RT Journal Article SR Electronic T1 Individual-Reader Diagnostic Performance and Between-Reader Agreement in Assessment of Subjects with Parkinsonian Syndrome or Dementia Using 123I-Ioflupane Injection (DaTscan) Imaging JF Journal of Nuclear Medicine JO J Nucl Med FD Society of Nuclear Medicine SP 1288 OP 1296 DO 10.2967/jnumed.114.140228 VO 55 IS 8 A1 John P. Seibyl A1 Andreas Kupsch A1 Jan Booij A1 Donald G. Grosset A1 Durval C. Costa A1 Robert A. Hauser A1 Jacques Darcourt A1 Nin Bajaj A1 Zuzana Walker A1 Kenneth Marek A1 Ian McKeith A1 John T. O’Brien A1 Klaus Tatsch A1 Eduardo Tolosa A1 Rudi A. Dierckx A1 Igor D. Grachev YR 2014 UL http://jnm.snmjournals.org/content/55/8/1288.abstract AB Establishing an early, accurate diagnosis is fundamental for appropriate clinical management of patients with movement disorders or dementia. Ioflupane 123I Injection (DaTscan, 123I-ioflupane) is an important adjunct to support the clinical diagnosis. Understanding individual-reader diagnostic performance of 123I-ioflupane in a variety of clinical scenarios is essential. Methods: Sensitivity, specificity, interreader, and intrareader data from 5 multicenter clinical studies were reviewed. The different study designs offered an assortment of variables to assess the effects on the diagnostic performance of 123I-ioflupane: on-site versus 3–5 blinded image readers, number of image evaluations, early/uncertain versus late/confirmed clinical diagnosis as reference standard, and subjects with movement disorders versus dementia. Results: Eight hundred eighteen subjects had individual-reader efficacy data available for analysis. In general, sensitivity and specificity were high and comparable between on-site versus blinded independent readers. In subjects with dementia, when the clinical diagnosis was made at month 12 versus baseline, specificity improved from 77.4%–91.2% to 81.6%–95.0%. In subjects with movement disorders, this effect was observed to an even greater extent, when diagnostic performance using month-18 diagnosis as a reference standard (sensitivity, 67.0%–73.7%; specificity, 75.0%–83.3%) was compared versus month-36 diagnosis (77.5%–80.3% and 90.3%–96.8%, respectively). Diagnostic performance was similar in subjects with dementia (74.4%–89.9% and 77.4%–95.0%, respectively) and subjects with movement disorders (67.0%–97.9% and 71.4%–98.4%, respectively). In most of the comparisons, between-reader agreement was very good (almost perfect), with κ ranging from 0.81 to 1.00. Within-reader agreement, measured in 1 study, was 100% for 3 blinded readers. Conclusion: Individual-reader diagnostic performance, as assessed by measuring sensitivity and specificity of 123I-ioflupane to detect the presence or absence of striatal dopaminergic deficit, using the clinical diagnosis as a reference standard, was high in subjects with either movement disorders or dementia and was similar in on-site readers versus blinded analyses. Between- and within-reader agreements were very good (almost perfect). Longer follow-up between imaging and clinical diagnosis improved the diagnostic accuracy, most likely due to improvement in the clinical diagnosis reference standard, rather than changes in reader accuracy.