RT Journal Article
SR Electronic
T1 MRI of the Swallow Tail Sign: A Useful Marker in the Diagnosis of Lewy Body Dementia?
JF American Journal of Neuroradiology
JO Am. J. Neuroradiol.
FD American Society of Neuroradiology
DO 10.3174/ajnr.A5274
A1 S. Shams
A1 D. Fällmar
A1 S. Schwarz
A1 L.-O. Wahlund
A1 D. van Westen
A1 O. Hansson
A1 E.-M. Larsson
A1 S. Haller
YR 2017
UL http://www.ajnr.org/content/early/2017/07/13/ajnr.A5274.abstract
AB BACKGROUND AND PURPOSE: There are, to date, no MR imaging diagnostic markers for Lewy body dementia. Nigrosome 1, containing dopaminergic cells, in the substantia nigra pars compacta is hyperintense on SWI and has been called the swallow tail sign, disappearing with Parkinson disease. We aimed to study the swallow tail sign and its clinical applicability in Lewy body dementia and hypothesized that the sign would be likewise applicable in Lewy body dementia.MATERIALS AND METHODS: This was a retrospective cross-sectional multicenter study including 97 patients (mean age, 65 ± 10 years; 46% women), consisting of the following: controls (n = 21) and those with Lewy body dementia (n = 19), Alzheimer disease (n = 20), frontotemporal lobe dementia (n = 20), and mild cognitive impairment (n = 17). All patients underwent brain MR imaging, with susceptibility-weighted imaging at 1.5T (n = 46) and 3T (n = 51). The swallow tail sign was assessed independently by 2 neuroradiologists.RESULTS: Interrater agreement was moderate (κ = 0.4) between raters. An abnormal swallow tail sign was most common in Lewy body dementia (63%; 95% CI, 41%–85%; P < .001) and had a predictive value only in Lewy body dementia with an odds ratio of 9 (95% CI, 3–28; P < .001). The consensus rating for Lewy body dementia showed a sensitivity of 63%, a specificity of 79%, a negative predictive value of 89%, and an accuracy of 76%; values were higher on 3T compared with 1.5T. The usefulness of the swallow tail sign was rater-dependent with the highest sensitivity equaling 100%.CONCLUSIONS: The swallow tail sign has diagnostic potential in Lewy body dementia and may be a complement in the diagnostic work-up of this condition.AbbreviationsADAlzheimer diseaseFTDfrontotemporal lobe dementiaLBDLewy body dementiaMCImild cognitive impairmentPDParkinson disease