Diagnostic accuracy of cardiac metaiodobenzylguanidine scintigraphy in Parkinson disease

Cardiac 123I-Metaiodobenzylguanidine (MIBG) Scintigraphy in Parkinson's Disease: A Comprehensive Review

Cardiac sympathetic denervation, as documented on 123I-metaiodobenzylguanidine (MIBG) myocardial scintigraphy, is relatively sensitive and specific for distinguishing Parkinson's disease (PD) from other neurodegenerative causes of parkinsonism. The present study aims to comprehensively review the literature regarding the use of cardiac MIBG in PD. MIBG is an analog to norepinephrine. They share the same uptake, storage, and release mechanisms. An abnormal result in the cardiac MIBG uptake in individuals with parkinsonism can be an additional criterion for diagnosing PD. However, a normal result of cardiac MIBG in individuals with suspicious parkinsonian syndrome does not exclude the diagnosis of PD. The findings of cardiac MIBG studies contributed to elucidating the pathophysiology of PD. We investigated the sensitivity and specificity of cardiac MIBG scintigraphy in PD. A total of 54 studies with 3114 individuals diagnosed with PD were included. The data were described as means with a Hoehn and Yahr stage of 2.5 and early and delayed registration H/M ratios of 1.70 and 1.51, respectively. The mean cutoff for the early and delayed phases were 1.89 and 1.86. The sensitivity for the early and delayed phases was 0.81 and 0.83, respectively. The specificity for the early and delayed phases were 0.86 and 0.80, respectively.

Optimal Protocol and Clinical Usefulness of 123I-MIBG Cardiac Scintigraphy for Differentiation of Parkinson's Disease and Dementia with Lewy Body from Non-Parkinson's Diseases

Purpose

123I-metaiodobenzylguanidine (MIBG) cardiac scintigraphy was a useful imaging modality for the diagnosis of Parkinson's disease, but its diagnostic performances were variably reported. This retrospective study compared the diagnostic performances and investigated the optimal imaging protocol of 123I-MIBG cardiac scintigraphy at various imaging time points in patients suspected of Parkinson's disease in clinical practice.

Methods

In patients suspected of Parkinson's disease, clinical records, autonomic function tests, and 123I-MIBG cardiac scintigraphy were retrospectively reviewed. Semi-quantitative parameters such as heart-to-mediastinum ratio (HMR) and washout rate (WR) were calculated and compared at 15 min, 1 h, 2 h, 3 h, and 4 h post-injection (p.i.). of 123I-MIBG cardiac scintigraphy. Group A consisted of Parkinson's disease (PD), Parkinson's disease dementia (PDD), and dementia with Lewy body (DLB), and group B consisted of non-Parkinson's diseases such as multiple system atrophy (MSA), progressive supranuclear palsy (PSP), drug-induced parkinsonism (DIP), essential tremor (ET), Parkinson-plus syndrome (PPS), and unspecified secondary parkinsonism (NA). The diagnostic performances of HMR and WR were compared for differentiation of group A from group B, and their clinical usefulness and optimal imaging time points were explored.

Results

Seventy-eight patients were included in group A (67 PD, 7 PDD, 4 DLB), and 18 patients were included in group B (5 MSA, 3 PSP, 2 DIP, 2 ET, 1 PPS, and 1 NA). Sensitivity, specificity, accuracy, positive predictive value (PPV), and negative predictive value of HMR and WR were maximized at 4 h p.i., (82.1%, 85.7%, 82.6%, 97.0%, and 46.2%; cutoff threshold < 1.717; area under curve 0.8086) and at the time interval between 1 and 4 h p.i. (65.4%, 85.7%, 68.5%, 96.2%, and 30.8%; cutoff threshold > 24.1%; area under curve 0.8246), respectively, and PPVs of both HMR and WR persistently showed greater than 92.7% at earlier time points and shorter time intervals.

Conclusion

This study reassured that 4-h-delayed imaging is recommended for the best diagnostic performances in 123I-MIBG cardiac scintigraphy. Although it showed suboptimal diagnostic performances to differentiate PD, PDD, and DLB from non-Parkinson's diseases, it can be useful as an auxiliary measure for the differential diagnosis in usual clinical practice.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13139-023-00790-w.

Neuromelanin magnetic resonance imaging of substantia nigra and locus coeruleus in Parkinson's disease with freezing of gait

Background

The downregulation of monoamines, especially dopamine in substantia nigra (SN) and norepinephrine in locus coeruleus (LC), may be responsible for freezing of gait (FOG) pathological basis in Parkinson's disease (PD).

Methods

Thirty-two Parkinson's disease patients with freezing of gait (PD-FOG), 32 Parkinson's disease patients without freezing of gait (PD-NFOG) and 32 healthy controls (HC) underwent neuromelanin magnetic resonance imaging (NM-MRI). The volume, surface area and contrast to noise ratio (CNR) of SN and LC were measured and compared. The correlation analyses were conducted between the measurements of SN and LC with clinical symptoms. We plotted the receiver operating characteristic (ROC) curve and determined the sensitivity and specificity of the CNR of SN and LC for discriminating the PD-FOG from the PD-NFOG.

Results

Both PD-FOG and PD-NFOG showed decreased volume, surface area and CNR of SN compared with HC. The PD-FOG exhibited decreased volume and surface area of LC compared with both PD-NFOG and HC groups, and decreased CNR of LC compared with HC group. The volume, surface area and CNR of SN were negatively correlated with the Unified Parkinson's Disease Rating Scale part III scores. The illness durations in PD patients were negatively correlated with the volume, surface area of SN, while not the CNR. And the volume and surface area of LC were negatively correlated with new freezing of gait questionnaire scores. ROC analyses indicated that the area under the curve (AUC) was 0.865 and 0.713 in the CNR of SN and LC, respectively, in PD versus HC, whereas it was 0.494 and 0.637 respectively, in PD-FOG versus PD-NFOG. Among these, for discriminating the PD from the HC, the sensitivity and specificity in the CNR of the SN was 90.6 and 71.9%, respectively, when the cut-off value was set at 2.101; the sensitivity and specificity in the CNR of the LC was 90.6 and 50.0%, respectively, when the cut-off value for CNR was set at 1.411.

Conclusion

The dopaminergic changes in the SN were found across both PD-FOG and PD-NFOG, whilst LC noradrenergic neuron reduction was more evident in PD-FOG.

