Harriet Carolina Thoeny MD, Presenter: Nothing to Disclose

Dominik Zumstein, Abstract Co-Author: Nothing to Disclose

Sonia Zoula, Abstract Co-Author: Nothing to Disclose

Frederik De Keyzer MS, Abstract Co-Author: Nothing to Disclose

Chris Boesch, Abstract Co-Author: Nothing to Disclose

Peter Vock MD, Abstract Co-Author: Nothing to Disclose

Peter Vermathen, Abstract Co-Author: Nothing to Disclose

et al, Abstract Co-Author: Nothing to Disclose

To prospectively evaluate the feasibility and reproducibility of diffusion-weighted magnetic resonance imaging (DW-MRI) for the assessment of kidney function in patients with transplanted kidneys and to correlate the results with age- and sex-matched native kidneys.

Fifteen randomly selected patients with transplanted kidneys and stable kidney function and 15 age- and sex-matched healthy volunteers underwent coronal DW-MRI (TR=2500msec,TE=71msec, slice thickness=5mm,modified sensitivity encoding (mSENSE)=2) of the entire kidneys with respiratory triggering on a 1.5T MR system. A large set of b-values (b=0-900sec/mm2) was used. Diffusion parameters were calculated in two different ways: 1) Apparent diffusion coefficient (ADC) was fitted assuming a monoexponential decay of the signal in dependence of b-values (yielding ADCtot). 2) In order to separate diffusion and micro-perfusion components, biexponential fitting was performed, yielding a diffusion coefficient (D), a “pseudo-perfusion” parameter (D*) and the perfusion fraction Fp. Cortex and medulla were analyzed separately. Seven of the 15 patients with transplanted kidneys (randomly selected) underwent a repeat study using the identical protocol to determine reproducibility.

In transplanted kidneys almost identical values were obtained in cortex and medulla for ADCtot, D, and for Fp. Only D* was significantly higher (p<0.02) in the medulla than in the cortex. In contrast, in native kidneys ADCtot, D and Fp were significantly higher in cortex than in medulla (p<0.0001, p<0.002 and p<0.01, respectively). No significant difference could be observed between D* of cortex and medulla. The reproducibility study showed a very low CVw (coefficient of variation within subjects) in cortex and medulla of less than 3.3% for ADCtot, D and Fp. The CVw for D* was greater with ~10%.

DW-MRI in patients with transplanted kidneys is feasible with highly reproducible results and is able to detect differences in diffusion-based corticomedullary differentiation as compared to native kidneys. It might therefore be able to noninvasively assess acute and chronic graft rejection after kidney transplantation.

Thoeny, H, Zumstein, D, Zoula, S, De Keyzer, F, Boesch, C, Vock, P, Vermathen, P, et al, , Diffusion-weighted Echo-Planar Magnetic Resonance Imaging of Transplanted Kidneys Using Parallel Imaging (mSENSE): A Feasibility Study.  Radiological Society of North America 2005 Scientific Assembly and Annual Meeting, November 27 - December 2, 2005 ,Chicago IL. http://archive.rsna.org/2005/4414142.html