U.S. Philips Corporation

Rudolf W De Boer

Johannes J Van Vaals

Marc Kouwenhoven

Lennart Hofland

The invention relates to A method for imaging jointed movable parts of an object by magnetic resonance, where a third part of the object moves along a trajectory near a pivot between a first and a second part of the object, and where the position of the third part is dependent, in conformity with a predetermined relation, on an orientation of the first and the second part relative to the pivot. The method is used, for example for forming a series of images of the patella during the movement of the knee of a human body. According to the method, the measuring zone is adjusted to the instantaneous position of the patella in order to generate imaging pulse sequences. An angle formed by the orientations of the lower leg and the upper leg with respect to one another is measured in order to determine the instantaneous position of the patella. The angle can be determined from the position of RF coils fastened to the lower leg and the upper leg. Another possibility for determining the angle between the lower leg and the upper leg involves the use of MR navigator signals.

MR method for the imaging of jointed movable parts

An off-resonance magnetization transfer contrast (MTC) RF-pulse (54, 64) is used in magnetic resonance angiography (MRA) to suppress the signal of various stationary tissues, such as brain tissue while avoiding significant suppression of signal from blood flowing in a general direction of blood flow into a slice being imaged. Application of a magnetic gradient (55, 65, 85) during the MTC RF-pulse (54, 64) directed in the general direction of blood flow increases the magnetization frequency offset (86) relative to the center frequency of the MTC RF-pulse for points within and feeding blood to the slice. The MTC RF-pulse thus causes only a small signal reduction of the blood flowing into the slice in the general direction of blood flow while producing a saturation of any blood flowing into the slice in the opposite direction. Consequently, both time and RF-power needed for a separate presaturation pulse can now be used for the MTC RF-pulse.

Growing community of inventors

Eindhoven, Netherlands

Rudolf W De Boer