Artificial intelligence to predict clinical disability in patients with multiple sclerosis using FLAIR MRI.

PURPOSE: The purpose of this study was to create an algorithm that combines multiple machine-learning techniques to predict the expanded disability status scale (EDSS) score of patients with multiple sclerosis at two years solely based on age, sex and fluid attenuated inversion recovery (FLAIR) MRI data. MATERIALS AND METHODS: Our algorithm combined several complementary predictors: a pure deep learning predictor based on a convolutional neural network (CNN) that learns from the images, as well as classical machine-learning predictors based on random forest regressors and manifold learning trained using the location of lesion load with respect to white matter tracts. The aggregation of the predictors was done through a weighted average taking into account prediction errors for different EDSS ranges. The training dataset consisted of 971 multiple sclerosis patients from the "Observatoire français de la sclérose en plaques" (OFSEP) cohort with initial FLAIR MRI and corresponding EDSS score at two years. A test dataset (475 subjects) was provided without an EDSS score. Ten percent of the training dataset was used for validation. RESULTS: Our algorithm predicted EDSS score in patients with multiple sclerosis and achieved a MSE=2.2 with the validation dataset and a MSE=3 (mean EDSS error=1.7) with the test dataset. CONCLUSION: Our method predicts two-year clinical disability in patients with multiple sclerosis with a mean EDSS score error of 1.7, using FLAIR sequence and basic patient demographics. This supports the use of our model to predict EDSS score progression. These promising results should be further validated on an external validation cohort.

Preoperative assessment of idiopathic scoliosis in adolescent and young adult with three-dimensional T2-weighted spin-echo MRI.

PURPOSE: To compare tridimensional (3D) T2-weighted spin-echo MRI and CT for minimal pedicle width measurements in the preoperative assessment of adolescent idiopathic scoliosis (AIS) in adolescent and young patients. MATERIALS AND METHODS: A total of 22 adolescents/young patients suffering from AIS were retrospectively included. There were 18 females and 4 males with a mean age of 15.3±2.3 (SD) years (range: 11-21years). Preoperative lumbar spine MRI and CT examinations of the 22 patients were reviewed by two independent readers who measured the minimal width of 259 pedicles. Inter-reader agreement for CT and MRI was assessed using intra-class correlation coefficient (ICC). Intra-reader agreement and relative differences in measurements between MRI and CT were also assessed for each reader. RESULTS: Inter-reader agreement was excellent (ICC≥0.8) for both CT and MRI. Relative differences in measurements between CT and MRI was 10.3% for reader 1 and 9.4% for reader 2. CONCLUSION: 3D T2-weighted spin-echo MRI underestimates minimal pedicle width by only 9.4 - 10.3% compared to CT. 3D T2-weighted MRI appears as a valuable alternative to CT for preoperative measurements of vertebral pedicles in AIS.

Comparison between enhanced susceptibility-weighted angiography and time of flight sequences in the detection of arterial occlusion in acute ischemic stroke.

PURPOSE: Optimizing the MRI protocol in acute ischemic stroke remains a challenging issue. In this field, susceptibility-weighted sequences have proved their superiority over T2*. Besides the strengthened susceptibility effect, enhanced susceptibility-weighted angiography (eSWAN) sequence provides also a time-of-flight (TOF) effect, allowing the exploration of the intracranial arterial circulation. The objective of our study was to compare eSWAN and 3D TOF, considered as the reference, in the detection of arterial occlusion in acute stroke. METHODS: Patients who underwent MRI between March and July 2014 for suspected acute stroke with an acute ischemic lesion on diffusion-weighted imaging (DWI) were prospectively included in this study. eSWAN and TOF images were analyzed under double-blind conditions by a junior radiologist and a senior neuroradiologist for the detection of arterial occlusion. eSWAN images were assessed in order to estimate the inter-observer agreement. After a consensus, eSWAN and TOF data were compared to calculate inter-modality agreement. RESULTS: Thirty-four patients were included. Inter-observer agreement was excellent (kappa: 0.96) for eSWAN detection of occlusion. After consensus, comparison between TOF and eSWAN showed substantial agreement (kappa: 0.71). eSWAN provided better detection of distal occlusions, but poorer performance for detection of siphon occlusions. CONCLUSIONS: Shortest echoes eSWAN images enabled detection of arterial occlusion with substantial agreement with TOF images. The susceptibility vessel sign associated with the TOF effect improved the identification of distal occlusions. In acute stroke protocol, eSWAN may represent a valuable alternative to T2* and TOF sequences.

Brain Magnetic Susceptibility Changes in Patients with Natalizumab-Associated Progressive Multifocal Leukoencephalopathy.

We investigated the brain magnetic susceptibility changes induced by natalizumab-associated progressive multifocal leukoencephalopathy. We retrospectively included 12 patients with natalizumab-progressive multifocal leukoencephalopathy, 5 with progressive multifocal leukoencephalopathy from other causes, and 55 patients with MS without progressive multifocal leukoencephalopathy for comparison. MR imaging examinations included T2* or SWI sequences in patients with progressive multifocal leukoencephalopathy (86 examinations) and SWI in all patients with MS without progressive multifocal leukoencephalopathy. Signal abnormalities on T2* and SWI were defined as low signal intensity within the cortex and/or U-fibers and the basal ganglia. We observed T2* or SWI signal abnormalities at the chronic stage in all patients with progressive multifocal leukoencephalopathy, whereas no area of low SWI signal intensity was detected in patients without progressive multifocal leukoencephalopathy. Among the 8 patients with asymptomatic natalizumab-progressive multifocal leukoencephalopathy, susceptibility changes were observed in 6 (75%). The basal ganglia adjacent to progressive multifocal leukoencephalopathy lesions systematically appeared hypointense by using T2* and/or SWI. Brain magnetic susceptibility changes may be explained by the increased iron deposition and constitute a useful tool for the diagnosis of progressive multifocal leukoencephalopathy.

Rate of intravenous thrombolysis for acute ischaemic stroke in the North-of-France region and evolution over time.

The proportion of patients with ischaemic stroke treated by intravenous (i.v.) recombinant tissue plasminogen activator (rt-PA) is an indicator of quality of stroke care. The objective of the study is to evaluate the rate of i.v. thrombolysis in the North-of-France region and its evolution over time. We determined the proportion of inhabitants treated by i.v. rt-PA in 2009-2010 (period A; 8 stroke units, no telemedicine) and 2012 (period B; population campaigns, 12 stroke units with telemedicine in 5). We used hospital registries from the 12 stroke units, and population-based data were collected in a subpopulation of 226,827 inhabitants (5.6% of the whole population). 1,563 inhabitants received i.v. rt-PA for stroke (period A: 835 in 24 months; period B: 728 in 12 months). Hospital and population data were similar. Annual rates of thrombolysis increased from 103 per million inhabitants [95% confidence interval (CI) 85-125] to 181 (95% CI 157-209; relative increase 76%, 95% CI 67-83%). This rate increased in 12 districts (significantly in 6), but the increase was greater in districts where new stroke units, telemedicine, or both were implemented. In conclusion, although the proportion of patients treated was already high in period A, there was still place for improvement. Implementation of new stroke units, extension of the telemedicine network and new population campaigns are necessary to improve the rate of thrombolysis in several areas, to ensure an equal access to treatment over the whole territory. The next step is now to determine whether this high rate of i.v. rt-PA delivery at the population level translates into clinical results.