Standard MRI scanners, used to view many organs of the body, do not always show the whole picture for kidneys. This is because the MRI equipment found in hospitals and clinics works by imaging water molecules in the body. But in water-logged kidneys, the image may not distinguish between different functional parts. Now, Prof. Hadassa Degani of the Biological Regulation Department and her lab team have found a way to see into the kidneys using magnetic resonance imaging (MRI) that scans sodium ions rather than water.

Their method takes advantage of a unique feature of kidney function. Kidneys filter the blood and maintain steady levels of materials such as sodium and potassium in the bloodstream. To sustain control, these organs employ a gradient a rising concentration of sodium from the outer layer, called the cortex, (where concentrations are around those of normal body tissues), towards the center, where levels reach up to five times the norm.

Prof. Degani, together with doctoral student Nimrod Maril and Raanan Margalit, was intrigued by a small number of MRI experiments that focus on sodium to attain images of various tissues, and wondered if the kidneys' sodium gradient could be imaged, and if so, what the image would reveal about kidney function. They enlisted the help of Dr. Joel Mispelter from the Institut Curie in France to help them build the special accessory needed to detect the sodium. Working at a high resolution allowed them to pick up the fine details of changing sodium concentration, particularly localized variations in the sodium gradient.

First the team imaged a healthy rat kidney, showin
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Contact: Alex Smith
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American Committee for the Weizmann Institute of Science
19-Apr-2004