Diagnostic Criteria for Dementia with Lewy Bodies: Updates and Future Directions

The aim of this article is to describe the 2017 revised consensus criteria for the clinical diagnosis of dementia with Lewy bodies (DLB) with future directions for the diagnostic criteria. The criteria for the clinical diagnosis of probable and possible DLB were first published as the first consensus report in 1996 and were revised in the third consensus report in 2005. After discussion at the International DLB Conference in Fort Lauderdale, Florida, USA, in 2015, the International DLB Consortium published the fourth consensus report including the revised consensus criteria in 2017. The 2017 revised criteria clearly distinguish between clinical features and diagnostic biomarkers. Significant new information about previously reported aspects of DLB has been incorporated, with increased diagnostic weighting given to rapid eye movement (REM) sleep behavior disorder (RBD) and iodine-123-metaiodobenzylguanidine (MIBG) myocardial scintigraphy. Future directions include the development of the criteria for early diagnosis (prodromal DLB) and the establishment of new biomarkers that directly indicate Lewy-related pathology, including α-synuclein imaging, biopsies of peripheral tissues (skin, etc.) for the demonstration of α-synuclein deposition, and biochemical markers (cerebrospinal fluid/blood), as well as the pathological evaluation of the sensitivity and specificity of the 2017 revised diagnostic criteria. In conclusion, the revised consensus criteria for the clinical diagnosis of DLB were reported with the incorporation of new information about DLB in 2017. Future directions include the development of the criteria for early diagnosis and the establishment of biomarkers directly indicative of Lewy-related pathology.

¹²³I-Meta-iodobenzylguanidine Sympathetic Imaging: Standardization and Application to Neurological Diseases / 전남의대학술지

¹²³I-meta-iodobenzylguanidine (MIBG) has become widely applied in Japan since its introduction to clinical cardiology and neurology practice in the 1990s. Neurological studies found decreased cardiac uptake of ¹²³I-MIBG in Lewy-body diseases including Parkinson's disease and dementia with Lewy bodies. Thus, cardiac MIBG uptake is now considered a biomarker of Lewy body diseases. Although scintigraphic images of ¹²³I-MIBG can be visually interpreted, an average count ratio of heart-to-mediastinum (H/M) has commonly served as a semi-quantitative marker of sympathetic activity. Since H/M ratios significantly vary according to acquisition and processing conditions, quality control should be appropriate, and quantitation should be standardized. The threshold H/M ratio for differentiating Lewy-body disease is 2.0-2.1, and was based on standardized H/M ratios to comparable values of medium-energy collimators. Parkinson's disease can be separated from various types of parkinsonian syndromes using cardiac ¹²³I-MIBG, whereas activity is decreased on images of Lewy-body diseases using both ¹²³I-ioflupane for the striatum and ¹²³I-MIBG. Despite being a simple index, the H/M ratio of ¹²³I-MIBG uptake is reproducible and can serve as an effective tool to support a diagnosis of Lewy-body diseases in neurological practice.

¹²³I-Meta-iodobenzylguanidine Sympathetic Imaging: Standardization and Application to Neurological Diseases / 전남의대학술지

¹²³I-meta-iodobenzylguanidine (MIBG) has become widely applied in Japan since its introduction to clinical cardiology and neurology practice in the 1990s. Neurological studies found decreased cardiac uptake of ¹²³I-MIBG in Lewy-body diseases including Parkinson's disease and dementia with Lewy bodies. Thus, cardiac MIBG uptake is now considered a biomarker of Lewy body diseases. Although scintigraphic images of ¹²³I-MIBG can be visually interpreted, an average count ratio of heart-to-mediastinum (H/M) has commonly served as a semi-quantitative marker of sympathetic activity. Since H/M ratios significantly vary according to acquisition and processing conditions, quality control should be appropriate, and quantitation should be standardized. The threshold H/M ratio for differentiating Lewy-body disease is 2.0-2.1, and was based on standardized H/M ratios to comparable values of medium-energy collimators. Parkinson's disease can be separated from various types of parkinsonian syndromes using cardiac ¹²³I-MIBG, whereas activity is decreased on images of Lewy-body diseases using both ¹²³I-ioflupane for the striatum and ¹²³I-MIBG. Despite being a simple index, the H/M ratio of ¹²³I-MIBG uptake is reproducible and can serve as an effective tool to support a diagnosis of Lewy-body diseases in neurological practice.

Evaluation of cardiac mitochondrial function by a nuclear imaging technique using technetium-99m-MIBI uptake kinetics

Mitochondria play an important role in energy production for the cell. The proper function of a myocardial cell largely depends on the functional capacity of the mitochondria. Therefore it is necessary to establish a novel and reliable method for a non-invasive assessment of mitochondrial function and metabolism in humans. Although originally designed for evaluating myocardial perfusion, [99m]Tc-MIBI can be also used to evaluate cardiac mitochondrial function. In a clinical study on ischemic heart disease, reverse redistribution of [99m]Tc-MIBI was evident after direct percutaneous transluminal coronary angioplasty. The presence of increased washout of [99m]Tc-MIBI was associated with the infarct-related artery and preserved left ventricular function. In non-ischemic cardiomyopathy, an increased washout rate of [99m]Tc-MIBI, which correlated inversely with left ventricular ejection fraction, was observed in patients with congestive heart failure. Increased [99m]Tc-MIBI washout was also observed in mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes [MELAS] and in doxorubicin-induced cardiomyopathy. Noninvasive assessment of cardiac mitochondrial function could be greatly beneficial in monitoring possible cardiotoxic drug use and in the evaluation of cardiac damage in clinical medicine