ISLES 2015 - A public evaluation benchmark for ischemic stroke lesion segmentation from multispectral MRI

Ischemic stroke is the most common cerebrovascular disease, and its diagnosis, treatment, and study relies on non-invasive imaging. Algorithms for stroke lesion segmentation from magnetic resonance imaging (MRI) volumes are intensely researched, but the reported results are largely incomparable due to different datasets and evaluation schemes. We approached this urgent problem of comparability with the Ischemic Stroke Lesion Segmentation (ISLES) challenge organized in conjunction with the MICCAI 2015 conference. In this paper we propose a common evaluation framework, describe the publicly available datasets, and present the results of the two sub-challenges: Sub-Acute Stroke Lesion Segmentation (SISS) and Stroke Perfusion Estimation (SPES). A total of 16 research groups participated with a wide range of state-of-the-art automatic segmentation algorithms. A thorough analysis of the obtained data enables a critical evaluation of the current state-of-the-art, recommendations for further developments, and the identification of remaining challenges. The segmentation of acute perfusion lesions addressed in SPES was found to be feasible. However, algorithms applied to sub-acute lesion segmentation in SISS still lack accuracy. Overall, no algorithmic characteristic of any method was found to perform superior to the others. Instead, the characteristics of stroke lesion appearances, their evolution, and the observed challenges should be studied in detail. The annotated ISLES image datasets continue to be publicly available through an online evaluation system to serve as an ongoing benchmarking resource (www.isles-challenge.org).Peer reviewe

The receptor tyrosine phosphatase CRYPα affects growth cone morphology

During development of the nervous system receptor tyrosine kinases and receptor protein tyrosine phosphatases act in a coordinate way during axon growth and guidance. In the developing avian retinotectal system, many different receptor protein tyrosine phosphatases are expressed. Most of them have unknown functions. Retinal ganglion cells express at least three different members of this receptor family on their axons and growth cones: CRYPα, CRYP‐2 and PTPμ. CRYPα interacts heterophilically with at least two different ligands found in the basal membranes of the retina and the optic tectum. To analyze the role of the CRYPα–ligand interaction, retinal ganglion cell axons were grown on retinal basal membranes (inner limiting membrane) and the receptor–ligand interaction was blocked from both the receptor side (by receptor specific antibodies) and from the ligand side by using a receptor‐alkaline phosphatase fusion protein. Both of these treatments reduced average retinal axon length and induced a dramatic change in morphology of retinal ganglion cell growth cones on basal membranes, but not on other substrates like laminin, N‐cadherin, matrigel‐ and detergent‐treated basal membranes. These results suggest that CRYPα and its ligand act as growth‐promoting molecules during intraretinal axon growth. © 2000 John Wiley & Sons, Inc. J Neurobiol 44: 204–218, 200

The Receptor Tyrosine Phosphatase Crypα Promotes Intraretinal Axon Growth

Retinal ganglion cell axons grow towards the optic fissure in close contact with the basal membrane, an excellent growth substratum. One of the ligands of receptor tyrosine phosphatase CRYPα is located on the retinal and tectal basal membranes. To analyze the role of this RPTP and its ligand in intraretinal growth and guidance of ganglion cell axons, we disrupted ligand- receptor interactions on the retinal basal membrane in culture. Antibodies against CRYPα strongly reduced retinal axon growth on the basal membrane, and induced a dramatic change in morphology of retinal growth cones, reducing the size of growth cone lamellipodia. A similar effect was observed by blocking the ligand with a CRYPα ectodomain fusion protein. These effects did not occur, or were much reduced, when axons were grown either on laminin-1, on matrigel or on basal membranes with glial endfeet removed. This indicates that a ligand for CRYPα is located on glial endfeet. These results show for the first time in vertebrates that the interaction of a receptor tyrosine phosphatase with its ligand is crucial not only for promotion of retinal axon growth but also for maintenance of retinal growth cone lamellipodia on basal membranes

ISLES 2015 - A public evaluation benchmark for ischemic stroke lesion segmentation from multispectral MRI

Ischemic stroke is the most common cerebrovascular disease, and its diagnosis, treatment, and study relies on non-invasive imaging. Algorithms for stroke lesion segmentation from magnetic resonance imaging (MRI) volumes are intensely researched, but the reported results are largely incomparable due to different datasets and evaluation schemes. We approached this urgent problem of comparability with the Ischemic Stroke Lesion Segmentation (ISLES) challenge organized in conjunction with the MICCAI 2015 conference. In this paper we propose a common evaluation framework, describe the publicly available datasets, and present the results of the two sub-challenges: Sub-Acute Stroke Lesion Segmentation (SISS) and Stroke Perfusion Estimation (SPES). A total of 16 research groups participated with a wide range of state-of-the-art automatic segmentation algorithms. A thorough analysis of the obtained data enables a critical evaluation of the current state-of-the-art, recommendations for further developments, and the identification of remaining challenges. The segmentation of acute perfusion lesions addressed in SPES was found to be feasible. However, algorithms applied to sub-acute lesion segmentation in SISS still lack accuracy. Overall, no algorithmic characteristic of any method was found to perform superior to the others. Instead, the characteristics of stroke lesion appearances, their evolution, and the observed challenges should be studied in detail. The annotated ISLES image datasets continue to be publicly available through an online evaluation system to serve as an ongoing benchmarking resource (www.isles-challenge.org).Maier O., Menze B.H., von der Gablentz J., Häni L., Heinrich M.P., Liebrand M., Winzeck S., Basit A., Bentley P., Chen L., Christiaens D., Dutil F., Egger K., Feng C., Glocker B., Götz M., Haeck T., Halme H., Havaei M., Iftekharuddin K.M., Jodoin P., Kamnitsas K., Kellner E., Korvenoja A., Larochelle H., Ledig C., Lee J., Maes F., Mahmood Q., Maier-Hein K.H., McKinley R., Muschelli J., Pal C., Pei L., Rangarajan J.R., Reza S.M.S., Robben D., Rueckert D., Salli E., Suetens P., Wang C., Wilms M., Kirschke J.S., Krämer U.M., Münte T.F., Schramm P., Wiest R., Handels H., Reyes M., ''ISLES 2015 - A public evaluation benchmark for ischemic stroke lesion segmentation from multispectral MRI'', Medical image analysis, vol. 35, pp. 250-269, January 2017.status: publishe