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The midbrain to pons ratio: a simple and specific MRI sign of progressive supranuclear palsy
Luke A Massey1, Hans R Jäger, Dominic C Paviour
1Sara Koe PSP Research Centre, Rita Lila Weston Institute for Neurology Studies and Queen Square Brain Bank, Department of Molecular Neurosciences, UCL Institute of Neurology, London, UK. l.massey@ion.ucl.ac.uk
Objectives:
MRI-based measurements used to diagnose progressive supranuclear palsy (PSP) typically lack pathologic verification and are not easy to use routinely. We aimed to develop in histologically proven disease a simple measure of the midbrain and pons on sagittal MRI to identify PSP.
Methods:
Measurements of the midbrain and pontine base on midsagittal T1-weighted MRI were performed in confirmed PSP (n = 12), Parkinson disease (n = 2), and multiple system atrophy (MSA) (n = 7), and in controls (n = 8). Using receiver operating characteristic curve analysis, cutoff values were applied to a clinically diagnosed cohort of 62 subjects that included PSP (n = 21), Parkinson disease (n = 10), MSA (n = 10), and controls (n = 21).
Results:
The mean midbrain measurement of 8.1 mm was reduced in PSP (p < 0.001) with reduction in the midbrain to pons ratio (PSP smaller than MSA; p < 0.001). In controls, the mean midbrain ratio was approximately two-thirds of the pontine base, in PSP it was <52%, and in MSA the ratio was greater than two-thirds. A midbrain measurement of <9.35 mm and ratio of 0.52 had 100% specificity for PSP. In the clinically defined group, 19 of 21 PSP cases (90.5%) had a midbrain measurement of <9.35 mm.
Conclusions:
We have developed a simple and reliable measurement in pathologically confirmed disease based on the topography of atrophy in PSP with high sensitivity and specificity that may be a useful tool in the clinic.
Insights
A new simple MRI measurement of midbrain and pons atrophy can accurately diagnose progressive supranuclear palsy (PSP). This method offers high specificity and sensitivity for identifying PSP in clinical settings.
Area of Science:
- Neurology
- Radiology
- Pathology
Background:
- Diagnosing progressive supranuclear palsy (PSP) using MRI is challenging due to a lack of pathological verification and routine usability.
- Existing MRI methods for PSP diagnosis require improvement for clinical application.
Purpose of the Study:
- To develop a simple, reliable midbrain and pons measurement on sagittal MRI for diagnosing PSP.
- To validate this measurement against histologically proven cases and clinical cohorts.
Main Methods:
- Midbrain and pontine base measurements were taken from midsagittal T1-weighted MRI in pathologically confirmed PSP, Parkinson disease, MSA, and controls.
- Receiver operating characteristic (ROC) curve analysis was used to determine cutoff values.
- The developed measurement was applied to a separate cohort of clinically diagnosed subjects.
Main Results:
- Progressive supranuclear palsy (PSP) showed a significantly reduced midbrain measurement (8.1 mm) and midbrain-to-pons ratio compared to controls and multiple system atrophy (MSA).
- A midbrain measurement <9.35 mm and a ratio of 0.52 demonstrated 100% specificity for PSP.
- In a clinically diagnosed cohort, 90.5% of PSP cases met the criterion of a midbrain measurement <9.35 mm.
Conclusions:
- A simple MRI measurement of midbrain and pons atrophy has been developed and validated.
- This novel measurement exhibits high sensitivity and specificity for diagnosing progressive supranuclear palsy (PSP).
- The developed MRI technique may serve as a valuable clinical tool for accurate PSP diagnosis.
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