Meta-analysis of dorsolateral nigral hyperintensity on magnetic resonance imaging as a marker for Parkinson's disease

Nice paper by friends in Austria... imaging markers for PD, beyond those we already have, are desperately needed. This nice meta-analysis shows that the MRI can be used differentiate patients from controls effectively. The results are shown for 3 Tesla MRI and 7 Tesla. Fortunately 3T MRI performs almost as well as 7T, because lots of hospitals may not have access to 7T imaging. Now it is important to try and work out far before diagnosis this change occurs, and whether it changes over time...

Mov Disord. 2017 Feb 2. doi: 10.1002/mds.26932. [Epub ahead of print]
Mahlknecht P, Krismer F, Poewe W, Seppi K.

http://onlinelibrary.wiley.com/doi/10.1002/mds.26932/abstract

BACKGROUND: Dorsolateral nigral hyperintensity on iron-sensitive magnetic resonance imaging (MRI) sequences seems to be a typical finding in Parkinson's disease (PD), but most studies have involved small samples and have had heterogeneous control populations.

OBJECTIVES: The objective of this study was to perform a meta-analysis on dorsolateral nigral hyperintensity as an imaging marker for PD.

METHODS: The methods included a systematic literature search and a hierarchical summary receiver operating characteristics curve approach.

RESULTS: Of the 16 identified studies, 10 were suitable for analysis, including 364 PD and 231 control cases. The meta-analysis showed an overall sensitivity and specificity of the absence of dorsolateral nigral hyperintensity for PD versus controls of 97.7% and 94.6% (3 and 7 Tesla) and of 94.6% and 94.4% (3 Tesla only). Descriptive analysis among the 4 studies including patients with non-PD parkinsonism showed that dorsolateral nigral hyperintensity was absent in 89.4% of cases with atypical parkinsonian disorders (n = 74), but only in 21.7% of cases with non-neurodegenerative parkinsonism (n = 69). Moreover, in 2 of these studies, the absence of dorsolateral nigral hyperintensity predicted ipsilateral dopamine-transporter deficiency with 87.5% sensitivity and 83.6% specificity.

CONCLUSIONS: Visual assessment of dorsolateral nigral hyperintensity on iron-sensitive MRI sequences provides excellent diagnostic accuracy for PD versus controls. Moreover, its loss appears to be a marker of nigral pathology and holds the potential for the differentiation of neurodegenerative from non-neurodegenerative parkinsonian disorders.