New Technique Quickly Builds 3D Images of Knees -- MEDICA Trade Fair

Developed at the University of Wisconsin-Madison, the faster technique will enable clinics to image more patients - particularly the burgeoning group of older adults with osteoarthritis-related knee problems - and can help researchers more rapidly assess new treatments for such conditions.

Magnetic resonance has long been touted as the ideal method for capturing 3-D images of the human body. "But unfortunately, it is kind of a slow technique," says Walter Block, associate professor of biomedical engineering and medical physics. "You can only sample a few pieces of information needed to build the image at a time." Consequently, most magnetic resonance technicians acquire images as a series of 2-D slices, which yield high resolution in a single plane and poor resolution in the remaining direction, he says.

Rather than using the conventional approach, which sweeps horizontally to gather magnetic resonance data, Block's technique acquires the body's signals radially. "We can essentially acquire data during the whole experiment, where in the (conventional) case, a lot of time was spent either prepping for the experiment or returning it to the steady state so that you could do the next experiment," Block says. "What we're doing now is capable of a study that you can visualise in any plane in about the same time as people are doing one plane."

For example, when imaging a joint like the knee - Block's inspiration for developing the new technique - suppressing the fat signal in bone provides image contrast between bone and the cartilage surface. The conventional data-acquisition method would spend half its scan time suppressing the signal from fat, instead of imaging cartilage. However, Block's technique exploits the difference in resonant frequencies between fat and water. During the scan time, then, the technique maximises each component of the image, so that a technician can view any aspect.; Source: University of Wisconsin-Madison