Evaluation of Kidney Function by Multi-modal Magnetic Resonance Imaging and Spectroscopy

Early and specific detection of dysfunction in kidney diseases and differential diagnosis of potential complications in the renal allograft are fundamental to initiate appropriate treatment. In addition, determination of renal function may reveal physiological mechanisms that may prove useful for future therapeutic procedures. Currently, used methods to access renal function like ultrasound, radionuclide imaging, and laboratory methods have several disadvantages, as they are nonspecific, require radioactive contrast agents or are limited in spatial information. Therefore, alternative non-invasive methods to detect early morphological and functional changes are required. Recently, a variety of very promising advanced magnetic resonance imaging (MRI) methods have evolved to obtain functional information of different organs. These methods include MR angiography, diffusion, perfusion and Blood-Oxygenation Level Dependent (BOLD) imaging. In addition to MRI, MR spectroscopy (MRS) provides renal functional information. In abdominal organs like the kidney, respiratory, and cardiac motion and susceptibility artifacts have limited the use of these functional MR methods for clinical applications. However, this may be overcome with the advent of greatly enhanced hardware, allowing very fast imaging times. Besides these in vivo techniques, novel processing algorithms for complex ex vivo MR spectra of body fluids have emerged recently. These methods, labeled "Metabonomics", access renal function by obtaining metabolic profiles that are indicative for renal dysfunction. The researchers hypothesize that these non-invasive methods correlate with histology as "gold standard" and compete favorably with conventional in part invasive evaluation methods, and thus provide specific and early detection of kidney diseases of various etiologies, drug toxicity or renal allograft dysfunction.