Current status of PET imaging in Huntington's disease

To review the developments of recent decades and the current status of PET molecular imaging in Huntington's disease (HD). A systematic review of PET studies in HD was performed. The MEDLINE, Web of Science, Cochrane and Scopus databases were searched for articles in all languages published up to 19 August 2015 using the major medical subject heading Huntington Disease combined with text and key words Huntington Disease, Neuroimaging and PET. Only peer-reviewed, primary research studies in HD patients and premanifest HD carriers, and studies in which clinical features were described in association with PET neuroimaging results, were included in this review. Reviews, case reports and nonhuman studies were excluded. A total of 54 PET studies were identified and analysed in this review. Brain metabolism ([F-18]FDG and [O-15]H2O), presynaptic ([F-18]fluorodopa, [C-11]beta-CIT and [C-11]DTBZ) and postsynaptic ([C-11]SCH22390, [C-11]FLB457 and [C-11]raclopride) dopaminergic function, phosphodiesterases ([F-18]JNJ42259152, [F-18]MNI-659 and [C-11]IMA107), and adenosine ([F-18]CPFPX), cannabinoid ([F-18]MK-9470), opioid ([C-11]diprenorphine) and GABA ([C-11]flumazenil) receptors were evaluated as potential biomarkers for monitoring disease progression and for assessing the development and efficacy of novel disease-modifying drugs in premanifest HD carriers and HD patients. PET studies evaluating brain restoration and neuroprotection were also identified and described in detail. Brain metabolism, postsynaptic dopaminergic function and phosphodiesterase 10A levels were proven to be powerful in assessing disease progression. However, no single technique may be currently considered an optimal biomarker and an integrative multimodal imaging approach combining different techniques should be developed for monitoring potential neuroprotective and preventive treatment in HD.