Clinical Validation and Correlates of the Cingulate Island Sign Visual Rating Scale for the Diagnosis of Dementia with Lewy Bodies

Abstract

AbstractBackgroundThe cingulate island sign (CIS) is a metabolic pattern on [18F]fluorodeoxyglucose ([18F]FDG) positron emission tomography (PET) associated with dementia with Lewy bodies (DLB). The aim of this study was to validate the visual CIS rating scale (CISRs) for the diagnosis of DLB and to explore the clinical correlates.MethodThis single‐center, retrospective study included 166 consecutive patients with DLB and 161 patients with Alzheimer’s disease (AD). The CIS on [18F]FDG‐PET scans was rated using the CISRs (0‐4) independently by three readers blinded to other patient data.ResultThe optimal cut‐off to differentiate DLB from AD was a CISRs score ≥ 1 (sensitivity = 66%, specificity = 84%) whereas a CISRs score ≥ 2 (sensitivity = 58%, specificity = 92%) was optimal to differentiate amyloid positive DLB (n = 43 (82.7%)) and AD. To identify DLB with abnormal (n = 53 (72.6%)) versus normal (n = 20 (27.4%)) dopamine transporter imaging (DaT), a CISRs cut‐off of 4 had a specificity of 95% for abnormal DaT. DLB patients with a CISRs score of 4 performed significantly better in tests of free verbal recall and picture based cued recall, but worse in test of processing speed compared with DLB with a CISRs score of 0.ConclusionThis study confirms the CISRs as a valid marker for the diagnosis of DLB with a high specificity and a lower, but acceptable, sensitivity. Concomitant AD pathology does not influence diagnostic accuracy of the CISRs. In DLB patients, presence of CIS is associated with relative preserved memory function and impaired processing speed.