Individual-Reader Diagnostic Performance and Between-Reader Agreement in Assessment of Subjects with Parkinsonian Syndrome or Dementia Using ¹²³I-Ioflupane Injection (DaTscan) Imaging

Abstract

Establishing an early, accurate diagnosis is fundamental for appropriate clinical management of patients with movement disorders or dementia. Ioflupane 123 I Injection (DaTscan, 123 I-ioflupane) is an important adjunct to support the clinical diagnosis. Understanding individualreader diagnostic performance of 123 I-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 123 I-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 individualreader 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, betweenreader 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 123 I-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.

Diagnostic Performance of the Visual Reading of 123I-Ioflupane SPECT Images With or Without Quantification in Patients With Movement Disorders or Dementia

“…among all readers and thus the k-values. These results are in agreement with those of other 123 I-ioflupane SPECT and amyloid brain PET studies, which also showed that high k-values for both intraobserver and interobserver agreements (14,(23)(24)(25)(26) improved as quantitative data were provided to readers (14,26).…”

Diagnostic accuracy of dopaminergic imaging in prodromal dementia with Lewy bodies

“…Seibyl et al . 2014). This reflects the greater difficulty in rating subjects whose scans are at an earlier disease stage and where more, therefore, have borderline abnormal scans.…”

The Parkinson's progression markers initiative (PPMI) – establishing a PD biomarker cohort

“…All images were visually interpreted as either positive or negative for DAT or VMAT‐2 deficit25 by two experienced, independent nuclear medicine readers blinded to clinical diagnosis. Visual interpretation for both DAT and VMAT‐2 images required the reader to interrogate the intensity and symmetry of radiotracer uptake in left and right putamen to determine whether the pattern was consistent with a dopaminergic deficit.…”