"FEEPI, TR/TE 60/30, echo train length 5, flip angle 19°"
"FEEPI, TR/TE 60/30, echo train length 5, flip angle 19°"
"FEEPI, TR/TE 60/30, echo train length 5, flip angle 19°"
"Absence of the sign (absent swallow tail sign) is reported to have a diagnostic accuracy of greater than 90% for Parkinson disease and dementia with Lewy bodies 1,2,4. In the original description, the negative predictive value was 100% 1 and for dementia with Lewy bodies 89% 2."
Expected headings
"Interpretation"
"The swallow tail sign describes the normal axial imaging appearance of a hyperintensity within the substantia nigra on high-resolution T2*/SWI weighted MRI. It was previously thought that this sign was caused by nigrosome-1, but this has not been found to be correct in subsequent studies, and thus, presence or absence of the swallow tail sign and nigrosome-1 should not be used synonymously."
"The cause for the swallow tail sign is unclear. It was initially postulated that nigrosome-1, which is present within the posterior third of the substantia nigra, had a high signal on axial SWI in a linear or comma shape. This, when surrounded anteriorly, laterally and medially by low SWI signal intensity, was thought to lead to the resemblance of the distinctive split tail of a swallow 5. However, since that initial hypothesis, multiple studies have shown that the hyperintensity on SWI only partially corresponds to nigrosome-1 in autopsy analyses, and thus there are likely to be other contributors to this sign 5."