Potential diagnostic value of 131I-MIBG myocardial scintigraphy in discrimination between Alzheimer disease and dementia with Lewy bodies.

OBJECTIVES: Clinical difficulty to discriminate between the Alzheimer disease (AD) and dementia with Lewy bodies (DLB) has led researchers to focus on highly sensitive functional imaging modalities. The aim of the present study was to assess 131I-MIBG cardiac imaging to distinguish between AD and DLB.

PATIENTS AND METHODS: Seventeen patients who were known cases of dementia underwent 131I-MIBG myocardial scintigraphy to differentiate AD from DLB. Planar and 131I-MIBG SPECT were obtained 2h after the injection of 1mCi 131I-MIBG on a dual head gamma camera. The visual assessment of the heart uptake compared with lungs and the quantification based on the heart to mediastinal ratio (HMR) were done. The cardiac receiver operating characteristic (ROC) curve was designed for the optimal HMR cut-off values to predict the diagnoses of the patients. The diagnoses were clinically confirmed during the follow up of 14±8.2 months.

RESULTS: Out of 17 patients (13 males; 76.5%), 10 patients had AD (7 males; 70%) and 7 patients had DLB (6 males; 85%). The pooled HMR was 1.74±0.33 in the study population; with 1.95±0.22 in the AD group and 1.43±0.20 in the DLB group to demonstrate significantly different HMR scores between patients with AD and DLB (p value=0.001). The visual interpretation was positive in 10 patients (accuracy of 88.2%). The shortest distance on the ROC curve to the optimal value corresponding to HMR=1.57 identified 10 patients with a high HMR (positive cardiac uptake) and 7 patients with a low HMR (negative cardiac uptake), the accuracy calculated at 88.2%.

CONCLUSION: 131I-MIBG myocardial scintigraphy is a potential alternative diagnostic modality for discrimination between AD and DLB when 123I is not available.