Functional imaging of the kidney by means of measurement of the apparent diffusion coefficient.
OBJECTIVE
To determine the relationship between the apparent diffusion coefficient (ADC) and renal function.


METHODS
Twenty-three volunteers and seven pigs underwent diffusion-sensitive magnetic resonance (MR) imaging of the kidneys with a stimulated-echo acquisition mode excitation and echo-planar imaging readout under various physiologic conditions. The effect of hydration and anisotropic diffusion was studied in human subjects, and the effect of renal artery stenosis, ureteral obstruction, and diuresis was studied in the animal model.


RESULTS
The renal ADC values of dehydrated subjects were substantially increased with rehydration. Diffusion was highest in the medulla, with a pronounced radial component in the renal collecting system. In the pig model, induced renal artery stenosis resulted in immediate decrease in renal ADC; the degree of change was related to the flow deficit. The ADC also decreased with ureteral obstruction, but diuresis had no meaningful effect.


CONCLUSIONS
In vivo measurement of ADC has the potential for use as a noninvasive means to explore the functional status of the kidney.
Department of Radiology, Harvard Medical School, Boston, MA 02215.
M F
MF
Müller
P V
PV
Prasad
D
D
Bimmler
A
A
Kaiser
R R
RR
Edelman
D000328:Adult; D000818:Animals; D016880:Anisotropy; D004058:Diffusion; D004231:Diuresis; D017352:Echo-Planar Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007668:Kidney / Q000033:anatomy & histology* / Q000502:physiology; D008297:Male; D012078:Renal Artery Obstruction / Q000175:diagnosis; D013552:Swine; D014517:Ureteral Obstruction / Q000175:diagnosis