The importance of accurate and early diagnosis of dementia with Lewy bodies (DLB) lies in its pharmacological management. Delayed imaging of cardiac I-123-MIBG scintigraphy allows differentiation between DLB and other neurodegenerative diseases with cognitive impairment. The aim of this study was to assess the utility of early imaging of cardiac I-123-MIBG scintigraphy for differentiating DLB from others neurodegenerative disease with cognitive impairment. Material and methods: We assess retrospectively 106 patients (51 men, mean age 78 years) with cognitive impairment that underwent a cardiac I-123-MIBG study. Planar images were acquired in anterior view of the thorax 15 min (early) and 4 h (delayed) after tracer administration. The heart-to-mediastinum ratios (HMR) at 15 m (HMR15m) and at 4 h (HMR4h) were obtained. Results: After four years, 52 patients were diagnosed of DLB.HMR15m and HMR4h were significantly inferior in DLB respect to the others neurodegenerative diseases (1,27 +/- 0,15 vs 1,76 +/- 0,15,p < 0,05) and (1,14 +/- 0,13 vs 1,68 +/- 0,19,p < 0.01), respectively. The ROC analysis showed a HMR15m cut off point of 1.56 to differentiated DLB from the other dementias with a sensitivity and a specificity of 98%. Conclusions: Early imaging of cardiac I-123-MIBG scintigraphy can help to differentiate DLB from other neurodegenerative diseases with cognitive impairment. (c) 2012 Elsevier Espana, S.L. and SEMNIM. All rights reserved.