Cardiac sympathetic innervation in Parkinson's disease versus multiple system atrophy

Purpose

The aims of this study were to evaluate the diagnostic accuracy of the dual imaging method combining cardiac iodine-¹²³-metaiodobenzylguanidine single-photon emission computed tomography combined with low-dose chest computed tomography compared to routine cardiac scintigraphy, and assess regional differences in tracer distribution and the relationships between imaging and autonomic function in Parkinson’s disease and multiple system atrophy.

Methods

A prospective study including 19 Parkinson’s disease and 12 multiple system atrophy patients was performed. Patients underwent clinical evaluation, iodine-¹²³-metaiodobenzylguanidine single-photon emission computed tomography combined with chest computed tomography, planar scintigraphy, and cardiovascular autonomic function tests.

Results

Co-registration of single-photon emission computed tomography and chest computed tomography resulted in three groups with distinct patterns of tracer uptake: homogeneous, non-homogeneously reduced and absent. There was a significant difference in group allocation among patients with multiple system atrophy and Parkinson’s disease (p = 0.001). Most multiple system atrophy patients showed homogeneous uptake, and the majority of Parkinson’s disease patients showed absent cardiac tracer uptake. We identified a pattern of heterogeneous cardiac tracer uptake in both diseases with reductions in the apex and the lateral myocardial wall. Sympathetic dysfunction reflected by a missing blood pressure overshoot during Valsalva manoeuvre correlated with cardiac tracer distribution in Parkinson’s disease patients (p < 0.001).

Conclusions

The diagnostic accuracy of the dual imaging method and routine cardiac scintigraphy were similar. Anatomical tracer allocation provided by the dual imaging method of cardiac iodine-¹²³-metaiodobenzylguanidine single-photon emission computed tomography and chest computed tomography identified a heterogeneous subgroup of Parkinson’s disease and multiple system atrophy patients with reduced cardiac tracer uptake in the apex and the lateral wall. Sympathetic dysfunction correlated with cardiac imaging in Parkinson’s disease patients.

It Is Time to Study Overlapping Molecular and Circuit Pathophysiologies in Alzheimer's and Lewy Body Disease Spectra

Alzheimer's disease (AD) is the leading cause of dementia due to neurodegeneration and is characterized by extracellular senile plaques composed of amyloid β1 - 42 (Aβ) as well as intracellular neurofibrillary tangles consisting of phosphorylated tau (p-tau). Dementia with Lewy bodies constitutes a continuous spectrum with Parkinson's disease, collectively termed Lewy body disease (LBD). LBD is characterized by intracellular Lewy bodies containing α-synuclein (α-syn). The core clinical features of AD and LBD spectra are distinct, but the two spectra share common cognitive and behavioral symptoms. The accumulation of pathological proteins, which acquire pathogenicity through conformational changes, has long been investigated on a protein-by-protein basis. However, recent evidence suggests that interactions among these molecules may be critical to pathogenesis. For example, Aβ/tau promotes α-syn pathology, and α-syn modulates p-tau pathology. Furthermore, clinical evidence suggests that these interactions may explain the overlapping pathology between AD and LBD in molecular imaging and post-mortem studies. Additionally, a recent hypothesis points to a common mechanism of prion-like progression of these pathological proteins, via neural circuits, in both AD and LBD. This suggests a need for understanding connectomics and their alterations in AD and LBD from both pathological and functional perspectives. In AD, reduced connectivity in the default mode network is considered a hallmark of the disease. In LBD, previous studies have emphasized abnormalities in the basal ganglia and sensorimotor networks; however, these account for movement disorders only. Knowledge about network abnormalities common to AD and LBD is scarce because few previous neuroimaging studies investigated AD and LBD as a comprehensive cohort. In this paper, we review research on the distribution and interactions of pathological proteins in the brain in AD and LBD, after briefly summarizing their clinical and neuropsychological manifestations. We also describe the brain functional and connectivity changes following abnormal protein accumulation in AD and LBD. Finally, we argue for the necessity of neuroimaging studies that examine AD and LBD cases as a continuous spectrum especially from the proteinopathy and neurocircuitopathy viewpoints. The findings from such a unified AD and Parkinson's disease (PD) cohort study should provide a new comprehensive perspective and key data for guiding disease modification therapies targeting the pathological proteins in AD and LBD.

Diagnostic Value of the Early Heart-to-Mediastinum Count Ratio in Cardiac 123I-mIBG Imaging for Parkinson's Disease

BACKGROUND

Early diagnosis of Parkinson's disease (PD) is of primary importance. The delayed (3-4 h after injection) Iodine-123-Metaiodobenzylguanidine (123I-mIBG) scintigraphy has been proven to be effective in early differential diagnosis for Lewy body disease. But early imaging (15-30 min after injection) has only been marginally studied for its possible diagnostic role. In this prospective study, a threshold for the early Heart-to-Mediastinum (H/M) count ratio has been investigated, obtaining a diagnostic accuracy analogous to conventional, delayed imaging.

METHODS

One hundred and eight patients with suspected Parkinson's disease (PD) were acquired after 15 and 240 minutes from the injection of 150-185 MBq of 123I-mIBG. The early and late H/M (He/Me and Hl/Ml) were evaluated by drawing Region-of-Interests on the heart and the upper half of the mediastinum. Optimal threshold (Youden index) and overall predictive performance were determined by receiver operating characteristic curve, classifying tentatively patients having an Hl/Ml lower than 1.6 as suffering from PD.

RESULTS

He/Me was not significantly different from Hl/Ml (p-value=0.835). The Area-under-curve was 0.935 (95%CI: 0.845-1.000). The He/Me optimal threshold was 1.66, with sensitivity, specificity, and diagnostic accuracy of 95.5%, 85.7 and 90.7% respectively.

CONCLUSION

The He/Me Ratio is almost as accurate as the widely used delayed 123I-mIBG imaging, reducing the burden of delayed imaging but preserving the diagnostic accuracy of the method. Moreover the differential diagnosis in Parkinson's disease can be made in just 25 minutes against the 4 hours currently needed, lowering costs of the healthcare system and improving patients compliance.

Electrogastrography for diagnosis of early-stage Parkinson's disease

INTRODUCTION

Patients with Parkinson's disease (PD) often present with gastric symptoms. Electrogastrography (EGG) can noninvasively assess gastric electric activity and may be useful for early PD diagnosis. The present study aimed to compare the efficacy of EGG in early PD diagnosis with those of ¹²³I-metaiodobenzylguanidine (MIBG) myocardial scintigraphy and odor stick identification test -Japanese version (OSIT-J).

