grant from GE Healthcare, Mayo Clinic Dorothy and Harry T. Mangurian Jr. Lewy Body Dementia Program, Deal Family Foundation and the Little Family Foundation.