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The Hough transform is a feature extraction technique used in image analysis, computer vision and digital image processing. Usually it is used for detecting straight lines and curves. The purpose of the technique is to find imperfect instances of patterns within a certain class of shapes by a voting procedure. An improved Hough transform is proposed by using interval arithmetics in the accumulation phase of the algorithm. The discreteness of the quantization space is considered. The use of interval arithmetics showed to be simpler than other statistical proposals. It is presented a modified Hough transform for detecting function patterns implemented with interval arithmetics. This modified Hough transform was used to analyze the movement of the lung in MR temporal sequence of images. The results obtained with the interval arithmetics implementation were much better when compared with the conventional Hough transform implementation.

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This work discusses the use of breathing patterns present in time sequences of MR images in the temporal registration of coronal and sagittal images. The registration is done without the use of any triggering information and any special gas to enhance the contrast. The temporal sequences of images are acquired in free breathing. As coronal and sagittal sequences of images are orthogonal to each other, their intersection corresponds to a segment in the three dimensional space. The registration happens by analyzing this intersection segment that is determined by a coronal-sagittal mapping. A time sequence of this intersection segment can be stacked, defining a two dimension spatio-temporal (2DST) image. It is assumed that the diaphragmatic movement is the principal movement and all the lungs structures do move almost synchronously. The synchronization was realized through a pattern named respiratory function. A Hough transform algorithm, using the respiratory function as input, searches for synchronized movements with the respiratory function. Finally, the composition of coronal and sagittal images that are in the same breathing phase is made by comparison of diaphragmatic respiratory patterns. Several results and conclusions are shown.