AUTHOR=Gosch Vitus , Villringer Kersten , Galinovic Ivana , Ganeshan Ramanan , Piper Sophie K. , Fiebach Jochen B. , Khalil Ahmed 

TITLE=Automated acute ischemic stroke lesion delineation based on apparent diffusion coefficient thresholds

JOURNAL=Frontiers in Neurology

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/neurology/articles/10.3389/fneur.2023.1203241

DOI=10.3389/fneur.2023.1203241

ISSN=1664-2295

ABSTRACT=<sec id="sec1"><title>Purpose</title><p>Automated lesion segmentation is increasingly used in acute ischemic stroke magnetic resonance imaging (MRI). We explored in detail the performance of apparent diffusion coefficient (ADC) thresholding for delineating baseline diffusion-weighted imaging (DWI) lesions.</p></sec><sec id="sec2"><title>Methods</title><p>Retrospective, exploratory analysis of the prospective observational single-center 1000Plus study from September 2008 to June 2013 (<ext-link xlink:href="http://clinicaltrials.org" ext-link-type="uri" xmlns:xlink="http://www.w3.org/1999/xlink">clinicaltrials.org</ext-link>; NCT00715533). We built a fully automated lesion segmentation algorithm using a fixed ADC threshold (≤620 × 10–6 mm<sup>2</sup>/s) to delineate the baseline DWI lesion and analyzed its performance compared to manual assessments. Diagnostic capabilities of best possible ADC thresholds were investigated using receiver operating characteristic curves. Influential patient factors on ADC thresholding techniques’ performance were studied by conducting multiple linear regression.</p></sec><sec id="sec3"><title>Results</title><p>108 acute ischemic stroke patients were selected for analysis. The median Dice coefficient for the algorithm was 0.43 (IQR 0.20–0.64). Mean ADC values in the DWI lesion (<italic>β</italic> = −0.68, <italic>p</italic> &lt; 0.001) and DWI lesion volumes (<italic>β</italic> = 0.29, <italic>p</italic> &lt; 0.001) predicted performance. Optimal individual ADC thresholds differed between subjects with a median of ≤691 × 10<sup>−6</sup> mm<sup>2</sup>/s (IQR ≤660–750 × 10<sup>−6</sup> mm<sup>2</sup>/s). Mean ADC values in the DWI lesion (<italic>β</italic> = −0.96, <italic>p</italic> &lt; 0.001) and mean ADC values in the brain parenchyma (<italic>β</italic> = 0.24, <italic>p</italic> &lt; 0.001) were associated with the performance of individual thresholds.</p></sec><sec id="sec4"><title>Conclusion</title><p>The performance of ADC thresholds for delineating acute stroke lesions varies substantially between patients. It is influenced by factors such as lesion size as well as lesion and parenchymal ADC values. Considering the inherent noisiness of ADC maps, ADC threshold-based automated delineation of very small lesions is not reliable.</p></sec>