Contribution of quantitative I-123-ioflupane SPECT/CT to the differential diagnosis of dementia with lewy bodies.

PURPOSE: Quantification of I-123-ioflupane uptake using modern SPECT/CT improves diagnostic accuracy for disorders affecting the nigrostriatal pathway. This study assessed whether absolute and relative standardized uptake values (SUV) could distinguish dementia with Lewy bodies (DLB) from non-DLB in patients with suspected DLB and explored associations with core clinical features, including visual hallucinations (VH) and REM sleep behavior disorder (RBD).

METHODS

Seventy-four patients (mean age 71.5 ± 9.26 years; 39% female) were retrospectively included. All underwent I-123-ioflupane SPECT/CT imaging with both iterative (Flash 3D) and quantitative reconstructions. SUVmax, SUVmean, and relative SUV (rSUV) values were extracted for the caudate, putamen, and striatum. Uptake metrics were compared between DLB and non-DLB groups and analyzed in relation to clinical features, including visual hallucinations (VH) and REM sleep behavior disorder (RBD).

RESULTS

Visual assessment classified 28/74 scans (38%) as abnormal (sensitivity 90%, specificity 80%, AUC 0.846). Quantitative SUVmax in the striatum and putamen showed the highest diagnostic performance (AUC up to 0.83). Striatal SUVmax remained an independent predictor of DLB in multivariable analysis (OR = 0.58, p = 0.003). Patients with VH had significantly lower striatal SUVmax than those without (p = 0.004), with an optimal cutoff of ≤ 6.0 g/mL (AUC = 0.70, sensitivity 64.3%, specificity 80.4%). No significant differences were observed for RBD.

CONCLUSION

Quantitative I-123-ioflupane uptake assessment using SUV measures offers clinically relevant diagnostic value for differentiating DLB from other neurodegenerative diseases. It also helps in identifying patients with visual hallucinations, supporting the broader integration of SUV-based dopaminergic imaging into clinical workflows.