Ben Shofty

Automatic segmentation, internal classification, and follow-up of optic pathway gliomas in MRI

This paper presents an automatic method for the segmentation, internal classification and follow-up of optic pathway gliomas (OPGs) from multi-sequence MRI datasets. Our method starts with the automatic localization of the OPG and its core with an anatomical atlas followed by a binary voxel classification with a probabilistic tissue model whose parameters are estimated from the MR images. The method effectively incorporates prior location, tissue characteristics, and intensity information for the delineation of the OPG boundaries in a consistent and repeatable manner. Internal classification of the segmented OPG volume is then obtained with a robust method that overcomes grey-level differences between learning and testing datasets. Experimental results on 25 datasets yield a mean surface distance error of 0.73 mm as compared to manual segmentation by experienced radiologists. Our method exhibits reliable performance in OPG growth follow-up MR studies, which are crucial for monitoring disease progression. To the best of our knowledge, this is the first method that addresses automatic segmentation, internal classification, and follow-up of OPG.

Visual outcome following chemotherapy for progressive optic pathway gliomas

Optic pathway gliomas (OPG) are relatively indolent tumors that may occur sporadically or in association with neurofibromatosis 1. Treatment is initiated only when a clear clinical or radiological deterioration is documented. Chemotherapy is the standard first line of treatment. Due to the indolent nature of this tumor, the most important challenge in OPG treatment is vision preservation.

MRI internal segmentation of optic pathway gliomas: clinical implementation of a novel algorithm

PurposeOptic pathway gliomas (OPGs) are diagnosed based on typical MR features and require careful monitoring with serial MRI. Reliable, serial radiological comparison of OPGs is a difficult task, where accuracy becomes very important for clinical decisions on treatment initiation and results. Current radiological methodology usually includes linear measurements that are limited in terms of precision and reproducibility.MethodWe present a method that enables semiautomated segmentation and internal classification of OPGs using a novel algorithm. Our method begins with co-registration of the different sequences of an MR study so that T1 and T2 slices are realigned. The follow-up studies are then re-sliced according to the baseline study. The baseline tumor is segmented, with internal components classified into solid non-enhancing, solid-enhancing, and cystic components, and the volume is calculated. Tumor demarcation is then transferred onto the next study and the process repeated. Numerical values are correlated with clinical data such as treatment and visual ability.ResultsWe have retrospectively implemented our method on 24 MR studies of three OPG patients. Clinical case reviews are presented here. The volumetric results have been correlated with clinical data and their implications are also discussed.ConclusionsThe heterogeneity of OPGs, the long course, and the young age of the patients are all driving the demand for more efficient and accurate means of tumor follow-up. This method may allow better understanding of the natural history of the tumor and provide a more advanced means of treatment evaluation.

Intrathecal or intraventricular therapy for post-neurosurgical Gram-negative meningitis: matched cohort study

Gram-negative post-operative meningitis due to carbapenem-resistant bacteria (CR-GNPOM) is a dire complication of neurosurgical procedures. We performed a nested propensity-matched historical cohort study aimed at examining the possible benefit of intrathecal or intraventricular (IT/IV) antibiotic treatment for CR-GNPOM. We included consecutive adults with GNPOM in two centres between 2005 and 2014. Patients receiving combined systemic and IT/IV treatment were matched to patients receiving systemic treatment only. Matching was done based on the propensity of the patients to receive IT/IV treatment. We compared patient groups with 30-day mortality defined as the primary outcome. The cohort included 95 patients with GNPOM. Of them, 37 received IT/IV therapy in addition to systemic treatment (22 with colistin and 15 with amikacin), mostly as initial therapy, through indwelling cerebrospinal fluid drains. Variables associated with IT/IV therapy in the propensity score included no previous neurosurgery, time from admission to meningitis, presence of a urinary catheter and GNPOM caused by carbapenem-resistant Gram-negative bacteria. Following propensity matching, 23 patients given IT/IV therapy and 27 controls were analysed. Mortality was significantly lower with IT/IV therapy: 2/23 (8.7%) versus 9/27 (33.3%), propensity-adjusted OR 0.19, 95% CI 0.04-0.99. Death or neurological deterioration at 30 days, 14-day and in-hospital mortality were lower with IT/IV therapy (OR <0.4 for all) without statistically significant differences. Among patients discharged alive, those receiving IT/IV therapy did not experience more neurological deterioration. Serious adverse events with IT/IV therapy were not documented. Our results support the early use of IT antibiotic treatment for CR-GNPOM when a delivery method is available.

Optic Pathway Gliomas

Optic pathway gliomas (OPGs) are among the most challenging neoplasms in modern pediatric neuro-oncology. Recent technological advances in imaging, surgery, and chemotherapy may lead to better understanding of the pathophysiology and better clinical results. This chapter reviews these advances and the current treatment paradigms.

