6 publications classées par:
type de publication
: Revue avec comité de lecture
Articles Ciller C., De Zanet S.I., Rüegsegger M.B., Pica A., Sznitman R., Thiran J.P. et al. (2015). Automatic Segmentation of the Eye in 3D Magnetic Resonance Imaging: A Novel Statistical Shape Model for Treatment Planning of Retinoblastoma. International Journal of Radiation Oncology, Biology, Physics, 92(4), 794-802. [doi] [web of science] [abstract]
PURPOSE: Proper delineation of ocular anatomy in 3-dimensional (3D) imaging is a big challenge, particularly when developing treatment plans for ocular diseases. Magnetic resonance imaging (MRI) is presently used in clinical practice for diagnosis confirmation and treatment planning for treatment of retinoblastoma in infants, where it serves as a source of information, complementary to the fundus or ultrasonographic imaging. Here we present a framework to fully automatically segment the eye anatomy for MRI based on 3D active shape models (ASM), and we validate the results and present a proof of concept to automatically segment pathological eyes.¦METHODS AND MATERIALS: Manual and automatic segmentation were performed in 24 images of healthy children's eyes (3.29 ± 2.15 years of age). Imaging was performed using a 3-T MRI scanner. The ASM consists of the lens, the vitreous humor, the sclera, and the cornea. The model was fitted by first automatically detecting the position of the eye center, the lens, and the optic nerve, and then aligning the model and fitting it to the patient. We validated our segmentation method by using a leave-one-out cross-validation. The segmentation results were evaluated by measuring the overlap, using the Dice similarity coefficient (DSC) and the mean distance error.¦RESULTS: We obtained a DSC of 94.90 ± 2.12% for the sclera and the cornea, 94.72 ± 1.89% for the vitreous humor, and 85.16 ± 4.91% for the lens. The mean distance error was 0.26 ± 0.09 mm. The entire process took 14 seconds on average per eye.¦CONCLUSION: We provide a reliable and accurate tool that enables clinicians to automatically segment the sclera, the cornea, the vitreous humor, and the lens, using MRI. We additionally present a proof of concept for fully automatically segmenting eye pathology. This tool reduces the time needed for eye shape delineation and thus can help clinicians when planning eye treatment and confirming the extent of the tumor.
Federau C., O'Brien K., Birbaumer A., Meuli R., Hagmann P. & Maeder P. (2015). Functional mapping of the human visual cortex with intravoxel incoherent motion MRI. Plos One, 10(2), e0117706. [doi] [web of science] [abstract]
Functional imaging with intravoxel incoherent motion (IVIM) magnetic resonance imaging (MRI) is demonstrated. Images were acquired at 3 Tesla using a standard Stejskal-Tanner diffusion-weighted echo-planar imaging sequence with multiple b-values. Cerebro-spinal fluid signal, which is highly incoherent, was suppressed with an inversion recovery preparation pulse. IVIM microvascular perfusion parameters were calculated according to a two-compartment (vascular and non-vascular) diffusion model. The results obtained in 8 healthy human volunteers during visual stimulation are presented. The IVIM blood flow related parameter fD* increased 170% during stimulation in the visual cortex, and 70% in the underlying white matter.
Marcus C. de Jong, Pim de Graaf, Hervé J. Brisse, Paolo Galluzzi, Sophia L. Göricke, Annette C. Moll et al. (2014). The potential of 3T high-resolution magnetic resonance imaging for diagnosis, staging and follow-up of retinoblastoma. Survey of Ophthalmology, 60(4), 346-355.
Tuleasca C, Negretti L., Magaddino V., Maeder P., Lhermitte B., Borruat FX. & Levivier M. (2014). Biphasic response of a tecto-mesencephalic pilocytic astrocytoma after Gamma Knife surgery - A case report. Neurochirurgie, 4. [doi]
Etudes de cas Tuleasca C., Jaquet Y., Schweizer V., Negretti L., Magaddino V., Maeder P. et al. (in press). Clinical and biochemical responses after Gamma Knife surgery for a dopamine-secreting paraganglioma: case report. Hormones (athens, Greece). [doi] [abstract]
INTRODUCTION: The efficacy of Gamma Knife surgery (GKS) in local tumor control of non-secreting paragangliomas (PGLs) has been fully described by previous studies. However, with regard to secreting PGL, only one previous case report exists advocating its efficacy at a biological level.¦CASE REPORT: The aims of this study were: 1) to evaluate the safety/efficacy of GKS in a dopamine-secreting PGL; 2) to investigate whether the biological concentrations of free methoxytyramine could be used as a marker of treatment efficacy during the follow-up. We describe the case of a 62-year-old man diagnosed with left PGL. He initially underwent complete surgical excision. Thirty months after, he developed recurrent biological and neuroradiological disease; the most sensitive biomarker for monitoring the disease, concentration of plasma free methoxytyramine, started to increase. GKS was performed at a maximal marginal dose of 16 Gy. During the following 30 months, concentration of free methoxytyramine gradually decreased from 0.14 nmol/l (2*URL) before GKS to 0.09 nmol/l, 6 months after GKS and 0.07 nmol/l at the last follow-up after GKS (1.1*URL), confirming the efficacy of the treatment. Additionally, at 30 months there was approximately 36.6% shrinkage from the initial target volume.¦CONCLUSION: The GKS treatment was safe and effective, this being confirmed clinically, neuroradiologically and biologically. The case illustrates the importance of laboratory tests taking into account methoxytyramine when analyzing biological samples to assess the biochemical activity of a PGL. In addition, the identification of methoxytyramine as a unique positive biomarker could designate it for the monitoring of tumor relapse after treatments, including Gamma Knife surgery.
Actes de conférence (partie)
Abstract Tuleasca C., Najdenovska E., Battistella G., Maeder P., Fornari E., Thiran J.-P. et al. (2015, Juin). Novel robust segmentation of the thalamic nuclei and validation of patients treated with Gamma Knife thalamotomy of the Vim : preliminary report in 2 cases [Abstract]. . 12-th International Stereotactic Radiosurgery Society Congress (ISRS), June 2015, Yokohama, Japan ; Journal of Radiosurgery and SBRT, Volume 3, Supllement 1, page 73.