Reduced 123I-MIBG uptake in the parotid and submandibular glands in patients with Parkinson's disease identified using a quantitative semi-automatic method

Value of multi-parameter 123I-MIBG scintigraphy in the differential diagnosis of Parkinson's disease

BACKGROUND

123I-MIBG scintigraphy plays a significant role in diagnosing Parkinson's disease (PD), with most studies primarily targeting cardiac uptake and relying on traditional ratio-based parameters for assessment. However, due to variations in scanning conditions and image processing methodologies, the clinical utility of different parameters remains a subject of debate. This study aims to evaluate the diagnostic accuracy of multi-parameter 123I-3-Iodobenzylguanidine (MIBG) scintigraphy and to identify the most reliable metrics for distinguishing PD from Parkinson-plus syndromes.

RESULT

We recruited 56 PD patients and 44 non-PD controls, who underwent 123I-MIBG scintigraphy and clinical evaluation. MIBG uptake and washout rates (WR) for the heart, salivary glands, and thyroid were assessed, with semi-quantitative methods used to calculate heart-to-mediastinum (H/M) and gland-to-background (P/B, S/B, T/B) ratios. Diagnostic efficacy was evaluated using receiver operating characteristic (ROC) curves. The H/M ratio and cardiac WR parameters scintigraphy exhibited excellent diagnostic efficacy for PD and PPS. The 4 h H/M ratio showed superior diagnostic performance with an area under the ROC curve (AUC) of 0.980. Background and time decay correction improved cardiac WR diagnostic performance (AUC = 0.963). Although P/B, S/B, and T/B ratios showed no significant differences for differential diagnosis, the WR values of the parotid and thyroid glands exhibited moderate diagnostic efficacy with AUCs of 0.648 and 0.638, respectively.

CONCLUSION

The heart H/M ratio and cardiac WR in 123I-MIBG scintigraphy show high diagnostic efficacy for both diagnosing and differentiating PD. Including cardiac WR in routine assessments is recommended. The diagnostic potential of WR in the parotid and thyroid glands also holds promise for PD diagnosis. Incorporating these parameters could enhance the accuracy of PD diagnosis, particularly in clinical scenarios where concurrent cardiac disease may confound the diagnosis.

Iodine-123 Metaiodobenzylguanidine (I-123 MIBG) in Clinical Applications: A Comprehensive Review

Iodine-123 metaiodobenzylguanidine (I-123 MIBG) is a crucial radiopharmaceutical widely used in nuclear medicine for its diagnostic capabilities in both cardiology and oncology. This review aims to present a comprehensive evaluation of the clinical applications of I-123 MIBG, focusing on its use in diagnosing and managing various diseases. In cardiology, I-123 MIBG has proven invaluable in assessing cardiac sympathetic innervation, particularly in patients with heart failure, where it provides prognostic information that guides treatment strategies. In oncology, I-123 MIBG is primarily utilized for imaging neuroendocrine tumors, such as neuroblastoma and pheochromocytoma, where it offers high specificity and sensitivity in the detection of adrenergic tissue. Additionally, its role in neurology, specifically in differentiating between Parkinson's disease, dementia, and Lewy body dementia, has become increasingly significant due to its ability to identify postganglionic sympathetic dysfunction. Despite its established clinical utility, the use of I-123 MIBG is not without limitations, including variability in imaging protocols and interpretation challenges. This review will explore these issues and discuss emerging alternatives, while also highlighting areas where I-123 MIBG continues to be a gold standard. By synthesizing the current research, this article aims to provide a clear understanding of the strengths, limitations, and prospects of I-123 MIBG in clinical practice.

Comparison of MIBG uptake in the major salivary glands between Lewy body disease and progressive supranuclear palsy

Introduction

Cardiac sympathetic denervation is specific to Lewy body disease (LBD). In Parkinson's disease (PD), sympathetic denervation in the major salivary glands (parotid glands [PG] and submandibular glands [SMG]) has been demonstrated by 123I-metaiodobenzylguanidine (MIBG) scintigraphy. We compared sympathetic denervation in the MSG between PD, dementia with Lewy bodies (DLB), and progressive supranuclear palsy (PSP).

