Colloque avec actes et comité de lecture. internationale.International audienceThe purpose of this study is to determine the intra- and inter-observer variability in the manual delineation of the boundaries of brain arterio-venous malformations (AVMs) on digital subtracted angiograms. Such delineation is used to define the target volume in stereotactic radiotherapy

Anxionnat, René

Berger, Marie-Odile

Bracard, Serge

Kerrien, Erwan

Picard, Luc

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HAL Id: inria-00107673https://hal.inria.fr/inria-00107673Submitted on 19 Oct 2006HAL is a multi-disciplinary open accessarchive for the deposit and dissemination of sci-entific research documents, whether they are pub-lished or not. The documents may come fromteaching and research institutions in France orabroad, or from public or private research centers.L’archive ouverte pluridisciplinaire HAL, estdestinée au dépôt et à la diffusion de documentsscientifiques de niveau recherche, publiés ou non,émanant des établissements d’enseignement et derecherche français ou étrangers, des laboratoirespublics ou privés.Intra- and inter-observer variability in the angiographicdelineation of brain arterio-venous malformations(AVMs)René Anxionnat, Marie-Odile Berger, Erwan Kerrien, Serge Bracard, LucPicardTo cite this version:René Anxionnat, Marie-Odile Berger, Erwan Kerrien, Serge Bracard, Luc Picard. Intra- andinter-observer variability in the angiographic delineation of brain arterio-venous malformations(AVMs). 17th International Congress and Exhibition on Computer Assisted Radiology and Surgery -CARS’2003, 2003, Londres, Royaume-Uni, pp.1297-1298. ￿inria-00107673￿Intra- and inter-observer variability in the angiographic delineation of brain arterio-venous malformations (AVMs)  R. Anxionnatab, M.O. Bergera, E. Kerriena, S. Bracardb, L. Picardb. aLORIA, Campus scientifique, BP 34; 54506 Vandoeuvre les Nancy cedex, France bService de Neuroradiologie, Hopital Neurologique ; 29, av. du Mal de Lattre de Tassigny ; 54035 Nancy cedex, France. r.anxionnat@chu-nancy.fr tel (0033) 3 83 85 22 03  Introduction. The purpose of this study is to determine the intra- and inter-observer variability in the manual delineation of the boundaries of brain arterio-venous malformations (AVMs) on digital subtracted angiograms. Such delineation is used to define the target volume in stereotactic radiotherapy.  Materiel and methods. Twenty brain AVMs were delineated each twice by 3 neuroradiologists in X-ray angiograms. The variability was assessed by a pair-wise comparison of the 6 contours obtained for each AVM angiograms using the similarity index , the Hausdorff distance and the mean distance [1]. Point to point correspondence between two contours was established thanks to a semi-automated method.  The mean distance was then calculated as the mean of the Euclidian distance between each corresponding points after by. As a result, 3 intra-observer and 12 inter-observer measurements were obtained for each AVM and for each of the above comparison measures.  Results. Table 1 shows the results averaged on the 20 AVMs. Similarity indices above 0.7 indicate a good agreement between experts. The distances are given in pixels (angiograms are 1024x1024 images). Knowing the approximated magnification factors in the angiograms enabled to infer an approximation of the distance values in millimeters (in parentheses).   Similarity Index Mean distance Hausdorff distance Intra-observer 0.85 13.27 px (2.0 mm) 37.53 px (5.7 mm) Inter-observer 0.88 15.39 px (2.3 mm) 44.72 px (6.7 mm) Discussion. The mean distance was found to be  around 2 mm. An upper bound error of 1 mm is generally admitted for the whole stereotactic procedure [2]. Therefore, our study proved that the manual delineation step in such procedures is an important factor which is widely under-estimated (to our knowledge, no study was ever performed to assess its impact). Moreover the big discrepancy between  Hausdorff and mean distances showed that the differences in the delineation were not regularly distributed around the contours. Visual assessment of the variability confirmed that high variation areas alternate with consensus segments on the contours for each AVM. This preliminary work shows that the comparison between two contours must be evaluated on a local basis in order to discern the sources of variability and control them. References  [1]  V. Chalana and Y. Kim. A methodology for evaluation of boundary detection algorithms on medical images. IEEE Transactions on Medical Imaging, vol.16, no. 5, pp. 642-652, 1997 [2]  Evaluation clinique et économique de la radiochirurgie intracranienne en conditions stereotaxiques. Rapport de l’ANAES mai 2000. Anxionnat PO 321   Anxionnat PO 321 

Intra- and inter-observer variability in the angiographic delineation of brain arterio-venous malformations (AVMs)

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Intra- and inter-observer variability in the angiographic delineation of brain arterio-venous malformations (AVMs)

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