METHODS

Thirty-seven untreated PD patients (mean age ± SD, 66 ± 8years; disease duration < 3 years) and 20 healthy control subjects (68 ± 6.9 years) were recruited. EGG and OSIT-J were performed in both groups, and MIBG scintigraphy in the PD group. EGG parameters were assessed in the preprandial and early and late postprandial segments using power spectrum analysis.

RESULTS

Irregular EGG waves were observed in PD patients. The preprandial instability coefficient of dominant frequency (ICDF), an index of EGG irregularity, in PD patients (9.5% [6.3%]) was higher than that in controls (3.9% [3.9%], p = 0.00005). The OSIT-J score was also lower in PD patients (4.6 [3.3]) than in controls (7.7 [3.3], p = 0.006). In receiver operating characteristics analyses, the areas under the curves of preprandial ICDF and OSIT-J were 0.83 and 0.72, respectively. The sensitivities of preprandial ICDF and MIBG (delayed-phase) scintigraphy were 73% and 70%, respectively.

CONCLUSIONS

Early and untreated PD patients showed irregular EGG waves and high ICDF. EGG showed better accuracy than the olfactory test for early PD diagnosis and similar sensitivity to MIBG scintigraphy.

[A Nationwide Survey on Additional Scan in Nuclear Medicine Imaging]

The aim of the present study was to clarify the routine protocols and the frequency of added or omitted imaging on nuclear medicine imaging in Japan. A nationwide survey on routine protocols and current state of added or omitted imaging in major nuclear medicine imaging were performed for Japanese nuclear medicine technologist. The survey showed that the routine protocols were almost 100% fixed, some of the routine protocols were found to be useful and percentage of imaging techniques such as single photon emission computed tomography/computed tomography that increased patient burden and reduced through put were low. Furthermore, the survey showed that additional or omission imaging were frequently performed on bone scintigraphy and positron emission tomography and added or omitted judgements were often depend upon the rule of thumb by nuclear medicine technologist. In this study, we have concluded that the quality of examination and the diagnosis might depend on the knowledge of nuclear medicine technologist, performed added or omitted imaging.

Takotsubo syndrome in a heart transplant recipient with poor cardiac sympathetic reinnervation

Takotsubo syndrome (TTS), also referred to as stress cardiomyopathy, is characterized by transient left ventricular apical ballooning in the absence of obstructive coronary artery disease. Catecholamine-induced cardiac injury or vasospasm has been implicated in this pathophysiology. We present a case of a 67-year-old man 10 years after heart transplantation diagnosed with TTS. Sympathetic reinnervation could not be detected by iodine-123 meta iodobenzylguanidine uptake, suggesting that TTS can occur in the absence of functional sympathetic nerve systems reconstruction.

Pure Autonomic Failure

Pure autonomic failure (PAF) is a neurodegenerative disorder of the autonomic nervous system clinically characterized by orthostatic hypotension. The disorder has also been known as Bradbury-Eggleston syndrome, named for the authors of the 1925 seminal description. Patients typically present in midlife or later with orthostatic hypotension or syncope. Autonomic failure may also manifest as genitourinary, bowel, and thermoregulatory dysfunction. With widespread involvement, patients may present to a variety of different specialties and require multidisciplinary treatment approaches. Pathologically, PAF is characterized by predominantly peripheral deposition of α-synuclein. However, patients with PAF may progress into other synucleinopathies with central nervous system involvement.

Parkinsonism Relating to Intoxication with Glyphosate

We herein report the case of a 38-year-old man who developed parkinsonism 4 years after ingesting glyphosate. The patient presented with right-sided bradykinesia and cogwheel rigidity without autonomic symptoms. Magnetic resonance imaging of the brain and [123I]-metaiodobenzylguanidine myocardial scintigraphy were normal. A drastic response to levodopa and the presence of levodopa-induced dyskinesia without strong non-motor symptoms were seen in this patient. We considered that young-onset atypical parkinsonism was associated with a history of sublethal glyphosate ingestion. Epidemiologic investigations have shown that exposure to pesticides is a risk factor for Parkinson's disease (PD). Our findings support the notion that glyphosate exposure might be related to the onset of PD.

Autonomic dysfunction in genetic forms of synucleinopathies

The discovery of genetic links between alpha-synuclein and PD has opened unprecedented opportunities for research into a new group of diseases, now collectively known as synucleinopathies. Autonomic dysfunction, including cardiac sympathetic denervation, has been reported in familial forms of synucleinopathies that have Lewy bodies at the core of their pathogenesis. SNCA mutations and multiplications, LRRK2 disease with Lewy bodies as well as other common, sporadic forms of idiopathic PD, MSA, pure autonomic failure, and dementia with Lewy bodies have all been associated with dysautonomia. By contrast, in familial cases of parkinsonism without Lewy bodies, such as in PARK2, the autonomic profile remains normal throughout the course of the disease. The degeneration of the central and peripheral autonomic systems in genetic as well as sporadic forms of neurodegenerative synucleinopathies correlates with the accumulation of alpha-synuclein immunoreactive-containing inclusions. Given that dysautonomia has a significant impact on the quality of life of sufferers and autonomic symptoms are generally treatable, a prompt diagnostic testing and treatment should be provided. Moreover, new evidence suggests that autonomic dysfunction can be used as an outcome prediction factor in some forms of synucleinopathies or premotor diagnostic markers that could be used in the future to define further research avenues. In this review, we describe the autonomic dysfunction of genetic synucleinopathies in comparison to the dysautonomia of sporadic forms of alpha-synuclein accumulation and provide the reader with an up-to-date overview of the current understanding in this fast-growing field. © 2018 International Parkinson and Movement Disorder Society.

Evaluation of autonomic functions of patients with multiple system atrophy and Parkinson's disease by head-up tilt test

The aim of this study was to evaluate the autonomic neural function in Parkinson's disease (PD) and multiple system atrophy (MSA) with head-up tilt test and spectral analysis of cardiovascular parameters. This study included 15 patients with MSA, 15 patients with PD, and 29 healthy control (HC) subjects. High frequency power of the RR interval (RR-HF), the ratio of low frequency power of RR interval to RR-HF (RR-LF/HF) and LF power of systolic BP were used to evaluate parasympathetic, cardiac sympathetic and vasomotor sympathetic functions, respectively. Both patients with PD and MSA showed orthostatic hypotension and lower parasympathetic function (RR-HF) at tilt position as compared to HC subjects. Cardiac sympathetic function (RR-LF/HF) was significantly high in patients with PD than MSA at supine position. RR-LF/HF tended to increase in MSA and HC, but decreased in PD by tilting. Consequently, the change of the ratio due to tilting (ΔRR-LF/HF) was significantly lower in patients with PD than in HC subjects. Further analysis showed that compared to mild stage of PD, RR-LF/HF at the supine position was significantly higher in advanced stage. By tilting, it was increased in mild stage and decreased in the advanced stage of PD, causing ΔRR-LF/HF to decrease significantly in the advanced stage. Thus, we demonstrated that spectral analysis of cardiovascular parameters is useful to identify sympathetic and parasympathetic disorders in MSA and PD. High cardiac sympathetic function at the supine position, and its reduction by tilting might be a characteristic feature of PD, especially in the advanced stage.

