Biomarkers.

Background: Dopamine transporter (I-FP-CIT) single-photon emission tomography (SPECT) and I-meta-iodobenzylguanidine (I-MIBG) image play roles as indicative biomarkers in diagnosing patients with dementia with Lewy bodies (DLB). Brain- and body-first subtypes of DLB were hypothesized implying that subset of DLB may have normal I-FP-CIT or I-MIBG results, respectively. The purpose of this study was to explore the diagnostic sensitivity of two combination imaging modalities (I-FP-CIT SPECT and I-MIBG image) in patients with DLB and examine the clinical difference between brain- and body-first subtype.

Method: Possible DLB patients, defined by the fourth consensus DLB criteria, who underwent both I-FP-CIT SPECT and I-MIBG image was retrospectively collected. Semi-automated software and their results were utilized to define abnormality for both scans. Demographic data, cognition, motor, and core features were compared between the brain-first and body first DLB subgroups.

Result: Of the 114 patients with DLB, 66 underwent both scans. Mean (SD) age was 74.1 (7.1) years, male was predominant (62.1%), min-mental state examination total score was 21.7 (4.8) and unified Parkinson's disease rating scale motort subscore was 14.7 (4.8). Thirty-six (54.5%) patients showed both abnormal scans and four patients (6.1%) were both normal scans. Seventeen patients (25.8%) showed abnormal I-FP-CIT result with normal I-MIBG result (brain-first DLB), nine patients (13.6%) showed normal I-FP-CIT result with abnormal I-MIBG result (body-first DLB). No clinical differences were observed between brain-first and body-first DLB subtypes.

Conclusion: Approximately 40% of DLB patients displayed normal result in either image. Normal results of a single imaging test may not refute the possibility of DLB. No clinical difference was observed between brain- and body-first DLB subtypes.