Abstract
PurposeThe 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.MethodsA 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.ResultsCo-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).ConclusionsThe 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.
Highlights
The Parkinson variant of multiple system atrophy (MSAP) and idiopathic Parkinson’s disease (IPD) are neurodegenerative disorders with distinct neuropathology and progression that share several clinical features hampering differential diagnosis, especially in the early stages of disease
There were three categories of cardiac 123I-MIBG tracer uptake identified by SPECT-CT: Group A consisted of 10 patients with homogeneous tracer uptake and was dominated by eight patients with MSA-P
VOIH/M of 123I-MIBG SPECT-CT and heart uptake/mean mediastinum uptake (H/M) of planar scintigraphy were significantly higher in MSA-P than in IPD (p < 0.001), and there was a significant association of the tracer uptake group and diagnosis (p < 0.01; Table 1)
Summary
The Parkinson variant of multiple system atrophy (MSAP) and idiopathic Parkinson’s disease (IPD) are neurodegenerative disorders with distinct neuropathology and progression that share several clinical features hampering differential diagnosis, especially in the early stages of disease. Up to 50% of de novo and early-stage IPD patients may show preserved cardiac sympathetic innervation, and reduced cardiac tracer uptake has been reported in one third of patients with MSA, consistent with a reduced number of postganglionic tyrosine hydroxylase immunoreactive axons and alpha-synuclein-positive inclusions in sympathetic ganglia of patients with MSA [17, 21,22,23,24,25,26,27]. Based on this knowledge gap, we sought to evaluate regional differences in cardiac tracer uptake in IPD and MSA-P. We compared the diagnostic accuracy of 123I-MIBG-SPECTCT to routine planar cardiac 123I-MIBG scintigraphy and determined the relationships between 123I-MIBG imaging and autonomic function
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