Neuropathology of Nonmotor Symptoms of Parkinson's Disease

Parkinson's disease (PD), a multiorgan neurodegenerative disorder associated with α-synuclein deposits throughout the nervous system and many organs, is clinically characterized by motor and nonmotor features, many of the latter antedating motor dysfunctions by 20 or more years. The causes of the nonmotor manifestations such as olfactory, autonomic, sensory, neuropsychiatric, visuospatial, sleep, and other disorders are unlikely to be related to single lesions. They are mediated by the involvement of both dopaminergic and nondopaminergic systems, and diverse structures outside the nigrostriatal system that is mainly responsible for the motor features of PD. The nonmotor alterations appear in early/prodromal stages of the disease and its further progression, suggesting a topographical and chronological spread of the lesions. This lends further support for the notion that PD is a multiorgan proteinopathy, although the exact relationship between presymptomatic and later developing nonmotor features of PD and neuropathology awaits further elucidation.

131I-MIBG myocardial scintigraphy for differentiation of Parkinson's disease from multiple system atrophy or essential tremor in Chinese population

OBJECTIVE

Clinical distinction of Parkinson's disease (PD) from multiple system atrophy (MSA) or essential tremor (ET) is sometimes difficult. The purpose of this study was to assess changes in cardiac sympathetic nerve function in PD, MSA, and ET by ¹³¹I-MIBG myocardial scintigraphy METHODS: Patients with PD (25), MSA (18), or ET (11) and 10 healthy controls (HC) were enrolled. ¹³¹I-MIBG myocardial scintigraphy was performed for each subject, and heart/mediastinum (H/M) ratios were calculated at two sample times (15min and 4h after the injection of ¹³¹I-MIBG), representing the ¹³¹I-MIBG myocardial uptake ratios. The washout ratio (WOR) of MIBG which indicates the activity tone of the presynaptic sympathetic nerves was calculated for each subject.

RESULTS

The H/M ratios at the two sample times (15min and 4h) were 1.65±0.36 and 1.50±0.43 in the PD group, 1.97±0.36 and 2.08±0.57 in the MSA group, 2.34±0.34 and 2.46±0.51 in the ET group, and 2.41±0.26 and 2.66±0.47 in the HC group. The H/M ratios at the two sample times were lower in the PD group than in the MSA, ET, or HC groups, with statistical significance (all P<0.05). The H/M ratios at the two sample times were significantly lower in the MSA group than in the HC group (all P<0.05). There was no significant difference in H/M ratios at either sample time between the ET and HC group (all P>0.05). The washout ratios (WORs) of MIBG were significantly increased in PD group compared with those in MSA, ET and HC groups. In subgroup analysis, The H/M ratios at the two sample times were decreased in early PD group compared with those in early MSA and early ET groups, with statistical significance (all P<0.05).

CONCLUSIONS

Cardiac sympathetic dysfunction can occur in both PD and MSA patients, especially in PD patients, whereas it remains normal in ET patients. ¹³¹I-MIBG myocardial scintigraphy can help distinguish patients with PD from those with MSA or ET with good sensitivity and specificity.

Biomarkers in Prodromal Parkinson Disease: a Qualitative Review

BACKGROUND

Over the past several years, the concept of prodromal Parkinson disease (PD) has been increasingly recognized. This term refers to individuals who do not fulfill motor diagnostic criteria for PD, but who have clinical, genetic, or biomarker characteristics suggesting risk of developing PD in the future. Clinical diagnosis of prodromal PD has low specificity, prompting the need for objective biomarkers with higher specificity. In this qualitative review, we discuss objectively defined putative biomarkers for PD and prodromal PD.

METHODS

We searched Pubmed and Embase for articles pertaining to objective biomarkers for PD and their application in prodromal cohorts. Articles were selected based on relevance and methodology.

KEY FINDINGS

Objective biomarkers of demonstrated utility in prodromal PD include ligand-based imaging and transcranial sonography. Development of serum, cerebrospinal fluid, and tissue-based biomarkers is underway, but their application in prodromal PD has yet to meaningfully occur. Combining objective biomarkers with clinical or genetic prodromal features increases the sensitivity and specificity for identifying prodromal PD.

CONCLUSIONS

Several objective biomarkers for prodromal PD show promise but require further study, including their application to and validation in prodromal cohorts followed longitudinally. Accurate identification of prodromal PD will likely require a multimodal approach. (JINS, 2016, 22, 956-967).

Comparison of the diagnostic performance of H/M ratio between early and delayed phases for Lewy body disease

OBJECTIVES

The aim of the study was to compare the diagnostic performance of early-phase I-metaiodobenzylguanidine (MIBG) scintigraphy with that of delayed-phase imaging in Lewy body disease (LBD).

METHODS

A retrospective cohort study of ¹²³I-MIBG scintigraphy was carried out in 192 patients who were suspected of having LBD. Clinical diagnosis was obtained using the UK Parkinson's Disease Brain Bank Criteria in some cases or the third report of the Dementia with Lewy bodies Consortium in others. The participants consisted of 81 patients with LBD and 111 nondiseased patients. An injection of 111 MBq of ¹²³I-MIBG was used. Planar images were obtained in an early phase and again in a delayed phase and the heart to mediastinum count ratio was calculated for both phases. Diagnostic performance was compared using a receiver-operator characteristic analysis. The cutoff value was chosen to maximize the Youden index. The sensitivity and specificity of each phase were calculated from the optimal cutoff value.

RESULTS

The heart to mediastinum ratio of the LBD group (median 1.8 and 1.45 for early and delayed phases, respectively) was significantly lower than that of the nondiseased group (median 2.93 and 3.18 for early and delayed phases, respectively). The area under the receiver-operating characteristic curve was not significantly different between the early and delayed phases (0.871 vs. 0.893; P=0.0914). Sensitivity and specificity were 80.2 and 91% for early-phase imaging (cutoff value at 2.28) and 81.5 and 95.5% (cutoff value at 1.91) for delayed-phase imaging, respectively.

