PubMed · 15692383
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Mohammed G Ellabban, Deemesh Oudit, Ali Juma. 2005. A simple model for practicing local flap design.. https://doi.org/10.1097/01.prs.0000149052.30124.e3
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OBJECTIVE: This study evaluates the hypothesis that current image guidance technology can effectively guide the resection of a predefined intracranial volume from the surgical field in the absence of a visually distinct lesion. METHODS: An in vitro model was constructed to simulate the resection of a visually nondistinct lesion. Preoperative CT was acquired, and the lesion was resected from the model with a cavitating ultrasonic aspirator using image guidance information provided by the SurgiScope system. RESULTS: On average, 77% of the 8.2-cm(3) surgical target volume was removed. Over a series of 5 trials, the underresection volume was 1.9 cm(3) on average or 23% of the surgical target volume. The overresection volume was 1.0 cm(3) on average, representing 13% of the surgical target volume. CONCLUSION: This in vitro model developed to evaluate the accuracy and limitations of our current image guidance technology provided quantitative data to demonstrate the potential for robotic navigation systems to guide the volumetric resection in the absence of visual differentiation between the lesion and the surrounding brain.
In this article we describe an application of active contour model for the segmentation of 3D histo-pathological images. The 3D images of a thick tissue specimen are obtained as a stack of optical sections using confocal laser beam scanning microscope (CLSM). We have applied noise reduction and feature enhancement methods so that a smooth and slowly varying potential surface is obtained for proper convergence. To increase the capture range of the potential surface, we use a combination of distance potential and the diffused gradient potential as external forces. It has been shown that the region-based information obtained from low-level segmentation can be applied to reduce the adverse influence of the neighbouring nucleus having a strong boundary feature. We have also shown that, by increasing the axial resolution of the image stack, we can automatically propagate the optimum active contour of one image slice to its neighbouring image slices as an appropriate initial model. Results on images of prostate tissue section are presented.
OBJECTIVE: To evaluate response to pressure and flow triggering in an experimental model of the normal, obstructive and restrictive lung with six non-invasive mechanical ventilation units: Vintil+ (VP), Respironics STD20 (RR), Puritan Bennet 335 (PB), Quantum (QT), DP90 (DP) and Sullivan II ST (SV). METHOD: Analog signals of volume, pressure and flow from a lung simulator were recorded by a Mingograph 34 polygraph. Positive inspiratory pressure (PIP) was 12 cmH2O, respiratory rate was 17 cycles/min, end expiratory pressure (PEEP) was 4 cmH2O, and inspiratory effort (P0.1) was 4 cmH2O. Parameters calculated were negative trigger pressure, trigger time (or the flow wave delay in triggering), and the percentage of peak inspiratory flow at which a change to exhalation or cycle phase. RESULTS: The RR and PB units had the best trigger response with pressure triggering below -1 cmH2O and trigger times less than 100 ms. VP proved to have the poorest response. The cycle of the RR agreed most closely with the standard (5-25% of peak inspiratory flow), whereas change to exhalation occurred with the other units with zero flow (in all patterns with DP90, and in restrictive patterns with PB and VP) or greater than 50% of peak inspiratory flow (in all models with QT). Analysis of pressure curves showed great differences in slope, plateau and depressurization. CONCLUSIONS: The RR unit proved to have the most homogeneous behavior for all the phase parameters studied as being the ones that most influence a patient's adaptation to a ventilator.