This chapter reviews relevant magnetic resonance imaging (MRI) methods and their application to various stages of disease including early or incident Parkinson's disease (PD), treated patients, including those with mild cognitive impairment (MCI), and those with Parkinson's disease with dementia (PDD) and dementia with Lewy bodies (DLB). In PD pathological changes have been found in the hippocampus, parahippocampus, amygdala, and the entorhinal cortex. Several groups of investigators have shown that the substantia innominata is atrophic in PD, with progressive loss in PD-MCI and PDD. The chapter also reviews longitudinal studies and the impact of white matter pathology. A study that compared progression of white matter changes between Alzheimer's disease (AD), PDD, and DLB and older controls found that AD patients had more white matter changes than controls; there was no difference in progression of white matter changes between the dementia groups.

This chapter reviews the usefulness of Meta-iodobenzylguanidine (123I-MIBG) in neurology-specific sleep disorders with a particular focus on rapid eye movement (REM) sleep behavior disorder (RBD). Several studies demonstrated the diagnostic reliability of reduced cardiac 123I-MIBG uptake in Parkinson's disease (PD) patients. In general, 123I-MIBG scintigraphy is regarded as an assessment of autonomic function. Autonomic dysfunction is common in α-synucleinopathies, and particularly marked in multiple system atrophy (MSA). Most patients with idiopathic RBD (iRBD) have reduced 123I-MIBG uptake, and an abnormal 123I-MIBG finding supports the diagnosis of RBD. Although an abnormal 123I-MIBG finding cannot predict the development of α-synucleinopathies among iRBD patients, the existence of RBD might be predictive of developing PD with dementia (PDD) in patients with PD. In the near future, 123I-MIBG findings might help predict the development of PDD among PD patients affected with RBD.