CONCLUSION

The diagnostic performance of ¹²³I-MIBG scintigraphy was not significantly different between early-phase and delayed-phase imaging.

Myocardial (123)I-MIBG Uptake and Cardiovascular Autonomic Function in Parkinson's Disease

Introduction. Patients with Parkinson's disease (PD) showed reduced myocardial ¹²³I-MIBG uptake, which may affect autonomic regulation. We investigated correlation between MIBC accumulation and cardiovascular autonomic function in PD. Methods. We performed myocardial MIBG scintigraphy, heart rate variability (HRV) analysis, and the head-up tilt test (HUT) in 50 PD patients (66.4 ± 7.8 years; duration 5.5 ± 5.9 years). Autonomic function tests were also performed in 50 healthy controls (66.5 ± 8.9 years). As HRV parameters, a high-frequency power (HF, 0.15–0.4 Hz), a low-frequency power (LF, 0.04–0.15 Hz), and LF/HF ratio were used. Results. Our PD patients had a significant reduction in LF and HF compared with the controls (P = 0.005 and P = 0.01). In HUT, systolic and diastolic blood pressure falls in the PD group were significantly greater than those in the controls (P = 0.02 and P = 0.02). The washout rate of MIBG was negatively correlated with blood pressure changes during HUT. Conclusion. Our PD patients showed reduced HRV, blood pressure dysregulation, and reduced MIBG accumulation, which was correlated with blood pressure dysregulation. Orthostatic hypotension in PD may be mainly caused by sympathetic postganglionic degeneration.

Adrenal Pheochromocytoma Incidentally Discovered in a Patient With Parkinsonism

To evaluate the diagnostic route of pheochromocytoma (PHEO) in a patient under dopaminergic treatment.A 70-year-old man with Parkinsonism and under treatment with levodopa and carbidopa came to our observation for evaluation of arterial hypertension and right adrenal mass discovered incidentally.To evaluate adrenal hormone levels we performed a dexamethasone suppression test, plasma aldosterone levels and 24-hr urinary metanephrine, which revealed elevated levels of catecholamines metabolities. 123-I-metaiodobenzylguanidine SPECT scintiscan revealed raised activity within the right adrenal gland concordant with the mass. The diagnosis of PHEO was posed and an elective laparoscopic adrenalectomy was performed; histopathological examination confirmed the PHEO diagnosis.Recently the coexistence of PHEO and Parkinsonism is a very rare association of diseases, with only 3 cases reported in literature. In this article, another case is reported and diagnostic procedures are discussed.

Impact of glucocerebrosidase mutations on motor and nonmotor complications in Parkinson's disease

Homozygous mutations of the glucocerebrosidase gene (GBA) cause Gaucher disease (GD), and heterozygous mutations of GBA are a major risk factor for Parkinson's disease (PD). This study examined the impact of GBA mutations on the longitudinal clinical course of PD patients by retrospective cohort design. GBA-coding regions were fully sequenced in 215 PD patients and GD-associated GBA mutations were identified in 19 (8.8%) PD patients. In a retrospective cohort study, time to develop dementia, psychosis, wearing-off, and dyskinesia were examined. Survival time analysis followed a maximum 12-year observation (median 6.0 years), revealing that PD patients with GD-associated mutations developed dementia and psychosis significantly earlier than those without mutations (p < 0.001 and p = 0.017, respectively). Adjusted hazard ratios of GBA mutations were 8.3 for dementia (p < 0.001) and 3.1 for psychosis (p = 0.002). No statistically significant differences were observed for wearing-off and dyskinesia between the groups. N-isopropyl-p[(123)I] iodoamphetamine single-photon emission tomography pixel-by-pixel analysis revealed that regional cerebral blood flow was reduced in the bilateral parietal cortex, including the precuneus of GD-associated mutant PD patients, compared with matched PD controls without mutations.

Chronological changes of 123I-MIBG myocardial scintigraphy and clinical features of Parkinson's disease

OBJECTIVES

The aim of this study was to investigate chronological changes of (123)I-meta-iodobenzylguanidine (MIBG) myocardial scintigraphy and its relation to clinical features in patients with Parkinson's disease (PD), and to characterise patients with PD with normal or mildly low MIBG uptakes at their early stages.

METHODS

The participants were 70 patients with PD who underwent (123)I-MIBG myocardial scintigraphy twice or more. A cluster analysis was performed using parameters calculated from heart to mediastinum (H/M) ratio and washout ratio (WR).

RESULTS

At baseline, the mean early H/M ratio (H/M(E)), delayed H/M ratio (H/M(D)) and WR were 1.83, 1.69 and 41.7%, respectively. After a mean interval of 3.0 years, follow-up studies showed significantly declined H/M(E) (1.69, p<0.001), declined H/M(D) (1.47, p<0.001) and enhanced WR (43.8%, p=0.007). Our longitudinal observations revealed that there existed heterogeneous changes in MIBG uptakes among patients. The cluster analysis classified the patients into two subgroups: 42 patients with markedly low MIBG uptakes at baseline (group A) and 28 patients with normal or mildly low MIBG uptakes at baseline (group B). Group B showed a significantly higher ratio of females, younger age at onset, lower Hoehn and Yahr stage and less demented, compared with group A.

CONCLUSIONS

Follow-up studies of MIBG divided the patients with PD into two major subgroups. A subgroup of patients with PD with normal or mildly low MIBG uptakes at the early stages of illness was characterised by female-dominant, young onset, slow progression in motor dysfunctions and preserved cognitive function.

TRIAL REGISTRATION NUMBER

1033.

PET/SPECT molecular imaging in clinical neuroscience: recent advances in the investigation of CNS diseases

Molecular imaging is an attractive technology widely used in clinical practice that greatly enhances our understanding of the pathophysiology and treatment in central nervous system (CNS) diseases. It is a novel multidisciplinary technique that can be defined as real-time visualization, in vivo characterization and qualification of biological processes at the molecular and cellular level. It involves the imaging modalities and the corresponding imaging agents. Nowadays, molecular imaging in neuroscience has provided tremendous insights into disturbed human brain function. Among all of the molecular imaging modalities, positron emission tomography (PET) and single photon emission computed tomography (SPECT) have occupied a particular position that visualize and measure the physiological processes using high-affinity and high-specificity molecular radioactive tracers as imaging probes in intact living brain. In this review, we will put emphasis on the PET/SPECT applications in Alzheimer's disease (AD) and Parkinson's disease (PD) as major CNS disorders. We will first give an overview of the main classical molecular neuroimaging modalities. Then, the major clinical applications of PET and SPECT along with molecular probes in the fields of psychiatry and neurology will be discussed.

