Diagnosis of dementia with Lewy bodies: diagnostic performance of combined 123I-IMP brain perfusion SPECT and 123I-MIBG myocardial scintigraphy

OBJECTIVE We assessed the value of combining (123)I-IMP brain perfusion SPECT and (123)I-MIBG myocardial scintigraphy for the discrimination of dementia with Lewy bodies (DLB) from other types of dementia. METHODS We subjected 252 consecutive patients with clinically suspected DLB to both (123)I-IMP brain perfusion SPECT and (123)I-MIBG myocardial scintigraphy. Patients with Parkinson's disease were included. The 252 patients were randomly assigned to an estimation (n = 152) or a validation group (n = 100). Using univariate analysis, we first analyzed the relationship between various variables and the presence or absence of DLB in estimation group and then proceeded to multivariate analysis to obtain a combined index that predicted the likelihood of DLB. The diagnostic value of the index was assessed by calculating the area under the receiver operating characteristic (ROC) curve (AUC) with the cutoff value selected from the ROC curve. We then tested the predictive accuracy of the index in validation group. RESULTS The combined index was an arithmetic expression that combined the age, early (123)I-MIBG heart-to-mediastinum uptake (E-H/M) ratio, and the parietal lobe hypoperfusion score. Values for the AUC of the combined index, the E-H/M ratio, the parietal lobe hypoperfusion score, and the patient age in validation group were 0.95, 0.90, 0.72, and 0.73, respectively. There was a significant difference in the AUC of the combined index among other indices (p < 0.05). The sensitivity, specificity, and accuracy of the combined index for a diagnosis of probable DLB in validation group were 88, 87, and 87 %, respectively. CONCLUSIONS The combinational diagnosis based on (123)I-IMP brain perfusion SPECT, (123)I-MIBG myocardial scintigraphy, and the patient age is a simple and reliable means for predicting probable DLB.