Imaging in Parkinson's disease.

The clinical presentation of Parkinson's disease (PD) is heterogeneous and overlaps with other conditions, including the parkinsonian variant of multiple system atrophy (MSA-P), progressive supranuclear palsy (PSP) and essential tremor. Imaging of the brain in patients with parkinsonism has the ability to increase the accuracy of differential diagnosis. Magnetic resonance imaging (MRI), single photon emission computed tomography (SPECT) and positron emission tomography (PET) allow brain imaging of structural, functional and molecular changes in vivo in patients with PD. Structural MRI is useful to differentiate PD from secondary and atypical forms of parkinsonism. 123I-ioflupane (DaTSCAN(TM)) SPECT is a valid tool in the differential diagnosis between PD and non-degenerative tremors, while cardiac 123I-metaiodobenzylguanidine SPECT and 18F-fluorodeoxyglucose PET are valid in the differential diagnosis between PD and atypical parkinsonism (MSA-P, PSP). However, despite significant evidence for the utility of neuroimaging in assessing parkinsonian patients, none of the neuroimaging techniques are specifically recommended for routine use in clinical practice. Hopefully, future larger trials will help to demonstrate additional evidence for the clinical utility of neuroimaging and will include an analysis of the financial benefits for the NHS in the longer term management of the patients.