Methods

We recruited 81 patients with PD, 12 with DLB, 13 with PSP and 25 with control subjects. We evaluated MIBG uptake in the major salivary glands and heart using a quantitative semi-automatic method. We compared MIBG uptake between PD, DLB, and PSP patients and controls, and we evaluated disease sensitivity and specificity. We compared olfactory function with MIBG uptake between PD and PSP patients.

Results

MIBG uptake in the PG and SMG in the delayed phase was significantly lower in PD and DLB patients than in PSP patients and controls. Conversely, MIBG uptake in the major salivary glands and heart was comparable between PD and DLB. Between LBD and non-LBD, MIBG uptake showed 56-100 % specificity in the PG, while it had 55.6-87.5 % sensitivity in the SMG. Between PD and PSP, MIBG uptake in the PG and SMG had higher disease specificity than olfactory function, while the sensitivity of SMG MIBG uptake was comparable to olfactory function.

Conclusion

PD and DLB patients showed lower MIBG uptake in the major salivary glands than PSP patients, especially in the delayed phase. MIBG uptake in the major salivary glands may differentiate PD from hyposmic PSP.

Brain-first vs. body-first Parkinson's disease: An update on recent evidence

We recently proposed a new disease model of Parkinson's disease - the a-Synuclein Origin site and Connectome model. The model posits that the initial pathology starts either in the olfactory bulb or amygdala leading to a brain-first subtype, or in the enteric nervous system leading to a body-first subtype. These subtypes should be distinguishable early in the disease course on a range of imaging, clinical, and neuropathological markers. Here, we review recent original human studies, which tested the predictions of the model. Molecular imaging studies were generally in agreement with the model, whereas structural imaging studies, such as MRI volumetry, showed conflicting findings. Most large-scale clinical studies were supportive, reporting clustering of relevant markers of the body-first subtype, including REM-sleep behavior disorder, constipation, autonomic dysfunction, neuropsychiatric symptoms, and cognitive impairment. Finally, studies of a-synuclein deposition in antemortem and postmortem tissues revealed distribution of pathology, which generally supports the model.

Clinical characteristics of patients with Parkinson's disease with reduced 123I-metaiodobenzylguanidine uptake in the major salivary glands and heart

BACKGROUND

Parkinson's disease (PD) shows cardiac sympathetic denervation (SD) in 123I-metaiodobezylguanidine (MIBG) scintigraphy. Recently, SD in the major salivary glands (MSG-SD) was introduced as a possible radiological feature of PD.

OBJECTIVE

To identify the clinical characteristics of patients with PD with reduced MSG and cardiac MIBG uptake (dual-SD) compared with those with reduced MSG or cardiac MIBG uptake only (single-SD).

METHODS

We recruited 90 patients with PD and 30 controls and evaluated their non-motor (e.g., hyposmia, autonomic dysfunction) and motor (e.g., Movement Disorder Society-Unified Parkinson's Disease Rating Scale) features. We also assessed MIBG uptake in the MSG and heart using a quantitative semi-automatic method, and compared MIBG uptakes between PD and controls. We set cut-off values for optimal sensitivity and specificity, and compared the clinical characteristics of patients with PD between dual- and single-SD groups.

RESULTS

MSG and cardiac MIBG uptakes were significantly reduced in PD. Sixty-one patients had dual-SD, 25 had single-SD, and four had non-SD. In patients with PD with normal cardiac SD, 76.5% (13/17) of whom showed abnormalities only in MSG-SD. When clinical characteristics were compared between the dual-SD and single-/non-SD groups, patients in the dual-SD group were older and had more severe hyposmia and autonomic dysfunction, except motor features. Multiple logistic regression analysis identified age as an important confounder.

CONCLUSIONS

Patients with PD with dual-SD have more severe non-motor features than other patients. Autonomic dysfunction might progress independently from dopaminergic degeneration. Furthermore, our findings indicate that aging is a crucial factor in PD progression.

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.