Abstract
1702
Objectives: The term Lewy body disease (LBD) refers to disorders characterized by the neural inclusion of pathologic-synuclein aggregates called Lewy bodies, and clinical manifestations of LBD include dementia with Lewy bodies, Parkinson's disease, Parkinson's disease dementia, and pure autonomic failure. Patients with LBD usually present with impairment of the sympathetic nervous system and abnormalities on 123I-MIBG myocardial scintigraphy studies. Because myocardial uptake of 123I-MIBG correlates with the functional integrity of adrenergic nervous system, involvement of myocardial postganglionic sympathetic nerves may account for the decrease of myocardial 123I-MIBG uptake [heart-to-mediastinum (H/M) ratio] in patients with LBD. However, some LBD patients showed normal myocardial 123I-MIBG uptake and may not be differentiated from non-LBD patients even using the H/M ratio.The aim of this study whether the washout rate (WR) are useful for diagnosing LBD, especially for the LDB patients with normal early 123I-MIBG H/M ratios.Materials and Methods:We included 479 patients with clinically suspected LBD who had undergone 123I-MIBG early (15 min) and delayed (3 h) myocardial imaging studies. The final diagnosis consisted of LBD in 222 patients (111 males, 111 females; mean age ± SD, 72.1 ± 10.4 years; range, 40 - 89 years) and non-LBD in 257 patients (110 males, 147 females; mean age, 70.8 ± 10.1 years; range, 35 - 92 years). First, we examined the usefulness of early and delayed H/M ratios and WR {[(early H/M ratio)-(delayed H/M ratio)] / (early H/M ratio) × 100} in the diagnosis of LBD in whole cases. Second, we evaluated whether WR can be useful in the group without decrease of H/M ratio (normal 123I-MIBG myocardial uptake group). The Mann-Whitney U test was used to assess the differences between 2 quantitative variables, and the diagnostic performance was evaluated by the area under the curve (AUC) values derived from the receiver operating characteristic (ROC) analysis.Results:In whole analysis, the LBD patients showed significantly lower early H/M ratio (1.9±0.5 vs. 2.9± 0.59, p<0.0001), lower delayed H/M ratio (1.6±0.7 vs. 3.0± 0.7, p<0.0001) and higher WR (46.0±17.3 vs. 24.8±19.0, p<0.0001) than the non-LBD patients. From the ROC analysis, the cutoff values for differentiating LBD from non-LBD were 2.1 [AUC, 0.897; 95% confidence interval (CI), 0.866 - 0.923] for the early H/M ratio, 2.0 (AUC, 0.893; 95% CI, 0.862 - 0.919) for the delayed H/M ratio, and 38.3% (AUC, 0.808; 95% CI, 0.769 - 0.842) for the WR. When we defined the early H/M ratio ≥2.1 as normal 123I-MIBG myocardial uptake group, 291 patients showed normal early myocardial uptake (52 LBD patients; 27 males and 25 females; mean age ± SD, 68.7 ± 13.9 years; range, 40 - 89 years and 239 non-LBD patients; 101 males and 138 females; mean age, 70.7 ± 10.2 years; range, 35 - 92 years). In the normal 123I-MIBG myocardial uptake group, the WR showed significantly higher in LBD patients than in non-LBD patients (29.1±18.7% vs. 22.7±17.0%, p=0.0125).Conclusion:All 3 indices (early and delayed H/M ratios and WR) were useful for diagnosing LBD. Furthermore, even in cases of early normal H/M ratios, acceleration of WR may be observed in LBD patients and WR may be a useful index for diagnosing LBD in such cases.