[object Object]Purpose Even though [123I]FP-CIT SPECT provides high accuracy
in detecting nigrostriatal cell loss in neurodegenerative
parkinsonian syndromes (PS), some patients with an inconclusive
diagnosis remain. We investigated whether the diagnostic
accuracy in patients with clinically uncertain PS with
previously inconclusive findings can be improved by the use
of iterative reconstruction algorithms and an improved
semiquantitative evaluation which additionally implemented
a correction algorithm for patient age and gamma camera dependency
(EARL-BRASS; Hermes Medical Solutions,
Sweden).
Methods We identified 101 patients with inconclusive findings
who underwent an [123I]FP-CIT SPECT between 2003
and 2010 as part of the diagnostic process of suspected PS at
the University of Munich, and re-evaluated these scans using
iterative reconstruction algorithms and the new corrected
EARL-BRASS. Clinical follow-up was obtained in 62 out
of the 101 patients and constituted the gold standard for the
re-evaluation to assess the possible improvement in diagnostic
accuracy.
Results Clinical follow-up confirmed the diagnosis of PS in
11 of the 62 patients. In patients in whom both visual and
semiquantitative analysis showed concordant findings (48 patients),
a high negative predictive value (93 %), positive predictive
value (100 %) and accuracy (94 %) were found, and
thus a correct diagnosis was obtained in 45 of the 48 patients.
Among the 14 patients with discordant findings, the additional
semiquantitative analysis correctly identified all five of nine
patients patients without PS by nonpathological semiquantitative
findings in visually pathological or inconclusive scans. In
contrast, four of the remaining five patients with decreased
semiquantitative values but visually normal scans did not
show a PS during follow-up.
Conclusion The age-corrected and camera-corrected mode of
evaluation using EARL-BRASS provided a notable improvement
in the diagnostic accuracy of [123I]FP-CIT SPECT in PS
patients with previously inconclusive findings. The gain in
accuracy might be achieved by better discrimination between
physiological low striatal [123I]FP-CIT binding due to agerelated
loss of the dopamine transporter or pathological loss
of binding.
