Purpose:To evaluate the signal-to-noise ratio (SNR), precision, and accuracy of phase-contrast flow measurements at 3 T with the help of an in vitro model and to compare the results with data from two 1.5-T scanners. Materials and Methods:Using an identical setup of a laminar flow model and sequence parameters, measurements were done at one 3-T and at two 1.5-T systems. Precision, accuracy, and SNR were obtained for velocity encodings ranging from 55 up to 550 cm -1 . SNRs were calculated from the magnitude as well as the flow encoded images.Results: Precision and accuracy for the in vitro flow model were similarly high in all scanners with no significant difference. For velocity encodings from 55 cm -1 up to 550 cm -1 , the SNR in magnitude as well as phase encoded images of the 3-T measurements was approximately 2.5 times higher than the SNR obtained from the two 1.5-T systems. Conclusion:Even without optimization for the 3-T environment, flow measurements show the same high accuracy and precision as is known from clinical 1.5-T scanners. The superior SNR at 3 T will allow further improvements in temporal and spatial resolution. This will be of interest for small-size vessels like coronary arteries or for slow diastolic flow patterns.

Preoperative radiotherapy is feasible with moderate toxicity and is able to induce down staging despite the short time interval between radiotherapy and surgery.

This document describes the implementation of an algorithm that computes a generalization of the distance transform with the squared euclidean metric.The generalization allows for interesting image operators, e.g. a morphologic dilation with euclidean ball structure elements that can vary in size across the image. Voronoi maps and the standard distance transform can be computed as well.The algorithm is provided as an image processing filter for ITK. Several example programs demonstrate its applications.

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