Head-to-Head Comparison Between Rabbit Sign and EANM/SNMMI Criteria for the 18F-DOPA Visual Assessment of Parkinsonian Syndromes in PET/MRI

Abstract

The aim of this study was to compare the diagnostic performance of the rabbit visual pattern versus the one endorsed by the EANM/SNMMI for the diagnosis of parkinsonian syndromes in PET/MRI. Patients and Methods: The 18 F-DOPA PET images of 129 consecutive patients (65 Park+ and 64 controls) with 1 year of clinical follow-up were reviewed independently by 5 experienced readers on the same imaging workstation, blinded to the final clinical diagnosis. Two visual methods were assessed independently, with several days to months of interval: the criteria endorsed by EANM/SNMMI and the "rabbit" shape of the striate assessed on 3D MIP images. The sensitivities, specificities, likelihood ratios, and predictive values of the 2 diagnostic tests were estimated simultaneously by using the "comparison of 2 binary diagnostic tests to a paired design" method. Results: The estimated 95% confidence interval (CI) of sensitivities and specificities ranged from 49.4% to 76.5% and from 83.2% to 97.7%, respectively. The 95% CI estimates of positive and negative likelihood ratios ranged from 3.8 to 26.7 and from 0.26 to 0.56, respectively. The 95% CI estimates of the positive and negative predictive values ranged from 78.1% to 96.7% and from 60.3% to 81.4%, respectively. For all the parameters, no statistical difference was observed between the 2 methods ( P > 0.05). The rabbit sign reduced the readers' discrepancies by 25%, while maintaining the same performance. Conclusions: The rabbit visual pattern appears at least comparable to the current EANM/SNMMI reference procedure for the assessment of parkinsonian syndromes in daily clinical practice, without the need of any image postprocessing. Further multicenter prospective studies would be of relevance to validate these findings.

Behavioral Variant Frontotemporal Dementia With the Dominantly Affected Caudate Nucleus in 18F-FP-CIT PET/CT

“…The "rabbit" shape of the striate in 18 F-FP-CIT and 18 F-DOPA PET has been known to be useful for the assessment of Parkinsonian syndrome. 1,2 Frontotemporal dementia is a heterogeneous disorder with characteristic clinical phenotypes associated with various neuropathologic entities. It is divided based on the clinical features into behavioral variant (bvFTD) and 2 language disorders classified as primary progressive aphasia (PPA), namely, the nonfluent/agrammatic PPA and the semantic variant PPA.…”

“…The activity of the bilateral caudate nucleus is hardly seen, and the binding of the bilateral putamen is relatively preserved in the 18 F-FP-CIT MIP image ( C ), different from normal findings showing preserved dopamine transporter activity in the caudate nucleus and putamen ( D ). The “rabbit” shape of the striate in 18 F-FP-CIT and 18 F-DOPA PET has been known to be useful for the assessment of Parkinsonian syndrome 1,2 . Frontotemporal dementia is a heterogeneous disorder with characteristic clinical phenotypes associated with various neuropathologic entities.…”