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Movement Disorders Parkinson’s Disease Magnetic Resonance Imaging and Dopamine Transporter Single Photon Emission Tomography in Parkinson’s Disease—When Should We Use Them? Meir Kestenbaum, MD 1 and Cheryl Waters, MD, FRCP 2 1. Movement Disorders Fellow; 2. Albert and Judith Glickman Professor of Neurology, Department of Neurology, College of Physicians and Surgeons, Columbia University, New York, New York, US Abstract Making an accurate diagnosis of Parkinson’s disease (PD) is critical for patient counseling and therapeutic management. The diagnosis of PD remains primarily clinical and is based on nonspecific findings on examination. Magnetic resonance imaging and nuclear imaging of the brain can assist in making timely diagnoses and managing treatment appropriately. These tests should not be used routinely, but only in a selected subgroup of patients where the diagnosis of PD is not clear. Keywords Parkinson’s disease, MRI, DaT SPECT Disclosure: Meir Kestenbaum, MD, and Cheryl Waters, MD, FRCP, have no conflicts of interest to declare. No funding was received in the publication of this article. Received: October 1, 2014 Accepted: October 8, 2014 Citation: US Neurology, 2014;10(2):90–1 Correspondence: Cheryl Waters, MD, FRCP, Department of Neurology, College of Physicians and Surgeons, Columbia University, 710 West 168th Street, New York, NY 10032- 3784, USA. E: cw345@cumc.columbia.edu Making an accurate diagnosis of Parkinson’s disease (PD) is critical for patient counseling and therapeutic management. The methods for diagnosing PD are limited by the lack of definitive diagnostic tests. Despite all the recent advances in imaging and genetics of parkinsonian disorders, the diagnosis of PD remains primarily clinical and is based on nonspecific findings of rest tremor, cogwheel rigidity, and bradykinesia. The most widely used clinical criteria for the diagnosis of PD are those introduced by the Queen Square Brain Bank (London, UK). 1 Numerous studies report that neuropathologic confirmation of a clinical diagnosis of PD may range from 65–93  % depending on the criteria used and the stage of the disease. 2,3 However, a recently published study shows that the accuracy of a diagnosis can be as low as 28 %, particularly in patients with disease duration of less than 5 years that have never been treated with dopaminergic medication. 4 The differential diagnosis of a parkinsonian syndrome is wide and includes PD, atypical parkinsonian syndromes, i.e. progressive supranuclear palsy (PSP), multisystem atrophy (MSA), and corticobasal basal syndrome (CBS). Additional diagnoses are drug-induced parkinsonism, essential tremor (ET), and secondary symptomatic parkinsonism due to other pathologies such as tumors, cerebral ischemia, or inflammatory diseases. In clinical practice, conventional magnetic resonance imaging (MRI) is commonly used for the exclusion of symptomatic parkinsonism due to other 90 pathologies such as tumors, cerebral ischemia, or inflammatory diseases and may help to differentiate between PD and atypical parkinsonian syndromes. 5 Routine MRI is frequently normal in PD with a minority of the cases showing T2 changes in putamen. 6 With the need to improve accuracy of clinical diagnosis, the neurologist has to decide if, when, and which imaging studies to use for a patient with suspected PD. In general, in patients with classic signs of PD (rest tremor, bradykinesia, rigidity), age of onset of symptoms above 50, significant and sustained response to dopaminergic medication, and without any atypical symptoms and signs, such as supranuclear gaze palsy, cerebellar signs, early severe autonomic involvement, and early severe dementia, it is not imperative to perform brain MRI since the accuracy of diagnosing PD correctly is very high, reaching 88 %. 4 On the other hand, absence of cardinal parkinsonian signs, appearance of atypical ‘red flags,’ or lack of response to dopaminergic medication should raise the suspicion that the patient does not have PD and raises the need to perform brain imaging. Brain MRI is the first imaging modality to perform, allowing the neurologist to obtain important anatomical information that could help in supporting diagnoses, such as secondary parkinsonism and atypical parkinsonian syndromes. Changes commonly seen in MRI in the atypical parkinsonian syndromes include midbrain atrophy and ‘hummingbird sign’ in PSP. Putaminal atrophy or hypointensity, ‘hot cross bun’ sign in the pons and cerebellar © TOU C H ME D ICA L ME D IA 2014