(123)I-Metaiodobenzylguanidine Myocardial Scintigraphy in Lewy Body-Related Disorders: A Literature Review

Lewy body-related disorders are characterized by the presence of Lewy bodies and Lewy neurites, which have abnormal aggregations of α-synuclein in the nigral and extranigral areas, including in the heart. ¹²³I-metaiodobenzylguanidine (MIBG) scintigraphy is a well-known tool to evaluate cardiac sympathetic denervation in the Lewy body-related disorders. MIBG scintigraphy showed low uptake of MIBG in the Lewy body-related disorders, including Parkinson’s disease, dementia with Lewy bodies, pure autonomic failure and rapid eye movement sleep behavior disorder. This review summarizes previous results on the diagnostic applications of MIBG scintigraphy in Lewy body-related disorders.

Accuracy and cutoff values of delayed heart to mediastinum ratio with (123)I-metaiodobenzylguanidine cardiac scintigraphy for Lewy body disease diagnoses

Background

Different studies have found diminished cardiac metaiodobenzylguanidine (MIBG) uptake in Lewy body (LB) related conditions (Parkinson’s disease (PD) and Lewy body dementia (LBD)). However, delayed heart/mediastinum (d-H/M) ratio diagnostic cutoff points are debated in parkinsonian syndromes.

Methods

We performed a monocentric retrospective analysis on 62 consecutive parkinsonian patients who underwent an ¹²³I-MIBG scintigraphy, brain imaging and dopaminergic imaging using ¹²³I-Ioflupane single photon emission computed tomography (SPECT) from 2009 to 2013. The optimal d-H/M ratio was determined from a Receiver Operating Characteristic (ROC) curve and the sensitivity (Se), specificity (Sp) and likelihood ratios (LR) were calculated. 42 patients were diagnosed with LB diseases (20 PD, 22 LBD) and 20 patients with other diseases.

Results

¹²³I-MIBG scintigraphy helped to distinguish PD (p < 0.001) and LBD (p = 0.03) from other diseases. The optimal d-H/M ratio was 1.48 (0.85 area under the ROC curve). Se and Sp were 83.3 %, and 85 % respectively with positive and negative LR of 5.5 and 0.2 respectively. Patients with LBD had a lower d-H/M ratio than patients with PD (result not statistically significant) and a cutoff point at 1.2 could help to differentiate the two diseases. We did not find any correlation between the d-H/M ratio and clinical or ¹²³I-Ioflupane SPECT data.

Conclusion

According to our population, the d-H/M ratio at 1.48 led to the best performance diagnosis with good Se, Sp and accuracy. In addition, a d-H/M ratio cutoff at 1.2 could help to differentiate PD from LBD.

Cardiac 123I-MIBG uptake in de novo Brazilian patients with Parkinson's disease without clinically defined dysautonomia

Myocardial scintigraphy with meta-iodo-benzyl-guanidine (123I cMIBG) has been studied in Parkinson's disease (PD), especially in Asian countries, but not in Latin America. Most of these studies include individuals with PD associated to a defined dysautonomia. Our goal is to report the cardiac sympathetic neurotransmission in de novo Brazilian patients with sporadic PD, without clinically defined dysautonomia. We evaluated retrospectively a series of 21 consecutive cases with PD without symptoms or signs of dysautonomia assessed by the standard bedside tests. This number was reduced to 14 with the application of exclusion criteria. 123I cMIBG SPECT up-take was low or absent in all of them and the heart/mediastinum ratio was low in 12 of 14. We concluded that 123I cMIBG has been able to identify cardiac sympathetic neurotransmission disorder in Brazilian de novo PD patients without clinically defined dysautonomia.

[Functional neuroimaging in the diagnosis of patients with Parkinsonism: Update and recommendations for clinical use]

Functional Neuroimaging has been traditionally used in research for patients with different Parkinsonian syndromes. However, the emergence of commercial radiotracers together with the availability of single photon emission computed tomography (SPECT) and, more recently, positron emission tomography (PET) have made them available for clinical practice. Particularly, the development of clinical evidence achieved by functional neuroimaging techniques over the past two decades have motivated a progressive inclusion of several biomarkers in the clinical diagnostic criteria for neurodegenerative diseases that occur with Parkinsonism. However, the wide range of radiotracers designed to assess the involvement of different pathways in the neurodegenerative process underlying Parkinsonian syndromes (dopaminergic nigrostriatal pathway integrity, basal ganglia and cortical neuronal activity, myocardial sympathetic innervation), and the different neuroimaging techniques currently available (scintigraphy, SPECT and PET), have generated some controversy concerning the best neuroimaging test that should be indicated for the differential diagnosis of Parkinsonism. In this article, a panel of nuclear medicine and neurology experts has evaluated the functional neuroimaging techniques emphazising practical considerations related to the diagnosis of patients with uncertain origin parkinsonism and the assessment Parkinson's disease progression.

Levodopa challenge test and (123) I-metaiodobenzylguanidine scintigraphy for diagnosing Parkinson's disease

OBJECTIVES

To explore the possibility of a generally applicable tool for the immediate diagnosis of Parkinson's disease (PD) in its early stage, we compared the sensitivity and specificity of an acute levodopa challenge test with that of (123) I-metaiodobenzylguanidine (MIBG) myocardial scintigraphy.

MATERIALS AND METHODS

A consecutive series of 45 patients with extrapyramidal symptoms were recruited to the acute levodopa challenge and evaluated for improvement by use of the Unified Parkinson's Disease Rating Scale motor scores. Of these patients, 32 of them were also examined by MIBG scintigraphy. The patients were followed up for at least 24 months, and 22 patients were diagnosed as having clinically definite PD.

RESULTS

The sensitivity and specificity of the acute levodopa challenge test to predict clinical diagnosis of PD were 81.8% and 81.8%, respectively, which were better than those obtained by MIBG scintigraphy (62.5% and 62.5%). In both early- and middle-stages of PD, the test gave better sensitivity than MIBG scintigraphy.

