Optimization of postprocessing - PowerPoint Presentation

1. Optimization of postprocessing parameters for abdominal forensic CT scans Pernille A Nielsen1, Dina M Bech1, Julie B Nielsen1 Pernille L Hansen1, Dennis L Hansen2, 3Svea D Mørup1, Peter M Leth4, Helle Precht1,51 CONRAD Research Program, University College, Odense, Denmark2 Department of Hematology, Odense University Hospital, Odense, Denmark3 Department of Clinical Research, University of Southern Denmark, Odense, Denmark4 Institute of Forensic Medicine, University of Southern Denmark, Odense, Denmark5 Cardiology Research department, Odense University hospital, Svendborg, Denmark

2. IntroductionPost-Mortem Computed Tomography is used as a supplement to autopsy However, imaging of the deceased is different from imaging living personsDecay, dismemberment, metal artefacts and dehydration affect image qualityReconstruction methods is needed that aims post-mortem conditions Reconstruction parameters has previously been suggested, but never evaluatedAbdominal CTNewly deceasedEarly decayLate decay

3. Materials and methodsIn forensics the aim is to determine between inflicted injuries, pathologies and accidentsWe chose to focus on imaging of abdomen, and the visceral organs In CT, even slight decay can impede distinction between visceral organsPersons found dead, or persons dead under suspicious circumstances, has often been dead in hours or days

4. Materials and methodsWe compares four reconstruction protocolsThree newly constructed and one routinely usedThe protocols was used on scans of 20 deceased, in various states of decay Image quality of the reconstructions was compared using visual grading analysis The images was evaluated separately by four forensically trained radiologistsRecon 1Recon 2Recon 3Recon 4AlgorithmDETAILSTANDARDSTANDARDSTANDARDHounsfieldWW / WL350/404000/803000/80350/40

5. ResultsVisual presentation of reconstructionsR1 - DETAILR2 – HU3000R3 – HU4000R4 - STND

6. ResultsScansR1 - DETAILR2 – HU3000R3 – HU4000R4 - STNDAll95,2%91,7%89,3%91,7%Decomposed bodies50%62,5%50%50%Excluding decomposed bodies100%94,7%93,4%97,4%Percentage of each reconstruction type deemed useful for diagnostic purpose

7. Results R1 – DETAILR2 – HU3000R3 – HU4000R4 - STNDSpatial Resolution4 [iqr: 3-4]2 [iqr: 1-3]2 [iqr: 1-3]4 [iqr: 3-4]Low Contrast Resolution4 [iqr: 3-4]2 [iqr: 2-3]3 [iqr: 2-3]4 [iqr: 3-4]Contrast2 [iqr: 2-3]3 [iqr: 3-4]3 [iqr: 3-4]2 [iqr: 2-3]Artifacts/ Beam Hardening4 [iqr: 3-4]4 [iqr: 4-5]4 [iqr: 4-4.5]4 [iqr: 3-4]Visual grading analysis of image quality criteriaGrading from 1 to 5 where 5 is the bestResults depicted as median, with interquartile range

8. ConclusionsStage of decomposition influenced the evaluation Above 90% of scans was rated usefull for non-decomposed in all reconstructions The new reconstructions increased soft tissue detailsHowever, several reconstructions are needed to visualize various tissuesProtocols must be targeted to different conditions of the deceased The study provides a basis for further research which could potentially improve the quality and/or utility of forensic CT scans

9. LimitationsObservers was experienced in forensic imaging but not in evaluating reconstructionsStudy population was limited to 20 scansOf the 20 deceased included, two was severely decomposed which resulted in mixed evaluations

10. Ethics committee approval / FundingThis study was a quality improvement study and did as such not require ethics committee approval under Danish lawThere has not been applied for funding for this study