Method and apparatus for determining the relative location of tomograph slices

Apparatus for three dimensional ultrasound imaging of an object comprising:

• transducers arrayed in a geometry to acquire ultrasound imaging data in an imaging slice of the object, which imaging slice is defined by a plane, so that data of the acquired data is acquired at points on both sides of the plane of the slice;
• a processor which processes said data to provide spatial derivatives of said data in a direction normal to the plane of the imaging slice;
• and wherein
• said processor determines the relative positions of a plurality of imaging slices using said acquired data and said derivatives to provide a three dimensional image of said object.

A method of ultrasound imaging comprising:

• (a) providing ultrasound image data in a first slice defined by a first plane in a first coordinate system;
• (b) providing ultrasound image data in a second slice defined by a second plane in a second coordinate system different from first coordinate system;
• (c) determining ultrasound image data in a region adjacent to at least one of said first and second planes, said region including at least a portion of one of said first and second planes;
• and
• (d) determining a coordinate transformation between the first and second coordinate systems based on said acquired ultrasound image data and said determined ultrasound image data.