123I-FP-CIT SPECT in the differential diagnosis between dementia with Lewy bodies and other dementias

Abstract

Aim: To systematically review the utility of dopamine system imaging using 123I-FP-CIT SPECT in the differential diagnosis between dementia with Lewy bodies (DLB) and other dementia syndromes.

Methods: We searched MEDLINE, CENTRAL and ClinicalTrials.gov to identify studies reporting enough data to determine accuracy measure of 123I-FP-CIT SPECT in differentiating between DLB and other dementia syndromes. Studies including patients with Parkinson's disease or other parkinsonisms associated with abnormal DAT imaging were excluded. The methodological quality of studies was evaluated with QUADAS-2.

Results: Eight studies were included. Studies adopting a clinical diagnosis as a reference standard showed sensitivity and specificity values of DaTSCAN in differentiating between DLB and non-DLB dementia syndromes (all subtypes, AD and FTD) consistently higher than 80%, both considering a visual and a semiquantitative analysis. The meta-analyses from the three studies using a neuropathological reference standard yielded sensitivity and specificity values higher than those adopting a clinical diagnostic reference.

Conclusions: 123I-FP-CIT SPECT can represent an accurate method to differentiate between DLB and other dementia syndromes. However, most data in the literature derive from studies adopting the clinical diagnosis as the reference diagnostic standard and which are therefore intrinsically unable to demonstrate an accuracy of DAT imaging above that of careful clinical diagnosis alone. The very few studies providing information on the neuropathologic correlation for the DaTSCAN findings show however high sensitivity and specificity values, suggesting that SPECT scan is more accurate than clinical diagnosis and may prove useful in supporting the clinical diagnosis of DLB.

Keywords: 123I-FP-CIT single photon emission computed tomography; Alzheimer's disease; Dementia with Lewy bodies; Meta-analysis; Sensitivity; Specificity.