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Booij J, Dubroff J, Pryma D, Yu JQ, Agarwal R, Lakhani P, Kuo PH
Diagnostic performance of the visual reading of 123I-ioflupane SPECT images when assessed with or without quantification in patients with movement disorders or dementia
J Nucl Med (2017) In process.
Visual interpretation of 123I-ioflupane single photon emission computed tomography (SPECT) images has high diagnostic accuracy to differentiate parkinsonian syndromes (PS) from essential tremor (ET) and probable dementia with Lewy bodies (DLB) from Alzheimer's disease. This study investigated the impact on accuracy and reader confidence offered by the addition of image quantification compared to visual interpretation alone. Methods: We collected 304 123I-ioflupane images from three trials, enrolling subjects with a clinical diagnosis of PS, non-PS (mainly ET), probable DLB and non-DLB (mainly Alzheimer's disease). Images were reconstructed with standardised parameters before striatal binding ratios were quantified against a normal database with DaTQUANT software. Images were assessed by five Nuclear Medicine physicians who had limited prior experience with 123I-ioflupane interpretation. Two reads were performed, at least 1 month apart, in which readers either performed a visual interpretation alone or a combined read (i.e. visual plus quantitative data were available). Readers were asked to rate confidence of image interpretation and judge scans as easy or difficult to read. Diagnostic accuracy was assessed comparing image results with the standard of truth (i.e. diagnosis at follow-up) by measuring the positive percent agreement (PPA, equivalent to sensitivity) and the negative percent agreement (NPA, equivalent to specificity). The hypothesis was tested that the results of the combined read was non-inferior to the visual read analysis. Results: The combined read compared to the visual read analysis showed a small, non-significant, increase of mean NPA (89.9% vs 87.9%) and equivalent PPA (80.2% vs 80.1%). Readers who initially read in the combined analysis had significantly greater accuracy (85.8% vs 79.2%, P = 0.018) and were close to the accuracy of the expert readers in the original studies (range 83.3% to 87.2%). Mean reader confidence in the interpretation of images showed a significant improvement using combined analysis (p<0.0001). Conclusion: Addition of quantification allowed readers with limited experience in the interpretation of 123I-ioflupane SPECT scans to have equivalent diagnostic accuracy as the experienced readers used in the initial studies. Also, the result of the combined read was non-inferior to the result of the visual read analysis, while offering an increase in reader confidence.
Publication Date: 2017-05-04.
Last updated on Wednesday, September 06, 2017