title: Differential Diagnosis of Patients with Inconclusive Parkinsonian Features Using [(18)F]FP-CIT PET/CT.
abstract: OBJECTIVE
  It is often difficult to differentiate parkinsonism, especially when patients show uncertain parkinsonian features. We investigated the usefulness of dopamine transporter (DAT) imaging for the differential diagnosis of inconclusive parkinsonism using [(18)F]FP-CIT PET.
  
  
  METHODS
  Twenty-four patients with inconclusive parkinsonian features at initial clinical evaluation and nine healthy controls were studied. Patients consisted of three subgroups: nine patients whose diagnoses were unclear concerning whether they had idiopathic Parkinson's disease or drug-induced parkinsonism ('PD/DIP'), nine patients who fulfilled neither the diagnostic criteria of PD nor of essential tremor ('PD/ET'), and six patients who were alleged to have either PD or atypical parkinsonian syndrome ('PD/APS'). Brain PET images were obtained 120 min after injection of 185 MBq [(18)F]FP-CIT. Imaging results were quantified and compared with follow-up clinical diagnoses.
  
  
  RESULTS
  Overall, 11 of 24 patients demonstrated abnormally decreased DAT availability on the PET scans, whereas 13 were normal. PET results could diagnose PD/DIP and PD/ET patients as having PD in six patients, DIP in seven, and ET in five; however, the diagnoses of all six PD/APS patients remained inconclusive. Among 15 patients who obtained a final follow-up diagnosis, the image-based diagnosis was congruent with the follow-up diagnosis in 11 patients. Four unsolved cases had normal DAT availability, but clinically progressed to PD during the follow-up period.
  
  
  CONCLUSIONS
  [(18)F]FP-CIT PET imaging is useful in the differential diagnosis of patients with inconclusive parkinsonian features, except in patients who show atypical features or who eventually progress to PD.
authors.affiliation: Department of Nuclear Medicine, Korea University College of Medicine, Seoul, Republic of Korea ; PET Center, Department of Diagnostic Radiology, Yale University School of Medicine, New Haven, CT USA.
authors.forename: Eunkyung
authors.initials: E
authors.lastname: Park
authors.affiliation: Center for Research Information, Korea University, Seoul, Republic of Korea.
authors.forename: Yu Mi
authors.initials: YM
authors.lastname: Hwang
authors.affiliation: Department of Neurology, Korea University College of Medicine, 126-1, Anam-dong 5-ga, Seongbuk-gu, Seoul, 136-705 Republic of Korea.
authors.forename: Chan-Nyoung
authors.initials: CN
authors.lastname: Lee
authors.affiliation: Department of Nuclear Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea.
authors.forename: Sujin
authors.initials: S
authors.lastname: Kim
authors.affiliation: Department of Nuclear Medicine, Korea University College of Medicine, Seoul, Republic of Korea.
authors.forename: Sun Young
authors.initials: SY
authors.lastname: Oh
authors.affiliation: Department of Nuclear Medicine, Korea University College of Medicine, Seoul, Republic of Korea.
authors.forename: Young Chul
authors.initials: YC
authors.lastname: Kim
authors.affiliation: Department of Nuclear Medicine, Korea University College of Medicine, Seoul, Republic of Korea.
authors.forename: Jae Gol
authors.initials: JG
authors.lastname: Choe
authors.affiliation: Department of Neurology, Korea University College of Medicine, 126-1, Anam-dong 5-ga, Seongbuk-gu, Seoul, 136-705 Republic of Korea.
authors.forename: Kun Woo
authors.initials: KW
authors.lastname: Park
keywords: Dopamine transporter; Inconclusive parkinsonian features; Parkinsonism; Positron emission tomography; [18F]FP-CIT