Novel Hypodensity Detection Tool improves clinician identification of hypodensity on non-contrast CT in stroke patients.

Background In acute stroke, identifying early changes (parenchymal hypodensity) on non-contrast CT (NCCT) can be challenging. We aimed to identify whether the accuracy of clinicians in detecting acute hypodensity in ischaemic stroke patients on a non-contrast CT is improved with the use of an automated HDT algorithm using MRI-DWI as the gold standard. Methods The study employed a case-crossover within-clinician design, where clinicians were tasked with identifying hypodensity lesions on NCCT scans for five a priori selected patient cases, before and after viewing the HDT. The DICE Similarity Coefficient (DICE score) was the primary measure of accuracy. Statistical analysis compared DICE scores with and without HDT using mixed-effects linear regression, with individual NCCT scans and clinicians as nested random effects. Results The HDT had a mean DICE score of 0.62 for detecting hypodensity across all NCCT scans and clinicians overall mean DICE score of 0.33 (SD 0.31) before HDT implementation and 0.40 (SD 0.27) after implementation. HDT use was associated with an increase of 0.07 (95% CI: 0.02-0.11, p=0.003) in DICE score accounting for individual scan and clinician effects. For scans with small lesions, clinicians achieved a mean increase in DICE score of 0.08 (95% CI: 0.02, 0.13, p=0.004) following HDT use. In a subgroup of 15 trainees, DICE score improved with HDT implementation (mean difference in DICE 0.09 [95% CI: 0.03, 0.14, p=0.004]). Conclusions The Hypodensity Detection Tool (HDT) has potential to enhance accuracy of detecting hypodensity in acute stroke diagnosis, especially for smaller lesions, and notably for less experienced clinicians. ### Competing Interest Statement The authors have declared no competing interest. ### Clinical Trial NA ### Funding Statement Australian Commonwealth government ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The INSPIRE had central ethics approval by the Hunter New England Human Research Ethics Committee (HNEHREC 11/08/17/14.01) I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes The authors confirm that the raw data supporting the findings of this study are available from the corresponding author upon reasonable request