CONCLUSIONS

Considering that the well-established and frequently referred clinical diagnostic criteria require longitudinal observation for at least 24 months, the acute levodopa challenge test can be used as an immediate diagnostic tool for PD with sensitivity and specificity comparable to those of MIBG.

Diagnostic accuracy of apparent diffusion coefficient and 123I-metaiodobenzylguanidine for differentiation of multiple system atrophy and Parkinson's disease

Background

It is often hard to differentiate Parkinson’s disease (PD) and parkinsonian variant of multiple system atrophy (MSA-P), especially in the early stages. Cardiac sympathetic denervation and putaminal rarefaction are specific findings for PD and MSA-P, respectively.

Purpose

We investigated diagnostic accuracy of putaminal apparent diffusion coefficient (ADC) test for MSA-P and ¹²³I-metaiodobenzylguanidine (MIBG) scintigram for PD, especially in early-stage patients.

Methods

The referral standard diagnosis of PD and MSA-P were the diagnostic criteria of the United Kingdom Parkinson’s Disease Society Brain Bank Criteria and the second consensus criteria, respectively. Based on the referral standard criteria, diagnostic accuracy [area under the receiver-operator characteristic curve (AUC), sensitivity and specificity] of the ADC and MIBG tests was estimated retrospectively. Diagnostic accuracy of these tests performed within 3 years of symptom onset was also investigated.

Results

ADC and MIBG tests were performed on 138 patients (20 MSA and 118 PD). AUC was 0.95 and 0.83 for the ADC and MIBG tests, respectively. Sensitivity and specificity were 85.0% and 89.0% for MSA-P diagnosis by ADC test and 67.0% and 80.0% for PD diagnosis by MIBG test. When these tests were restricted to patients with disease duration ≤3 years, the sensitivity and specificity were 75.0% and 91.4% for the ADC test (MSA-P diagnosis) and 47.7% and 92.3% for the MIBG test (PD diagnosis).

Conclusions

Both tests were useful in differentiating between PD and MSA-P, even in the early stages. In early-stage patients, elevated putaminal ADC was a diagnostic marker for MSA-P. Despite high specificity of the MIBG test, careful neurological history and examinations were required for PD diagnosis because of possible false-negative results.

Catecholamines and Neurodegeneration in Parkinson's Disease-From Diagnostic Marker to Aggregations of α-Synuclein

Parkinson's disease is the second most prevalent disease of the brain. It is characterized by midbrain dopaminergic neuronal degeneration accompanied by Lewy bodies, intra-cytoplasmic neuronal inclusions that consist mainly of alpha-synuclein. The cardinal motor features are muscular rigidity, bradykinesia, and resting tremor and, in advanced cases, postural instability. Symptoms are relieved by dopamine replacement therapy, but progress slowly. Clinical diagnosis is made according to medical history, neurological examinations and the response to anti-Parkinsonian drugs. There are no laboratory tests for diagnosis of the disease; however, for development of disease-modifying treatment, early diagnosis by objective laboratory test is required. Recently, postsynaptic sympathetic norepinephrine nerve terminals were found to be degenerated as well as mesencephalic dopaminergic neurons. Cardiac norepinephrine denervation can be seen by meta-iodine-benzyl guanidine scintigraphy, and may be a reliable diagnostic marker. Degeneration of norepinephrinergic and dopaminergic neurons suggests that catecholamines may play a central role in the neurodegeneration in Parkinson's disease. Recently several studies showed that alpha-synuclein aggregates in cells exposed to dopamine. Here, we review findings relating to an early diagnostic marker for detecting degeneration of the peripheral sympathetic nerves, and propose the hypothesis that catecholamines cause alpha-synuclein to aggregate and play an important role in disease pathogenesis.

[Initial diagnosis of Parkinson's disease - neuroradiological diagnosis]

Brain MRI is essential for differentiating Parkinson's disease (PD) from other parkinsonian syndromes. The purpose of performing brain MRI is not to make a diagnosis of PD but is to exclude other parkinsonian syndromes. Recently, several new MRI techniques such as voxel based morphometry, relaxometry, magnetization transfer, spectroscopy, tractography, and functional MRI have been introduced in the diagnosis of PD. Neuromelanin imaging is one of the new techniques and can be useful to make an initial diagnosis of PD. MIBG myocardial scintigraphy is a sensitive imaging tool to differentiate PD from other parkinsonian syndromes and is one of the good tools to make an initial diagnosis of PD. Brain perfusion imaging is sometimes useful to make an initial diagnosis of PD, because reduced brain perfusion area can be detected before brain MRI detects morphological changes of the brain. Dopamine transporter imaging, not available in Japan, is a sensitive tool to detect very early parkinsonism and is useful to make an initial diagnosis of PD. However, it is difficult to differentiate PD from other parkinsonian syndromes.

Different patterns of cardiac sympathetic denervation in tremor-type compared to akinetic-rigid-type Parkinson's disease: molecular imaging with ¹²³I-MIBG

The aim of this study was to evaluate the correlation between the clinical motor phenotypes of Parkinson's disease (PD) and ¹²³I-MIBG myocardial uptake. In total, 53 patients with PD [31 males and 22 females, mean age 62±10 years; 19 Hoehn & Yahr (H&Y) stage 1, 9 stage 1.5, 15 stage 2 and 10 at stage 3] were examined and subdivided into different clinical forms on the basis of dominance of resting tremor (n=19, TDT) and bradykinesia plus rigidity (n=34, ART). This status was correlated with the semi-quantitative analysis of ¹²³I-MIBG myocardial uptake. An age-matched control group of 18 patients was recruited (8 males and 10 females, mean age 62.4±16.3 years). ¹²³I-MIBG myocardial uptake significantly correlated with disease duration in early (r²=0.1894; P=0.0028) and delayed images (r²=0.1795; P=0.0037) in PD patients, while no correlation was found when considering age at examination, UPDRS III motor examination section score and H&Y score. PD patients showed a reduced ¹²³I-MIBG myocardial uptake compared to the control group in early (P=0.0026) and delayed images (P=0.0040), and ¹²³I-MIBG myocardial uptake was significantly lower in delayed images in TDT patients compared with ART patients (P=0.0167). A decrease was detected in the heart-to-mediastinum (H/M) ratio in delayed images compared to that of the early images in TDT patients (P=0.0040) and in the whole PD population (P=0.0012), while no differences were found in ART patients (P=0.1043). The results of the present study revealed that the cardiac sympathetic system is more severely impaired in TDT than in ART patients and ¹²³I-MIBG molecular imaging has the potential help in improving therapeutic planning in these patients.

