Cardiac Imaging in Lewy Body Disorders

Lewy body disorders encompass a spectrum of neurodegenerative conditions characterised by abnormal intraneuronal aggregates of α-synuclein, including Parkinson’s disease, dementia with Lewy bodies and prodromal rapid eye movement sleep behaviour disorder. Cardiac imaging, primarily via iodine-123 metaiodobenzylguanidine (MIBG) scintigraphy, has emerged as a non-invasive biomarker of postganglionic sympathetic denervation in these conditions. By quantifying tracer uptake in the myocardium relative to a mediastinal reference region, clinicians can detect reductions in cardiac sympathetic nerve function that often precede or accompany central neurodegeneration. In Parkinson’s disease and dementia with Lewy bodies, markedly decreased myocardial MIBG uptake distinguishes these synucleinopathies from other forms of parkinsonism and dementia. In isolated rapid eye movement sleep behaviour disorder, early reductions in cardiac tracer uptake identify individuals at high risk of phenoconversion to overt Lewy body disease. Beyond nuclear scintigraphy, complementary approaches such as cardiac magnetic resonance imaging and echocardiographic assessment of autonomic modulation are under investigation to refine diagnosis, monitor progression and evaluate therapeutic interventions aimed at preserving peripheral autonomic integrity. As cardiac imaging methods become more standardised and widely available, they offer the potential for earlier diagnosis, improved patient stratification in clinical trials and a deeper understanding of the interplay between peripheral and central neurodegenerative processes.

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Cardiac Imaging in Lewy Body Disorders publication trend

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Technical terms

123I-MIBG scintigraphy: A nuclear imaging technique using iodine-123 metaiodobenzylguanidine to assess cardiac sympathetic innervation by measuring tracer uptake in myocardial tissue.

Heart-to-mediastinum ratio (H/M ratio): The quantitative index obtained by comparing tracer counts in the heart to those in a mediastinal reference region; lower values indicate sympathetic denervation.

Lewy body disorders: A group of neurodegenerative diseases characterised by intraneuronal α-synuclein inclusions, encompassing Parkinson’s disease, dementia with Lewy bodies and prodromal rapid eye movement sleep behaviour disorder.

Rapid eye movement sleep behaviour disorder (RBD): A parasomnia marked by loss of normal muscle atonia during REM sleep, often serving as an early clinical manifestation of underlying synucleinopathy.

Postganglionic sympathetic denervation: Loss of nerve fibres originating from autonomic ganglia to target organs, detectable in the heart by reduced radiotracer uptake on MIBG scintigraphy.

References

1. Reduced cardiac 123I-MIBG uptake is a robust biomarker of Lewy body disease in isolated rapid eye movement sleep behaviour disorder. Brain Communications (2024).
2. Iodine-123 Metaiodobenzylguanidine (I-123 MIBG) in Clinical Applications: A Comprehensive Review. Pharmaceuticals (2024).
3. Cardiac 123I-Metaiodobenzylguanidine (MIBG) Scintigraphy in Parkinson’s Disease: A Comprehensive Review. Brain Sciences (2023).