Advances in Molecular Diagnosis of Neurofibromatosis Type 1

Neurofibromatosis 1 (NF1) is a common neurocutaneous and tumor predisposing genetic disorder with an autosomal dominant mode of inheritance. NF1 is solely caused by mutations in the NF1 gene, and disease-causing mutations can be found in more than 95% of individuals with a clinical diagnosis. Although NF1 has a distinctive clinical phenotype, it has a highly variable expression, even among individuals from the same family. Identifying the specific mutation does not usually assist in determining disease course and severity, and relatively few genotype-phenotype correlations have thus far been found. This review discusses the basic clinical aspects of NF1 and the current explanations for the high phenotypic variability, and provides the recently detected genotype-phenotype correlations.

The effect of chemotherapy on optic pathway gliomas and their sub-components: A volumetric MR analysis study

Optic pathway gliomas (OPG) represent 5% of pediatric brain tumors and compose a major therapeutic dilemma to the treating physicians. While chemotherapy is widely used for these tumors, our ability to predict radiological response is still lacking. In this study, we use volumetric imaging to examine in detail the long‐term effect of chemotherapy on the tumor as well as its various sub‐components.

Optic pathway gliomas in adults.

BACKGROUND Optic pathway gliomas (OPGs) are considered relatively benign pediatric tumors. Adult patients with OPG can be divided into 2 groups: adult patients with tumors diagnosed in childhood and adult patients diagnosed during adulthood. OBJECTIVE To characterize the clinical course of adult patients with OPG. METHODS We retrospectively collected clinical and imaging data of all adult OPG patients monitored in our medical center between 1990 and 2012. RESULTS Twenty-two adult patients were included. Age at diagnosis varied widely (6 months-66 years), as did age at last follow-up (18-74 years). Ten patients were diagnosed at adulthood and 12 in childhood. Of the patients diagnosed at childhood, 6 had radiological progression during childhood, and 3 of those patients suffered visual impairment. From this group, 1 patient had further progression during adulthood accompanied by additional visual decline, and 2 patients had additional visual decline during adulthood despite no signs of progression. Of the 6 patients whose tumors were stable during childhood, all 6 remained stable during adulthood. Of 10 patients diagnosed at adulthood, 6 patients suffered visual deterioration; in 5 of them, a concomitant progression was noted. Two patients were diagnosed with high-grade gliomas. CONCLUSION OPGs may be active during childhood or adulthood. Those patients who experienced anatomic activity during childhood are prone to continue experiencing active disease during adulthood. A significant percentage of patients diagnosed with low-grade OPG at adulthood may suffer progression, visual decline, or both. ABBREVIATIONS NF1, neurofibromatosis 1OPG, optic pathway gliomas.

Prediction of brain MR scans in longitudinal tumor follow-up studies

We present a new method for the estimation of the next brain MR scan in a longitudinal tumor follow-up study. Our method effectively incorporates information of the past scans in the time series to predict the future scan of the patient. Its advantages are that it requires no user intervention and does not assume any particular tumor growth model. Instead, the patient-specific tumor growth parameters are estimated individually from the past patient scans. To validate our method, we conducted an experimental study on four patients with Optic Path Gliomas (OPGs) and four patients with glioblastomas multiforma (GBM), each scanned at five time points. The tumor volumes in the predicted and actual future scans, both segmented by an expert radiologist, yield a mean volume overlap difference of 13.65% for the OPG patients, and 34.23% for the GBM patients.

Japanese encephalitis among patients with acute encephalitic syndrome admitted to a tertiary hospital in Chitwan, Nepal--a prospective observational study.

Introduction The reported incidence of JE among patients with acute encephalitic syndrome (AES) in Nepal ranges between 20% to 62%. In light of the lack of up-to-date data, we sought to describe the epidemiology of JE in Chitwan, Nepal. Methods A prospective observational study was conducted during 2010–2012 in the College of Medical Science in the Chitwan District. Patients with suspected JE were tested for anti-JE IgM in serum and cerebrospinal fluid (CSF). Results Of 227 all patients tested, 18 (7.9%) were found positive for JE. 17/202 (8.4%) patients with AES had JE. All, with the exception of two patients, were diagnosed on the basis of positive a serologic test, both in serum and CSF samples. Patients with JE were significantly older (42.1±27.6 years) than patients without JE (25.6±25.2 years, p = 0.02). Half of JE cases occurred in adults older than 50. More of the JE cases (11/18, 61.1%) occurred during the rainy season when compared to the JE negative patients [71/209, (34%), p = 0.01]. None of the JE patients had a relevant travel history, and one recalled having been immunized against JE. There was a variation in the geographic distribution of cases across the districts of the central Terai. Conclusions In this cohort, the proportion of patients with AES who had JE was lower than in previous studies. In addition, most patients were adults, and cases were not distributed uniformly across the central Terai region. The risk of acquiring JE by short-term travelers in the area is likely to be low. Vector-control programs and the promotion of mosquito avoidance behavior in the Terai region should continue. The high proportions of adults among patients with JE may suggest recent changes in the epidemiology of JE in the central Terai region, and routine immunization of all adults should be considered.