PET SCANS FOR A MORE ACCURATE DIAGNOSIS OF PARKINSON'S

PET scans good for accurate Parkinson's
diagnosis
OnMedica Staff
Monday, 11 January 2010
PET scans can identify with high accuracy the form of
Parkinsonism that a patient has, according to a study
published Online First and in a February edition of The Lancet
Neurology.
Author Dr David Eidelberg, of the Center for Neurosciences,The Feinstein Institute for
Medical Research, Manhasset, NY, USA, and colleagues, suggests positron emission
tomography (PET) can help with early diagnosis, noting that this is essential to ensure
patients receive the correct treatment.
Idiopathic Parkinson’s disease can present with symptoms similar to those of multiple
system atrophy or progressive supranuclear palsy, explained Dr Eidelberg. In this study,
the investigators aimed to assess whether metabolic brain imaging combined with
pattern analysis could accurately discriminate patients with different forms of
Parkinsonism.
The study assessed 167 patients from the New York area who were recruited between
1998 and 2006, each of whom had parkinsonian features but uncertain clinical diagnosis.
The patients underwent PET and the research team developed an automated
image-based classification procedure to differentiate individual patients with idiopathic
Parkinson’s disease, multiple system atrophy, and progressive supranuclear palsy.
For each patient, the likelihood of having each of the three diseases was calculated, and
a classification was made according to probability measurements. After imaging, patients
were assessed by movement disorders specialists (who were unaware of the PET results)
for a mean of 2.6 years before a final clinical diagnosis was made. The accuracy of the
initial image-based classification was assessed by comparison with the final clinical
diagnosis.
The researchers found that image-based classification for idiopathic Parkinson’s disease
had 84% sensitivity, 97% specificity, 98% positive predictive value (PPV), and 82%
negative predictive value (NPV). Imaging classifications were also accurate for multiple
system atrophy (85% sensitivity, 96% specificity, 97% PPV, and 83% NPV) and
progressive supranuclear palsy (88% sensitivity, 94% specificity, 91% PPV, and 92%NPV).
Dr Eidelberg said: “The excellent specificity and PPV of the imaging classification makes
this test suitable for diagnostic use rather than as a screening tool.”
As well as the reasons above, the authors point out that early correct diagnosis is
essential to ensure that patients with the correct diagnosis are enrolled in drug trials for
potentially disease-modifying drugs for the various parkinsonian disorders. They also
hope to extend their work to be able to differentiate other forms of parkinsonism.
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