Minimally invasive transforaminal lumbar interbody fusion with unilateral pedicle screw fixation (UNILIF): morbidity, clinical and radiological 2-year outcomes of a 66-patient prospective series.

PURPOSE: To assess clinical and radiological outcomes at 2-year follow-up of one-level minimally invasive transforaminal interbody fusion with unilateral pedicle screw fixation (UNILIF) in the treatment of stable lumbar degenerative diseases. METHODS: From January 1, 2012 to January 31, 2013, we prospectively collected clinical and radiological data on patients with stable degenerative lumbar disease managed by UNILIF in a single institution. Preoperatively and at 2 years, we recorded ODI, SF-12, Quebec and VAS. Interbody fusion was analyzed on radiography and on a CT scan, and sagittal balance was tested on full spine radiography. RESULTS: Mean operation time was 74.5 min ± 16.8, mean blood loss was 130.8 ml ± 210.9. At 2 years, ODI, SF-12, Quebec and VAS were significantly improved (p > 0.005).The fusion rate was 96.8% on radiographic analysis and was 87.9% on CT scan analysis. CONCLUSIONS: One-level UNILIF constitutes an effective alternative for management of stable lumbar degenerative diseases. These slides can be retrieved under Electronic Supplementary Material.

Dual-pass feature extraction on human vessel images.

We present a novel algorithm for the extraction of cavity features on images of human vessels. Fat deposits in the inner wall of such structure introduce artifacts, and regions in the images captured invalidating the usual assumption of an elliptical model which makes the process of extracting the central passage effectively more difficult. Our approach was designed to cope with these challenges and extract the required image features in a fully automated, accurate, and efficient way using two stages: the first allows to determine a bounding segmentation mask to prevent major leakages from pixels of the cavity area by using a circular region fill that operates as a paint brush followed by Principal Component Analysis with auto correction; the second allows to extract a precise cavity enclosure using a micro-dilation filter and an edge-walking scheme. The accuracy of the algorithm has been tested using 30 computed tomography angiography scans of the lower part of the body containing different degrees of inner wall distortion. The results were compared to manual annotations from a specialist resulting in sensitivity around 98 %, false positive rate around 8 %, and positive predictive value around 93 %. The average execution time was 24 and 18 ms on two types of commodity hardware over sections of 15 cm of length (approx. 1 ms per contour) which makes it more than suitable for use in interactive software applications. Reproducibility tests were also carried out with synthetic images showing no variation for the computed diameters against the theoretical measure.

Cardiac function estimation from MRI using a heart model and data assimilation: advances and difficulties.

In this paper, we present a framework to estimate local ventricular myocardium contractility using clinical MRI, a heart model and data assimilation. First, we build a generic anatomical model of the ventricles including muscle fibre orientations and anatomical subdivisions. Then, this model is deformed to fit a clinical MRI, using a semi-automatic fuzzy segmentation, an affine registration method and a local deformable biomechanical model. An electromechanical model of the heart is then presented and simulated. Finally, a data assimilation procedure is described, and applied to this model. Data assimilation makes it possible to estimate local contractility from given displacements. Presented results on fitting to patient-specific anatomy and assimilation with simulated data are very promising. Current work on model calibration and estimation of patient parameters opens up possibilities to apply this framework in a clinical environment.

Simulation of cardiac pathologies using an electromechanical biventricular model and XMR interventional imaging.

Simulating cardiac electromechanical activity is of great interest for a better understanding of pathologies and for therapy planning. Design and validation of such models is difficult due to the lack of clinical data. XMR systems are a new type of interventional facility in which patients can be rapidly transferred between X-ray and MR systems. Our goal is to design and validate an electromechanical model of the myocardium using XMR imaging. The proposed model is computationally fast and uses clinically observable parameters. We present the integration of anatomy, electrophysiology, and motion from patient data. Pathologies are introduced in the model and simulations are compared to measured data. Initial qualitative comparison on the two clinical cases presented is encouraging. Once fully validated, these models will make it possible to simulate different interventional strategies.