Neurochemistry and the non-motor aspects of PD

Parkinson disease (PD) is a systemic disease with variegated non-motor deficits and neurological symptoms, including impaired olfaction, autonomic failure, cognitive impairment and psychiatric symptoms, in addition to the classical motor symptoms. Many non-motor symptoms appear before or in parallel with motor deficits and then worsen with disease progression. Although there is a relationship, albeit not causal, between motor symptoms and the presence of Lewy bodies (LBs) and neurites filled with abnormal α-synuclein, other neurological alterations are independent of the amount of α-synuclein inclusions in neurons and neurites, thereby indicating that different mechanisms probably converge in the degenerative process. This may apply to complex alterations interfering with olfactory and autonomic nervous systemfunctions, emotions, sleep regulation, and behavioral, cognitive and mental performance. Involvement of the cerebral cortex leading to impaired behavior and cognition is related to several convergent altered factors including: a. dopaminergic, noradrenergic, serotoninergic and cholinergic cortical innervation; b. synapses; c. cortical metabolism; d. mitochondrial function and energy production; e. oxidative damage; f. transcription; g. protein expression; h. lipid composition; and i. ubiquitin–proteasome system and autophagy, among others. This complex situation indicates that multiple subcellular failure in selected cell populations is difficult to reconcilewith a reductionistic scenario of a single causative cascade of events leading to non-motor symptoms in PD. Furthermore, these alterationsmay appear at early stages of the disease and may precede the appearance of substantial irreversible cell loss by years. These observations have important implications in the design of therapeutic approaches geared to prevention and treatment of PD.

SPECT molecular imaging in Parkinson's disease

Parkinson's disease (PD) is a common disorder, and the diagnosis of Parkinson's disease is clinical and relies on the presence of characteristic motor symptoms. The accuracy of the clinical diagnosis of PD is still limited. Functional neuroimaging using SPECT technique is helpful in patients with first signs of parkinsonism. The changes detected may reflect the disease process itself and/or compensatory responses to the disease, or they may arise in association with disease- and/or treatment-related complications. This paper addresses the value of SPECT in early differential diagnosis of PD and its potential as a sensitive tool to assess the pathophysiology and progression, as well as the therapeutic efficacy of PD.

Autonomic involvement in Parkinson's disease: pathology, pathophysiology, clinical features and possible peripheral biomarkers

Autonomic nervous system involvement occurs at early stages in both Parkinson's disease (PD) and incidental Lewy body disease (ILBD), and affects the sympathetic, parasympathetic, and enteric nervous systems (ENS). It has been proposed that alpha-synuclein (α-SYN) pathology in PD has a distal to proximal progression along autonomic pathways. The ENS is affected before the dorsal motor nucleus of the vagus (DMV), and distal axons of cardiac sympathetic nerves degenerate before there is loss of paravertebral sympathetic ganglion neurons. Consistent with neuropathological findings, some autonomic manifestations such as constipation or impaired cardiac uptake of norepinephrine precursors, occur at early stages of the disease even before the onset of motor symptoms. Biopsy of peripheral tissues may constitute a promising approach to detect α-SYN neuropathology in autonomic nerves and a useful early biomarker of PD.

[Clinical and imaging diagnostics of Parkinson's disease and multiple system atrophy]

The diagnosis of Parkinson's disease (PD) and multiple system atrophy (MSA) is primarily made by clinical symptoms, but might still remain challenging even for experienced neurologists. Neuroradiologic imaging may be a useful tool in the diagnostic work-up, particularly for excluding other diseases, such as normal pressure hydrocephalus, multi-infarct dementia and cerebellar lesions. Nuclear medicine methods can additionally support the diagnosis and differential diagnosis of PD and MSA.

Differentiating Parkinson's disease from multiple system atrophy by [123I] meta-iodobenzylguanidine myocardial scintigraphy and olfactory test

We aimed to study whether either [(123)l] myocardial meta-iodobenzylguanidine (MIBG) myocardial scintigraphy or the odor stick identification test for Japanese (OSIT-J) is effective in differentiating Parkinson's disease (PD) from multiple system atrophy (MSA). We compared the MIBG accumulation and olfactory score between 42 PD and 42 MSA (19 MSA-P and 23 MSA-C) patients in the early stages. [(123)l] MIBG myocardial scintigraphy showed higher sensitivity and the olfactory test higher specificity in differentiating PD from MSA. There were significant differences between PD and MSA-C (p = 0.0019) instead of MSA-P (p > 0.05) in the MIBG accumulation, while there were significant differences between PD and MSA-P (p = 0.0003) or MSA-C (p = 0.0003) in the OSIT-J score. Our data suggest that the olfactory test can be useful as a clinical tool with its higher specificity in differentiating PD from MSA in the early stages and, moreover, support the discrimination of PD from MSA-P.

MIBG scintigraphy in differential diagnosis of Parkinsonism: a meta-analysis

OBJECTIVE

Differential diagnosis between Parkinson's disease (PD) and other Parkinsonism using clinical criteria or imaging methods is often difficult. The purpose of this study is to systematically review and meta-analyze published data about the diagnostic performance of myocardial innervation imaging using (123)I-metaiodobenzylguanidine (MIBG) scintigraphy in differential diagnosis between PD and other Parkinsonism.

METHODS

A comprehensive computer literature search of studies published through March 2011 regarding MIBG scintigraphy in patients with PD and other Parkinsonism was performed in PubMed/MEDLINE and Embase databases. Only studies in which MIBG scintigraphy was performed for differential diagnosis between PD and other Parkinsonism were selected. Pooled sensitivity, pooled specificity and area under the ROC curve were calculated to measure the accuracy of MIBG scintigraphy in differential diagnosis between PD and other Parkinsonism.

RESULTS

Nineteen studies comprising 1,972 patients (1,076 patients with PD, 117 patients with other Lewy body diseases and 779 patients with other diseases) were included in this meta-analysis. The pooled sensitivity of MIBG scintigraphy in detecting PD was 88% (95% CI 86-90%); the pooled specificity of MIBG scintigraphy in discriminating between PD and other Parkinsonism was 85% (95% CI 81-88%). The area under the ROC curve was 0.93.

CONCLUSIONS

In patients with clinically suspected PD, myocardial innervation imaging demonstrated high sensitivity and specificity. MIBG scintigraphy is an accurate test in this setting. Nevertheless, possible causes of false-negative and false-positive results should be kept in mind when interpreting the scintigraphic results.